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Marcello ROMAGNOLI

Professore Ordinario
Dipartimento di Ingegneria "Enzo Ferrari"


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Pubblicazioni

- Reflective paint and a method for its use [Brevetto]
Abelli, Michele; DE BASTIANI, Francesco; Romagnoli, Marcello
abstract

A highly reflective coating painting product, particularly suitable as a coating for integrating spheres, comprises a diffusely reflective product such as, for example, barium sulphate, and an acrylic binder or glue, Which are dispersed in a liquid vehicle, preferably constituted by a mixture of Water and alcohol. The acrylic binder or glue is a product based on acrylic polymer or copolymer the quantity of Which in the coating product is between about 1% and 15%, and preferably between 3% and 4%, by Weight, relative to the reflective product. The coating product is applied to a surface in successive layers until a thickness of at least 0.5 mm is reached.The surface coated With the product is then subjected to heating, preferably at about 100° C., for about 1 hour.


2022 - An experimental approach to evaluate drying kinetics and foam formation in inks for inkjet printing of fuel-cell layers [Articolo su rivista]
Santangelo, Paolo Emilio; Romagnoli, Marcello; Puglia, Marco
abstract

Inkjet printing is a deposition technique that has remarkably evolved over the last two decades, becoming widely employed for various applications. Notably, it has proven very promising for catalyst and ionomer layer deposition in assembling CCM (Catalyst Coated Membranes) of PEMFC (Polymer Electrolyte Membrane Fuel Cells). However, fast drying of the processed inks at the outlet often causes nozzle clogging and foam formation within the supply circuit often yields poor release: these are the main challenges in applying inkjet printing on a large scale. So, an experimental approach for the evaluation of drying kinetics and foam formation in inks typically employed in fuel-cell manufacturing is presented. It allows to evaluate ink printability, compare different inks quantitatively and assess the performance of commonly used additives. Evaluation of drying kinetics is based on releasing ink droplets onto a support, then recording mass, ambient temperature and relative humidity. Foam formation is evaluated by filling a syringe with a known amount of ink, then injecting air at a set flow rate into the sampling volume: foam may be ultimately generated and its amount can be measured. Those relatively simple approaches were applied to various inks; validation was conducted by statistical analysis and by comparison with physical relationships and datasets available in the open literature.


2022 - Graphite/epoxy composite for building Bipolar Plates [Articolo su rivista]
Spinelli, Luca; Roncaglia, Fabrizio; Biagi, Roberto; di Bona, Alessandro; Romagnoli, Marcello; Mucci, Adele
abstract


2022 - Insight into t->m transition of MW treated 3Y-PSZ ceramics by grazing incidence X-ray diffraction [Articolo su rivista]
Riva, V.; Boccaccini, D.; Cannio, M.; Maioli, M.; Valle, M.; Romagnoli, M.; Mortalo, C.; Leonelli, C.
abstract

The influence of a microwave hybrid heat treatment (MHH) on the surface and in-depth mineralogical transformation of pre-sintered 3Y-PSZ was investigated. 3Y-PSZ samples were prepared by slip casting and sintered by conventional firing (1270 °C). Then, different MHH treatments from 5 to 15 min. at 1200 °C were applied to obtain a fully stabilized 3Y-TZP. The monoclinic fraction depth profiles in the first micrometres (up to 5) of thickness were investigated by means of the grazing incident X-ray diffraction technique (GIXRD). A good sintering degree with practically nil closed porosity and grain growth was achieved after MHH of 15 min. MHH increases the tetragonal phase content both in the surface and in-depth, reducing completely the monoclinic phase shell typically found after conventional sintering. A new parabolic model is proposed for the convoluted monoclinic fraction depth profile, which through the value of its horizontal asymptote allows the determination of the monoclinic shell thickness.


2022 - Multilayer additive manufacturing of catalyst-coated membranes for polymer electrolyte membrane fuel cells by inkjet printing [Articolo su rivista]
Willert, Andreas; Tabary, Farzin Z.; Zubkova, Tatiana; Santangelo, Paolo Emilio; Romagnoli, Marcello; Baumann, Reinhard R.
abstract

Inkjet printing is a versatile, contactless and accurate material deposition technology. The present work is focused on developing innovative strategies for inkjet printing of Catalyst-Coated Membranes (CCM) by performing Additive Manufacturing (AM) applied to Polymer Electrolyte Membrane Fuel Cells (PEMFC), without resorting to intermediate substrates. Three different approaches for AM are presented and discussed: a) inkjet-printing of the membrane ionomer layer and the top catalyst layer; b) inkjet-printing of both catalyst layers onto a membrane; c) inkjet-printing of the ionomer layer as well as the catalyst layers onto the reinforcement layer of the membrane. The produced catalyst and membrane layers were characterized and proved uniform in terms of catalyst loading (0.2 – 0.4 and 0.08 mgPt cm-2 for cathode and anode, respectively), ionomer distribution and thickness homogeneity (4 μm for catalyst layers). The fully inkjet-printed CCM outperformed conventionally made assemblies in electrochemical-performance testing, even reaching 15% higher power density.


2021 - Development of Graphite-Epoxy Composites for Bipolar Plates in PEM Fuel Cells [Abstract in Atti di Convegno]
Roncaglia, Fabrizio; Spinelli, Luca; Imperato, Manuel; Biagi, Roberto; Romagnoli, Marcello; di Bona, Alessandro; Mucci, Adele
abstract

Graphite-Epoxy composites can be a good alternative to metals and metal alloys to build Bipolar Plates (BPs),1 that are important components of Proton Exchange Membrane Fuel Cells (PEMFC), mainly used in hydrogen-powered electric vehicles. We are currently working2 on the preparation of graphite-epoxy composites, suitable for manufacturing BPs meeting the technical targets for 2025.3 Among the overall properties expected for BPs, we are mainly focussing on conductivity, flexural strength and permeability and we are tuning the preparation steps, i.e. composite formulation, mixing and molding, trying to optimize these properties. We compared different resin to filler ratios, dry and wet mixing, mechanical and magnetic stirring and different temperature and pressure ranges. A two-level full factorial Design Of Experiment (DOE) approach was performed to analyze the molding parameters. We observed substantial changes in the properties of the composites, depending on the type of graphite, the mixing method, the epoxy resin to filler ratio and the molding pressure, temperature and time. The results of these studies will be presented.


2021 - FCHgo: Fuel Cells Hydrogen educational model for schools, an imaginative approach to hydrogen and fuel cell technology for young students and their teachers [Articolo su rivista]
Dumont, E; Fuchs, H U; Corni, F; Contini, A; Altiero, T; Romagnoli, M; Karwasz, G P
abstract

In this paper we will describe didactic elements in the Horizon 2020 project FCHgo. This project is directed at children and adolescents between 8 and 18 years old. Its ultimate goal is to raise awareness for renewable energy sources, in particular hydrogen as a fuel and fuel cells for electric power. As part of the project, we are developing a toolkit for teachers and pupils, based upon a narrative approach to physical science and engineering. We believe the narrative approach to be best suited for this project because it allows us to take into account the cognitive tools available to pupils at various stages of their development.


2021 - Graphite/epoxy composite for building Bipolar Plates [Abstract in Atti di Convegno]
Spinelli, L.; Roncaglia, F.; Biagi, R.; di Bona, A.; Romagnoli, M.; Mucci, A.
abstract


2021 - Graphite-epoxy composites for fuel-cell bipolar plates: Wet vs dry mixing and role of the design of experiment in the optimization of molding parameters [Articolo su rivista]
Roncaglia, Fabrizio; Romagnoli, Marcello; Incudini, Simone; Santini, Elena; Imperato, Manuel; Spinelli, Luca; di Bona, Alessandro; Biagi, Roberto; Mucci, Adele
abstract

Bipolar plates (BPs) are key components of Proton Exchange Membrane Fuel Cells mainly employed in hydrogen-powered electric vehicles. Here, a reliable and detailed experimental method to prepare graphite-epoxy composites suitable for manufacturing BPs is reported. Dry and wet mixing procedures were compared and a simple composition was optimized, with regard to electrical conductivity. The adoption of wet mixing of the components and the choice of the conductive filler were the main factors that contributed to the achievement of good electrical and mechanical properties. The addition of a small percentage of carbon black as a secondary filler was also advantageous. The effects of molding parameters (pressure, temperature, and time) on a graphite-epoxy composite of fixed-composition were modeled using a Design Of Experiments approach, which provided valuable information for future improvements. Conductivity values well above the US DOE requirements were obtained


2021 - Smart catalyst deposition by 3D printing for Polymer Electrolyte Membrane Fuel Cell manufacturing [Articolo su rivista]
Cannio, Maria; Righi, Stefania; Santangelo, Paolo Emilio; Romagnoli, Marcello; Pedicini, Rolando; Carbone, Alessandra; Gatto, Irene
abstract

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are arguably the most employed fuel-cell types in various industry sectors, as they operate at low temperature and exhibit short start-up time and high durability. PEMFC manufacturing is currently transitioning from low-volume to mass production. Within this effort, efficient catalyst deposition to produce MEA (Membrane Electrode Assembly) electrodes has become instrumental, since very expensive raw materials are involved. This work focuses on an Additive Manufacturing (AM) technique e a modified 3D printing approach e used to release catalytic inks onto PEMFC electrodes. Some catalyst-free suspensions were designed to resemble a catalytic ink and characterized to assess their printability by microextrusion. Mixtures of distilled water, ethanol and graphite were prepared and tested. Granulometric and rheometric analyses were conducted to optimize the composition towards low viscosity values and short drying time. Repeatability of the released amount and its homogeneousness onto the target surface were evaluated. The most suitable ink formulation was loaded with platinum, a perfluorosulfonic ionomer, a pore former (NH4CO3) and deposited onto Gas Diffusion Layers (GDL). Scanning Electron Microscopy (SEM) measurements were performed on the 3D-printed electrodes to characterize it. Preliminary electrochemical fuel-cell tests were carried out towards a comparison with conventional electrodes: the proposed deposition technique appears able to produce electrodes that align with state-of-the-art performance level.


2020 - Artificial neural networks test for the prediction of chemical stability of pyroclastic deposits-based AAMs and comparison with conventional mathematical approach (MLR) [Articolo su rivista]
Finocchiaro, Claudio; Barone, Germana; Mazzoleni, Paolo; Sgarlata, Caterina; Lancellotti, Isabella; Leonelli, Cristina; Romagnoli, Marcello
abstract

Abstract: The investigation on the reticulation degree of volcanic alkali-activated materials, AAMs, were experimentally determined in terms of chemico-physical properties: weight loss after leaching test in water, ionic conductivity and pH of the leachate and compressive strength. Artificial neural network (ANN) was successfully applied to predict the chemical stability of volcanic alkali-activated materials. Nine input data per each chemico-physical parameter were used to train each ANN. The training series of specific volcanic precursors were tested also for the other one. Excellent correlations between experimental and calculated data of the same precursor type were found reaching values around one. The evidence of strong effect on chemical stability of the alkaline activator SiO2/Na2O molar ratio as well as the Si/Al ratio of precursor mixtures on the reticulation degree of ghiara-based formulation with respect to volcanic ash-based materials is presented. It must be noted that such effect was much less pronounced on the compressive strength values, appearing more insensitive the molar ratio of the alkaline activator. The comparison of the ANN results with more conventional multiple linear regression (MLR) testifies the higher prediction performance of the first method. MLRs results, less significant, are useful to confirm the powerful capacity of ANNs to identify the more suitable formulation using a set of experimental AAMs. This study, as few others, on the correlation between chemical stability and compressive strength of AAMs provide a great contribution in the direction of durability and in-life mechanical performance of these class of materials. Graphic abstract: [Figure not available: see fulltext.].


2020 - Experimental Validation of a 3D-CFD Model of a PEM Fuel Cell [Relazione in Atti di Convegno]
Riccardi, M.; D'Adamo, A.; Vaini, A.; Romagnoli, M.; Borghi, M.; Fontanesi, S.
abstract

The growing energy demand is inevitably accompanied by a strong increase in greenhouse gas emissions, primarily carbon dioxide. The adoption of new energy vectors is therefore seen as the most promising countermeasure. In this context, hydrogen is an extremely interesting energy carrier, since it can be used as a fuel in both conventional energy systems (internal combustion engines, turbines) and in Fuel Cells (FC). In particular, PEM (Polymeric Electrolyte Membrane) FC are given growing attention in the transportation sector as a Life-Cycle viable solution to sustainable mobility. The use of 3D CFD analysis of for the development of efficient FC architectures is extremely interesting since it can provide a fast development tool for design exploration and optimization. The designer can therefore take advantage of a robust and accurate modelling in order to define and develop fuel cell systems in a more time-efficient and cost-efficient way, to optimize their performance and to lower their production costs. So far, studies available in the scientific literature lack of quantitative validation of the CFD simulations of complete PEM fuel cells against experimental evidence. The proposed study presents a quantitative validation of a multi-physics model of a Clearpak PEM cell. The chemistry and physics implemented in the methodology allow the authors to obtain both thermal and electrical results, characterizing the performance of each component of the PEM. The results obtained, compared with the experimental polarization curve, show that the model is not only numerically stable and robust in terms of boundary conditions, but also capable to accurately characterize the performance of the PEM cell over almost its entire polarization range.


2020 - Manufacturing of BaCe0.65Zr0.20Y0.15O3-δ-Ce0.85Gd0.15O2-δ structures by micro-extrusion 3D-printing [Articolo su rivista]
Cannio, M.; Mortalo, C.; Prestianni, M.; Andreola, F.; Deambrosis, S. M.; Miorin, E.; Zin, V.; Boccaccini, D. N.; Romagnoli, M.
abstract

BaCe0.65Zr0.20Y0.15O3-δ-Ce0.85Gd0.15O2-δ (BCZ20Y15-GDC15) is currently one of the most studied composites for applications as dense ceramic membranes for H2 purification and membrane reactors. However, the efficiency of the structure represents a crucial issue to be solved for its practical uses. In this work the optimization of suitable slurries for the manufacturing of green asymmetric BCZ20Y15-GDC15 structures by μ-extrusion 3D-printing was investigated. The effect of the composition and rheological behavior on the stability and printability of the slurries was evaluated. Then, optimized slurries with different solid content were printed by a home-made μ-extrusion 3D printer through a step by step process: smooth and defect-free as-printed asymmetric structures with planar architecture were obtained.


2020 - Numerical Simulation of a High Current Density PEM Fuel Cell [Relazione in Atti di Convegno]
D'Adamo, A.; Riccardi, M.; Locci, C.; Romagnoli, M.; Fontanesi, S.
abstract

The ever-increasing quest for sustainable mobility is pushing the automotive sector towards electric-based technologies, allowing the reduction of localized emission sources in highly populated urban areas. Among the many possible solutions, Proton Exchange Membrane Fuel Cells (PEMFC) have the potential to de-carbonise the automotive sector without the range anxiety of present and future batteries. The interaction between physical and chemical processes in PEMFC is crucial to their maximum attainable efficiency, albeit the complexity of such interplay still limits a complete understanding of the governing processes. In this paper a canonical PEMFC from literature is simulated using 3D-CFD, and results are compared against experiments. A Eulerian multi-phase/multi-physics non-isothermal framework is used to account for both fluid (gas channels, porous gas diffusion layers) and solid (bi-polar plates, membrane), as well as for electrochemical and sorption reactions. The model is also able to account for the heat balance and for the liquid water formation at cathode catalyst layer, as well as to predict the water transport and the membrane hydration state fundamental for high-efficiency operation. Simulations are compared with measurements and polarization curves are analysed for two membrane thicknesses and rib/channel spacing. The study presents the investigation possibilities given by 3D-CFD in the field of PEMFC and how this can be used to design high efficiency fuel cells. The presented numeric analysis shows how the virtual design of high-efficiency PEMFC for the automotive sector can be guided by simulations amongst multiple degrees of freedom, thus aiding the development of innovative PEMFC.


2020 - Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae [Articolo su rivista]
Boschetti, Cristina; Leonelli, Cristina; Rosa, Roberto; Romagnoli, Marcello; Valero Tévar, Miguel Ángel; Schibille, Nadine
abstract

Calcium antimonate (in the hexagonal or cubic form) dispersed in the glass matrix is an artificially synthesized phase commonly documented as opacifier for white glasses during the Roman period. Glasses of this type occasionally contain variable amounts of lead oxide. There is no consensus about the origin and role of the lead component in white glasses, whether it was functional to modify the workability of the glass and/or to help the precipitation of the particles, or whether it was an unintentional pollutant introduced with the raw materials. A group of lead and lead-free white mosaic tesserae from the fourth-century CE villa of Noheda in Spain were analyzed by differential scanning calorimetry (DSC) and high temperature X-ray diffraction (HTXRD) to evaluate the impact of variable amounts of lead oxide in the precipitation of calcium antimonate on the viscosity of the glass. The analyzed glasses show thermal events that have been related to the composition of the glass via multicomponent linear regression model. CaSb2O6 and Ca2Sb2O7 formed in the glass during the cooling phase and the glass was not reheated. Lead oxide influences the thermal behavior of the glass, lowering the onset temperatures of all the events, implying a more cost-effective production process. We propose that lead was added intentionally or that lead-bearing raw materials were selected specifically by the ancient glass artisans


2019 - EFFECT OF COMPRESSION MOLDING PARAMETERS ON GRAPHITE/EPOXY COMPOSITE BIPOLAR PLATES [Poster]
Roncaglia, Fabrizio; DI BONA, Alessandro; Imperato, Manuel; Biagi, Roberto; Romagnoli, Marcello; Mucci, Adele
abstract


2019 - INVESTIGATION OF MOLDING PARAMETERS ON GRAPHITE/EPOXY COMPOSITE-BASED BIPOLAR PLATES [Relazione in Atti di Convegno]
Roncaglia, F.; Di Bona, A.; Biagi, R.; Romagnoli, M.; Degrandis, D.; Mucci, A.
abstract

In order to obtain a material suitable for manufacturing bipolar plates for PEM Fuel Cells the effect of molding parameters (pressure, temperature and time), relative to a graphite/epoxy composite of fixed composition, were studied and modeled by means of a two-level full factorial Design Of Experiment approach. In-plane conductivity and mechanical strength were the dependent variables.


2019 - MAMA-MEA, Mass Manufacture of MEAs Using High Speed Deposition Processes [Relazione in Atti di Convegno]
Romagnoli, Marcello; Santangelo, Paolo Emilio
abstract

The scope of MAMA-MEA is to develop an innovative additive-layer deposition process that integrates all the main CCM (Catalyst Coated Membrane) components within a single, continuous roll-to-roll production line. This project is focused on PEMFC Polymer Electrolyte Membrane Fuel Cell) industry. Its mission is to foster an increase of the manufacturing rate up to 10 times faster than that currently achieved by state-ofthe-art processes. The current manufacturing methods will not be able to meet CCM demand over the next 10 years, therefore, new strategies needs be sought, explored and translated into high volume production lines to augment the capacity and follow the expected trend. The whole effort also has the potential to improve material utilisation and manufacturing costs. Preliminary one-off prototypes have already established the feasibility of the proposed approach and patent applications have been filed. The engineering design of an ALM sealed CCM production line will be provided.


2019 - Review of catalyst-deposition techniques for PEMFC electrodes [Articolo su rivista]
Santangelo, Paolo Emilio; Cannio, Maria; Romagnoli, Marcello
abstract

Catalyst deposition has been a significant part of fuel-cell manufacturing since their entry into mass-production industry, especially to limit the inevitable use of critical raw materials. This review focuses on a variety of techniques that may be applied towards a controlled deposition onto PEMFC substrates. The current manufacturing process consists of depositing inks onto decal-transfer carrier films, then bound to the membrane by heat and pressure. Among the conventional methods for ink deposition, gravure printing and screen printing appear the most promising. The former consists of engraving the desired image areas into the surface of a cylinder; the ink lies ultimately within engraved cells and is transferred from those cells to the substrate. In screen printing, the ink is forced through a fine fabric screen and flows through the open meshes, according to the desired pattern. Additive layer manufacturing and inkjet printing are also considered as prominent alternatives, thanks to their higher ink-deposition control onto the substrate, mainly through the drop-on-demand approach. The need for achieving higher flexibility and quality in MEA production seems to favor inkjet printing and additive layer manufacturing, able to lead to a significantly higher catalyst-layer homogeneousness. However, they require assessment of ink rheological properties and formulation.


2019 - Smart catalyst deposition by 3D printing for low temperature fuel cells [Abstract in Atti di Convegno]
Cannio, Maria; Santangelo, Paolo Emilio; Romagnoli, Marcello; Pedicini, Rolando; Gatto, Irene
abstract

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are arguably the most robust and integrated into various industry sectors among fuel cells, as they operate at low temperature and exhibit short start-up time. Currently, PEMFC manufacturing is transitioning from low-volume to mass production. However, the major hindrance against their massive use consists of high materials costs, low power density and relatively short lifetime. Notably, the need for employing platinum as a catalyst promotes exploring more convenient and effective manufacturing routes. The present work focuses on applying a microextrusion-based 3D printing system to deposit catalyst layers onto the Membrane-Electrode Assembly (MEA). A commercial 3D printer was modified to support the MEA substrate; furthermore, a peristaltic pump was inserted to supply the microextrusion printhead with the catalyst-endowed ink, finally released by a syringe. The main objectives of this work were to provide optimized compositions of catalyst inks suitable for MEA and (Gas Diffusion Layer) GDL preparation, and to assess the effectiveness of the microextrusion-based 3D printing technique in yielding homogeneous coatings. The ink was a mixture of distilled water, ethanol and graphite. Granulometric and rheometric analyses were carried out to characterize inks in a quest for low viscosity and short drying time. Repeatability of released flow rate and ink homogeneity onto the GDL target surface were also evaluated by statistical analysis. The final assessment of the coated substrates was performed by measuring the characteristic polarization curve. The results suggest that microextrusion-based 3D printing can be considered as a promising technology for fuel-cell manufacturing.


2018 - Milling of peat-wood fly ash: Effect on water demand of mortar and rheology of cement paste [Articolo su rivista]
Rissanen, J.; Ohenoja, K.; Kinnunen, P.; Romagnoli, M.; Illikainen, M.
abstract

The milling of fluidized bed combustion fly ashes is a promising method to improve ashes’ properties as a cement replacement material. Two fly ashes from the co-combustion of peat and wood, as well as inert sand were milled at varying times. The physical properties of materials, water demand of mortar and rheology of cement paste were studied. At 25% cement replacement rate, the milling decreased the water demand of mortar by 10% and the yield stress of cement paste by 33%. It was found that milling disintegrated irregularly shaped particles, which were the main reason for high water demand of ashes, and tapped density could be used as a simple parameter to estimate the water demand for all studied materials.


2018 - Review of catalyst-deposition techniques for PEMFC electrodes [Relazione in Atti di Convegno]
Santangelo, Paolo Emilio; Cannio, Maria; Romagnoli, Marcello
abstract

Catalyst deposition has been a significant part of fuel-cell manufacturing since their entry into mass-production industry, especially to limit the inevitable use of critical raw materials. This review focuses on a variety of techniques that may be applied towards a controlled deposition onto PEMFC substrates. The current manufacturing process consists of depositing inks onto decal-transfer carrier films, then bound to the membrane by heat and pressure. Among the conventional methods for ink deposition, gravure printing and screen printing appear the most promising. The former consists of engraving the desired image areas into the surface of a cylinder; the ink lies ultimately within engraved cells and is transferred from those cells to the substrate. In screen printing, the ink is forced through a fine fabric screen and flows through the open meshes, according to the desired pattern. Additive layer manufacturing and inkjet printing are also considered as prominent alternatives, thanks to their higher ink-deposition control onto the substrate, mainly through the drop-on-demand approach. The need for achieving higher flexibility and quality in MEA production seems to favor inkjet printing and additive layer manufacturing, able to lead to a significantly higher catalyst-layer homogeneousness. However, they require assessment of ink rheological properties and formulation.


2016 - Characterization of natural clays from italian deposits with focus on elemental composition and exchange estimated by edx analysis: potential pharmaceutical and cosmetic uses [Articolo su rivista]
Iannuccelli, Valentina; Maretti, Eleonora; Sacchetti, Francesca; Romagnoli, Marcello; Bellini, Alessia; Truzzi, Eleonora; Miselli, Paola; Leo, Eliana Grazia
abstract

Purification processes performed on natural clays to select specific clay minerals are complex and expensive and can lead to over-exploitation of some deposits. The present study aimed to examine physicochemical (mineralogy, morphology, size, surface charge, chemical composition, cation exchange capacity [CEC], and pH) and hydration (swelling, wettability, water sorption, and rheological behavior) properties of three native clays from Italian deposits for potential pharmaceutical and cosmetic uses due to the presence of phyllosilicate minerals. Particular emphasis was placed on energy dispersive X-ray (EDX) microanalysis coupled with the ‘cesium method’ to assay clay elemental composition and CEC. One bentonite of volcanic origin (BNT) and two kaolins, one of hydrothermal origin (K-H) and another of lacustrine-fluvial origin (K-L), were evaluated in comparison with a commercial, purified bentonite. The CEC assay revealed the complete substitution of exchangeable cations (Na+ and Ca2+) by Cs+ in BNT samples and CEC values consistent with those of typical smectites (100.64 7.33 meq/100 g). For kaolins, partial substitution of Na+ cations occurred only in the K-L samples because of the interstratified mineral component which has small CEC values (11.13 5.46 meq/100 g for the K-H sample and 14.75 6.58 meq/100 g for the K-L sample). The degree of isomorphous substitution of Al3+ by Mg2+ affected the hydration properties of BNT in terms of swelling, water sorption, and rheology, whereas both of the poorly expandable kaolins exhibited significant water-adsorption properties. The EDX microanalysis has proved to be of considerable interest in terms of providing more information about clay properties in comparison with other commonly used methods and to identify the role played by both chemical and mineralogical composition of natural clays for their appropriate use in pharmaceutical and cosmetic fields.


2016 - Interactive powder mixture concept for the preparation of geopolymers with fine porosity [Articolo su rivista]
Gualtieri, Eva Magdalena; Cavallini, Alice; Romagnoli, Marcello
abstract

A new concept of chemical foaming is proposed for the preparation of geopolymers with fine porosity. The use of an interactive powder mixture of gas releasing agent and carrier particles, potentially combines the benefits of small point sources of gas with easy homogenization in the fresh geopolymer. This concept was exploited here for the preparation of porous flyash-based geopolymers. The interactive powder mixture was a SiC powder containing reactive submicron FeSi/FeSi2 particles. Premature foaming was avoided due to prolonged induction period and slow reaction rate of the active phase. Samples were characterized using scanning electron microscopy, mercury porosimetry, tree-point bending tests and thermal conductivity measurements. In addition, total porosity was determined using measured apparent and real densities. It was found that fine pore structure (diameter 140 ± 80 μm) not normally obtained using chemical foaming, was achieved in a reproducible manner with this approach.


2016 - Preparation of an aqueous graphitic ink for thermal drop-on-demand inkjet printing [Articolo su rivista]
Romagnoli, Marcello; Gualtieri, Eva Magdalena; Cannio, Maria; Barbieri, Francesco; Giovanardi, Roberto
abstract

A graphitic ink for thermal DOD inkjet printing was developed. Challenges to be met were related to the small size of the getting nozzle (20 μm), demanding high dispersion stability of submicron particles, as well as to the physical requirements of the printer. In addition, solvents potentially hazardous to human health were excluded a priori. These necessities led to the development of a ternary aqueous solvent system based on 2-propanol and monoethylene glycol, offering an environmental-friendly alternative to conventional graphene solvents. In addition, high flexibility in terms of physical properties (e.g. surface tension, viscosity, density) important for jetting is obtained. Size reduction and exfoliation, accomplished by wet-grinding of graphite in the presence of a surfactant, were followed by laser diffraction and XRD line broadening analyses, respectively. The separated graphitic colloids used for preparation of inks were composed of ca 30 layers of AB–stacked graphene flakes, as determined by line broadening analyses (XRD data). Jetting of an ink with a solid content of 0.3 mg/mL gave a thickness increase of ca. 25 nm/pass, as determined by FESEM. Electrical characterization evidenced the need to remove residual organic molecules to regain the electrical properties of the graphitic particles.


2016 - Solid Lipid Nanoparticle assemblies (SLNas) for an anti-TB inhalation treatment-A Design of Experiments approach to investigate the influence of pre-freezing conditions on the powder respirability [Articolo su rivista]
Maretti, Eleonora; Rustichelli, Cecilia; Romagnoli, Marcello; Balducci, Anna Giulia; Buttini, Francesca; Sacchetti, Francesca; Leo, Eliana Grazia; Iannuccelli, Valentina
abstract

For direct intramacrophagic antitubercular therapy, pulmonary administration through Dry Powder Inhaler (DPI) devices is a reasonable option. For the achievement of efficacious aerosolisation, rifampicin-loaded Solid Lipid Nanoparticle assemblies (SLNas) were developed using the melt emulsifying technique followed by freeze-drying. Indeed, this drying method can cause freezing or drying stresses compromising powder respirability. It is the aim of this research to offer novel information regarding pre-freezing variables. These included type and concentration of cryoprotectants, pre-freezing temperature, and nanoparticle concentration in the suspension. In particular, the effects of such variables were observed at two main levels. First of all, on SLNas characteristics – i.e., size, polydispersity index, zeta-potential, circularity, density, and drug loading. Secondly, on powder respirability, taking into account aerodynamic diameter, emitted dose, and respirable fraction. Considering the complexity of the factors involved in a successful respirable powder, a Design of Experiments (DoE) approach was adopted as a statistical tool for evaluating the effect of pre-freezing conditions. Interestingly, the most favourable impact on powder respirability was exerted by quick-freezing combined with a certain grade of sample dilution before the pre-freezing step without the use of cryoprotectants. In such conditions, a very high SLNas respirable fraction (>50%) was achieved, along with acceptable yields in the final dry powder as well as a reduction of powder mass to be introduced into DPI capsules with benefits in terms of administered drug dose feasibility.


2016 - Stabilization and thermal conductivity of aqueous magnetite nanofluid from continuous flows hydrothermal microwave synthesis [Articolo su rivista]
Cannio, Maria; Ponzoni, Chiara; Gualtieri, Magdalena Lassinantti; Lugli, Eleonora; Leonelli, Cristina; Romagnoli, Marcello
abstract

Magnetite, Fe3O4, nanoparticles, synthesized by hydrothermal microwave assisted technique in continuous flow, are characterized by X-ray diffraction, FTIR and TEM. The suspension stabilization of the nanoparticles dispersed in aqueous media is evaluated by the zeta potential trend and particle size distribution. The effect of the pH, the addition of a phosphate based dispersant and the sonication time on the suspension stabilization are investigated in detail. Moreover, once identified the most stable nanofluid, its thermal properties are measured to evaluate its possible application as heat transfer fluid. The preliminary results indicate a significant enhancement of magnetite water based nanofluid thermal conductivity with respect to water (up to 25%) and conventional water based fluid.


2015 - Facile Zeolite Synthesis from Municipal Glass and Aluminum Solid Wastes [Articolo su rivista]
Terzano, Roberto; D'Alessandro, Caterina; Spagnuolo, Matteo; Romagnoli, Marcello; Medici, Luca
abstract

A clean and cheap procedure for the synthesis of zeolites is presented, using glass and aluminum wastes as starting materials. The products are aluminosilicate materials with a high cation exchange capacity (CEC: 259–389.5 meq/100 g) containing 25–30% of crystalline zeolites. Since the synthesized materials are free of potentially toxic elements, they could be safely used for environmental and agricultural applications. More specifically, a material containing 30% of zeolite A has been synthesized at 60°C in one week, using NaOH as mineralizing agent. About 15% of zeolite A has been obtained at room temperature in six months. When KOH was employed, 25% of edingtonite has been produced in the final material after one week at 90°C. All the materials have been characterized for crystallinity, crystal morphology, particle size, pore size, surface area, and CEC. The whole process has been designed with the aim to recycle useful waste materials and reduce at minimum energy consumption and the production of harmful greenhouse gases.


2015 - Inhaled SLM for anti-TB therapy by DPI device: process parameters affecting freeze-drying and breathability [Abstract in Atti di Convegno]
Maretti, Eleonora; Porcheddu, Eleonora; Imbuluzqueta, Edurne; Balducci, Anna Giulia; Buttini, Francesca; Sacchetti, Francesca; Romagnoli, Marcello; Leo, Eliana Grazia; Iannuccelli, Valentina
abstract

The advantages of an inhaled anti-TB therapy over parenteral or oral administration are inherent to drug delivery directly to the alveolar macrophages, in which M. tuberculosis survives, bypassing gastrointestinal barriers and hepatic metabolism, so obtaining rapid clinical response, decreased dose, dose frequency, treatment period, side-effects and drug-resistance. Moreover, since 75-80% of TB cases remain localized in the lungs, inhalation therapy could also arrest TB dissemination to other organs by maximizing drug concentration at the infected sites in the lungs, also achieving therapeutic but non toxic systemic levels of drugs. Concerning inhaled anti-TB therapy, very limited marketed, pre-clinical and clinical trials are available, although successful results of few research studies on volunteers. Recently, the scientific research has revived an interest in the administration of anti-TB drugs by inhalation especially due to the advent of multi-drug-resistance (MDR-TB) and extensively drug resistant (XDR-TB) strains. However, studies with dried powder formulations are relatively scarce although the benefits of a DPI device compared with MDI or nebulizers: no propellants, no coordination between the patient and the device, drug stability owing to its dry state which makes DPIs suitable for developing countries in warm climates, higher drug payload delivery, portability, and patient compliance. The inhalation of antibiotics alone fails in its attempt to reach alveoli owing to negative powder physical properties. Moreover, inhaled antibiotics alone showed poor uptake by alveolar macrophages (AM) in cell line studies (Hirota et al., 2009). Technological approach to obtain powder fluidization, deaggregation and flowability with proper breathability to target the most distal lung airways, and capacity to be taken up by alveolar macrophages are needed. Among the strategies aiming to make antibiotics breathable, particle engineering on drug alone (controlled crystallization, different morphology by spray-drying technique), or on drug embedded into microcarriers (liposomes, microparticles) were proposed. Microparticles could modify drug flowability acting on their density, surface features and interparticle cohesive forces, drug release and AM phagocytosis. Microparticles were found also able to activate AM innate bactericidal mechanism. Among the breathable microparticulate systems, most of the studies have focused on polymeric microparticles or liposomes, and less attention has been paid to Solid Lipid Microparticles (SLM) although their advantages in terms of stability. Based on these assumptions, biocompatible, biodegradable and eco-friendly processable SLM loaded with rifampicin, a first-line anti-TB drug, able to be taken up by AM and induce intracellular bactericidal effect were designed in a perspective of an inhaled therapy by means a DPI device for the treatment of TB infection. SLM were previously in vitro characterized showing proper aerodynamic size, drug bactericidal activity maintenance, low cytotoxicity and good capacity to be taken up by murine macrophage cell lines J774 (Maretti et al., 2014). In the present work parameters affecting interparticle forces such as sample water dilution before the freeze-drying process, quick freezing at lower temperature, and cryoprotectant use were evaluated in order to improve the powder breathability.


2015 - Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties [Articolo su rivista]
Gualtieri, Eva Magdalena; Romagnoli, Marcello; Pollastri, Simone; Gualtieri, Alessandro
abstract

Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties.


2015 - Preparation of phosphoric acid-based geopolymer foams using limestone as pore forming agent - Thermal properties by in situ XRPD and Rietveld refinements [Articolo su rivista]
Gualtieri, Eva Magdalena; Romagnoli, Marcello; Gualtieri, Alessandro
abstract

In this work, geopolymer foams were obtained by reacting metakaolin with phosphoric acid and using natural calcite/dolomite as foaming agent. Total porosity and thermal conductivity were ca. 70% and 0.083 ± 0.008 W/mK, respectively. Rietveld refinements, using both ex- and in situ XRPD data, were performed in order to elucidate the phase stability of the formed binder up to 1200°C. The results showed that the amorphous matrix partially crystallized in tridymite and cristobalite type structures of AlPO4-SiO2 solid solutions at about 700°C. At 1000 °C, 3:2 mullite started to crystallize, possibly from unreacted metakaolinite, resulting in co-crystallization of SiO2 cristobalite. At the same time, the amount of tridymite-type structure decreased, possibly due to selective phase transformation of AlPO4 tridymite to cristobalite, leaving behind the SiO2 isostructure. The geopolymer paste composition allows to tailor the mullite content in the refractory foam.


2015 - PROGETTAZIONE E OTTIMIZZAZIONE DI SISTEMI MICROPARTICELLARI PER LA VEICOLAZIONE AI MACROFAGI ALVEOLARI DI FARMACI ANTITUBERCOLARI PER VIA INALATORIA [Poster]
Maretti, Eleonora; Rustichelli, Cecilia; Romagnoli, Marcello; Leo, Eliana Grazia; Iannuccelli, Valentina
abstract

La tubercolosi (TBC), causata dal Mycobacterium tuberculosis, è una patologia infettiva trasmissibile per via aerea che interessa un terzo della popolazione mondiale e rappresenta il principale fattore di mortalità per le persone colpite da HIV. E’ stata dichiarata dall'OMS “a major global health problem” con una elevata incidenza e un aumento dei casi di farmacoresistenza (MDR-TB). La strategia del piano proposto dall’OMS per ridurre l’impatto della TBC comprende lo sviluppo di strumenti nuovi ed efficaci al fine di prevenire, individuare e trattare la patologia (WHO, 2014). I limiti dall’attuale terapia di tipo convenzionale, per via orale o parenterale, risiedono nell’elevato dosaggio, nel lungo periodo di trattamento e nei numerosi effetti collaterali che possono essere evitati mediante lo sviluppo di Drug Delivey Systems innovativi in grado di modulare l’azione di farmaci già in uso. Poiché la tubercolosi polmonare è caratterizzata dal coinvolgimento dei macrofagi alveolari nei quali i bacilli rimangono vitali, la somministrazione di farmaci anti-TBC direttamente ai polmoni mediante carrier microparticellari consentirebbe il vantaggioso targeting ai macrofagi alveolari di antibiotici impossibilitati a diffondere attraverso le membrane cellulari. Ciò nonostante, non esistono, ad oggi, farmaci anti-TBC somministrabili per via inalatoria approvati per l’uso umano. Ancora meno studiati, nella progettazione di microcarrier per questa terapia, nonostante i benefici in termini di biocompatibilità, risultano i materiali naturali, quali i lipidi. Tra questi, quelli in grado di generare superfici microparticellari cariche o contenenti molecole coinvolte nel processo endocitico potrebbero promuovere l’uptake macrofagico del farmaco. Al fine di ottenere una polvere biocompatibile che, una volta inalata mediante Dry Powder Inhaler (DPI), favorisca la captazione del farmaco da parte dei macrofagi alveolari, il presente studio è stato finalizzato allo sviluppo e ottimizzazione di microparticelle caratterizzate da dimensioni nell'ambito della respirabilità (0.5-5 µm) per la veicolazione di un farmaco di prima linea quale la rifampicina. A tale scopo, sono stati impiegati materiali naturali, biocompatibili e biodegradabili, quali lipidi solidi, trattati con metodologie eco-friendly, in assenza di solventi organici. Sono state, pertanto, sviluppate Solid Lipid Microparticles (SLM) di acido stearico stabilizzate con sodio taurocolato al fine di direzionare il chemioterapico ai macrofagi alveolari. Il microcarrier formulato è stato caratterizzato dal punto di vista chimico-fisico per determinarne morfologia, dimensioni, carica superficiale, densità, diametro aerodinamico, livello di caricamento e rilascio in vitro del farmaco, attività antimicrobica, frazione respirabile, citotossicità e capacità di internalizzazione su linee cellulari macrofagiche J774. Il microcarrier è risultato idoneo per proprietà aerodinamiche, citotossicità e internalizzazione da parte di macrofagi murini (Maretti, 2014). Inoltre, l’analisi di alcuni parametri coinvolti nel processo di liofilizzazione, quali temperatura di congelamento, presenza di crioprotettori e diluizione del campione, eseguita mediante uno studio statistico di Design of Experiment (DOE), ha evidenziato la loro rilevante influenza sulla frazione respirabile del prodotto finale permettendone l’ottimizzazione.


2015 - Rheology parameters of alkali-activated geopolymeric concrete binders [Capitolo/Saggio]
Leonelli, Cristina; Romagnoli, Marcello
abstract

Industrially . a material has a practical interest if a shape. however complex. can be produced quickly and at low cost. Given the characteristics of the geopolymeric fresh pastes , colloidal dispersions featuring temporary structural stability prior to the polymerization process, some forming methods are eligible as best suitable for this purpose. As already mentioned above, the scientific and technical literature is unfortunately not very rich in examples on this topic in relation to the geopolymeric systems. For such a reason, in this section we briefly describe not only the most commonly used forming methods, but also those of potential applicaiton that have only received a limited and quick reference: casting, extrusion, double-diaphragm forming, compression molding, injection molding, hand lay-up, rotational molding, shaping by 3D printer. In some cases it has been possible to trace only a brief reference about the experimentation without any additional information on the actual efficiency of the forming technique. Nevertheless, the techniques which are presented in the following are all potentially usable dependently on the characteristics of the geopolymer paste before consolidation which have to match the parameters requested by each single forming processes.


2015 - SOLID LIPID MICROPARTICLES FOR INHALED ANTI-TB THERAPY BY DPI: INFLUENCE OF THE PRODUCTION PROCESS ON DRUG STABILITY AND POWDER BREATHABILITY [Poster]
Maretti, Eleonora; Bellani, Martina; Rustichelli, Cecilia; Sacchetti, Francesca; Romagnoli, Marcello; Balducci, Anna Giulia; Buttini, Francesca; Leo, Eliana Grazia; Iannuccelli, Valentina
abstract

According to the WHO global report, tuberculosis (TB) remains one of the world’s deadliest communicable diseases. The current therapy involves three/four drug oral regimen, long-term therapy, high and frequent doses so producing several side-effects [1]. To overcome these drawbacks and improve treatment efficacy, the new strategies could involve new formulation design for old drugs. Among these, the shortest-term goal is represented by Drug Delivery Systems (DDS). In this latter context, considering that 75-80% of TB cases remain localized in the lungs, pulmonary route appears the most strategical route [2]. For an efficient drug delivery by Dry Powder Inhaler (DPI) device, several powder properties (particle microsize, irregular shape, low tap density, surface charge, weak adhesion between particles, good flowability) contribute to determining powder aerodynamic performance and, consequently, deposition onto alveolar epithelium, and phagocytosis by alveolar macrophages [3]. Based on these assumptions, Solid Lipid Microparticles (SLM), known to be biocompatible, biodegradable and physically stable were designed as the carrier for rifampicin (RIF). The present research focused on the evaluation of both RIF stability during the production phases and the role of variables relating to freeze-drying process (freezing conditions, sample dilution, cryoprotectants) affecting the powder aerosolization. Considering the complexity of the factors involved in a successful breathable powder, a statistical Design of Experiments (DOE) was adopted to study the critical variables that influence the final product. SLM were obtained by the melt emulsification technique under sonication by using stearic acid and sodium taurocholate as lipid and surfactant, respectively [4]. Loaded SLM were prepared by adding RIF in the melted lipid. All the emulsions were rapidly cooled to room temperature providing SLM that were purified by dialysis and freeze-dried. Freeze-drying was carried out following dilution with water, mixture with cryoprotectant (trehalose or mannitol), and lowering temperature of freezing. SLM exhibited an irregular shape and the following value ranges: size (470 - 1700 nm), PDI (0.32 – 0.94), circularity (0.43 – 0.66), bulk density (0.02 – 0.24 g/cm3), tapped density (0.04 – 0.31 g/cm3) and drug loading level (11.85 – 15.88%). The Emitted Dose and the Fine Particle Mass were between 92.1-103.4% and 0.9-6.83 mg, respectively. DOE approach highlighted the combination of the water dilution before freezing with the cryoprotectant use as the most important parameter to obtain a highly breathable powder as well as the influence of water dilution and freezing temperature on SLM breathability. For a powder to be inhaled by a DPI device, many parameters can guarantee quality and efficacy of the product. The analysis performed demonstrated RIF stability and proved to be efficient in distinguishing the major contribution factors on the final product and identifying the key factors that are helpful for the improvement of SLM production process.


2015 - Solid Lipid Microparticles for inhaled anti-TB therapy by DPI: influence of the production process on drug stability and powder breathability [Abstract in Atti di Convegno]
Maretti, Eleonora; Sacchetti, Francesca; Romagnoli, Marcello; Balducci, Anna Giulia; Buttini, Francesca; Leo, Eliana Grazia; Iannuccelli, Valentina
abstract

According to the WHO global report 2014, tuberculosis (TB) remains one of the world’s deadliest communicable diseases, despite implementation of highly standard treatment regimen that has caused the number of cases began to decline from 1992. The current therapy following WHO guidelines involves three/four drug oral regimen (first-line drugs), long-term therapy (6/7 months), high and frequent doses so producing several side-effects, in particular hepatotoxicity (WHO, 2014). The long therapy, responsible for patient’s non-compliance that is the most common reason for treatment failure, is connected to Mycobacterium tuberculosis (Mtb) nature. Unlike most microbes, Mtb survives in AM phagosomes, has a slow growing and metabolism besides death, so that the drugs have to be taken for a long period. To overcome these drawbacks and improve treatment efficacy, the new strategies could involve vaccination (limited success), new drug development (no new drugs in the last 30 year) and new formulation design for old drugs. Among these, the shortest-term goal is represented by new technological approaches or Drug Delivery Systems (DDS). In this latter context, considering that 75-80% of TB cases remain localized in the lungs, pulmonary route appears the most logical route to reach promptly the primary infected site providing to reduced dose and dose frequency, treatment duration, TB dissemination in other organs risk of drug-resistant mutants and toxicity as well as improving patient’s compliance (Pham D-D., 2015). Among the portable inhalation devices, Dry Powder Inhaler (DPI) appears more advantageous than Metered Dose Inhaler (MDI), considering low water solubility of most anti-TB drugs, propellant absence and drug stability in its dry state (Hoppentocht, 2014). For an efficient drug delivery by DPI, several powder properties (particle microsize, irregular shape reducing particle contact area so favoring powder deaggragation, low tapped density, surface charge, weak adhesion between particles, good flowability) contribute to determining powder aerodynamic performance and, consequently, dose emission and dispersion, deposition onto alveolar epithelium, and phagocytosis by alveolar macrophages (Claus, 2014). Based on these assumptions, Solid Lipid Microparticles (SLM), constituted by a solid lipid core stabilized by a surfactant on their surface, are known to be biocompatible, biodegradable, physically stable, and obtainable by using low cost materials and eco-friendly processes without organic solvents. More, SLM are suitable to incorporate firmly high lipophilic drug loading levels, and they are not hygroscopic avoiding so powder flowability compromising. In a previous study, SLM loaded with rifampicin (RIF), a first-line anti-TB drug, were designed in a perspective of an inhaled therapy by means a DPI device and found capable of preserving drug antimicrobial activity and being taken up by murine macrophages cell lines (Maretti, 2014). The present research focused on the evaluation of both RIF stability during the production phases and the role of variables relating to freeze-drying process (freezing conditions, sample dilution, cryoprotectants) affecting the powder aerosolization. The freezing method can gave a significant effect on the ice structure affecting both water-vapor flow during the primary drying and the ice crystal size, so influencing the dry final product. Considering the complexity of the factors involved in a successful breathable powder, a statistical Design of Experiments (DOE) was adopted to study the critical variables that influence the final product.


2014 - Facile synthesis of B-type carbonated nanoapatite with tailored microstructure [Articolo su rivista]
Gualtieri, M. L.; Romagnoli, M.; Hanuskova, M.; Fabbri, E.; Gualtieri, A. F.
abstract

Nanolime and a phosphate-based chelating agent were used to synthesize B-type carbonated apatite. Developed Rietveld refinement strategies allowed one to determine process yield, product crystallinity as well as structural (unit cell) and microstructural (size, strain) parameters. The effect of synthesis temperature (20-60 °C) as well as Ca/P ratio (1.5-2.5) and solid content (10-30 wt%) of the starting batch on these properties were investigated. FTIR, TEM and gas adsorption data provided supporting evidence. The process yield was 42-60 wt% and found to be governed by the Ca/P ratio. The purified products had high specific surface area (107-186 m2/g) and crystallinity (76-97%). The unit cell parameters, correlated to the degree of structural carbonate, were sensitive to the Ca/P ratio. Instead, temperature governed the microstructural parameters. Less strained and larger crystals were obtained at higher temperatures. Long-term aging up to 6 months at 20 °C compensated for higher crystal growth kinetics at higher temperature. © 2014 Elsevier Inc.


2014 - In vivo penetration of bare and lipid-coated silica nanoparticles across the human stratum corneum [Articolo su rivista]
Iannuccelli, Valentina; Bertelli, Davide; Romagnoli, Marcello; S., Scalia; Maretti, Eleonora; Sacchetti, Francesca; Leo, Eliana Grazia
abstract

Skin penetration of silica nanoparticles (NP) currently used in pharmaceutical and cosmetic products is a topic of interest not only to evaluate their possible toxicity, but also to understand their behaviour upon contact with the skin and to exploit their potential positive effects in drug or cosmetic delivery field. Therefore, the present work aimed to elucidate the in vivo mechanism by which amorphous hydrophilic silica NP enter human stratum corneum (SC) through the evaluation of the role played by the nanoparticle surface polarity and the human hair follicle density. Two silica samples, bare hydrophilic silica (B-silica, 162 ± 51 nm in size) and hydrophobic lipid-coated silica (LC-silica, 363 ± 74 nm in size) were applied on both the volar and dorsal side of volunteer forearms. Twelve repetitive stripped tapes were removed from the human skin and evaluated for elemental composition by Energy Dispersive X-ray (EDX) analysis and for silicon content by Inductively Coupled Plasma quadrupole Mass Spectrometry (ICP-MS). All the stripped tapes revealed nanosized structures generally located in the broad spaces between corneocytes and characterized by the same elemental composition (relative weight percentage of silicon and silicon to oxygen weight ratio) than that of the applied samples. However, only about 10% B-silica permeated until the deepest SC layers considered in the study indicating a silica retention in the upper layers of SC, regardless of the hair follicle density. Otherwise, the exposure to LC-silica led to a greater silica skin penetration extent into the deeper SC layers (about 42% and 18% silica following volar and dorsal forearm application, respectively) indicating that the NP surface polarity played a predominant role on that of their size in determining the route and the extent of penetration.


2014 - Lipid-based microparticles for TB inhaled therapy: physical properties and cell internalization [Abstract in Atti di Convegno]
Maretti, Eleonora; Rossi, Tiziana; Leo, Eliana Grazia; Montanari, Monica; Romagnoli, Marcello; Sacchetti, Francesca; Iannuccelli, Valentina
abstract

Tuberculosis (TB) disease is caused by Mycobacterium tuberculosis that survives and replicates within human alveolar macrophages and is characterized by a long chronic stage of infection and progressive pathology mainly compromising (90% of cases) the respiratory system. Current TB therapies have exploited conventional routes of administration, such as oral or intramuscular, based on high and frequent dosages to maintain the drug therapeutic concentration in infection site because of poor drug permeability, poor drug bioavailability and pre-systemic clearance. An alternative acceptable therapy to systemic treatments involves inhalation route delivering the drug directly to the desired site, enabling a rapid onset of the action and avoiding the long period of the current treatment and the first-pass metabolism, as well as the use of high doses of drug resulting in drug resistance onset and in severe side effects on other organs. Inhaled TB therapy can presuppose the development of micro- or nanoparticles acting as drug carriers toward the alveolar region in the deepest lung so inducing the endocytosis process of alveolar macrophages being many antimicrobials difficult to cross cell membranes (1-3). Lipid-based particulate systems have been poorly investigated for TB inhaled therapy (4) though they were generally recognized as safe, poor liable to swell upon contact with the moisture located into the lungs and, consequently, to release the drug before the target site. Among the lipid-based particulate systems, Solid Lipid Microparticles (SLM), constituted by a solid lipid core stabilized by a surfactant at the surface, exhibit several favourable properties as production without organic solvents and long-term stability. In the present study, SLM loaded with rifampicin, a first-line anti-TB drug, were developed by the melt emulsification technique and evaluated in a perspective of an inhaled therapy for the treatment of TB infection. The lipid-based microparticles designed as rifampicin carrier showed features proper to be delivered from a DPI device, to deposit onto alveolar epithelium and to be internalized by macrophages in which Mycobacterium tuberculosis resides.


2014 - New Methods for the Assessment of Thermal Shock Resistance in Refractory Materials [Voce in Dizionario o Enciclopedia]
Cannio, Maria; Boccaccini, Dino Norberto; Romagnoli, Marcello
abstract


2014 - Rheological characterization of fly ash-based suspensions [Articolo su rivista]
Romagnoli, Marcello; Sassatelli, Paolo; Gualtieri, Eva Magdalena; G., Tari
abstract

The importance of flow properties in most handling techniques requires specific characterizations of geopolymer rheology in the fresh state. In this work, a Design of Experiment (DOE) approach was used to evaluate the influence of solid load, temperature and dispersant on apparent viscosity and yield stress of fly ash-based geopolymers. The solid load was found to be the most influential variable on viscosity. An increase in solid load led to an increase in apparent viscosity but also of yield stress. Apparent viscosity was found to have an Arrhenius type relationship with temperature. The influence of dispersant on yield stress and viscosity appeared to be minor.


2013 - Anisotropy of green stoneware evaluated by ultrasound measurements in combination with texture analyses [Articolo su rivista]
Romagnoli, Marcello; Gualtieri, Eva Magdalena; Gualtieri, Alessandro; Reimondas, Šliteris; Rymantas, Kažys; Giuliano, Tari
abstract

Anisotropic microstructure of uniaxially pressed powders has been reported in the literature, and is often reflected in direction-dependent physical properties such as thermal conductivity and firing shrinkage. Quantification of direction-dependency could be an important tool to predict such physical variations. For the first time, an ultrasound technique in combination with a microstructural investigation were applied to access anisotropy in green uniaxially pressed stoneware tiles. The longitudinal ultrasound wave velocity was measured parallel and perpendicular to the pressing direction. The sample microstructure was investigated by scanning electron microscopy, porosimetry and X-ray powder diffraction analyses in combination with crystallographic texture analyses using the Rietveld method. It was found that the anisotropic character, quantified as the ratio between the velocities measured perpendicular and parallel to the pressing direction, increased with increasing compact density. Based on the microstructure analyses, these results were attributed to texture of the porous structure as well as the constituting minerals.


2013 - Effect of drying method on the specific surface area of hydrated lime: A statistical approach [Articolo su rivista]
Romagnoli, Marcello; Gualtieri, Eva Magdalena; Hanuskova, Miriam; Rattazzi, Andrea; Polidoro, Costantino
abstract

Lime putty is a traditional binder, experiencing a new advent in the preservation of historical buildings. Recently it was shown that lime putty microstructure evolves with ageing time, generally resulting in a continuous quality improvement, but possibly also passing a minima/maxima. Hence, periodical quality checks during ageing are needed to optimize quality and avoid excessive storage. The specific surface area (SSA) of lime putty is a potentially valuable parameter for quality control as it influences the workability and setting of lime mortars. Gas adsorption and the Brunauer–Emmet–Teller (BET) theory is a popular method for its determination, requiring a dry powder. Generally, freeze-drying is used for powder preparation as this method is assumed to diminish particle aggregation. However, no systematic investigation of the effect of powder preparation method on BET SSA has previously been reported. In addition, reproducibility evaluations of such methods are also lacking. This work was aimed to fulfil these gaps, using both calcitic and dolomitic lime putties. Freeze-drying was compared to heat-induced drying (105 °C) under air as well as at low pressure. In addition, sample microstructure was evaluated using X-ray Powder Diffraction data and Rietveld refinements as well as Electron Microscopy techniques (SEM, TEM). It was statistically proven that freeze-drying, compared to the other dehydration methods, resulted in a 20–35% higher BET SSA for calcitic lime putties consisting mainly of nanoparticles. Instead, BET SSA of a dolomitic lime putty containing micrometre-sized hexagonal platelet crystals was not influenced by drying method. No statistically significant difference in phase composition was found between the samples dried by the different methods, excluding carbonation of the hydroxides as influencing factor. Finally, high reproducibility of BET specific surface area was obtained regardless of drying method which is an important characteristic of a standard test method for quality control.


2013 - In vivo detection of lipid-based nano- and microparticles in the outermost human stratum corneum by EDX analysis [Articolo su rivista]
Iannuccelli, Valentina; Coppi, Gilberto; Romagnoli, Marcello; Sergi, Santo; Leo, Eliana Grazia
abstract

Lipid-based particulate delivery systems have been extensively investigated in the last decade for both pharmaceutical and cosmetic skin application although their translocation across the skin is not yet clarified. The aim of this paper was to investigate on humans the ability of Solid Lipid Nanoparticles (SLN) and Solid Lipid Microparticles (SLM) to penetrate the outermost stratum corneum (SC) and to be modified upon contact with the cutaneous components by using the Tape Stripping Test coupled with the Energy Dispersive X-ray (EDX) analysis. SLN and SLM were prepared by the melt emulsification technique and loaded with nanosized titanium dioxide (TiO2) to become identifiable by means of X-ray emission. Following human skin application, the translocation of the particulate systems was monitored by the analysis of twelve repetitive stripped tapes using non-encapsulated metal dioxide as the control. Intact SLN as well as non-encapsulated TiO2 were recorded along the largest SC openings until the 12th stripped tape suggesting the intercluster region as their main pathway. Evidences of a concurrent biodegradation process of the lipid matrix, as the result of SLN interaction with the lipid packing between the corneocyte clusters, were found in the deepest SC layers considered. On the contrary, SLM were retained on the skin surface without undergoing biodegradation so preventing the leaching and the subsequent SC translocation of the loaded TiO2.


2013 - In vivo silica nanoparticle translocation across human stratum corneum: the effect of surface hydrophobization in relation to hair follicle density. [Abstract in Atti di Convegno]
Iannuccelli, Valentina; Bertelli, Davide; Romagnoli, Marcello; Maretti, Eleonora; Sacchetti, Francesca; Leo, Eliana Grazia
abstract

Insoluble nano- and submicron-scale metal dioxides are widely used in pharmaceutical and cosmetic formulations designed for being applied on the skin surface and acting mainly as thickeners, sunscreens and pigments. Since it’s primarily for the insoluble nanoparticles that health concerns related to possible skin uptake arise, the EU requires producers to submit a detailed safety report on the nanomaterials used as well as declaring their presence on the label. As noted in the 2007 FDA Nanotechnology Task Force report, there may be a higher degree of uncertainty associated with nanoscale materials compared to conventional chemicals, both with respect to knowledge about them and the way that testing is performed. Indeed, the issue of insoluble nanoparticle skin penetration, mainly focusing on nanosized TiO2 and ZnO, is still controversial, divided between a penetration limited to the hair follicles and the translocation across the lipid pathway within SC cells sometimes reaching living skin cells. Among the metal dioxide materials, colloidal silicon dioxide, a submicroscopic amorphous hydrophilic silica is one of the most used in terms of commercial production amounts together with TiO2, ZnO and silver nanoparticles. With regard to topical formulations, it is used to stabilize emulsions and as a thixotropic thickening or suspending agent in gels, microemulsions, and semisolid preparations. Although amorphous silica is generally regarded as an essentially nontoxic and non-irritant excipient [1] also proposed for implants, the nano-scale feature might alter the bioavailability of the cosmetic formulation [2]. Actually, silica nanoparticles have been shown in vitro to modulate the diffusion through animal skin of hydrophilic and hydrophobic model drugs (caffeine, retinol, quercetin) from topical emulsions to affect skin properties and also to penetrate up to the viable epidermis and upper dermis of excised porcine skin [3, 4]. Previously, we demonstrated on human beings that colloidal silica is able to penetrate in the upper region of the human stratum corneum (SC) and different mechanisms of translocation were hypothesized [4]. A similar finding arose from a research on ultra-fine TiO2 [5]. Therefore, the goal of the present work was to investigate in vivo the mechanism of silica entry into SC by means of qualitative and quantitative assays performed on stripped tapes removed from volunteers treated with silica incorporated in a standard cream. With this objective, the study took into account the influence of human hair follicle density by means of sample application on both volar and dorsal forearm. Moreover, by considering that skin surface is hydrophobic and skin penetration requires particle wetting by the SC lipids, the effect of silica surface hydrophobization was also investigated. Twelve repetitive tape strips removed from each forearm of the volunteers following sample application were evaluated by EDX analysis by points. All the tapes removed from the skin that has received silica and H-silica application showed nanosized and nearly spherical structures generally located in rather broad intercellular spaces. Their EDX spectra exhibited the characteristic peaks owing to X-ray emission from Si atoms (Fig. n. 1). The relative weight percentages of the metal and the metal to oxygen weight ratio were found to be equivalent to those detected in the samples before their application. These findings could give evidence of a movement of both the nanoparticles across the outermost part of SC reaching the corneum compactum along broad channels between the corneocytes. Silicon quantitative analysis carried out on the removed tapes indicated silica accumulation in the outer part of SC corresponding to the corneum disjunctum and its significant decrease inside the deepest tapes, regardless of the sample and the hair follicle density. Nevertheless, the higher silica level detect


2012 - A lifetime prediction method based on Cumulative Flaw Length Theory [Articolo su rivista]
Boccaccini, Dino Norberto; Maioli, Marco; Cannio, Maria; I., Dlouhy; Romagnoli, Marcello; Leonelli, Cristina; A. R., Boccaccini
abstract

Ultrasonic pulse velocity testing (UPVT) was carried out to perform non-destructive quality control of refractory plates. Used in conjunction with fracture mechanics, ultrasonic velocity measurements have proved a powerful technique for detecting, positioning and sizing internal voids and cracks in the samples, originated from the manufacturing process. Two cordierite-mullite refractory compositions exhibiting different microstructure and crack propagation behaviour were characterized through their lifetime during which they were subjected to thermal shock loading. In this paper, a new statistical method is proposed which allows to estimate the lifetime when the stress state that will be applied in service (loading) and the scattering of the ultrasonic velocity data in the as-received state are known. Since this lifetime prediction method is based on a non-destructive technique, it could be implemented into a code in an automatic quality control device for continuous lifetime estimation. The correlation between crack propagation behaviour and thermal shock resistance is discussed and semi-empirical models were developed to predict the service life of refractory plates from the measured values of ultrasonic velocities on as-received samples.


2012 - Full quantitative phase analysis of hydrated lime using the Rietveld method [Articolo su rivista]
Gualtieri, Eva Magdalena; Romagnoli, Marcello; Miselli, Paola; Cannio, Maria; Gualtieri, Alessandro
abstract

Full quantitative phase analysis (FQPA) using X-ray powder diffraction and Rietveld refinements is a well-established method for the characterization of various hydraulic binders such as Portland cement and hydraulic limes. In this paper, the Rietveld method is applied to hydrated lime, a non-hydraulic traditional binder. The potential presence of an amorphous phase in this material is generally ignored. Both synchrotron radiation and a conventional X-ray source were used for data collection. The applicability of the developed control file for the Rietveld refinements was investigated using samples spiked with glass. The results were cross-checked by other independent methods such as thermal and chemical analyses. The sample microstructure was observed by transmission electron microscopy. It was found that the consistency between the different methods was satisfactory, supporting the validity of FQPA for this material. For the samples studied in this work, the amount of amorphous material was in the range 2–15 wt.%.


2012 - Rheology of geopolymer by DOE approach [Articolo su rivista]
Romagnoli, Marcello; Leonelli, Cristina; Elie, Kamse; Magdalena Lassinantti, Gualtieri
abstract

The effects of solid/liquid content, temperature, curing time and deflocculant concentration on some fundamental rheological parameters of metakaolin-based geopolymer suspensions activated by NaOH were studied by statistical DOE approach. Solid content appears to be the most important parameter among the studied ones. As well known, it has an influence both on viscosity, shear behaviour and yield stress. Instead the additive, an industrial grade sodium polyacrilate, has demonstrated to have a poor effect on the viscosity and yield stress. In synergy with curing time, temperature showed a different effect with respect to its classic rheological influence. In countertrend, increasing the temperature resulted in an increased viscosity due to acceleration of the geopolymerisation reactions.Rheological parameters have proven to be very sensitive to chemical changes in the studied system. In combination with DOE methodology, it is a potent tool for monitoring the microstructural evolution of geopolymers during curing.


2011 - Anodic aqueous electrophoretic deposition of titanium dioxide using carboxylic acids as dispersing agents [Articolo su rivista]
Hanaor, D.; Michelazzi, Marco; Veronesi, Paolo; Leonelli, Cristina; Romagnoli, Marcello; Sorrell, C.
abstract

The dispersion of anatase phase TiO2 powder in aqueous suspensions was investigated by zeta-potential and agglomerate size analysis. The iso-electric point (IEP) of anatase was determined to be at pH 2.8 using monoprotic acids for pH adjustment. In comparison, it was found that the use of carboxylic acids, citric and oxalic, caused a decrease in zeta-potential through the adsorption of negatively charged groups to the particle surfaces. The use of these reagents was shown to enable effective anodic electrophoretic deposition (EPD) of TiO2 onto graphite substrates at low pH levels with a decreased level of bubble damage in comparison with anodic EPD from basic suspensions. The results obtained demonstrate that the IEP of TiO2 varies with the type of reagent used for pH adjustment. The low pH level of the IEP and the ability to decrease the zeta-potential through the use of carboxylic acids suggest that the anodic EPD of anatase is more readily facilitated than cathodic EPD


2011 - Geopolimeri e tecniche di formatura [Capitolo/Saggio]
Romagnoli, Marcello
abstract

Il volume riassume lo stato dell’arte sui geopolimeri: leganti idraulici e materiali ceramici di composizione prevalentemente alluminosilicatica, a bassissimo contenuto di calcio. Il testo si rivolge ai tecnologi dei materiali e ai ricercatori che operano nelle università e nei centri di ricerca. Il capitolo in particolare descrive i metodi di formatura utilizzabili per dare forma ai materiali geopolimerici. Inoltre descrive i concetti reologici di base e i comportamenti atti a ottenere una formatura ottimale. Il capitolo si conclude con una rassegna dei possibili difetti che si possono avere su manufatti geopolimerici in fase di formatura e delle cause che li originano.


2011 - Influence of body composition on the technological properties and mineralogy of stoneware: A DOE and mineralogical–microstructural study [Articolo su rivista]
Gualtieri, Eva Magdalena; Romagnoli, Marcello; Gualtieri, Alessandro
abstract

This paper reports a systematic and comprehensive investigation of the effects of the starting mixture composition on the mineralogy and propertiesof porcelain stoneware tiles using mixture design and full quantitative phase analyses by the Rietveld method. Functional relationships betweenproperties and the raw material mixture proportions were obtained and related to the mineralogical composition of the fired product. Mullitecrystallisation depended on the chemical environment. Dissolved quartz mounted to 10 wt% of the dry body regardless on initial amount, indicatingsaturation of the surrounding melt. The paramount role of the amorphous content on the stoneware properties was disclosed quantitatively. Openporosity decreased with increasing amount of amorphous content, and consequently both the stain and wear resistance increased. The CIE-Labcolour parameters a* and b* increased with increased amorphous content due to interaction with surface iron in hematite. The mullite contentincreased wear resistance, thus supporting the mullite strengthening theory.


2010 - Effect of the suspension composition on the microstructural properties of high velocity suspension flame sprayed (HVSFS) Al2O3 coatings [Articolo su rivista]
Bolelli, Giovanni; Cannillo, Valeria; R., Gadow; A., Killinger; Lusvarghi, Luca; J., Rauch; Romagnoli, Marcello
abstract

Seven different Al2O3-based suspensions were prepared by dispersing two nano-sized Al2O3 powders (having analogous size distribution and chemical composition but different surface chemistry), one micron-sized powder and their mixtures in a water+isopropanol solution. High velocity suspension flame sprayed (HVSFS) coatings were deposited using these suspensions as feedstock and adopting two different sets of spray parameters. The characteristics of the suspension, particularly its agglomeration behaviour, have a significant influence on the coating deposition mechanism and, hence, on its properties (microstructure, hardness, elastic modulus). Dense and very smooth (Ra ~ 1.3 μm) coatings, consisting of well- flattened lamellae having a homogeneous size distribution, are obtained when micron-sized (~1 -2 μm) powders with low tendency to agglomeration are employed. Spray parameters favouring the break-up of the few agglomerates present in the suspension enhance the deposition efficiency (up to >50%), as no particle or agglomerate larger than ~2.5 μm can be fully melted. Nano-sized powders, by contrast, generally form stronger agglomerates, which cannot be significantly disrupted by adjusting the spray parameters. If the chosen nanopowder forms small agglomerates (up to few microns), the deposition efficiency is satisfactory and the coating porosity is limited, although the lamellae generally have a wider size distribution, so that roughness is somewhat higher. If the nanopowder forms large agglomerates (on account of its surfacechemistry), poor deposition efficiencies and porous layers are obtained. Although suspensions containing the pure micron-sized powder produce the densest coatings, the highest deposition efficiency (~70%) is obtained by suitable mixtures of micron-and nano-sized powders, on account of synergistic effects


2010 - The pO-Index and R Ratio Gap Methods for the Assessment of Corrosion Risk in Refractory Materials in Contact with Glass Melts [Articolo su rivista]
Boccaccini, D. N.; Cannio, Maria; Romagnoli, Marcello; Veronesi, Paolo; Leonelli, Cristina; Boccaccini, ALDO ROBERTO
abstract

Corrosion of refractories used in glass melting technology is a complex phenomenon involving chemical wear (corrosion) and physical/mechanical wear (such as erosion and abrasion) processes as well as thermal shock and spalling. Besides the complexity in the hydrodynamics of a molten silicate bath with which refractory materials are in contact, refractories are polycrystalline heterogeneous materials containing a relatively high porosity. Pores are centers for accelerated corrosion, spalling, and penetration by the hot liquid. In this work, a corrosion study of aluminosilicate refractory crucibles by chromium and calcium oxides during the melting of Cr-containing soda lime glasses as a function of temperature (1400°–1500°C) and glass basicity has been performed. The features and mechanism of the corrosion process were compared and analyzed as a function of glass acidobasicity (pO-index) and of the ratio of network-dwelling cations to A13+ cations (R). The advantage of the pO-index and ΔR gap methods to assess refractory corrosion risk as a function of the acidobasicity differential between the refractory glassy phase and the glass melt was demonstrated. The change of the concentrations of glass constituents was monitored by ICP analysis of glass samples and correlated to the observed extent of corrosion. The crystalline composition and microstructure of the refractory materials before and after being corroded were studied by XRD analyses and SEM. Cr-doped corundum was found to be the main crystalline phase in the refractory microstructure and other mixed phases with chromium and aluminum and/or silica, which formed at the boundary layer (interface) between the glasses and the aluminosilicate refractory, were identified. The results provide a useful guide to the selection of refractory materials for application in glass and glass–ceramic manufacture in terms of their corrosion risk.


2009 - A Review of: “Introduction to Particle Technology, 2nd ed. [Articolo su rivista]
Romagnoli, Marcello
abstract

A Review of: “Introduction to Particle Technology, 2nd ed., Martin Rhodes, Editor


2009 - A statistical approach for the assessment of reliability in ceramic materials from ultrasonic velocity measurement: Cumulative Flaw Length Theory [Articolo su rivista]
Boccaccini, Dino Norberto; Maioli, Marco; Cannio, Maria; Romagnoli, Marcello; Veronesi, Paolo; Leonelli, Cristina; A. R., Boccaccini
abstract

A primary objective of statistical fracture approach is to predict the probability of failure of a component for an arbitrary stress state when the failure statistics are known. This study introduces the fundamentals and application of a new approach to characterize the mechanical behaviour of high temperature ceramic materials, including refractory materials, by coupling non-destructive methods, in particular ultrasonic velocity measurement, and the Batdorf statistical fracture theory. A new approach, termed Cumulative Flaw Length Theory (CFLT), has been developed for the case of macroscopically homogeneous isotropic materials containing randomly oriented microcracks uniformly distributed in a location subjected to non-uniform multiaxial stresses. A function representing the number of cracks per unit volume is estimated based on the histograms of ultrasonic velocity measurements. This function is used without additional assumptions to determine the probability of fracture under an arbitrary stress condition. Two different cordierite-mullite high temperature ceramic materials were characterized under the assumptions of this theory to provide experimental evidence to support the model.


2009 - Advantages in using Design of Experiment and Artificial Neural Networks in the study and optimisation of ceramic systems [Articolo su rivista]
Romagnoli, Marcello; Gualtieri, Eva Magdalena
abstract

Design of Experiments (ODE) and Artificial Neural Networks (ANN) are suitable for studies of complex systems. In DOE, experiments are properly distributed within the factor space in order to minimize the number of experiments required to obtain a statistically valid functional relationship between a response and factors. ANN is a computer model inspired by the neural network structure of the brain. Although these methods are based on mathematical theories, their use do not require advanced mathematical skills as efficient PCs and software tools are available. Major advantages of these experimental approaches over traditional ones, such as the onefactor-at-a-time method (OFATl, include the possibility to reveal interactions between factors and determine their setting for a desired response. Despite these advantages, their use is still limited, probably due to lack of familiarity. This report will give a short introduction to these methods and their use in traditional ceramics.


2009 - Application of a neural network approach to the electrophoretic deposition of PEEK–alumina composite coatings [Articolo su rivista]
I., Corni; Cannio, Maria; Romagnoli, Marcello; A. R., Boccaccini
abstract

Nano-size Al2O3–polyetheretherketone(PEEK) composite thick films have been prepared on stainless steel substrates from non-aqueous colloidal suspensions by electrophoretic deposition (EPD). The effects on the deposition efficiency of process parameters, such as the deposition time, the difference of potential applied and their interactions were studied using a neural network approach to develop a quantitative understanding of the system. Furthermore the use of the neural network was optimized in the number of epochs, hidden layers and artificial neurons in each hidden layer by a design of experiment (DOE) analysis, demonstrating that these two methods can work together improving the final results of the neural network approach. Afterwards, a MonteCarlo analysis based on a simulation of 100,000 virtual depositions has permitted to deeply investigate the effect of independent variables (e.g. deposition time and difference of potential applied) on the deposition yield (dependent variable).


2009 - Ceramic rheology [Monografia/Trattato scientifico]
Romagnoli, Marcello
abstract

Il corso in modalità e-learning si propone di fornire le basi teoriche e pratiche per comprendere e controllare il comportamento reologico di sospensioni ceramiche.


2009 - Corrigendum to "Densification and crystallization of Ba-exchanged zeolite A powders" [Ceram. Int. 34 (2008) 543-549] (DOI:10.1016/j.ceramint.2006.12.010) [Articolo su rivista]
Andreola, F.; Romagnoli, M.; Siligardi, C.; Manfredini, T.; Ferone, C.; Pansini, M.
abstract


2009 - Microwave-assisted consolidation of coatings obtained by electrophoretic deposition (EPD) [Abstract in Atti di Convegno]
Veronesi, P.; Leonelli, C.; Corradi, A. B.; Poli, G.; Romagnoli, M.; Giovanardi, R.; Rosa, R.; Cannio, M.; Michelazzi, M.; Rizzuti, A.; Boccaccini, A. R.
abstract

Electrophoretic deposition (EPD) is an electrochemical method attracting increasing interest as a material processing technique. In the first step of EPD an electric field is applied between two electrodes and charged particles suspended in a suitable liquid move toward the oppositely charged electrode; in the second step the particles accumulate at the deposition electrode and create a relatively compact and homogeneous film, which, however, requires a further consolidation step in order to fully develop satisfactory mechanical properties. In the present work, EPD conditions have been varied in order to control the initial porosity of the deposits of nano- and sub-micrometric zirconia powders, applying an innovative "zerointegral" approach. Microwave heating was then applied to rapidly sinter the deposited powders, trying to minimize grain growth. EPD and microwave heating allow to influence the final product properties and thus its end use like thermal barrier coating or for tribological applications.


2009 - Optimisation: Keyword in Ceramic Application [Articolo su rivista]
Romagnoli, Marcello
abstract

Optimisation is a key factor that technicians and researchers cannot neglect to improve the quality and economic efficiency of processes. When many variables play a role, approaches such as DOE (Design of Experiment) and ANN (Artificial Neural Network) are of fundamental importance to disentangle ourselves from a mass of parameters that seem to be out of control. The setting-up of models for optimisation requires numerical information regarding the process or product. An objective knowledge minimises the space for subjective aspects. Certainly, systematic optimisation approaches can be used in numerous fields. This article focuses on the optimisation of the rheological behaviour of ceramic suspensions as well as of the particle size distribution.


2008 - Assessment of viscoelastic crack bridging toughening in refractory materials [Articolo su rivista]
Boccaccini, Dino Norberto; Cannio, Maria; T. D., Volkov Husoviæ; I., Dlouhy; Romagnoli, Marcello; Veronesi, Paolo; Leonelli, Cristina
abstract

Viscoelastic bridges can be formed in refractory ceramics while cooling from high temperatures. Such bridges can shield crack tips, thus reducingthe effective crack tip stress intensity factors leading to higher resistance to creep and thermal shock. The extent to which the crack tip stress intensityis reduced can be estimated from fracture mechanics models that include experimental measurement of crack bridging and microstructuralparameters. In this paper a novel approach is proposed for the assessment of the effective crack bridging toughening from combining destructiveand non-destructive test methods. Fracture toughness values were determined applying chevron notched specimen technique and surface damage ofthe specimen was monitored by image analysis. Different cordierite–mullite compositions characterized by different microstructure morphologiesand crack propagation behaviour were investigated. A brief discussion about the correlation between thermo-mechanical properties, microstructure,crack propagation behaviour and thermal shock resistance is presented. Moreover, an empirical model able to determine the presence andeffectiveness of the viscoelastic crack bridging ligaments acting in the microstructure under thermal shock conditions and their degradation withincreasing thermal shock cycles from parameters measured at room temperature is presented.


2008 - Densification and crystallization of Ba-exchanged zeolite A powders [Articolo su rivista]
Andreola, Nora Maria; Romagnoli, Marcello; Siligardi, Cristina; Manfredini, Tiziano; C., Ferone; M., Pansini
abstract

The effect of thermal treatment, Na content and mineralizer ion on the sintering process of Ba-exchanged zeolite A on the zeolite ! celsianthermal transformation are investigated. The powder samples containing different amounts of Na+ and Li+ were pressed at 30 MPa and thermallytreated at temperatures from 1000 to 1400 8C for times up to 5 h and subsequently were characterized by room temperature X-ray diffraction and byscanning electron microscopy. Increasing the Na residual content in the Ba-zeolite A samples improves the sintering process, even if the highest Nacontent appears to inhibit the zeolite! celsian transformation, since a new crystalline phase appears at the highest temperature. Moreover, theporosity of all samples thermally treated is quite high. Finally the manufacture of pressed samples allowed lower temperatures and times to be usedto obtain the transformation zeolite Ba-A ! monoclinic celsian, which suggests it is a potential method to prepare celsian low temperaturerefractory materials. At last an ANOVA analysis was carried out to identify the independent parameters from a statistical point of view.


2008 - DOE analyses on aqueous suspensions of TiO2 nanoparticles [Articolo su rivista]
S., Baldassari; A., Bonamartini Corradi; F., Bondioli; Ferrari, Anna Maria; Romagnoli, Marcello; C., Villa
abstract

Nanosized titanium oxide (TiO2) powders have been prepared by conventional and microwave hydrothermal methods by forced hydrolysis of TiOCl2. As-prepared powders have been completely characterised by qualitative and quantitative XRD and TEM. The obtained titania powders have been redispersed (45 and 60 wt%) in an aqueous hydroxypropylcellulose (HPC) solution (0.5-1 wt%) and rheometry has been performed in order to evaluate the influence of HPC on particles agglomerations. Moreover, the effect of mixing time, HPC and TiO2 concentration and their mutual interactions on apparent viscosity have been evaluated with a Design Of Experiment (DOE) approach.


2008 - Il tape casting per la formatura dei materiali ceramici [Articolo su rivista]
Romagnoli, Marcello
abstract

Il tape casting per la formatura dei materiali ceramici


2008 - Neural network approach for color matching of ceramic glazes [Relazione in Atti di Convegno]
Romagnoli, Marcello; Bondioli, Federica; M., Barattini
abstract

Aesthetical quality of ceramic tiles is a winning and indispensable requirement in production. Pigment oxides play an important role and more and more sophisticated applications are required in industrial applications. In the present work a neural network model was tested to define the final apparence due to the mixture of ceramic pigment used for wall tiles. Samples were prepared using thirty industrial pigments and one frit for wall tiles. Mixing the pigments, seventy nine samples were prepared in a fast ball mill and applied on tiles. After firing in a industrial cycle, the L*,a* and b* coordinates in CIElab spaces of the surfaces were measured using a spectrophotometer and put in relationship with the pigment compositions to define a model able to calculate the colour when the pigment composition is known. The results show a good efficiency of the color matching algorithm.


2008 - Neural network approach for colour matching of ceramic glazes [Relazione in Atti di Convegno]
Romagnoli, M.; Bondioli, F.; Barattini, M.
abstract

Aesthetical quality of ceramic tiles is a winning and indispensable requirement in production. Pigment oxides play an important role and more and more sophisticated applications are required in industrial applications. In the present work a neural network model was tested to define the final apparence due to the mixture of ceramic pigment used for wall tiles. Samples were prepared using 30 industrial pigments and one frit for wall tiles. Mixing the pigments, 79 samples were prepared in a fast ball mill and applied on tiles. After firing in a industrial cycle, the L*,a* and b* coordinates in CIElab spaces were measured using a spectrophotometer and put in relationship with the pigment compositions to define a model able to calculate the colour when the pigment composition is known. The results show a good efficiency of the color matching algorithm.


2008 - Prediction of service life of cordierite-mullite refractory materials by non-destructive methods [Relazione in Atti di Convegno]
Boccaccini, Dino Norberto; Kamseu, Elie; Volkov Husoviæ, T. D.; Cannio, Maria; Romagnoli, Marcello; Veronesi, Paolo; Dlouhy, I.; Boccaccini, A. R.; Leonelli, Cristina
abstract

Ultrasonic pulse velocity testing was used to perform non-destructive quality control of refractory plates used as substrates in fast firing of porcelain whitewares. The measurement of the ultrasonic velocity was used to asses the presence of internal voids or cracks originated from the manufacturing procedure. Image analysis was used to predict thermal stability of the refractory materials. Two cordierite-mullite compositions were investigated that are characterized by different microstructure morphologies and crack propagation behaviour. A brief discussion about the correlation between microstructure, crack propagation behaviour and thermal shock resistance is presented. Moreover, empirical models were developed to predict the service life of refractory plates from measured values of ultrasonic velocities in plates in the as-received state.


2008 - Service life prediction for refractory materials [Articolo su rivista]
D. N., Boccaccini; M., Cannio; T. D., Volkov Husoviae; E., Kamseu; Romagnoli, Marcello; Veronesi, Paolo; Leonelli, Cristina; I., Dlouhy; A. R., Boccaccini; A., R.
abstract

Ultrasonic pulse velocity testing and image analysis were used to predict the thermal stability of cordierite–mullite refractories. Two compositions used as substrates in fast firing of porcelain whiteware, characterized by different microstructure and crack propagation behavior, were investigated. Fracture strength and fracture toughness values were obtained from three point bending test and chevron notched specimen technique, respectively. The measurement of the ultrasonic velocity was used to assess the material degradation with increasing number of thermal-shock cycles and specimen damage was monitored using image analysis to obtain further evidence of material degradation. The correlation between thermo-mechanical properties, ultrasonic velocity, microstructure, crack-propagation behavior and thermal-shock resistance was discussed. A remarkable similarity was found between the variation of ultrasonic velocity (when measured through the length of the refractory plates) and fracture strength with number of thermal shock cycles. On the other hand, the development of surface microcracking, as monitored by image analysis, is in good agreement with the variation of K IC with the number of thermal-shock cycles. The variation of the $$\frac{d\sigma_{\rm f}}{dE_{\rm dyn}}$$ ratio with number of thermal-shock cycles shows the highest gradient of the investigated trends and it is proposed as a promising parameter to differentiate refractory materials regarding their different thermal shock behavior. Service life prediction models for refractory plates, from measured values of ultrasonic velocity and surface damage analysis, were proposed and validated.


2007 - A non-destructive method to assess delamination of ceramic tiles [Articolo su rivista]
Romagnoli, Marcello; Burani, M; Tari, G; Ferreira, Jmf
abstract

Delamination is a typical defect of ceramic tiles. It originates from the presence of trapped air during pressing, and elastic recovery of the pressed material, which prevents the consolidation of the pressed material. Although delamination greatly reduces the quality of the final product, standard tests for ceramic tiles are not currently available. In this work the problem of detecting delamination of green and fired ceramic tiles is approached by using ultrasonic pulse velocity measurement, a non-destructive technique normally used to assess concrete structures and the density of ceramic tiles. It was assumed that an increase in travel time for a given thickness (i.e., decrease in travel velocity) would indicate the presence of delamination, as the sound wave has to travels around the flat pore. The problems connected with measurement uncertainty and repeatability are discussed in the paper, in particular concerning the standardisation of the measurement. (c) 2006 Elsevier Ltd. All rights reserved.


2007 - Ceramizzazione di vetri mediante tecnica D.O.E. (Design of Experiment) [Articolo su rivista]
Siligardi, Cristina; Romagnoli, Marcello
abstract

Il procedimento descritto in questo articolo è volto ad ottimizzare il processo termico adottato per la de-vetrificazione del vetro al fine di ottenere materiali vetro-ceramici. Questo studio è stato realizzato adottando la tecnica DOE, che consiste nel programmare le prove e valutare i dati sperimentali su base statistica. Tre fattori sono stati identificati in grado di caratterizzare il trattamento termico: la temperatura di nucleazione, il tempo di nucleazione e il temperatura di accrescimento. Tali variabili indipendenti sono stati messe in relazione, per mezzo di equazioni polinomiali, con variabili dipendenti quali durezza e resistenza. I campioni sono stati inoltre esaminati mediante SEM-examd e caratterizzati con diffrattometria a raggi X su polveri. La tecnica DOE ha permesso di individuare per ogni campione, il corretto trattamento termico, che è il risultato della combinazione ottimizzata dei fattori presi in considerazione, in grado di ottimizzare la durezza e la resistenza dei campioni. I modelli sono poi stati convalidati con la realizzazione di ulteriori campioni i cui valori sperimentali sono stati confrontati con quelli calcolati.


2007 - Characterization of thermal shock damage in cordierite-mullite refractory materials by non-destructive methods. [Articolo su rivista]
D. N., Boccaccini; E., Kamseu; T. D., Volkov Husovic; M., Cannio; Romagnoli, Marcello; Veronesi, Paolo; Leonelli, Cristina; I., Dlouhy; A. R., Boccaccini
abstract

Ultrasonic pulse velocity testing and image anal. were used to predict thermal stability of refractories. Two cordierite-mullite compns. used as substrates in fast firing of porcelain whiteware characterized by different microstructure morphologies and crack propagation behavior were investigated. The measurement of the ultrasonic velocity was used to assess the material degrdn. with increasing thermal shock cycles and specimen damage was monitored using image anal. and further results of material degrdn. were obtained. A brief discussion about the correlation between thermomech. properties, microstructure, crack propagation behavior and thermal shock resistance is presented. Moreover, empirical models are developed to predict thermomech. properties from ultrasonic velocity and surface damage measurements. Then, service life prediction models of refractory plates from measured values of ultrasonic velocities in plates in the as-received state are presented.


2007 - Determination of thermal shock resistance in refractory materials by ultrasonic pulse velocity measurement [Articolo su rivista]
D. N., Boccaccini; Romagnoli, Marcello; E., Kamseu; Veronesi, Paolo; Leonelli, Cristina; Pellacani, Gian Carlo
abstract

Thermal shock resistance of refractory materials is one of the most important parameters in refractory material characterization since it determines their performance in many applications. Ultrasonic pulse velocity testing was used for non-destructive quantification of thermal shock damage in refractory plates used as support for the firing of porcelain articles. When refractory materials are subjected to the industrial thermal cycles crack nucleation and propagation occurs resulting in loss of strength and material degradation. The formation of cracks decreases the velocity of ultrasonic pulses travelling in the refractory because it depends on the density and elastic properties of the material. Therefore measuring either of these properties can directly monitor the development of thermal shock damage level. Young's modulus of representative samples was calculated using measured values of ultrasonic velocities obtained by ultrasonic pulse velocity technique. Results were compared with industrial statistical data of thermal shock behaviour of the investigated materials. The capability of the ultrasonic velocity technique for simple, sensitive, and reliable non-destructive characterisation of thermal shock damage was demonstrated in this investigation. (c) 2006 Elsevier Ltd. All rights reserved.


2007 - DOE and ANN models for powder [Articolo su rivista]
S., Akkurt; Romagnoli, Marcello; M., Sutcu
abstract

Design of expts. (DOE) and artificial neural network techniques (ANN) were used to study packing of fused alumina powders composed of three different sizes of particles. Two techniques have been used for prediction of powder compact porosities in mixts. of three different-sized fused alumina powders. The first is the mixt. design technique that produces a polynomial model of the powder-packing system. The second is the ANN technique that is extensively used to model complex systems in many fields. Three sizes (3, 30, and 350 .mu.m) of fused alumina powder were mixed and uniaxially compacted in the form of cylindrical pellets to measure their packing ability in the green state. Porosities of the cylindrical pellets were generated by prepg. powder mixts. in such proportions that were planned using mixt. design, which is a DOE method. A multilayer feed-forward back-propagation learning algorithm was used as an ANN tool to predict porosity, which was the response variable. Based on the training data, an ANN model of porosity as a function of constituent mix proportions was created with low av. error levels (2.7%). The results indicated that the mixt. model and the ANN model provided good predictions for powder packing.


2007 - Gastroretentive multiple-unit delivery system in the treatment of Helicobacter pylori infection [Abstract in Atti di Convegno]
Iannuccelli, Valentina; Romagnoli, Marcello; Sergi, Santo; Coppi, Gilberto
abstract

Calcium alginate floating units loaded with tetracycline were prepared by means an interfacial crosslinking reaction of sodium alginate drops with calcium ions and freeze-drying providing porous units with apparent density values less than that of the gastric juice. Such a technological approach has simplified a previous manufacture for the development of calcium alginate air-compartment floating units which showed actual buoyancy properties and prolonged Gastric Residence Time (GRT) in human trials in fed conditions. The formulation study provided a sample with optimum property in terms of drug loading level for the treatment of Helicobacter pylori infection.


2007 - Mixture of deflocculants: A systematic approach [Articolo su rivista]
Romagnoli, Marcello; Andreola, Nora Maria
abstract

In the production of ceramic tiles, during wet grinding, chemical additives are normally used to increase the solid loading of the suspensions. Commonly, mixtures of organic and inorganic chemical additives are used to reduce viscosity and costs. In literature, only few papers consider the combined effect of two or more deflocculants and a modest knowledge has developed on possible competitive or synergic interactions among them. The most common rheological additives show different behaviour depending on the clay. With mixture design it is possible to define mathematical models by means of which it is possible to engineer the rheological behaviour of a suspension. (c) 2006 Elsevier Ltd. All rights reserved.


2007 - Optimal size distribution to obtain the densest packing: A different approach [Articolo su rivista]
Romagnoli, Marcello; Rivasi, Maria Rosa
abstract

Historically a number of models were proposed about the problem of the best size distribution for densest particle packing. In general, they show a weak point in the insufficient consideration of particle morphology that, on the contrary, it is a fundamental parameter to shape an optimal size distribution. In the present work a different approach with respect the traditional models is proposed. By means of a mixture design it was possible to define models able to predict the density in function of size distribution. The results shown the effect of particles morphology: mixtures rich in fine particles permit to obtain the densest packing. The mathematical models obtained, in the form of polynomial, fit well the experimental data. (c) 2006 Elsevier Ltd. All rights reserved.


2007 - Quality control and thermal shock damage characterization of high-temperature ceramics by ultrasonic pulse velocity testing [Articolo su rivista]
Boccaccini, Dino Norberto; Romagnoli, Marcello; Veronesi, Paolo; Cannio, Maria; Leonelli, Cristina; Pellacani, Gian Carlo; T. V., Husovic; A. R., Boccaccini
abstract

Ultrasonic pulse velocity testing was carried out to perform nondestructive quality control of refractory plates used as substrates in fast firing of porcelain whiteware. Two cordierite-mullite refractory compositions characterized by different microstructure morphologies and crack propagation behavior were investigated after a number of industrial thermal cycles. Ultrasonic velocity measurements were used to determine the presence of internal voids/cracks in the samples, originating from the manufacturing procedure. A brief discussion about the correlation between microstructure, crack propagation behavior, and thermal shock resistance is presented. Empirical models were developed to predict the service life of refractory plates from measured values of ultrasonic velocities on as-received samples.


2007 - Recycling of microwave inertised asbestos containing waste in refractory materials [Articolo su rivista]
Boccaccini, Dino Norberto; Leonelli, Cristina; Rivasi, Maria Rosa; Romagnoli, Marcello; Veronesi, Paolo; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

Asbestos is a health hazard and its removal a priority for pollution prevention. Asbestos containing wastes (ACW) can be transformed into inert silicate phases by means of microwave irradiation. The aim of this investigation was to recycle microwave inertised ACW in mullite-cordierite refractory materials. A MgO-rich talc was replaced by inertised asbestos keeping approximately equal oxide composition of the raw materials. No significant variations of water absorption, linear shrinkage and Young's modulus but a higher occurrence of cordierite phase with the change of raw material was found. This can be considered an important technological result. (c) 2006 Elsevier Ltd. All rights reserved.


2007 - RELEASE OF IONS FROM KAOLINITE DISPERSED IN DEFLOCCULANT SOLUTIONS. [Articolo su rivista]
Andreola, Nora Maria; Castellini, Elena; Lusvardi, Gigliola; Menabue, Ledi; Romagnoli, Marcello
abstract

Chem. investigations have been performed on deflocculated suspensions of kaolinite previously treated with two widely employed dispersants: sodium hexametaphosphate (NaHMP) and sodium disilicate (NaDIS). F. Andreola et al. (2006) showed remarkable differences in the rheol. behavior between untreated and treated samples. The release of ions by kaolinite dispersed in deflocculant solns. results strongly affected by the nature of the treatment. The chem. anal. of the soln. phase sepd. from the suspensions of treated and untreated kaolinite provides relevant information about the deflocculation mechanism of HMP and DIS and gives reason of the obsd. differences in the rheol. responses.


2007 - The effect of sintering conditions on linear shrinkage in porcelainized stoneware tiles as studied in a two-level full factorial experimental design [Articolo su rivista]
Bondioli, Federica; Ferrari, Anna Maria; Romagnoli, Marcello
abstract

Linear firing shrinkage, together with water absorption, apparent density and the modulus of rupture, is commonly used as a process control parameter in industrial ceramics. In this paper its optimization is studied with a two-level full factorial experimental design approach. In particular, the influence of forming pressure, sintering temperature and time have been inves-tigated. It has been verified that a Design of Experiment (DOE) approach is a suitable tool to identify the significantfactors that control the densification process of porcelainized stoneware tiles. Moreover a mathematical model has been proposed and tested with good results. The results evidenced that the variable with the higher influence is the sintering temperature followed by forming pressure while time has influence only in sinergy with temperature.


2007 - Thermal shock behavior of mullite-cordierite refractory materials [Articolo su rivista]
Boccaccini, Dino Norberto; Leonelli, Cristina; Romagnoli, Marcello; Pellacani, Gian Carlo; Veronesi, Paolo; I., Dlouhy; A. R., Boccaccini
abstract

The characterisation of thermal shock damage in cordierite–mullite refractory plates used as substrates in fast firing of porcelain whiteware has been investigated. Two different refractory compositions (termed REFO and CONC), characterised by different silica to alumina ratios, were studied. Thermal shock damage was induced in as received samples by water quenching tests from 1250degC. Thermal and mechanical properties were measured at room temperature by means of standard techniques and then the thermal shock resistance parameter R was calculated. The fracture toughness of selected samples was measured before and after thermal shock by the chevron notched specimen technique. The reliability of this technique for evaluation of small differences in fracture toughness after a given number of thermal shock cycles was investigated.The suitability of KIc measurements by the chevron notched specimen technique to characterise the development of thermal shock damage in refractory materials was proved in this investigation.


2007 - UNATEORIA STATISTICA PER VALUTARE L’AFFIDABILITÀ DI MATERIALI CERAMICI BASATA SU MISURE DI VELOCITÀ ULTRASONICA: CUMULATIVE FLAW LENGTH THEORY [Relazione in Atti di Convegno]
Boccaccini, Dino Norberto; Maioli, Marco; Cannio, Maria; Veronesi, Paolo; Romagnoli, Marcello; Leonelli, Cristina
abstract

Uno dei principali obiettivi della teoria statistica della frattura è prevedere la probabilità di rottura per uno stress arbitrario, quando è nota la statistica di rottura. E’ stata sviluppata una nuova teoria “Cumulative Flaw Lenght Theory(CFLT)” per il caso di materiali omogenei isotropici a livello macroscopico contenenti microcricche con orientazioni random distribuite uniformemente sotto stress poliassiali. La funzione rappresentante il numero di cricche per unità di volume è basata su istogrammi relativi a misure di velocità ultrasoniche. Questa funzione è usata senza ulteriori assunzioni per determinare la probabilità di rottura in condizioni arbitrarie di stress. Questa teoria può essere facilmente incorporata in un modello a elementi finiti per prevedere la probabilità di rottura di una struttura sottoposta a stress. Inoltre il confronto della teoria con programmi esistenti usati per prevedere la probabilità di rottura di materiali ceramici e che sono basati su parametri determinati mediante prove distruttive, ad es. three point bending strenght, sottolinea il vantaggio di previsionibasate su tecniche non distruttive. Questo fatto ne permette l’impiego non solo in fase di design, ma anche per il monitoraggio dell’aumento di probabilità di rottura durante la vita in servizio. Una certa varietà di fratture introdotte durante le fasi iniziali dei metodi tradizionali di processo può portare a una affidabilità non accettabile dei materiali ceramici impiegati ad alta temperatura. Le impurezze presenti nelle materie prime (polveri, leganti..) e agglomerati formati durante il processo di formatura delle polveri sono esempi di difetti che influenzano la resistenza. Tali fratture non solo limitano la resistenza dei materiali ma incrementano lo scattering dei dati portando a affidabilità bassa (basso modulo di Weibull). La Cumulative Flaw Lenght Theory permette di valutare la funzione densità delle cricche e la probabilità di rottura a partire da dati di misura di velocità a ultrasuoni in materiali ceramici. Un nuovo metodo statistico è proposto che, basato su risultati ottenuti dalla CFLT per i campioni come ricevuti permette di valutare il vita in servizio quando il materiale è sottoposto a stress. Due diversi ceramici refrattari a base di cordierite mullite sono stati caratterizzati nell’assunzione che la teoria fosse validata in campo sperimentale. I modelli empirici di vita in servizio sono stati ottenuti considerando il numero di cicli termici sostenuti/sopportati da un numero di campioni. La buona correlazione ottenuta tra le curve teoriche e le curve ottenute con dati sperimentali mette in risalto la validità del metodo proposto.


2006 - Aspetti reologici delle polveri [Capitolo/Saggio]
Romagnoli, Marcello
abstract

Coniugando teoria e pratica relativa alla reologia aiuta a comprendere cosa succede nella ceramica, come trovare le migliori condizioni operative, come razionalizzare i processi e stabilizzare i parametri tecnologici, suggerendo possibili soluzioni.Stampato in versione bilingue, italiano e inglese, l’opera si presta alla massima diffusione internazionale e si caratterizza per l’esaustiva trattazione degli argomenti e la ricchezza delle illustrazioni.Il capitolo "Aspetti reologici delle polveri" propone una rapida carrellata dei fondamenti della reologia delle polveri allo stato secco, descrivendone comportamenti principali, metodi di misura della fluidità più utilizzati, parametri che influenzano il comportamento a scorrimento e principali difetti che una reologia non ottimale può causare su manufatti ceramici.


2006 - Color matching algorithms in ceramic tile production [Articolo su rivista]
Bondioli, Federica; Manfredini, Tiziano; Romagnoli, Marcello
abstract

In the present work, the possibility of transferring in the ceramic tiles production the know-how developed in the field of the paints by using the Kubelka-Munk theory, in the form used for opaque surface coatings, have been evaluated. Five different target colors have been chosen as target and tried to reproduce with an industrial glaze in a cycle for fine porcelain stoneware tiles. Four industrial pigments have been chosen as basic stains for the formulations. The results show a good efficiency of the color matching algorithm applied to pigments for glazes for fine porcelain stoneware tiles. All the formulations, in fact, have allowed to obtain a value of Delta E* lower to the accepted limit.


2006 - Effect of sodium hexametaphosphate and ageing on the rheological behaviour of kaolin dispersions [Articolo su rivista]
Andreola, Nora Maria; J. M. F., Ferreira; S., Olhero; Romagnoli, Marcello; Castellini, Elena
abstract

Concentrated dispersions (35% v, v) of ceramic grade kaolin dispersed with sodium hexametaphosphate (NaHMP) were prepared at three different experimental conditions: in distilled water at 30 and 60 degrees C, and in a 5 * 10(-3) M Ca(NO3)(2)(.)4H(2)O solution, at 30 degrees C. The dispersions were kept at constant temperatures for different ageing times (2, 4, 6, 18, 24, 48 h). After each ageing period they were submitted to rheological measurements and centrifuged to measure the concentration of HMP- ion in the supernatant solution by ICP. Measurements of the electrophoretic mobility in dispersions containing Ca(NO3)(2)(.)4H(2)O and KCl as background electrolyte were also performed both in the presence and in absence of NaHMP. The results allow a better understanding of the roles played by calcium ions and ageing of kaolin dispersions in the presence of NaHMP. They also shed light on the deflocculating mechanism of NaHMP. Correlations between theological parameters and chemical properties of the dispersions could be established.


2006 - Evaluation of thermal shock damage in refractory materials by ultrasonic pulse velocity testing [Relazione in Atti di Convegno]
Leonelli, Cristina; Romagnoli, Marcello; Kamseu, Elie; Boccaccini, Dino Norberto; Veronesi, Paolo
abstract

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2006 - Fracture behaviour of refractory ceramics after cyclic thermal shock [Articolo su rivista]
Z., Chlup; Boccaccini, Dino Norberto; Leonelli, Cristina; Romagnoli, Marcello; A. R., Boccaccini
abstract

Two commercially available refractory ceramic materials primary used as substrates for fast firing of porcelain stoneware were investigated. The first one, commercially known as CONC, contains cordierite and mullite in the ratio 50:50. The REFO refractory composite material with coarser microstructure compared to CONC has a cordierite-to-mullite ratio of 50:45 and the balance is filled by quartz. Both materials were exposed to water-quench tests from 1250 degrees C, applying various numbers of thermal cycles (shocks). Subsequently the fracture toughness was evaluated on both as-received and shocked samples using the Chevron notched specimen technique. The results were analysed with respect to the microstructure damage caused by the thermal loading. Scanning electron microscopy was used to analyse both microstructure and fracture surfaces in samples with different thermal loading history.


2006 - Metodi di studio ed ottimizzazione utili nel processo ceramico. La previsione del ritiro ceramico ed applicazioni in campo industriale [Articolo su rivista]
Romagnoli, Marcello; T., Bellarmi; Gualtieri, Alessandro; C., Bes; S., Celestini; A., Sevagen
abstract

E' stata mostrata la possibilità di raggiungere rapidamente l'ottimizzazione di formulazioni d'impasti con evidenti vantaggi economici e qualitativi. I metodi proposti sono quelli della regressione lineare a più variabili e dell'approccio neurale. Entrambe consentono di ottenere un modello matematico col quale simulare virtualmente il comportamento del sistema in diverse condizioni. Quest'ultimo viene ottenuto utilizzando i dati storici presenti in azienda oppure da dati sperimentali. Nell'intervento è stata mostrato un esempio applicato agli impasti: ì modelli sono stati costruiti sui dati di ritiro in relazione alla composizione, espressa comepercentuale delle singole materie prime, e alla temperatura massima di cottura. I modelli sono stati testati con venti formulazioni di prova mostrando una ottima capacità predittiva. La disponibilità di softwares in grado dì eseguire i calcoli necessari e la ridotta richiesta di conoscenze matematiche rende le due metodologie di facile e rapida introduzione in ambito industriale.Based on the linear regression with variables and artificial neural network, a math. model was developed enabling the simulation of the system behavior under different conditions. Existing historical data or through test results were employed in obtaining the model. As an example, the capability of the model to predict the shrinkage in processing of ceramic materials, i.e. between the dried state and after heat treatment cycles, was shown, the compn. expressed as raw materials percentage, and max. firing temp. being taken into account. The models were tested with twenty different formulas and showed excellent predictive capacity. The availability of software packages that could perform all necessary calcns. and the little math. knowledge enabled the easy and rapid introduction of the developed model in industrial processes.


2006 - Role of the surface treatment in the deflocculation of kaolinite [Articolo su rivista]
Andreola, Nora Maria; Romagnoli, Marcello; Castellini, Elena; Lusvardi, Gigliola; Menabue, Ledi
abstract

Suspensions of untreated and properly treated Na-exchanged kaolinite have been subjected to rheological investigations using sodium hexametaphosphate (NaHMP) or sodium disilicate (DIS) as deflocculants. The treatment of the clay consisted of a 24 h contact with solutions of NaHMP or DIS and separation of the resulting solid phase. This was then used to form the suspensions subjected to the rheological measurements. The results indicate that the dispersion ability of each deflocculants is remarkably influenced by the type of treatment. In particular, with respect to the untreated kaolinite, the efficiency of DIS is dramatically increased when the clay has been previously treated with a NaHMP solution. On the other hand, a decrease in the dispersant ability of NaHMP is observed from the untreated kaolinite to the one previously treated with DIS.


2005 - Determination of thermal shock resistance in refractories by Ultrasonic Pulse Velocity Measurement [Articolo su rivista]
Romagnoli, Marcello; Leonelli, Cristina; D., Boccaccini
abstract

Thermal shock resistance of refractory materials is one of the most important parameters in refractory material characterization since it determines their performance in many applications. Ultrasonic pulse velocity testing was used for non-destructive quantification of thermal shock damage in refractory plates used as support for the firing of porcelain articles. When refractory materials are subjected to the industrial thermal cycles crack nucleation and propagation occurs resulting in loss of strength and material degradation. The formation of cracks decreases the velocity of ultrasonic pulses travelling in the refractory because it depends on the density and elastic properties of the material. Therefore measuring either of these properties can directly monitor the development of thermal shock damage level. Young's modulus of representative samples was calculated using measured values of ultrasonic velocities obtained by ultrasonic pulse velocity technique. Results were compared with industrial statistical data of thermal shock behaviour of the investigated materials. The capability of the ultrasonic velocity technique for simple, sensitive, and reliable non-destructive characterisation of thermal shock damage was demonstrated in this investigation.


2005 - Il Color Matching: Fondamenti Teorici della Formulazione Computerizzata del Colore [Articolo su rivista]
L., Maccarini Schabbach; Bondioli, Federica; Manfredini, Tiziano; Romagnoli, Marcello; Ferrari, Anna Maria
abstract

L'articolo riporta alcuni studi sperimentali sulla possibilità di gestire il colore in ceramica


2005 - L’Experiment Design come strumento nello studio dei materiali e nell’ottimizzazione del processo ceramico. Parte I. [Articolo su rivista]
Romagnoli, Marcello
abstract

Sono fornite alcune informazioni di base ed esempi legati ai materiali ceramici. Lo scopo e quello di mostrare la validità della metodologia del Design Of Experiment o DOE applicata alla produzione di piastrelle ceramiche.


2005 - Microstructural investigations in cordierite-mullite refractories [Articolo su rivista]
Boccaccini, Dino Norberto; Leonelli, Cristina; Rivasi, Maria Rosa; Romagnoli, Marcello; A. R., Boccaccini
abstract

The influence of the mineralogical composition and phase distribution on crack initiation and propagation in cordierite-mullite refractory plates used as substrates in fast firing of porcelain whiteware is investigated. Two different refractory compositions (termed REFO and CONC), characterised by different silica to alumina ratios, were studied. Propagation of cracks introduced by Vickers´ indentations was observed by scanning electron microscopy. Chemical analysis by EDS was used for phase identification together with X-ray diffraction analysis. Microstructural features and crack propagation behaviour were correlated and used to draw conclusions on the behaviour of the two different refractory compositions under thermal shock. It was found that the presence of alpha-quartz crystals and favourable residual stress field are responsible for room temperature fracture toughness in REFO samples. The CONC material contains a larger amount of residual glassy phase than REFO material, which should lead to better high-temperature mechanical properties and higher thermal shock resistance, as the glass phase may close (heal) propagating cracks.


2005 - Optimizing stain resistance in tile [Articolo su rivista]
Romagnoli, Marcello
abstract

Stain resistance is one of the most important properties of porcelain stoneware. It is directly related to the porosity of the material. The design of experiments (DOE) approach can be used to optimise the production of porcelain stoneware. The effect of compaction pressure, temperature and time at the maximum temperature in the firing cycle was studied using two-level full-factorial experimental design. The parameters were fixed according to the industrial values used in producing porcelain stoneware tiles. Their influence on stain resistance was determined using spectrophotometry. A mathematical model was used and experimentally verified. The results are presented and discussed. Good agreement was obtained between calculated and experimental values, with a high coefficient of correlation.


2005 - REFRACTORIES CONTAINING INERTISED ASBESTOS AS RAW MATERIAL [Articolo su rivista]
Leonelli, Cristina; Boccaccini, Dino Norberto; Rivasi, Maria Rosa; Romagnoli, Marcello; Veronesi, Paolo; Pellacani, Gian Carlo; A. R., Boccaccini
abstract

It is well known that asbestos is a health hazard and its progressive elimination is a priority for pollution prevention. Asbestos can be transformed into non hazardous silicate phases by means of thermal treatments. This investigation describes the recycling of microwave inertised asbestos in refractory materials of both alumina-mullite and mullite-cordierite compositions. The increase of cordierite content found in samples containing inertised asbestos should lead to an improvement in thermal shock behaviour of the refractory materials. In the case of mullite-cordierite refractories, it was found that inertised asbestos can be used as raw material to replace the currently used MgO-rich talc. No significant variation of the Young’s modulus of samples made with inertised asbestos compared to the commercial based composition was found, indicating that inertised asbestos containing refractories should behave similarly to commercial refractory materials in terms of mechanical properties.


2005 - Thermal shock resistance of cordierite-mullite refractory composites [Relazione in Atti di Convegno]
Zden, ; K., Chlup; Ivo, Dlouhy; A. R., Boccaccini; Boccaccini, Dino Norberto; Leonelli, Cristina; Romagnoli, Marcello
abstract

The design of composite materials leads to the development of multi-component systems where each constituent has a specific function in the material, from technological and/or application points of view. Examples of such composite systems are the cordierite-mullite refractory materials investigated in this contribution. Two different commercially available compositions were selected for evaluation of the influence of microstructure on fracture behaviour under thermal shock conditions. The materials were exposed to water-quench tests from 1250 degrees C and subsequently the fracture toughness was evaluated using the chevron notched specimen technique. The results were compared to those obtained on as-received materials. Microstructural damage was also studied applying fractographic techniques with the aim to gain knowledge on the thermal shock damage mechanisms acting in the materials.


2004 - Comparison of models for dense particle packing [Relazione in Atti di Convegno]
Romagnoli, Marcello; Siligardi, Cristina
abstract

Analisi di modelli per l'ottenimento della massima densità di impaccamento di polveri con morfologia irregolare.


2004 - Influence of size distribution on flowability of granulated and spry-dried powder for ceramic tiles. [Relazione in Atti di Convegno]
Romagnoli, Marcello; Rivasi, Maria Rosa
abstract

La distribuzione granulometrica è stata studiata al fine di definirne l'effetto sulla fluidità di aggregati per la produzione di piastrelle per pressatura come granulati e atomizzati ceramici.


2004 - Microwave-treated gelatin microspheres as drug delivery system [Articolo su rivista]
Vandelli, Maria Angela; Romagnoli, Marcello; A., Monti; M., Gozzi; P., Guerra; F., Rivasi; Forni, Flavio
abstract

The crosslinking process of natural macromolecules with microwave energy should have the potentiality to overcome the problems due to the toxicity of the residuals of chemical crosslinking agents and moreover of the in vivo biodegradation products of the chemical crosslinked macromolecule. To evaluate the effective crosslinking of the gelatin forming the microspheres, the water-soluble fraction at 37 degreesC, the water absorption capability, the free amino and free carboxylic acid groups of the gelatin were determined. The structural change in the gelatin microspheres has been detected by the porosity studies. Moreover, both the in vitro biodegradability and the biocompatibility of the gelatin microspheres microwave-treated after a subcutaneous injection into female albino guinea pigs were tested. As the results suggest only the gelatin microspheres microwave-treated for 10 min at an inlet temperature of 250 degreesC could have been modified by the crosslink formation among the macromolecular chains. The gelatin microspheres treated with the microwave energy were very well biodegraded as indicated both by the in vitro enzymatic degradation studies and mainly by the histopathological examination. This latter study has also demonstrated the biocompatibility of the gelatin microspheres crosslinked with the microwave energy. In order to evaluate the feasibility of the microwave crosslinking process for pharmaceutical applications, both the drug loading and the drug release processes were evaluated using diclofenac as drug model, either as acidic form or as sodium salt. The microspheres were swollen in aqueous solution of diclofenac sodium salt, followed by a washing procedure with cool water to maintain the sodium salt into the microspheres or with pH 1.5 HCl to induce the diclofenac precipitation. To increase the amount of diclofenac acid form in the microspheres, the procedure was repeated three times washing with pH 1.5 HCl after each swelling process. Both the X-ray diffractometry and thermal analysis investigations showed a different physical state of the two drug forms in the microspheres, i.e. the amorphous state of the sodium salt and the crystalline state of the acidic form. According to the experimental results, the drug is released from gelatin microspheres according to the drug loading and the drug solubility.


2004 - Powder flowability characterizing techniques [Articolo su rivista]
Romagnoli, M.; Bondioli, F.
abstract

The experimentally determined indexes for describing the flow of behavior of powder streams in industrial storage, transport, and processing operations are discussed. A better control of powder flow during manufacturing optimizes the quality of the product in terms of uniformity and efficiency. Flowability is important in several industrial processes in the ceramic industry, where flowability of a spray-dried or a granulated powder, in the step of mold filling, affects the green-body homogeneity velocity after compaction. Flowability is also important in dry-powder decoration, a technique that will become much more used in the future, where the reproducibility and the precision of the drawing are strictly dependent on powder flowability. .


2004 - Powder flowability charaterizing technique [Articolo su rivista]
Bondioli, Federica; Romagnoli, Marcello
abstract

Experimentally determined indices for describing the flow behaviour of powder streams in industrial storage, transport and processing operations are reviewed and discussed in terms of their range of applicability and difficulty of measurement. It is emphasised that no flowability test is universally applicable.


2004 - Studio dell’effetto di miscele di additivi sulla fluidita’ di polveri mediante l’approccio del mixture design. [Relazione in Atti di Convegno]
Romagnoli, Marcello; M. R., Rivasi
abstract

In diversi campi industriali, ai materiali in polvere sono aggiunte sostanze chimiche per accrescerne e/o regolarne la fluidità. Generalmente gli additivi sono utilizzati singolarmente e perciò poco si conosce dei loro effetti combinati. In questo lavoro il mixture design e stato impiegato per comprendere l'influenza di tre additivi: Bentonite; Zn stearato e Silice amorfa; sulla scorrevolezza di un granulato industriale per la produzione di piastrelle.


2004 - The role of sodium hexametaphosphate in the dissolution process of kaolinite and kaolin [Articolo su rivista]
Andreola, Nora Maria; Castellini, Elena; Manfredini, Tiziano; Romagnoli, Marcello
abstract

Suspensions of kaolinite and ceramic grade kaolin in sodium hexametaphosphate solutions at different concentrations were prepared and kept at constant temperature for 4 h: the solutions obtained after centrifugation and filtration were analysed using a ICP technique to determine the concentration of significant cations. The results allowed to stress the role of NaHMP in the dissolution process of kaolinite and ceramic grade kaolin. The role of accessory minerals in ceramic grade kaolin dissolution was discussed in the light of the obtained data.


2003 - Effect of ionic strength and temperature on the interaction between kaolin suspensions and sodium hexametaphosphate [Abstract in Atti di Convegno]
Andreola, Nora Maria; Castellini, Elena; Manfredini, Tiziano; Romagnoli, Marcello
abstract

The effect of ionic strength on the interaction between kaolin and sodium hexametaphosphate has been investigated at different temperatures.


2003 - Porcelainized stoneware: processing and characteristics [Articolo su rivista]
Manfredini, Tiziano; Romagnoli, Marcello
abstract

Unglazed fast fired porcelainized stoneware tiles, for pavering and for exteriors, are the main innovative products present on the tile market. They are prepared using mainly kaolinitic clays, quartz and large amounts of fluxes to increase the sintering. The raw materials are more highly milled than those used for other kinds of tiles and the bodies are fired at 1200-1220°C. Tiles are not glazed and may be coloured. Its structure consists of a glassy matrix with mullite and residual quartz. The basic product presents high mechanical and technical qualities and peculiar abrasion resistance and surface hardness.


2002 - Chemical additives for pressure tape casting [Articolo su rivista]
Andreola, Nora Maria; Castellini, Elena; Romagnoli, Marcello
abstract

Suspensions of ceramic raw material and different deflocculant polyelectrolytes were prepared with a solid content of about 78% in industrial water. The rheological behavior of these suspensions was tested by evaluation of the shear dependence in a 4-step cycle and by a modified off-on procedure that reproduced the typical times involved in tape casting. The best deflocculants were found to be Na hexametaphosphate and polyacrylate, but their capability differed a little from mixtures of hexametaphosphate and Na disilicate or from ternary mixtures. The deflocculants made the suspensions slightly dilatant, had a low viscosity and yield stress values close to zero, that permitted an easy degasification of the suspensions. The additives, alone or in mixture, had adequate characteristics for use in pressure tape casting.


2002 - Effetto di additivi promotori di fluidità su materiali ceramici tradizionali ottenuti per pressatura uniassiale. [Relazione in Atti di Convegno]
Manfredini, Tiziano; Romagnoli, Marcello; Siligardi, Cristina
abstract

Studio di additivi capaci di incrementare la fluidità di polveri ceramiche per pressatura uniassiale.


2002 - Influencia das caracteristicas fisicas e quimicas dos pos no proprio transpose [Articolo su rivista]
Romagnoli, Marcello; S., Ramponi
abstract

Trabalho apresentado na Jornada de estudos sobre o tema "Moagem e transporte de massas; coloracao na prensa e prensagem do gres porcelanato" organizada pelo Gruppo Editoriale Faenza Editrice em Modena.Na fase do projeto de urn sistema de transporte, sao necessaries informacoes sobre o material que devera ser tratado. Estas sao obtidas atraves de provas que determinam caracteristicas tecnologicas tais como: compactacao, abrasao, fluidez, permeabilidade ao gas, etc. Na apresentacao sao evidenciadas as ligacoes entre as propriedades quimico-fisicas e as caracteristicas dos materiais, consideradas pelos projetistas como em fase de estudo do equipamento de transporte.


2002 - La fabbricazione e l'applicazione di ossidi nell'industria ceramica [Articolo su rivista]
Bondioli, Federica; Manfredini, Tiziano; Romagnoli, Marcello
abstract

In questo articolo gli autori presentano i principali ossidi ceramici utilizzati nell'industria ceramica


2002 - L'analisi di densita' per determinare la purezza di ossidi utilizzati per smalti ceramici [Relazione in Atti di Convegno]
Miselli, Paola; Romagnoli, Marcello
abstract

La misura della densità mediante picnometria ad Elio viene testata come metodo rapido di misura del grado di purezza di ossidi utilizzati per la produzione di smalti ceramici.


2002 - Rotational Rheometry used as Laboratory Technique to Test Commercial Deflocculants [Articolo su rivista]
Andreola, Nora Maria; Romagnoli, Marcello
abstract

This study considers the use of rotational rheometry as a laboratory technique to control the efficiency of different commercial deflocculants on kaolin suspensions. In particular, three commercial Penta Sodium Tripolyphosphates (STPP), which are widely used in the ceramics industry, were tested. In order to characterise the Tripolyphosphate (TPP) salts, chemical and physical analyses were carried out. The aim of this study is to highlight the ability of rheometric techniques to describe the effects of the different additives with fast and easy procedures that can be utilised on industrial or laboratory scale. The rheological measures were performed on kaolin suspensions with different amounts of TPPs salts addition. As a liquid medium, industrial water with calcium and magnesium ions was simulated.


2002 - Tape casting sotto pressione di sospensioni acquose di allumina [Relazione in Atti di Convegno]
Andreola, Nora Maria; Manfredini, Tiziano; Romagnoli, Marcello
abstract

Tape casting sotto pressione di sospensioni acquose di allumina


2002 - Tecniche per la misura di fluidità di polveri. Parte II [Articolo su rivista]
Romagnoli, Marcello
abstract

L'articolo riprende le tecniche per la misura di fluidità di polveri già pubblicate in una prima parte nel numero di Ceramica Informazione dicembre 2001, pag. 982.Vengono riprese in questo lavoro le metodiche più complesse alla luce delle più recenti ricerche. L'analisi dell'insieme delle metodiche consente di affermare che lo strategia piu ragionevole e quella di scegliere il metodo in grado di dare le migliori risposte alle nostre domande e di utilizzarlo correttamente.


2002 - Valorizzazione di rifiuti inorganici nel settore ceramico [Relazione in Atti di Convegno]
Andreola, Nora Maria; Barbieri, Luisa; Corradi, Anna; Lancellotti, Isabella; Romagnoli, Marcello
abstract

Valorizzazione di rifiuti inorganici nel settore ceramico


2002 - Zeta potential and rheological behaviour of aqueous kaolin suspensions dispersed with sodium hexametaphosphate [Capitolo/Saggio]
Andreola, F.; Castellini, E.; Romagnoli, M.; Olhero, S. M.; Ferreria, J. M. F.
abstract

Deflocculants adsorb on particles' surfaces, increase the repulsive forces among them, reducing viscosity, while the soluble salts have an opposite effect on viscosity. This work studies the influence of deflocculant and salt concentration on zeta potential and correlates the results with rheological measurements.


2001 - Binary and ternary mixtures of deflocculant additives for whiteware slurries [Relazione in Atti di Convegno]
Andreola, F.; Pellacani, G. C.; Romagnoli, M.
abstract

In the traditional ceramic field, during the wet grinding stage liquid mixtures of additives are commonly used to guarantee high solids content (65-72 wt%) and a viscosity low enough to allow the suspension's workability. These characteristics are indispensable for using the new technologies for wet grinding (cylindrical and conical continuous mills) that require only 3-4 h of milling and permit considerable productivity (20 t/h). This work reports a laboratory study on the rheological behavior of whiteware slurries added with binary and ternary deflocculant mixtures.


2001 - Binary and ternary mixtures of deflocculating additives for whitewares slurries. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; Pellacani, Gian Carlo
abstract

In the traditional ceramic field, during the wet grinding stage liquid mixtures of additives are commonly used to guarantee high so/ids content (65–72 wt%) and a viscosity low enough to allow the suspension's workability. These characteristics are indispensable for using the new technologies for wet grinding (cylindrical and conical continuous mills) that require only 3–4 h of milling and permit considerable productivity (20 t/h). This work reports a laboratory study on the rheological behavior of whiteware slurries added with binary and ternary deflocculant mixtures.


2001 - Comportamento Reologico di smalti ceramici: influenza della composizione e delle variabili di preparazione delle fritte [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello
abstract

Comportamento Reologico di smalti ceramici: influenza della composizione e delle variabili di preparazione delle fritte


2001 - Enhancing the mechanical properties of porcelain stoneware tiles: a microstructural approach [Articolo su rivista]
Leonelli, C.; Bondioli, F.; Veronesi, Paolo; Romagnoli, Marcello; Manfredini, Tiziano; Pellacani, Gian Carlo; Cannillo, Valeria
abstract

This paper focuses on the complexities of the microstructure and phase development in porcelain stoneware tiles produced following industrial fast single firing cycles. A microstructural investigation was conducted to determine if the addition of selected low cost minerals would improve mechanical properties. The minerals tested were quartz, mullite and kyanite. Uniaxially pressed samples were submitted to the same industrial firing schedule and tested according to the European tile standards before further microstructural analysis. All the requirements specified in UNI EN normative concerning BIa class tiles were fulfilled; moreover, mullite and kyanite added formulations showed sensible increases in mechanical properties, especially as far as flexural strength and abrasion resistance are concerned.


2001 - La fluidità delle polveri ceramiche: metodi di misura e variabili che influenzano lo scorrimento [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello
abstract

ISBN-88-8138-097-8


2001 - L'analisi di densità per determinare la purezza di ossidi utilizzati per smalti ceramici [Articolo su rivista]
P., Miselli; Romagnoli, Marcello
abstract

Nell'articolo viene presa in esame la purezza degli ossidi ceramici impiegati negli smalti. Vengono affrontate le metodiche di analisi della densità di quest! ossidi, correlate alla possibilità di determinarne la purezza.


2001 - Micromechanics principles applied to fracture propagation in porcelain stoneware tiles [Relazione in Atti di Convegno]
Leonelli, Cristina; F., Bondioli; Veronesi, Paolo; Cannillo, Valeria; Romagnoli, Marcello; Manfredini, Tiziano
abstract

The possibility of discussing the mech. properties of porcelain stoneware tiles with a scientific approach typically used in the investigation of the composite materials is studied. A thorough microstructural investigation was conducted to det. if the addn. of selected low-cost minerals would improve mech. properties. The minerals tested were quartz, mullite, and kyanite. Uniaxially pressed samples were submitted to the same industrial firing schedule and tested according to European tile stds. before further microstructural anal.


2001 - Sistemi ceramici innovativi per aumentare le caratteristiche superficiali del gres porcellanato. Parte I [Articolo su rivista]
Romagnoli, Marcello; G., Guidotti
abstract

L'articolo riprende ed esamina a fondo I'aspetto delta macchiabilità delle superfici di gres porcellanato levigato individuando una soluzione interessante.I ricercatori dell'Universita di Modena hanno messo a punto una composizione ceramica che, applicata in strato sottile sopra ad una base di impasto di gres porcellanato, riesce a dare una superficie compatta difficilmente macchiabile.


2001 - Tecniche per la misura di fluidità di polveri. 1a Parte [Articolo su rivista]
Romagnoli, Marcello
abstract

La manipolazione delle polveri, stivaggio, trasporto, compattazione, miscelazione, pressatura incide in maniera notevole anche sui costi di lavorazione. Risulta quindi di fondamentale importanza riuscire a standardizzare i parametri che influiscono sul loro comportamento nel processo produttivo. In questa prima parte vengono presi in esame alcuni semplici metodi per la determinazione delta fluidita delle polveri.


2000 - A New Physical Method To Crosslink The Gelatin Microspheres. [Relazione in Atti di Convegno]
Vandelli, Maria Angela; Forni, Flavio; M. T., Bernabei; R., Cameroni; Romagnoli, Marcello
abstract

New Physical Method To Crosslink The Gelatin Microspheres.


2000 - Applicabilità del color matching nell'industria cramica [Articolo su rivista]
Bondioli, Federica; Romagnoli, Marcello; V., Morisi
abstract

In questo articoli gli autori, dopo una breve introduzione sul color matching e sulla teoria di Kubelka-Munk, evidenziano la possibilità e limiti dell'applicazione nella predizione del colore in campo ceramico.


2000 - Ceramic facing tiles (EN 159) obtained from dry-ground Italian raw materials. Part I. [Articolo su rivista]
Manfredini, T.; Romagnoli, Marcello; Visentin, C.; Visentin, P.; Manuskova, M.
abstract

Optimization of dry grinding of paste, contg. exclusively Italian raw materials, for use in prodn. of porous ceramic facing tiles (EN 159) was studied using a rolling vertical mill (Pfeiffer MPS 141A); the results obtained demonstrate that it is possible, using cycles of single-firing (39 min at max. temp 1080 C) and rapid double-firing (28 min firing, 7 min drying, inertization at max. temp 1065 C, and glazing 45 min at max. temp. 1055 C), to obtain products with the functional properties required by the strict European std. Baiso 160 clay is predominantly illite and chlorite with high contents of Ca and Mg oxides; Alloero Refrattoria is predominantly illite and chlorite with high content of free qt and trace carbonates.


2000 - Efeito de adição de wolastonita no processo de consolidação de massas cerâmicas para grês porcelanato [Articolo su rivista]
M., Hanuskovà; Manfredini, Tiziano; Romagnoli, Marcello
abstract

O artigo reporta um amplo estudo sobre o emprego da wollastonita em ceramica, em particular como coadjuvante na sinterizacao das massas.


2000 - Effects of chemical and physical characteristics of powders on their transport. [Articolo su rivista]
Romagnoli, Marcello; S., Ramponi
abstract

While designing and developing a project for a means of transport, information are necessary on the material that will be handled on it. This kind of information is obtained through some tests that det. such technol. qualities as: abrasive quality, flowability, powderiness, gas permeability, etc. This article illustrates the relation between the chem. and phys. properties and the characteristics of a material, that projects managers take into account during the design state for the development of a means of transport.


2000 - Effetti dell'aggiunta di wollastonite sul consolidamento degli impasti ceramici per grès porcellanato. [Articolo su rivista]
Manfredini, Tiziano; Romagnoli, Marcello; M., Hanuskovà
abstract

La wollastonite è una materia prima di notevole interesse ceramico impiegata nella preparazione di fritte, di smalti ceramici e nella formulazione di impasti in particolare per la produzione di piastrelle di gres porcellanato. L'articolo riporta un ampio studio condotto sull'impiego della wollastonite in ceramica in particolare come coadiuvante nella sinterizzazione degli impasti.


2000 - Effetto di Additivi Chimici sulle Caratteristiche Reologiche di Sospensioni Ceramiche Tradizionali per Tape-Casting. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Castellini, E.; Romagnoli, Marcello
abstract

Sono presentati i risultati di una sperimentazione che ha visto l'utilizzo di tre diverse tipologie di additivi su un impasto di tipo industriale e avente come intento l'individuazione di additivi che permettano, a parità di contenuto solido, di ridurre la viscosità della sospensione, attraverso una razionale serie di prove. Viene mostrato quali additivi o miscele permettono di ottenere i comportamenti reologici piu adeguati a tale tecnica di formatura. Parametri reologici quali la viscosità e la tissotropia delle sospensioni sono messi in relazionealla composizione degli additivi.


2000 - Optimization of fritting parameters of ceramic frits: effect on the rheological behavior of the glaze suspensions. [Articolo su rivista]
Andreola, Nora Maria; Castellini, E.; Romagnoli, Marcello
abstract

Studies to optimize the prepn. parameters used in industrial frits are reported. Two frit compns. widely used for the prodn. of single-fired ceramic-glazes were chosen: an alk. boric and an earth-alk. boric compn. The chem. durability and rheol. behavior of the frit suspensions were studied in relation to changes in the fritting temp. and time. The results confirm that the two frits studied react differently to changes in fritting parameters due to the dependence on their chem. durability and compn. Suspensions prepd. with the alk.-boric frit displayed no significant change in their rheol. properties; the earth-alk.-boric frit suspensions were more markedly affected.


2000 - Optimization of fritting parameters of ceramic frits: effect on the rheological behaviour of the glaze suspensions [Articolo su rivista]
Andreola, Nora Maria; Castellini, Elena; Romagnoli, Marcello
abstract

Studies to optimize the preparation parameters used in industrial frits are reported. Two frit compositions widely used for the production of single-fired ceramic-glazes were chosen: an alkaline boric and an earth-alkaline boric composition. The chemical durability and rheological behavior of the frit suspensions were studied in relation to changes in the fritting temperature and time. The results confirm that the two frits studied react differently to changes in fritting parameters due to the dependence on their chemical durability and composition. Suspensions prepared with the alkaline-boric frit displayed no significant change in their rheological properties; the earth-alkaline-boric frit suspensions were more markedly affected.


2000 - Piastrelle ceramiche da rivestimento (EN 159) ottenute con materie prime nazionali macinate a secco. Parte I: aspetti tecnologici. [Articolo su rivista]
Manfredini, T.; Romagnoli, Marcello; Visentin, C.; Visentin, P.; Hanuslova, M.
abstract

L'articolo riporta i risultati piu important! di uno studio per l'ottimizzazione della macinazione a secco di impasti, contenenti esclusivamente materie prime nazionali, da utilizzare nella produzione di piastrelle ceramiche porose da rivestimento (EN 159). I risultati ottenuti dimostrano come sia possibile, mediante cicli di monocottura e bicottura rapida, ottenere prodotti con le proprieta funzionali richieste dalla normative europea vigente.


2000 - Preparation of (Fe,Cr)2O3 solid solution as black pigment [Articolo su rivista]
Manfredini, Tiziano; Bondioli, Federica; Romagnoli, Marcello
abstract

in this paper the authors report the optimal synthesis condition to obtain a black ceramic pigment


2000 - Recent Advances in Textiles Filtering Media Characterization: Comparision Among Mercury Porosimetry, VDI and Image Analysis. [Relazione in Atti di Convegno]
G., Bonifazi; S., Ramponi; Romagnoli, Marcello
abstract

Diverse tecniche vengono messe a confronto per determinare la porosità di media filtranti


2000 - Techniques used to determine porosity [Articolo su rivista]
Andreola, Nora Maria; Leonelli, Cristina; Romagnoli, Marcello; Miselli, Paola
abstract

A comparison is made of the principal techniques (mercury porosimetry, helium pycnometry, image analysis and water absorption) that are used to measure porosity


2000 - Tecniche a confronto per la determinazione della porosità. Parte II [Articolo su rivista]
Andreola, Nora Maria; Leonelli, Cristina; Romagnoli, Marcello; P., Miselli
abstract

Viene presentata I'applicazione delle tecniche presentate nella parte I a sei prodotti ceramici con diverse proprietà. Ogni tecnica utilizzata infatti risulta idonea per determinate classi di materiali; pertanto la scelta del procedimento di analisi viene fatta a seconda del tipo di risultato che si vuole ottenere. Lo scopo di tale lavoro e quello di evidenziare i vantaggi e gli svantaggi di ognuna a seconda del materiale sottoposto ad analisi.


2000 - The influence of additives on the rheological behavior of acqueous concentrated glaze suspensions. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; Pellacani, Gian Carlo
abstract

Influenza di alcuni additivi chimici sul comportamento reologico di sospensioni di fritte ceramiche.


1999 - Applicazioni della cromite Naturale nella Colorazione degli Impasti per Grés Porcellanato [Articolo su rivista]
Bondioli, Federica; Manfredini, Tiziano; Romagnoli, Marcello
abstract

In questo articolo gli autori, dopo una caratterizzazione chimica, fisica e mineralogica, valutano l'applicabilità di cromite naturale per la colorazione di materiali ceramici industriali


1999 - Ceramic Oxide (MeO2) Solid Solution Obtained by Mechanical Alloying [Relazione in Atti di Convegno]
Bondioli, Federica; Romagnoli, Marcello; Barbieri, Luisa; Manfredini, Tiziano
abstract

This work has to be regarded as a laboratory study concerning the synthesis and the application as ceramic pigments of powders obtained by mechanochemistry. In ceramic industry pigments, that must show thermal and chemical stability at high temperature and must be inert to the chemical action of the molten glazes, were traditionally obtained by calcination of raw materials. These heat treatment was carried out adding mineralizers (fluorides) to lower the high synthesis temperatures (1200-1400°C). The possibility to obtain them at room temperature and without mineralizers is of great interest: avoiding high calcination temperatures can cause dramatic reduction in toxic gase emission and minimizes high temperature technology investments.


1999 - Dry glazing in ceramic tile production. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello
abstract

The efficiency of four different methods used to measure the flowability of the powders has been studied. The results obtained on pigments used in the production of tiles were correlated with the data obtained in semi-industrial conditions.The influence of the powder moisture on the amount of pigment that falls on the tile's surface was evaluated.


1999 - Influence of the operative parameters on chemical durability and rheological behavior frits ceramic suspensions. [Relazione in Atti di Convegno]
Andreola, Nora Maria; D., Bernardelli; Romagnoli, Marcello; Pozzi, Paolo
abstract

Glaze application is the phase in a productive process that is more conditioned from the rheological properties of the glaze itself. During the preparation step in the mill, at moderately high temperatures (60-70°C), reactions between frits and the aqueous medium can occur and consequently begin the leaching of glassy network and the diffusion of the modifying ions through the leached frit layer. In the industrial process, variations on the pH and the ionic strength of glaze suspensions happen during the milling. Consequently changes on the rheological parameters (apparent viscosity, yield point, thixotropy) of glaze suspensions will verified. It is important to control these variables for keeping unaffected the aesthetic characteristics of the final products, after firing.


1999 - Iron- and calcite-rich ceramic bodies for porous tiles manufacturing by fast double-firing [Articolo su rivista]
Manfredini, Tiziano; Romagnoli, Marcello
abstract

Porous glazed tiles are very important products used for decorative wall coverings. It ¡s possible to obtain porous fast-fired biscuit (35-40 min firing cycle) to produce fast double-fired tiles by using natural ¡ron- and calcite-rich clays, as used in the production of traditional, slow-fired cottoforte (20-30 h firing cycle). Anorthite and diopside are the main crystalline phases developed ¡n fired pressed tiles. A large amount of chlorite and calcite is fundamental to diopside-anorthite formation and to the enhancement of mechanical properties and dimensional stability.


1999 - LASER PARTICLE SIZE ANALYSIS: A TOOL IN DESIGNING TRADITIONAL CERAMIC PROCESSES [Articolo su rivista]
Manfredini, Tiziano; M., Hanuskova; Romagnoli, Marcello
abstract

Simply by using modern analysis techniques based on light scattering, it is possible to check the characteristics of raw materials or semi-finished products, to impose production control in various stages of the process or to intervene to solve production problems.


1999 - Reologìa de suspensiones de esmaltes cerámicos para monococción: estudio de la influencia de los aditivos utilizados. [Articolo su rivista]
Andreola, Nora Maria; Pozzi, Paolo; Romagnoli, Marcello
abstract

En este trabajo se presentan los resultados obtenidos a partir de la caracterización y el estudio del comportamiento reológico de suspensiones de fritas cerámicas para la elaboración de esmaltes para baldosas de monococión porosa.En particular se evidencian los efectos que los distintos componentes y aditivo, ejercen sobre los parámetros reológicos que oontrolan las fases de preparacion y de aplicación


1999 - Rheology of ceramics slurries with mixtures of deflocculanting agents. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Castellini, Elena; Romagnoli, Marcello
abstract

In whiteware processing, as in most other technical processes involving concentrated suspensions, additives are used to decrease viscosity and control stability. Silicate, phosphate and polyacrylate sodium salts are the most used additives in the production of tiles, tablewares, sanitarywares etc. They are commercially available products with good deflocculant abilities and performance/costs ratio. The chemical action of each single component was studied1,2,3 but the authors are not aware of any studies on mixtures. The systems are complex because they are multi-phases and constituted by natural raw material. In the industrial field, liquid mixture of additives are generally used. They take an inferior amount of time before being active with respect to when they are used as solid salts and permit a better management in the plant.


1998 - Caratterizzazione di sospensioni acquose di fritte ceramiche additivate di materiali plastici [Relazione in Atti di Convegno]
Andreola, Nora Maria; Pozzi, Paolo; Romagnoli, Marcello
abstract

Caratterizzazione di sospensioni acquose di fritte ceramiche additivate di materiali plastici


1998 - Comparison Between poly(vynil acetate) and poly(vynil alcohol) as Binders for whiteware body composition. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; W., Carty
abstract

Comparison Between poly(vynil acetate) and poly(vynil alcohol) as Binders for whiteware body composition to avoid spring-back phenomena during forming.


1998 - L'ANALISI GRANULOMETRICA PER LA CARATTERIZZAZIONE DELLE POLVERI CERAMICHE - Seconda Parte [Articolo su rivista]
M., Hanuskovà; Romagnoli, Marcello
abstract

L'articolo descrive alcuni esempi di applicazione dell'analisi granulometrica ottenuti mediante diffusione elastica di luce a basso angolo nella caratterizzazione di polveri ceramiche, nell'ottimizzazione del processo di produzione delle polveri e nella soluzione di problematiche di processo. I risultati ottenibili mostrano chiaramente come tutto ciò può rappresentare un contributo all'ottimizzazione dei processo ed alla qualità per migliorare la competitività.


1998 - L’analisi granulometrica per la caratterizzazione delle polveri ceramiche. Parte I: aspetti teorici [Articolo su rivista]
Hanuskova, Miriam; Romagnoli, Marcello
abstract

Nell'articolo vengono riportate le basi teorico-pratiche dell'analisi granulometrica al fine di caratterizzare polveri di materie prime utilizzate in ceramica.


1998 - L’analisi granulometrica per la caratterizzazione delle polveri ceramiche. Parte II: aspetti applicativi [Articolo su rivista]
Hanuskova, Miriam; Romagnoli, Marcello
abstract

Nell'articolo vengono riportati esempi di applicazione dell'analisi granulometrica a polveri ceramiche. Si riportano esempi di curve e possibili effetti.


1997 - Filtering systems for mechanical - processing: composition and characteristics of devices for the separation of polluting emissions. [Articolo su rivista]
S., Ramponi; G., Marchi; Romagnoli, Marcello
abstract

The state of art in filtering systems for mech. processing and related problems is reviewed with 3 refs. In particular, different compns. and characteristics of device for the sepn. of polluting emissions are considered. The aspects of compactness, modularity with the machine, vacuum cleaner noise inspectability of the device, flameproof controls, explosion-proof systems, geometry of the filtering media, antistatic properties, media with PTFE membrane for the pollutant sepn. systems are also object of considerations.


1997 - Impiego di carbossimetilcellulose come leganti negli smalti ceramici : studio del comportamento reologico [Relazione in Atti di Convegno]
Andreola, Nora Maria; R., Lapasin; Pozzi, Paolo; Romagnoli, Marcello
abstract

Studio reologico dell'aggiunta di CMC in sospensioni di smalti ceramici per piastrelle.


1997 - Sintering and modification of porous structure caused by binders added to whiteware body composition [Relazione in Atti di Convegno]
Andreola, Nora Maria; Romagnoli, Marcello; Pozzi, Paolo
abstract

The behavior of 2 viscosity-grade polyvinyl alcohols. was studied at 2 different percentages added to the slurry used for the preparation of tableware by isostatic pressing. The modification of the porous structure, the apparent d., and the elimination of the binder were examined. Results obtained show that binders do not modify the reactions during the firing process. More evident differences are verifiable in the porosity of the green and fired bodies, according to their mol. wt. and concn. Porosity decreased until 350°C (200°C for the binder with high mol. wt.), while from 450°C (350°C high wt. binder) to 700°C it increased quickly. At higher temps., as an effect of sintering, porosity fell dramatically to <3% and residual porosity is concd. in large pores. Effect of mol. wt. is to det. a higher porosity using the binder with longer chain while the bulk d. is lower. The green body with higher percentage of adhesive presents a lower open porosity and bulk d.


1997 - Wet grinding ceramic frits: effects of the size of the grinding media, grinding time and solid content. [Articolo su rivista]
Andreola, Nora Maria; Pozzi, P.; Romagnoli, Marcello
abstract

The effect of variables in the wet grinding process, such as the size of the grinding media, grinding time and solid content, was investigated using an aq. suspension of glassy frit, typically used for the prodn. of glazes in the manuf. of ceramic tiles. The aim was to examine the process parameters which will enable optimization of the grinding process for brittle materials. The frit was ground with three mill charges, formed of sintered alumina balls of different sizes, and the particle size dimensions were measured as a function of grinding time and of the amt. of solid content of the aq. suspensions. The results indicate that the mill charge ( ratio of grinding ball diams.), grinding times and solid content of the suspensions must be carefully controlled in order to optimize the grinding process. A lower limit of particle size dimensions, after very long grinding times, was obtained.


1997 - Wood machines air pollution EEC certification. [Articolo su rivista]
M., Bortolamasi; Romagnoli, Marcello
abstract

As of Jan. 1, 1993 EEC regulation came into force. This regulation establishes the essential safety requirements that the machines must comply with, so as to be able to be freely moved in the Community territory, as rules became more stringent, all wood machines industries were subjected to the control of air pollution. This paper focuses primarily on the test methods and reviews the traditional safety requirements from the perspective of EEC regulation.


1996 - Additives used in the pressing of tableware [Articolo su rivista]
Andreola, Nora Maria; Pozzi, Paolo; Romagnoli, Marcello; Bresciani, A; Pasquali, G.
abstract

Binder monomer chain length and concentration affect the mechanical behavior of tableware during fabrication by isostatic pressing.


1996 - Additives used in the pressing of tableware [Articolo su rivista]
Andreola, Fernanda; Pozzi, Paolo; Romagnoli, Marcello; Bresciani, Andrea; Pasquali, Guelfo
abstract

Reported here is the study of the rheological behavior of three viscosity-grade poly(vinyl alcohol)s added at three concentrations to a slurry that is used for the preparation of tableware by isostatic pressing. The formation of fracture during pressing, mechanical characteristics of the body and recycling of scrap also are reported.


1996 - Comparison of the binding behavior of poly(vinyl alcohol) with varying molecular weight and poly(vinyl acetate) in compositions for white body plates obtained by isostatic pressing. [Articolo su rivista]
Andreola, Nora Maria; Pozzi, P.; Romagnoli, Marcello; Pasquali, G.; Bresciani, A.
abstract

Over the past few years, the isostatic pressing method has been successfully applied for the prodn. of refractories and tableware. This method may be used for the prodn. of practically all shapes of plates, and also for more complex non-sym. pieces. This procedure leads to a rapid expansion of the piece after pressing, possibly resulting in damage. To avoid this problem, binding agents are added to the bodies which are capable of combating the expansion phenomenon. The effects of three types of poly(vinyl alc.) (varying mol. wt.), added in three different quantities, and poly(vinyl acetate) on this expansion phenomenon in the isostatic pressing of plates were examd.


1996 - CONFRONTO TRA IL COMPORTAMENTO LEGANTE Dl ALCOOLPOLIVINILICI A DIVERSO PESO MOLECOLARE E ACETATO Dl POLIVINILE IN COMPOSIZIONI PER PIATTI A IMPASTO BIANCOOTTENUTI PER PRESSATURA ISOSTATICA [Articolo su rivista]
Andreola, Nora Maria; Pozzi, Paolo; Romagnoli, Marcello; G., Pasquali; A., Bresciani
abstract

La pressatura isostatica, negli ultimi anni, e stata applicata con successo nella fabbricazione di refrattari e stoviglieria, può essere utilizzata nella fabbricazione di quasi tutte le forme di piatti e anche di articoli più complessi non simmetrici; tale procedimento tuttavia presenta il fenomeno della rapidaespansione del pezzo dopo la pressatura, con conseguente danneggiamento del manufatto. Al fine di evitare l'inconveniente si aggiungono all'impasto leganti in grado di opporsi all'espansione. Il lavoro qui riportato riferisce sui risultati ottenutidall'impiego di tre alcool polivinilici, aggiunti in tre diverse percentuali in barbottine utilizzate per la preparazione di piatti con la pressatura isostatica.


1996 - Gres porcelanico: aplicaciones arquitectonicas, procesado ypropiedades fisico - mecanicas [Porcelainized stoneware: architectural, processing and physico-mechanical properties] [Articolo su rivista]
Romagnoli, Marcello; J. M., Rincon; Manfredini, Tiziano
abstract

Porcelainized stoneware is an extremely hard and homogeneous unglazed ceramic material obtained by fast-firing of kaolinitic ceramic bodies containing a large amount of fluxes. The obtained tiles, available in a large variety of colours, shape size and surface finish, are characterized by very low porosity (<0.3wt% expressed as wafer absorption) and are ideal for heavy-traffic areas subject to mechanical and chemical stresses. Porcelainized stoneware tiles offer alternative valid (and in many cases necessary) solutions to the traditional glazed tiles either for interiors or for exteriors both in modem or classic constructions for flooring and covering.


1996 - Quantitative determination of pyrite in, ceramic clay raw materials by DTA [Articolo su rivista]
Corradi, Anna; Leonelli, Cristina; Manfredini, Tiziano; Pennisi, L; Romagnoli, Marcello
abstract

The thermal oxidative decomposition in air of 0-1.5 wt% of pyrite added to two traditional powdered clays was investigated by non-isothermal DTA. It emerged that the first step of the exothermic oxidation of pyrite, in the 350-500 degrees C range, partly overlapped the endothermic dehydroxylation of clay minerals, centred at 590 degrees C, and the result was dependent on the pyrite contents. Based on the values of the area of the oxidative peak and of the corresponding oxidation heat, it is possible to calculate quantitatively the amount of pyrite present in the industrial clay bodies and therefore to inform the technicians of the factories so they can avoid the negative effects of reducing reactions that could occur during firing of ceramic raw materials.


1996 - Studio della tempo dipendenza in presenza di effetti irreversibili in sospensioni di fritte ceramiche [Relazione in Atti di Convegno]
Andreola, Nora Maria; R., Lapasin; Pozzi, Paolo; Romagnoli, Marcello
abstract

Studio della tempo dipendenza in presenza di effetti irreversibili in sospensioni di fritte ceramiche


1995 - Microestructura y propriedades de baldosas de ares porcelanico obtenidas por monococcion rapida de una tipica pasta ceramica caolinitica [Articolo su rivista]
Andreola, Nora Maria; Manfredini, T.; Pellacani, G. C.; Romagnoli, Marcello
abstract

Este estudio tiene como objetivo profundizar el conocimiento de la evoluciòn de la microestructura y correlarlas a las materias primas utilizadas; investigar las reacciones quìmicas entre los componentes presentes en las formulaciones de las pastas usadas para la producciòn de grès porcelànico y en particular los efectos de los materiales caolìniticos en el desarrollo de la microestructura del producto durante la cocciòn.


1995 - PORCELAINIZED STONEWARE TILE [Articolo su rivista]
Manfredini, Tiziano; Pellacani, Gian Carlo; Romagnoli, Marcello; Pennisi, L.
abstract

Dense, low-porosity, small-pore-size tile can be manufactured from kaolin clays at maximum firing temperatures. The unglazed porcelainized stoneware tile can be used for exterior applications and as frost-resistant materials.


1995 - Recycling of Ceramic wastes to reduce pollution [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

Exhausted limes and sludges (containing prevalently glass frits and glaze components), are waste substances to be eliminated. Recycling of about 0.10-0.15 wt% of exhausted lime and about 0.50 wt% of glass frits permits their complete elimination without affecting the industrial process. Release tests demonstrate as the firing process acts in the inertization of soluble heavy-metals ions.


1995 - Reologia di sospensioni acquose di argille deflocculate con TPF a differenti fasi cristalline [Relazione in Atti di Convegno]
Andreola, Nora Maria; Pozzi, Paolo; Romagnoli, Marcello
abstract

Reologia di sospensioni acquose di argilla deflocculate con tripolifosfato di sodio a differenti fasi cristalline.


1995 - THE MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF SINTERED CELSIAN AND STRONTIUM-CELSIAN GLASS-CERAMICS [Articolo su rivista]
Barbieri, Luisa; Corradi, Anna; Leonelli, Cristina; Manfredini, Tiziano; Romagnoli, Marcello; Siligardi, Cristina
abstract

In this paper the capability of surface nucleated barium and strontium feldspars glass-ceramics of being sintered was investigated by means of density and porosity measurements, X-ray diffraction measurements, microscopic observations and indentation testing and the results compared with those recorded on the corresponding bulk crystallized samples. The densification degree, higher than 95% of the theoretical density, and the favoured formation of thermally stable crystalline phases, such as celsian and Sr-celsian, with respect to those which present non-linear thermal expansion, hexacelsian, make sintering very useful for the production of low porosity, less than 3 vol%, materials. The microhardness values (470-780 Kg/mm2) and elastic modulus (57-115 GPa) of the sintered glass-ceramics, together with the refractoriness of the developed phases make these systems particularly suitable for structural applications.


1995 - Use of Kaolin in Stoneware Tile [Articolo su rivista]
Manfredini, T.; Pellacani, Gc; Romagnoli, Marcello; Pennisi, L.
abstract

Dense, low porosity, small-pore size tile can be manifactured from Kaolin clays at maximum firing temperature. The unglased porcelainised stoneware tile can be used for exterior application and as frost resistant materials.


1994 - Bodies, glazes and frits for single-fired tiles [Articolo su rivista]
Romagnoli, M.; Pastor, A. S.
abstract

This paper, which was held on the occasion of the conference at Rakovnicke Keramicke Zavody (Sept. 8, 1993 in Raknovik), deals with the prerequisites for the compositions of bodies as well as glazes, engobes and frits as regards their application in single-firing technology. The tiles produced by means of single-firing have a higher porosity and, in turn, a lower weight per square meter and very good adhesion to the wall when tiling. This results in cost and application advantages for monocottura tiles.


1994 - Rheological behaviour of aqueous concentrated suspensions of an Italian zeolite [Articolo su rivista]
Andreola, Nora Maria; Manfredini, T.; Pellacani, G. C.; Pozzi, Paolo; Romagnoli, Marcello
abstract

The paper reports a laboratory study on the rheological behaviour of concentrated aqueous suspensions of zeolitite, belonging to the geological formations of «tufo giallo napoletano» in the Phlegraean Fields (Campania). Rheological measurement performed by means of a rotational viscometer demonstrated how the suspensions show a practically newtonian behaviour up to about 40 wtOfo of solid content in absence of deflocculants and up to about SO wtOfo of solid content in presence of Na-SIL and Na-TPP detlocculants. At higher solid concentrations they assume a non-newtonian behaviour. Na-TPP shows a greater deflocculating ability toward zeolite suspensions than Na-SIL. This may be explained by considering, in particular, its sequestering action towards the flocculating ions.


1994 - Utilization of an Italian zeolitite in ceramic bodies [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Passaglia, Elio; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

UTILIZATION OF ITALIAN ZEOLITITE IN CERAMIC BODIESThe papers reports a laboratory and industrial study on the possibility of using an Italian natural zeolitite, both in natural and Pb-; Ba- exchanged form, in a tile ceramic body. Because of their exchangeable cation contents (Na+, K+; Ca+2, Ba+2, Pb+2), natural and exchanged zeolitites can be added (up to 20 and 5wt%, respectively) in a ceramic body, thus favouring its sinterability and unaffecting the crystalline phase formation and the final products characteristics. The addition of higher amounts enhaces the swelling of the tiles during firing and strongly modifies the features of the fired tiles. Release tests in acetic and nitric acid solutions on unfired and fired tiles containing exchanged zeolitites demostrated the inertization of lecheable Pb+2 during firing.


1993 - Addition of exhausted lime in ceramic bodies: possibilities for an environmentally compatible tile production [Articolo su rivista]
Andreola, Nora Maria; L., Bonfatti; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

Pollution caused by inorganic wastes in the traditional ceramics industry is minimised by utilising exhausted limes, which are the byproducts in bag filters after the purification of flue gases in wet tile production. This study determined which quantities of exhausted lime added to tile bodies did not significantly affect the physico-chemical properties of the slips (i.e. density /viscosity/deflocculant amount) during wet grinding in ball mills. The results demonstrated that these conditions are obtained when exhausted lime in the bodies does not exceed 0.10 to 0.12 mass%. Furthermore, any increase in fluorine emission in the firing of tiles with exhausted lime can be trapped in the bag filters by increasing the lime content by about 10 mass%. The laboratory and industrial results are also compared.


1993 - Addition of exhausted lime in ceramic bodies: possibilities for an environmentally compatible tile production III: Industrial Results [Articolo su rivista]
Andreola, Nora Maria; Bonfatti, L.; Manfredini, T.; Pellacani, G. C.; Pozzi, Paolo; Romagnoli, Marcello
abstract

study uses exhausted lime in ceramic


1993 - Non-isothermal kinetic equations applied to crystallization of glasses [Articolo su rivista]
Barbieri, Luisa; Leonelli, Cristina; Manfredini, Tiziano; Romagnoli, Marcello; Pellacani, Gian Carlo; Siligardi, Cristina
abstract

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1993 - Preparation end properties of fast-fired porcelain tiles containing natural chromite [Articolo su rivista]
Corradi, Anna; Leonelli, Cristina; Manfredini, Tiziano; Pozzi, Paolo; Romagnoli, Marcello
abstract

Natural magnesium iron chromite can be used as a pigment for coloring high-sintered porcelain tiles. However, it is important to control the amount, firing time and temperature, and size distribution of the chromite powders to produce different color shades of the fired tiles from gray to black.


1993 - Recycling of ceramic wastes in tile bodies to reduce pollution [Articolo su rivista]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Pozzi, Paolo; Romagnoli, Marcello
abstract

During recent years, special attention has been devoted both to solving pollution problems during the manufacturing of ceramics and to learning how ceramics can themselves be a solution. Waste encapsulation opportunities for structural clay products have been studied. These opportunities affect environmental isolation within the semivitreous matrix of the product and remove and destroy volatile organic components of the waste and recrystallized incinerator slags and encapsulant for such heavy metals as lead. To reduce hazards to workers and community and to realize a safe environment, some manufacturers have planned for a production process that recycles wastes. This plan represents the best option to reduce or minimize pollution by permitting the complete elimination of wastes and thus avoiding their very expensive storage in appropriate dumps. Studies have been performed to evaluate the effects of the presence of exhausted lime and sludges in tile bodies and to obtain information for the rationalization of the recycling process. The focus has been on the evaluation of the effects of the presence of wastes on the rheological and thermal behavior of the tile bodies. In addition, the efficiency of the firing process on the wastes and heavy-metals inertization has been determined by release tests of the fired products in different acidic media.


1993 - Reuse of waste lime in a ceramic body that generated it. [Articolo su rivista]
Andreola, Nora Maria; Manfredini, T.; Romagnoli, Marcello
abstract

Results are presented from studies of the effect of addns. of waste lime on the rheol. behavior of tile-body slips, the dilatometric behavior of tile bodies, water absorption and shrinkage of fired tiles, and the tile microstructure development during firing. A <0.1 wt.% addn. of waste lime had negligible effect on the apparent viscosity of slips, and an .apprx.0.5 wt.% addn. did not product significant changes in the microstructure. Control of F emissions due to recycling of the CaF2-contg. waste lime is discussed.


1993 - Rheology of a Low-Plastic Ceramic Body Containing Na-Bentonite. [Relazione in Atti di Convegno]
FERNANDA ANDREOLA, N. M.; Manfredini, T.; Pellacani, G. C.; Pozzi, Paolo; Romagnoli, Marcello
abstract

This paper reports the results of a study on the rheological behavior of slips prepared using a low-plastic body with 0-4 wt% of alkali-activated bentonite added as strengthening agent. The presence of bentonite increases the plasticity of the slips and their viscosity and thixotropy, and addition of bentonite to about2 wt% does not greatly affect the rheological conditions that regulate the industrial steps. Higher percentages of bentonite strongly modify the rheology of the slips, and in order for them to be workable, it is necessary to reduce the solid content and/or amounts of deflocculant greater than 0.5 wt%.


1992 - Reactivity of CaF2 Toward Components of Ceramic Bodies. [Relazione in Atti di Convegno]
Andreola, Nora Maria; Manfredini, Tiziano; Pellacani, Gian Carlo; Romagnoli, Marcello
abstract

The production of ceramic tiles results in the expulsion of many wastes. One of the waste substances which could be eliminated from the tile-making process is the exhausted lime which contains calcium fluoride as the main component. The maximum amount of exhausted lime which can be recycled without modifying the properties of the tiles is determined. The effects of the calcium fluoride on the microstructure of the tiles is investigated. It is discovered that addition of CaF2 greater than 0.5-1.0 wt% results in a strongly modified microstructure. Anorthite is produced at the expense of mullite leading to swelling of the tiles at the industrial firing temperatures.