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Pagina personale di Alessandro GUALTIERI

Dipartimento di Scienze Chimiche e Geologiche
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

Ventruti, Gennaro; Ventura, Giancarlo Della; Corriero, Nicola; Malferrari, Daniele; Gualtieri, Alessandro F.; Susta, Umberto; Lacalamita, Maria; Schingaro, Emanuela ( 2016 ) - In situ high-temperature X-ray diffraction and spectroscopic study of fibroferrite, FeOH(SO4)·5H2O - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 43(8) - pp. da 587 a 595 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal dehydration process of fibroferrite, FeOH(SO4)·5H2O, a secondary iron-bearing hydrous sulfate, was investigated by in situ high-temperature synchrotron X-ray powder diffraction (HT-XRPD), in situ high-temperature Fourier transform infrared spectroscopy (HT-FTIR) and thermal analysis (TGA-DTA) combined with evolved gas mass spectrometry. The data analysis allowed the determination of the stability fields and the reaction paths for this mineral as well as characterization of its high-temperature products. Five main endothermic peaks are observed in the DTA curve collected from room T up to 800 °C. Mass spectrometry of gases evolved during thermogravimetric analysis confirms that the first four mass loss steps are due to water emission, while the fifth is due to a dehydroxylation process; the final step is due to the decomposition of the remaining sulfate ion. The temperature behavior of the different phases occurring during the heating process was analyzed, and the induced structural changes are discussed. In particular, the crystal structure of a new phase, FeOH(SO4)·4H2O, appearing at about 80 °C due to release of one interstitial H2O molecule, was solved by ab initio real-space and reciprocal-space methods. This study contributes to further understanding of the dehydration mechanism and thermal stability of secondary sulfate minerals.

Lassinantti Gualtieri, E.M.; Romagnoli, M.; Gualtieri, A. ( 2015 ) - Preparation of phosphoric acid-based geopolymer foams using limestone as pore forming agent - Thermal properties by in situ XRPD and Rietveld refinements - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 35 - pp. da 3167 a 3178 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
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.

Remitti, F.; Smith, S. A. F.; Mittempergher, S.; Gualtieri, A. F.; Di Toro, G. ( 2015 ) - Frictional properties of fault zone gouges from the J-FAST drilling project (Mw9.0 2011 Tohoku-Oki earthquake) - GEOPHYSICAL RESEARCH LETTERS - n. volume 42 - pp. da 2691 a 2699 ISSN: 0094-8276 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Smectite-rich fault gouges recovered during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project (J-FAST)) from the plate boundary slip zone of the 2011 Mw 9.0 Tohoku-Oki earthquake were deformed at slip velocities of 10 µm s−1 to 3.5 m s−1 and normal stresses up to 12 MPa. Water-dampened gouges (1) are weaker (apparent friction coefficient, μ* <0.1) than room-humidity gouges (apparent friction coefficient, μ* ~0.1–0.35) at all slip velocities, (2) are velocity insensitive to velocity weakening at all slip velocities, unlike room-humidity gouges that are velocity strengthening at intermediate velocities (V = 0.001–0.1 m s−1), and (3) have negligible peak μ* at high slip velocities (V > 0.1 m s−1). A significant amount of amorphous material formed in room-humidity experiments at low- and high-slip velocities, likely by comminution and disordering of smectite. Our results indicate that the frictional properties of water-dampened gouges could have facilitated propagation of the Tohoku-oki rupture to the trench and large coseismic slip at shallow depths.

Sciancalepore, Corrado; Bondioli, Federica; Manfredini, Tiziano; Gualtieri, Alessandro ( 2014 ) - Quantitative phase analysis and microstructure characterization of magnetite nanocrystals obtained by microwave assisted non-hydrolytic sol–gel synthesis - MATERIALS CHARACTERIZATION - n. volume 100 - pp. da 88 a 97 ISSN: 1044-5803 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An innovative preparation procedure, based on microwave assisted non-hydrolytic sol-gel synthesis, to obtain spherical magnetite nanoparticles was reported together with a detailed quantitative phase analysis and microstructure characterization of the synthetic products. The nanoparticle growth was analyzed as a function of the synthesis time and was described in terms of crystallization degree employing the Rietveld method on the magnetic nanostructured system for the determination of the amorphous content using hematite as internal standard. Product crystallinity increases as the microwave thermal treatment is increased and reaches very high percentages for synthesis times longer than 1 h. Microstructural evolution of nanocrystals was followed by the integral breadth methods to obtain information on the crystallite size-strain distribution. The results of diffraction line profile analysis were compared with nanoparticle grain distribution estimated by dimensional analysis of the transmission electron microscopy (TEM) images. A variation both in the average grain size and in the distribution of the coherently diffraction domains is evidenced, allowing to suppose a relationship between the two quantities. The traditional integral breadth methods have proven to be valid for a rapid assessment of the diffraction line broadening effects in the above-mentioned nanostructured systems and the basic assumption for the correct use of these methods are discussed as well.

Remitti, F.; Smith, S.; Gualtieri, A.; Di Toro, G.; Nielsen, S. ( 2014 ) - Frictional properties of fault rocks along the shallow part of the JapanTrench décollement: insights from samples recovered during the Integrated Ocean Drilling Project Expedition 343 (the JFAST project). ( EGU General Assembly 2014 - - 27 April – 02 May 2014) ( - EGU General Assembly 2014 ) - GEOPHYSICAL RESEARCH ABSTRACTS - n. volume 16 [Abstract in rivista (266) - Abstract in Rivista]
Abstract

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Marcello Romagnoli;Magdalena Lassinantti Gualtieri;Alessandro F. Gualtieri; Reimondas Šliteris; Rymantas Kažys; Giuliano Tari ( 2013 ) - Anisotropy of green stoneware evaluated by ultrasound measurements in combination with texture analyses - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 33 - pp. da 2785 a 2792 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
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.

Gualtieri, Alessandro ( 2013 ) - Recycling asbestos containing material (ACM) from construction and demolition waste (CDW) ( - Handbook of Recycled Concrete and Demolition Waste ) (Woodhead Publishing Cambridge (UK) GBR ) - pp. da 500 a 525 ISBN: 0857096907 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Asbestos containing materials (ACMs) are a class of hazardous waste ...

GUALTIERI, Alessandro, C. Giacobbe, C. Rinaudo, A. Croce, M. Allegrina, G. Gaudino, H. Yang, M, Carbone ( 2013 ) - Preliminary results of the spectroscopic and structural characterization of mesothelioma inducing crocidolite fibers injected in mice - PERIODICO DI MINERALOGIA - n. volume 82(2) - pp. da 299 a 312 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

To investigate the structure and microstructure changes of crocidolite asbestos incorporated in biological tissues, fibers of this mineral phase were injected in mice peritoneum. Histological sections of different organs of mice developing mesothelioma after crocidolite inoculation were prepared and analysed by optical microscopy. The tumours developed within the peritoneal cavity, wrapped around the surrounding organs. Many fibres were observed in the fibrotic areas of the peritoneum lining pancreas and spleen. The raw fibers before inoculation and those embedded in mice tissues were characterized using Micro-Raman spectroscopy and in situ synchrotron X-ray diffraction at ESRF- Grenoble. Preliminary results indicate shifts of some bands on the Raman spectra and enlargement of the X-Ray diffraction peaks of the fibers localized in the mice tissue sections. A preliminary structural picture of the fibers incorporated in mice tissues suggests inter-crystalline migration of the iron and sodium ions.

Ventruti, Gennaro; Scordari, Fernando; Ventura, Giancarlo Della; Bellatreccia, Fabio; GUALTIERI, Alessandro; Lausi, Andrea ( 2013 ) - The thermal stability of sideronatrite and its decomposition products in the system Na2O–Fe2O3–SO2–H2O - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 40 - pp. da 659 a 670 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal stability of sideronatrite, ideally Na2Fe3+(SO4)2(OH)·3(H2O), and its decomposition products were investigated by combining thermogravimetric and differential thermal analysis, in situ high-temperature X-ray powder diffraction (HT-XRPD) and Fourier transform infrared spectroscopy (HT-FTIR). The data show that for increasing temperature there are four main dehydration/transformation steps in sideronatrite: (a) between 30 and 40 °C sideronatrite transforms into metasideronatrite after the loss of two water molecules; both XRD and FTIR suggest that this transformation occurs via minor adjustments in the building block. (b) between 120 and 300 °C metasideronatrite transforms into metasideronatrite II, a still poorly characterized phase with possible orthorhombic symmetry, consequently to the loss of an additional water molecule; X-ray diffraction data suggest that metasideronatrite disappears from the assemblage above 175 °C. (c) between 315 and 415 °C metasideronatrite II transforms into the anhydrous Na3Fe(SO4)3 compound. This step occurs via the loss of hydroxyl groups that involves the breakdown of the [Fe3+(SO4)2(OH)] ∞ 2− chains and the formation of an intermediate transient amorphous phase precursor of Na3Fe(SO4)3. (d) for T > 500 °C, the Na3Fe(SO4)3 compound is replaced by the Na-sulfate thenardite, Na2SO4, plus Fe-oxides, according to the Na3Fe3+(SO4)3 → 3/2 Na2(SO4) + 1/2 Fe2O3 + SOx reaction products. The Na–Fe sulfate disappears around 540 °C. For higher temperatures, the Na-sulfates decomposes and only hematite survives in the final product. The understanding of the thermal behavior of minerals such as sideronatrite and related sulfates is important both from an environmental point of view, due to the presence of these phases in evaporitic deposits, soils and sediments including extraterrestrial occurrences, and from the technological point of view, due to the use of these materials in many industrial applications.

Viani, A.; GUALTIERI, Alessandro; Secco, M.; Peruzzo, L.; Artioli, G.; Cruciani, G. ( 2013 ) - Crystal chemistry of cement-asbestos - AMERICAN MINERALOGIST - n. volume 98 - pp. da 1095 a 1105 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

A study of a representative number of cement-asbestos (CA) samples removed from different localities in Italy has been accomplished with a combination of analytical techniques, including XRF, XRPD, SEM/EDS, micro-Raman, and electron backscattered diffraction (EBSD), to elucidate the mineralogical and chemical variability of this class of building materials on a large scale. We describe a complex mineralogy including phases of cement hydration, residual non-hydrated components, and a relevant fraction attributed to various processes of deterioration. With the aid of the CaO-MgO-SiO2 compositional diagram, three groups of CAs have been identified on the basis of their chemical parameters. This result is important for environmental and waste management issues.

Magdalena Lassinantti Gualtieri; Marcello Romagnoli; Paola Miselli; Maria Cannio; Alessandro F. Gualtieri ( 2012 ) - Full quantitative phase analysis of hydrated lime using the Rietveld method - CEMENT AND CONCRETE RESEARCH - n. volume 42(9) - pp. da 1273 a 1279 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
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.%.

Alessandro F. Gualtieri; Alberto Viani; Giulia Sgarbi; Gigliola Lusvardi ( 2012 ) - In vitro biodurability of the product of thermal transformation of cement–asbestos - JOURNAL OF HAZARDOUS MATERIALS - n. volume 205-206 - pp. da 63 a 71 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

To safely recycle the product of the thermal transformation of cement–asbestos as secondary raw material,its toxicity potential should be assessed by in vitro biodurability tests. In this work, the acellularin vitro biodurability of the products of transformation of cement–asbestos at 1200 ◦C (named KRY·AS)was tested using both inorganic and organic simulated lung fluids at pH 4.5. The dissolution kineticswere followed using chemical, mineralogical and microstructural analyses. The total dissolution timeestimated from the experiments with inorganic HCl diluted solution is one order of magnitude higherthan that determined from the experiments with buffered Gamble solution (253 days vs. 20 days). Thekey parameter determining the difference in dissolution rate turns out to be the solidus/liquidus ratiowhich prompts a fast saturation of the solution with monosilicic acid. The calculated dissolution rateconstants showed that the biodurability in vitro of KRY·AS is much lower with respect to that of standardchrysotile asbestos (total estimated dissolution time of 20 days vs. 298 days, respectively). This proves alow potential toxicity of this secondary raw material.

GUALTIERI, Alessandro; PADOVANI, VERONICA editori; autori capitoli: R. Bertolani, A.I. Telloni, A.F. Gualtieri, V. Padovani, F. Catellani Degani, C. Jacoboni, A. Forni, A. Vescogni, A. Chiesi, R. Mattioli, B. Salvarani ( 2012 ) - Symmetria frammenti di armonia universale (Edizioni il Fiorino Modena ITA ) - pp. da 1 a 125 ISBN: 978-88-7549-417-9 ISSN: - [Monografia o trattato scientifico (276) - Monografia/Trattato scientifico]
Abstract

non diponibile

GUALTIERI, Alessandro ( 2012 ) - Mineral fibrebased building materials and their health hazards ( - Toxicity of building materials ) (Woodhead Publishing Cambridge (UK) GBR ) - pp. da 166 a 195 ISBN: 0857096354 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Asbestos minerals have always been considered somehow magic ...

GUALTIERI, Alessandro; Veratti, Linda; Tucci, Antonella; Esposito, Leonardo ( 2012 ) - Recycling of the product of thermal inertization of cement-asbestos in geopolymers - CONSTRUCTION AND BUILDING MATERIALS - n. volume 31 - pp. da 47 a 51 ISSN: 0950-0618 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials has become a priority of waste handling in the worldwide environmental agenda. A novel secondary raw material of great importance is the product of the thermal transformation of cement-asbestos, which is chemically comparable to a Mg-rich clinker. Recently, this secondary raw material called KRY•AS has been successfully used for the production of concrete. In this work it has been used for the production of geopolymers. Geopolymers represent a class of synthetic alumino-silicate based materials potentially used in several industrial fields, and in particular in substitution of cements or mortars, with the positive advantage of reducing the emissions of carbon dioxide developed during the clinkering phase. Geopolymers are the result of a reaction of an alumino-silicate, usually metakaolinite, activated with an alkaline silicate solution at room temperature. In the present work, geopolymers obtained from alumino-silicate natural materials mixed with KRY•AS were prepared and characterized. The composition with 2.5 wt.% of KRY•AS presents the best physical and mechanical properties. The presence of KRY•AS introduces about 30 wt.% of amorphous phase in the system. The crystalline component of KRY•AS decomposes in strong basic conditions releasing elements such as calcium and silicon that promote the formation of calcium precipitates and/or minor paracrystalline silicate hydrates. These are responsible for the improved technological performances.

Tobaldi, David M.; Gao, Lian; GUALTIERI, Alessandro; Škapin, Andrijana Sever; Tucci, Antonella; Giacobbe, Carlotta ( 2012 ) - Mineralogical and Optical Characterization of SiO2-, N-, and SiO2/N-Co-Doped Titania Nanopowders - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 95 - pp. da 1709 a 1716 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silica, nitrogen, and nitrogen-plus-silica co-doped titania powders were synthesized via sol–gel method. The products of the synthesis were thermally treated in air and under ammonia flow. The determination of Si and/or N into the TiO2 lattice, and the doped samples' crystal structure, was made by means of X-ray powder diffraction, whilst the occurrence of amorphous phase was obtained using the combined Rietveld-RIR method. The optical properties of the powders were obtained by diffuse reflectance spectroscopy and their energy band gaps were calculated using the differential reflectance method. The photocatalytic activity of the doped samples was assessed in gas phase under UV-light and visible-light irradiation, monitoring the degradation of an organic compound. In addition, the morphology of the samples was further on characterized by means of HRTEM. Nitrogen, silica, and co-doping shifted the anatase-to-rutile (A [RIGHTWARDS ARROW] R) phase transition toward higher temperatures. Silica was found to enter the anatase lattice, and nitrogen was presumed to enter the titania crystal structure as well. Nitrogen doping and SiO2/N-co-doping shifted the light absorption toward the visible region.

GUALTIERI, Alessandro; Giacobbe, C.; Viti, C. ( 2012 ) - The dehydroxylation of serpentine group minerals - AMERICAN MINERALOGIST - n. volume 97 - pp. da 666 a 680 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal transformation, stability field, and reaction kinetics of serpentine minerals (antigorite, chrysotile, and lizardite) have been studied to draw a comprehensive model for their dehydroxylation and recrystallization reactions. In situ X-ray powder diffraction (XRPD) and kinetic studies were combined with transmission electron microscopy (TEM) observations to describe the mechanisms of dehydroxylation and later high-temperature crystallization. During dehydroxylation, a metastable transition phase with a characteristic peak around 9 Å was observed in antigorite and, to a minor extent, in lizardite. Rietveld refinements confirmed that the 9 Å phase actually possesses a talc-like structure. The appearance of this phase is controlled by structure and kinetic factors. The kinetic parameters and reaction mechanism for lizardite and antigorite dehydroxylation in air at ambient pressure were calculated using the Avrami models and compared to those of chrysotile. For both lizardite and antigorite, the kinetics of dehydroxylation is controlled by diffusion. Apparent activation energy of the reaction in the temperature range 612–708 °C was 221 and 255 kJ/mol for lizardite and antigorite, respectively. The reaction sequences of chrysotile, lizardite, and antigorite leading to the formation of stable high-temperature products (i.e., forsterite and enstatite) are described taking into account previous topotactic and dissolution-recrystallization models.

A. F. Gualtieri; M. Boccaletti ( 2011 ) - Recycling of the product of thermal inertization of cement-asbestos for the production of concrete. - CONSTRUCTION AND BUILDING MATERIALS - n. volume 25 - pp. da 3561 a 3569 ISSN: 0950-0618 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A novel field of research in materials science is the recycling of secondary raw materials for constructionand building materials such as concrete. This paper describes the successful recycling of as much as20 wt% of the product of thermal transformation of cement–asbestos for the formulation of concrete.The main mineralogical phases present in the product of transformation of cement–asbestos are C2S, ferrite,and Al-, Ca-, Mg-rich silicates such as akermanite (ideally Ca2MgSi2O7) and merwinite (ideallyCa3Mg2Si2O8). The behavior of this secondary raw material, termed KRYAS, in commercial concretewas investigated using five different mixtures in which various portions (0, 5, 10, 15 and 20 wt%) ofcement were substituted by KRYAS. The results of preliminary technological tests (slump test, compressivestrength, flexural strength after 28 days, and depth of penetration of water under pressure after28 days) were discussed and interpreted with the aid of chemical, mineralogical and SEM analyses.One of the major results is that after 28 days, although all the concrete samples are invariably classifiedas ‘‘ordinary concrete’’ according to the UNI 6132 tests, those diluted with KRYAS display a lower resistanceto compression with respect to the standard. On the other hand, they recover compressive strengthand display values identical to that of the standard after 90 days. The addition of the secondary raw materialhas the effect to slow down the kinetics of setting/hardening because the main cement phase presentin KRYAS is C2S which has a slower rate of hydration with respect to C3S.

M. Lassinantti Gualtieri; M. Romagnoli; A.F. Gualtieri ( 2011 ) - Influence of body composition on the technological properties and mineralogy of stoneware: A DOE and mineralogical–microstructural study - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 31 - pp. da 673 a 685 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
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.

Alessandro Francesco Gualtieri; Giovanni B. Andreozzi; Carlotta Giacobbe;Gigliola Lusvardi;Cecilia Viti ( 2011 ) - Structural and spectroscopic characterization of anorthite synthesized from secondary raw materials - PERIODICO DI MINERALOGIA - n. volume 80,2 - pp. da 231 a 245 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials is a priority of waste handling in the countries of theEuropean community. A virtual secondary raw material of great importance is the product ofthe thermal transformation of cement – asbestos. This work illustrates the study of calcinationproducts obtained starting from the product of the thermal transformation of cement-asbestosat 1200 °C, added to primary raw materials (kaolin, aluminum hydroxide) and boric acid asmineralizing agent. The calcination has been conducted at 1200 °C for 1 hour. Thecrystallization kinetics has been monitored using in situ high temperature X-ray powderdiffraction. The microscopic characterization of the final product of calcination has beenconducted with SEM and TEM imaging supported by X-ray microanalysis. The structurerefinement was conducted on the powder sample using the Rietveld method. The results arecompared with the spectroscopic characterization including Mössbauer and UV-Visspectroscopies. The final product of the calcination is essentially anorthite (about 89 wt%)with minor spinel (11 wt%). All experimental data converge to support the hypothesis thatthe anorthite is stoichiometric, and the small amounts of iron detected (1.32 wt%) is Fe3+hosted in the structure of spinel

F. Scordari; G. Ventruti; A.F. Gualtieri; A. Lausi ( 2011 ) - Crystal structure of Na3Fe(SO4)3: a high-temperature product (ca. 400 °C) of sideronatrite [Na3Fe(SO4)2OH•3H2O]. - AMERICAN MINERALOGIST - n. volume 96 - pp. da 1107 a 1111 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The iron sulfate Na3Fe(SO4)3 studied here has been obtained as a high-temperature (HT) product (∼400 °C) from the thermal decomposition of sideronatrite from Sierra Gorda (Chile) having compositionNa2Fe(SO4)2(OH)⋅3H2O. The structure determination was carried out using synchrotron X‑ray powder diffraction. Structural data refined by the Rietveld method, up to Rp = 11.95%, are: space group R3, lattice parameters a = b = 13.6231(1) Å and c = 9.0698(1) Å, V = 1457.76(2) Å3, and Z = 6. The structure of Na3Fe(SO4)3 can be described in terms of FeO6 octahedra connected to sulfate tetrahedra by corner-sharing to form infinite chains [Fe(SO4)3]∞, running along c. These chains are joined together by Na atoms to build up a three-dimensional network of strong (Fe-O-S) and weak (Na-O) bonds. The topological relationships of Na3Fe(SO4)3 to the structure of some analog minerals are also discussed.

C. Viti; C. Giacobbe; A.F. Gualtieri ( 2011 ) - Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations. - AMERICAN MINERALOGIST - n. volume 96 - pp. da 1003 a 1011 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

There is increasing concern about the health hazard of asbestos from natural geologic deposits such as greenstones [natural occurring asbestos (NOA)]. Therefore, quantitative determination of the chrysotile asbestos content within massive serpentinites is a recurrent requirement of recent asbestos-inherent law regulations, due to the possible health hazard associated with the release of chrysotile fibers. Unfortunately, the obtainment of accurate and precise quantitative figures of the actual chrysotile content is strongly complicated by typical serpentinite textures, consisting of fine-to-ultrafine intergrowths of fibrous and non-fibrous serpentine minerals, often difficult to identify by conventional methods, such as X-ray diffraction or microanalytical approaches.In this paper, we propose a reliable and straightforward method for the quantitative determination of chrysotile asbestos within bulk massive serpentinites, based on thermal analysis data and, specifically, on the distinctive thermal behavior of chrysotile, lizardite, and antigorite during dehydroxylation at 500–800 °C. Deconvolution processing of DTA endothermic signals in the dehydroxylation temperaturerange revealed good linear correlation between peak area ratios and chrysotile content, for both lizardite + chrysotile and antigorite + chrysotile samples. The DTA correlation curves have been used to determine the chrysotile content in two test serpentinites, revealing surprisingly high-chrysotile content. This novel method is of vast importance as it represents one of the most promising tools for chrysotile quantitative determinations in massive serpentinites, providing unbiased and accurate responses to recent asbestos-related law requirements.

Alessandro F. Gualtieri;Carlotta Giacobbe;Lorenza Sardisco;Michele Saraceno;Magdalena Lassinantti Gualtieri; Gigliola Lusvardi;Cinzia Cavenati; Ivano Zanatto ( 2011 ) - Recycling of the product of thermal inertization of cement–asbestosfor various industrial applications - WASTE MANAGEMENT - n. volume 31 - pp. da 91 a 100 ISSN: 0956-053X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials is a priority of waste handling in the countries of the Europeancommunity. A potentially important secondary raw material is the product of the thermal transformationof cement–asbestos, produced by prolonged annealing at 1200–1300C. The product is chemically comparableto a Mg-rich clinker. Previous work has assured the reliability of the transformation process. Thecurrent challenge is to find potential applications as secondary raw material. Recycling of thermally treatedasbestos-containing material (named KRY-AS) in traditional ceramics has already been studied withsuccessful results.The results presented here are the outcome of a long termed project started in 2005 and devoted to therecycling of this secondary raw materials in various industrial applications. KRY-AS can be added in medium-high percentages (10–40 wt%) to commercial mixtures for the production of clay bricks, rock-woolglasses for insulation as well as Ca-based frits and glass–ceramics for the production of ceramic tiles. Thesecondary raw material was also used for the synthesis of two ceramic pigments; a green uvarovite-basedpigment [Ca3Cr2(SiO4)3] and a pink malayaite-based pigment [Ca(Sn,Cr)SiO5]. The latter is especiallyinteresting as a substitute for cadmium-based pigments. This work also shows that KRY-AS can replacestandard fillers in polypropylene plastics without altering the properties of the final product. For eachapplication, a description and relevant results are presented and discussed.

A.F. Gualtieri; C. Giacobbe; M. Tonelli; C. Viti ( 2010 ) - Se Plinio avesse un diffrattometro… le trasformazioni ad alta temperatura del serpentino rivelate. - ATTI DELLA SOCIETÀ DEI NATURALISTI E MATEMATICI DI MODENA - n. volume 141 - pp. da 61 a 71 ISSN: 0365-7027 [Articolo in rivista (262) - Articolo su rivista]
Abstract

La famiglia dei minerali del serpentino comprende principalmente il crisotilo (o amianto bianco), la lizardite e l’antigorite. Il più famoso di questi è sicuramente l’amianto bianco che grazie alle sue eccezionali proprietà è noto sin dall’antichità. Plinio il vecchio nel Naturalis Historiae (36, 139 D.C.) ne descrive la capacità di resistere al fuoco. Oggi siamo in grado di comprendere a fondo questa proprietà e definire fino a che punto la struttura molecolare è in grado di resistere al fuoco.In questo lavoro, è stato studiato il campo di stabilità in temperatura dei minerali del serpentino, i relativi prodotti di trasformazione e le cinetiche di reazione dei tre principali polimorfi per una migliore comprensione dei fenomeni petrologici e delle applicazioni in campo industriale ed ambientale.

Federica, Giantomassi; Gualtieri, Alessandro; Lory, Santarelli; Marco, Tomasetti; Lusvardi, Gigliola; Guendalina, Lucarini; Mario, Governa; Armanda, Pugnaloni ( 2010 ) - Biological effects and comparative cytotoxicity of thermal transformed asbestos-containing materials in a human alveolar epithelial cell line - TOXICOLOGY IN VITRO - n. volume 24 - pp. da 1521 a 1531 ISSN: 0887-2333 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Asbestos fibres can be transformed into potentially non-hazardous silicates by high-temperature treatmentvia complete solid-state transformation.A549 cells were exposed to standard concentrations of raw cement asbestos (RCA), chrysotile and cement asbestos subjected to an industrial process at 1200C (Cry_1200 and KRY-AS, respectively),raw commercial grey cement (GC). Cell growth rate and viability (MTT test) were detected in vitro. RCA and KRY-AS subjected to comprehensive microstructural study by electron microscopy were furtherin vitro assayed to compare their cytotoxic potential by morphostructural studies, proliferation index (Ki-67 antigen), apoptosis induction (AO/EB staining) assays and detection of intracellular reactive oxygen species (ROS) with the fluorescent DCFA dye. More severe cytotoxic damage was induced by RCA than by KRY-AS after each incubation period. Exposure to KRY-AS and GC resulted in comparable cell growth rates and cytotoxic effects. Cells incubated with RCA showed greater apoptotic induction and ROS production and a lower cell proliferation index than those exposed to KRY-AS. Chrysotile asbestos and RCA subjected to heat treatment underwent complete microstructure transformation. The final productof heat treatment of cement asbestos, KRY-AS, was considerably more inert and had lower cytotoxic potential than the original asbestos material in all in vitro tests

Alessandro F. Gualtieri; Dario Mangano; Magdalena Lassinantti Gualtieri; Anna Ricchi; Elisabetta Foresti; Giorgio Lesci; Norberto Roveri; Mauro Mariotti; Giovanni Pecchini ( 2009 ) - Ambient monitoring of asbestos in selected Italian living areas - JOURNAL OF ENVIRONMENTAL MANAGEMENT - n. volume 90 - pp. da 3540 a 3552 ISSN: 0301-4797 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper presents the results of an intensive monitoring activity of the particulate, fall-out and soil of selected living areas in Italy with the aim to detect the asbestos concentration in air and subsequent risk of exposure for the population in ambient living environments, and to assess the nature of the other mineral phases composing the particulate matrix. Some areas were sorted out because of the presence of asbestos containing materials on site whereas others were used as blank spots in the attempt to detect the background environmental concentration of asbestos in air. Because the concentration of asbestos in ambient environments is presumably very low, and it is well known that conventional low-medium flow sampling systems with filters of small diameter (25 mm) may collect only a very small fraction of particulate over a short period, for the first time here, an intense monitoring activity was conducted with a high flow sampling system. The high flow system requires the use of large cellulose filters with the advantage that, increasing the amount of collect dust, the probability to collect asbestos fibers increases. Both the protocol of monitoring and analysis are novel and prompted by the need to increase the sensitivity towards the small number of expected fibers. With this goal, the collection of fall-out samples (the particulate falling into a collector filled with distilled water during the monitoring shift) and soil samples was also accomplished. The analytical protocol of the matrix particulate included preliminary X-ray powder diffraction (XRPD), optical microscopy and quantitative electron microscopy (SEM and TEM). Correlations with climatic trends and PM10 concentration data were also attempted.The surprising outcome of this work is that, despite the nature of the investigated site, the amount of dispersed asbestos fibers is very low and invariably lower than the theoretical method detection limits of the SEM and TEM techniques for identification and counting of asbestos fibers. The results are compared to the literature data worldwide and an updated model for asbestos fibers dispersion in ambient environment is proposed.

M. Lassinantti Gualtieri; A. F. Gualtieri; M. Prudenziati ( 2008 ) - Seeded growth of TPA-MFI films using the fluoride methods - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 111 - pp. da 604 a 611 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The fluoride route in combination with surface seeding was used for the preparation of TPA-MFI films on dense amorphous silica glass supports. The use of F− as mineralizing agent allowed the crystallization of TPA-MFI at near-neutral pH (6.7 ± 0.1). The supports were seeded with colloidal TPA-MFI crystals and hydrothermally treated in a synthesis gel at 100 °C for various durations (24–192 h). The synthesis products were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). A film growth rate of about 9 nm/h was found. The crystals in these films exhibit a preferred orientation, with the (1 0 1) planes of the crystals parallel or near parallel to the support surface. Film growth in the near-neutral synthesis gel was also attempted on seeded porous α-alumina supports. However, epitaxial growth of the seed crystals was inhibited by the formation of a uniform layer of colloidal silica particle which covered the seed crystals even in an early stage of hydrothermal treatment. Continuous films could only be prepared by increasing the pH of the initial synthesis mixture from 6.7 to 9.6, thus using both OH− and F− as mineralizing agents. These films are composed of a columnar layer on top of a layer built up of small grains. Such microstructure has previously been reported in the literature for TPA-MFI films grown in conventional synthesis mixtures.

E. Galli; A.F. Gualtieri ( 2008 ) - Direnzoite, [NaK6MgCa2(Al13Si47O120)•36H2O], a new zeolite from Massif Central (France): Description and crystal structure - AMERICAN MINERALOGIST - n. volume 93 - pp. da 95 a 102 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structure of direnzoite, a new natural zeolite found in the cavities of a xenolitic rock from the Massif Central (France) is reported. Apparently, direnzoite was formed throughout a process of hydrothermal crystallization within the vugs of a highly porphyric basalt. The determination of the crystal structure of this new zeolite was at the limits of the existing experimental techniques because of the paucity of available specimen, mainly composed of three tiny aggregates of fibrous microcrystals. The structure of direnzoite, solved by powder methods, was shown to be the K-dominant equivalent of the synthetic zeolite ECR-1 with a framework composed of layers of mordenite (MOR) and mazzite (MAZ) connected in a regular 1:1 stacking sequence with assigned framework topology EON. The chemical composition of direnzoite determined from the structure refinement is (Na0.94K6.62Mg1.42 Ca2.24)(Si,Al)60O120·36.8H2O. The unit cell determined from the Rietveld structure refinement is a = 7.57887(18) Å, b = 18.20098(57) Å, c = 26.15387(83) Å, and the space group is Pmmn.Six extra-framework sites and 14 water molecules were identified within the zeolite micropores. Three extra-framework sites are occupied by K+ ions. The others are occupied by Na+, Ca++, and Mg++. Although direnzoite and ECR-1 share the same framework, the distribution of their extra-framework cations is rather different. In direnzoite, there are no equivalent positions to C1, C2, and C4 positionsfound in ECR-1. Only sites C3 and C3b correspond respectively to K3 and Ca in direnzoite. In direnzoite, K1, K2, and Na correspond to water molecules sites (H2O1, H2O11, and H2O8, respectively)in ECR-1.

A. F. Gualtieri; C. Cavenati; I. Zanatto; M. Meloni; G. Elmi; M. Lassinantti Gualtieri ( 2008 ) - The transformation sequence of cement-asbetsos slates up to 1200 °C and safe recycling of the transformation product in stoneware tile mixtures - JOURNAL OF HAZARDOUS MATERIALS - n. volume 152 - pp. da 563 a 570 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cement–asbestos is the main asbestos containing material still found in most of the European countries such as Italy. Man- and weatheringinduceddegradation of the cement–asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern.This concern is the main prompt for the actual policy of abatement and disposal of asbestos containing materials in controlled wastes. An alternativesolution to the disposal in dumping sites is the direct temperature-induced transformation of the cement–asbestos slates into non-hazardous mineralphases. This patented process avoids the stage of mechanical milling of the material before the treatment, which improves the reactivity of thematerials but may be critical for the dispersion of asbestos fibres inworking and life environment. For the first time, this paper reports the descriptionof the reaction path taking place during the firing of cement–asbestos slates up to the complete transformation temperature, 1200 ◦C. The reactionsequence was investigated using different experimental techniques such as optical and electron microscopy, in situ and ex situ quali-quantitativeX-ray powder diffraction. The understanding of the complex reaction path is of basic importance for the optimization of industrial heating processesleading to a safe recycling of the transformed product.For the recycling of asbestos containing materials, the Italian laws require that the product of the crystal chemical transformation of asbestoscontaining materials must be entirely asbestos-free, and should not contain more than 0.1 wt% fraction of the carcinogenic substances such ascristobalite. Moreover, if fibrous phases other than asbestos (with length to diameter ratio >3) are found, they must have a geometrical diameterlarger than 3m. We have demonstrated that using an interplay of different experimental techniques, it is possible to safely verify the completetransformation of asbestos minerals in this temperature-induced process.The product of transformation of cement–asbestos (CATP) has a phase composition similar to that of a natural or a low temperature clinker withthe exception of having a larger content of aluminium, iron and magnesium. This product can be safely recycled for the production of stonewaretile mixtures. The addition of 3–5 mass% of CATP does not bear significant variations to the standard parameters of white porcelain tile mixtures.

M. LASSINANTTI GUALTIERI; C. ANDERSSON; F. JAREMAN; J. HEDLUND; A. GUALTIERI; M. LEONI; C. MENEGHINI ( 2007 ) - Crack formation in a-alumina supported MFI zeolite membranes studied by in situ high temperature synchrotron powder diffraction (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - JOURNAL OF MEMBRANE SCIENCE - n. volume 290 - pp. da 95 a 104 ISSN: 0376-7388 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cracks are frequently formed in α-alumina supported MFI membranes during calcination. To better understand crack formation, in situ powder diffraction data were collected during calcination of a type of MFI membrane (ca. 1800 nm thick) which is known to crack reproducibly. In addition, data for MFI powder and a blank support were also collected. Both a synchrotron radiation facility and an in-house instrument were used. The unit cell parameters were determined with the Rietveld method, and the strain in the direction perpendicular to the film surface was calculated for the film as well as for the support. The microstrain in the support was also estimated. Based on the results obtained here, a model for crack formation in this type of MFI membrane was proposed. The lack of cracks in other types of MFI membranes (ca. 500 nm) prepared in our laboratory is also explained by the model. In thicker MFI films, the crystals are well intergrown. During heating, the MFI crystals contract and the α-alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks in the film and structural defects in the support. In thinner films, the crystals are less well intergrown and the thermal expansion mismatch leads to opening of grain boundaries rather than cracks.

MAGDALENA LASSINANTTI GUALTIERI; M. PRUDENZIATI; ALESSANDRO F. GUALTIERI ( 2007 ) - Quantitative determination of the Amorphous Content in Plasma Sprayed Alumina Coatings using the Rietveld method (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - SURFACE & COATINGS TECHNOLOGY - n. volume 201 - pp. da 2984 a 2989 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Plasma-sprayed Al2O3 coatings mainly consist of gamma-Al2O3 with minor amountts of alpha-Al2O3 due to incorporation of incompletely fused powder. The presence of amorphous materials was also mentioned in the literature, but not quantified. In this work, x-ray powder diffraction and Rietveld refinements were explored as potential tools for the determination of the amorphous content in plasma sprayed Al2O3 coatings. To cross-check the accuracy of the Rietveld analysis, stardard additions of amorphous Al2O3 were performed. Both approaches provided consistent results supporting the validity of the Rietveld method for routine quantification of the amorphous phase in plasma-sprayed Al2O3. For the as-sprayed coatings studied in the present work, the amount of amorphous Al2O3 was found to be 12.0 % +-0.7 wt.%.

A.F. Gualtieri ( 2007 ) - Thermal behavior of the raw materials forming porcelain stoneware mixtures by combined optical and in situ X-Ray dilatometry - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 90(4) - pp. da 1222 a 1231 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The dilatometric behavior of the raw materials forming a porcelainstoneware tile mixture was investigated at a molecular/microscopical scale by combined in situ optical dilatometry andX-ray powder diffraction. Each single raw material was investigatedseparately and mixed with all the others to simulate astandard production mixture. Thus, it was possible to evaluatewhether the reaction path taking place during the firing of theraw materials is changed during the firing of the combined mixture.A general classification of the causes of contraction and/orexpansion events has been attempted. Causes are subdivided intostructural (S, intra-mineral) and microstructural (M, inter-mineral).Contractions can be generated by: loss of volatiles (S);structure collapse of the pseudo-amorphous products of dehydroxylationof clay minerals (S); solid state or viscous sintering(M); crystallization from amorphous precursor (S) and relatedvolume reduction (densification) (M); displacive phase transitionwith a volume decrease (S); and melting generally at T48001C(S). Expansion can be generated by thermal expansion (S);displacive phase transition with a volume increase (S); glasstransitions (S) and related volume change (M); and overfiring/pyroplastic deformation (M). Many reactions observed in thesingle raw materials have also been observed in the mixture. Themajor variations concern (i) crystallization of cristobalite is observedonly in the kaolin and not in the mixture, where silicasegregated from the reaction of formation of mullite from metakaoliniteis readily incorporated in the alkaline amorphousphase; (ii) quartz alone is stable with temperature but tends tobe partly decomposed in contact with the alkaline melt in themixture; and (iii) in the illite-rich clay, melting of the system andsubsequent expansion caused by pyroplastic deformation of theK-rich melt begins at relatively low temperature (11501C). Thisbehavior is not observed in the mixture below 13501C where apresumably less viscous melt is formed.

M. LASSINANTTI GUALTIERI; M. PRUDENZIATI; A. GUALTIERI ( 2006 ) - Quantitative determination of the amorphous phase in plasma sprayed alumina coatings using the Rietveld method (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - SURFACE & COATINGS TECHNOLOGY - n. volume 201 - pp. da 2984 a 2989 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Plasma-sprayed alumina coatings mainly consist of γ-alumina with minor amounts of α-alumina due to incorporation of incompletely fused powder. The presence of amorphous materials has also been mentioned in the literature, but not quantified. In this work, X-ray powder diffraction and Rietveld refinements were explored as potential tools for the determination of the amorphous content in plasma sprayed alumina coatings. To cross-check the accuracy of the Rietveld analysis, standard additions of amorphous alumina were performed. Both approaches provided consistent results supporting the validity of the Rietveld method for routine quantification of the amorphous phase in plasma-sprayed alumina. For the as-sprayed coatings studied in the present work, the amount of amorphous alumina was found to be 12.0 ± 0.7 wt.%.

A. GUALTIERI; G. ELMI ( 2006 ) - Understanding the high temperature reaction sequence during the thermal treatment of cement-asbestos slates ( European Conference on Asbestos Risks and management - - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (Pubblicazione ISPESL ROMA ITA ) - n. volume - - pp. da 187 a 192 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This paper reports the description of the reaction path taking place during the firing of cement-asbestos slates followed using different experimental techniques (optical microscopy, SEM, TEM , quali- quantitative X-Ray powder diffraction, FTIR). It will be demonstrated that only an interplay of different experimental techniques (mainly diffraction end electron microscopy) can lead to a safe verification of the yield of thermal transformation of asbestos minerals. The understanding of the complex temperature induced reaction path is of paramount importance for the optimization of industrial heating processes to yield a safe transformed product to be eventually recycled.

D. MANGANO; A. GUALTIERI; S. FERRARI; A. RICCHI; E. FORESTI; G. LESCI; N. ROVERI; M. MARIOTTI; G. PECCHINI ( 2006 ) - Asbestos monitoring in civil and industrial environments of selected Italian sites ( Conference on Asbestos Risks and management - - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (ISPESL Roma ITA ) - n. volume - - pp. da 140 a 145 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This paper presents the results of an intensive monitoring activity of thè air, fall-out and soil of a Ceramic factory in Sassuolo (Modena, Italy) with sheds made of cement-asbestos. The monitoring protocol accomplished a 1 week long collection time performed during each season. Filters and samples of fall-out and soils were analysed with XRPD, electron and optical microscopy, and FTIR. The surprising outcome of this work is that the calculated amount of dispersed asbestos fibers is practically null with a minor concentration during thè autumn season.

G. PECCHINI; A. GUALTIERI; E. RENNA; O. SALA; L. CALZAVACCA; T. BACCHI; F. PAOLI; V. BIANCOLINI ( 2006 ) - Analytical evaluation of wastes containing asbestos after inertization treatment by pirolitic process ( European Conference on Asbestos Risks and management - - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (ISPESL Roma ITA ) - n. volume - - pp. da 183 a 186 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Wastes recovery efficiency bave been slightly improved by Decree n.248 of 29/7/2004 on" Rules on determination and disciplines of recovery activities of products and goods of asbestos and containing asbestos" by defining processes and treatment able to bring to a complete transformation of crystallochemical features of asbestos.Such treatments if properly applied allows to avoid thè disposai of wastes in dumps. They also allow thè reutilizalion of processed wastes. No adequate power plants suitable for thè mentioned treatment presently exist in Italy.Intense research activity is devoted to thè start up of pyrolitic processes applied to wastes deriving from concrete/asbestos to be reutilized in environmental recovery. Decree n.248 reports characteristics of processed material whìch must be asbestos free and accompanied by mineralogical composition of final produci.Present paper propose an analytical protocol suitable for law need and able to guarantee safety conditions of wastes after crystallochemical transformation.In order to verìfy such trans formations analytical procedures adopted in qualifìed laboratories on asbestos analysis nave been utilized. Pure chrysotile and concrete/asbestos samples have been analyzed by MOCF, DRX, SEM and FTIR after 2 hours heating at 600-700-800-900-1000 °C in muffle fornace. Some samples processed by pilot power plani by Aspireco have also been analyzed.

M. LASSINANTTI GUALTIERI; A. GUALTIERI; J. HEDLUND ( 2006 ) - The influence of heating rate on template removal in silicalite-1: An in situ HT-XRPD study (Elsevier Science Incorporated / NY Journals:Madison Square Station, PO Box 882:New York, NY 10159:(212)633-3730, EMAIL: usinfo-f@elsevier.com, INTERNET: http://www.elsevier.com, Fax: (212)633-3680 ) - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 89 - pp. da 1 a 8 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The effect of heating rate on thermal behavior of TPA-silicalite-1 during calcination and the reaction kinetics for TPA decomposition were investigated. The cell parameters of the TPA-silicalite-1 during the heating cycles were determined with the aid of high temperature X-ray diffraction data and the Rietveld method. The template decomposition is accompanied by a large contraction of the unit cell. The unit cell dimensions during template removal are not affected significantly by the heating rate. Consequently, the rate of contraction is approximately proportional to the heating rate. The intensity of some diffraction peaks changes during heating, especially the 101/011 and the 200/020 peaks. The intensity change of those peaks shows the same dependence with temperature as the TPA occupancy, indicating that these parameters are related. An analysis of the kinetics for TPA decomposition based on the intensity change of the 101/011 and the 200/020 peaks was performed. The apparent activation energy (Ea) of the template decomposition in silicalite-1 determined with the Kissinger and the Flynn–Wall–Ozawa methods was 138 (±25) and 138 (±29) kJ mol−1, respectively. The reaction order, determined with the method of Kennedy and Clark, was close to 0.5 indicating that the rate-limiting step is mono-dimensional diffusion. Ea was 140 (±30) kJ mol−1, in good agreement with the results obtained with the other methods.

G. PECCHINI; A. GUALTIERI; E. RENNA; O. SALA; L. CALZAVACCA; T. BACCI; F. PAOLI; V. BIANCOLINI ( 2006 ) - Valutazione analitica del rifiuto di cemento amianto dopo trattamento di inertizzazione con processo pirolitico (Assn Italiana Igienisti Indust(AIDII):via GB Morgagni 32, 20129 Milan Italy:011 39 02 20240956, EMAIL: aidii.consul@flashnet.it, Fax: 011 39 02 20241784 ) - GIORNALE DEGLI IGIENISTI INDUSTRIALI - n. volume 31 - pp. da 98 a 107 ISSN: 1122-1666 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In questo studio è stata fatta la valutazione analitica del rifiuto di cemento amianto dopo trattamento di inertizzazione con processo pirolitico. Sono stati valutati gli effetti sia sull'amianto di serpentino che quello di anfibolo. Le tecniche utilizzate sono state XRPD, FTIR e SEM.

A. GUALTIERI; A. VIANI; C. MONTANARI ( 2006 ) - Quantitative phase analysis of hydraulic limes using the Rietveld method - CEMENT AND CONCRETE RESEARCH - n. volume 36 - pp. da 401 a 406 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Quantitative phase analyses of three commercial samples of hydraulic limes have been per-formed using the Rietveld method. Although the Rietveld method has been already applied to cement analysis, we report here the first application to different classes of hydraulic binders, such as hydraulic limes (HL) and natural hydraulic limes (NHL). Unlike HL, that are simple diluted cement, NHL are specific product of great interest for its application in building restoration and conservation. Samples were also characterized by laser granulometry and chemical analysis. Thermogravimetric analysis/Differential Scanning Calorimetry (TG/DSC) and calcimetric analyses were conducted to compare the results of such well-established techniques with those obtained with the Rietveld method. Taking advantage of the Rietveld method with the addition of an internal standard, the phase fraction of all the crystalline phases as well as the amorphous component, have been accurately determined. This technique offers a valid support for the characterization of hydraulic limes in the light of the EN classification of such industrial products.

A. GUALTIERI; S. FERRARI ( 2006 ) - Kinetics of illite dehydroxylation - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 33 - pp. da 490 a 501 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Illite is a dioctahedral K-deficient mica with an interlayer cation content of 0.6-0.85 atoms per formula unit. 1M and 2M(1) are the illite polytypes more abundant in nature. Because illite is one of the major component of clays used for the production of traditional ceramics, the understanding of its high temperature transformations is of paramount importance for the knowledge of the structural and microstructural properties of fired ceramic products. To our knowledge, the study of the illite dehydroxylation kinetics has not been attempted to date. Hence, this work presents the investigation of the reaction mechanism of dehydroxylation of illite for the first time. The natural sample investigated in this study is a 1M-polytype from Hungary. Several classical methods of kinetic analysis were used (isoconversional method, Avrami method, direct fit with kinetic expressions, and others) to achieve a complete picture of the dehydroxylation mechanism. The proposed model for the dehydroxylation of illite is a multi-step reaction sequence with (1) condensation of the water molecule in the octahedral layer; (2) one-dimensional diffusion of the water molecules through the tetrahedral ring (rate limiting step of the reaction); (3) two-dimensional diffusion of the water molecules through the interlayer region (rate limiting step of the reaction).

S. FERRARI; A. GUALTIERI ( 2006 ) - The use of illitic clay in the production of stoneware tile ceramics - APPLIED CLAY SCIENCE - n. volume 32 - pp. da 73 a 81 ISSN: 0169-1317 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Illite is one of the main clay phases used for the preparation of mixtures for traditional ceramics. The raw materials used for production of white porcelain stoneware tiles mainly consist of feldspars, quartz, and clay minerals (kaolinite, smectite and illite). In this study, eight clayey raw materials with a different content of illite up to 70 wt.%, have been considered. The crystalline phases present in different amounts are illite, smectite, kaolinite, illite-smectite mixed-layers, K-feldspar, plagioclases, quartz, and accessory phases (anatase, goethite). The clays have been chemically and physically characterized as raw and fired materials with X-ray diffraction, X-ray fluorescence, and SEM. Moreover they were added in the percentage of 35 wt.% to a mixture composed of albite, feldspar sand and quartz sand, to reproduce that commonly used for the production of porcelain stoneware tiles. We focused on the quantitative mineralogical aspects of the unfired and fired bodies and their relationship with the technological properties due to the presence of illite. Increasing illite content yields higher percentage of glass phase and lower water absorption because of the lowering of the melting point. Because of the pyroplastic deformation, linear shrinkage decreases with illite content. The presence of illite inhibits the formation of mullite and cristobalite, since silica and alumina tend to form alkaline glass. Although in clays from Hungary, transition elements are present in very low percentage, the colour of the fired bodies is darker. These clays contain goethite, which may be rapidly oxidized with temperature, and show a very low percentage of newly formed mullite which could eventually host Fe in its structure.

S. FERRARI; E. ORI; A. GUALTIERI; A. TUCCI; A. CSEBI; J. BIBER ( 2005 ) - Possibilità di impiego dell’illite di Füzérradvány (Ungheria) in impasti da grès porcellanato (Gruppo Editoriale Faenza Editrice:via Pier de Crescenzi 44, I 48018 Faenza Italy:011 39 0546 670111, EMAIL: info@faenza.com, Fax: 011 39 0546 660440 ) - CERAMICA INFORMAZIONE - n. volume 444 - pp. da 524 a 531 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Con il termine illite si intende un i di alluminio e potassio simile alle miche, che non espande, diottraedrìco e che si ritrova nella frazione argillosa. Insieme alla caolinite, alla clorite e alla smectite è uno dei 4 maggiori costituenti delle rocce argillose. L'illite è una fase in parte ancora sconosciuta a causa della difficile reperibilità come minerale puro; spesso è associata a smectite, dalla quale è impossìbile separarla.In questo lavoro viene presentato un giacimento illite situatonell'Ungheria Nord-orientale, vicino al paese di Fuzérradvany, non ancora descrìtto nella letteratura mineralogica intenazionale. La regione dell'Ungheria Nord-orientale ai confini con la Slovacchia, appartiene al complesso monfuoso dei Monti Tokaj, ed in quanto tale è costituita da rocce acide dì origine vulcanica. La formazione di questo importante giacimento è dovuta all'alterazione da parte di fluidi idrotermali, che hanno interessato rocce riolitiche.La miniera dì Fuzérradvany è in grado di produrre 4 diverse qualità dì argilla illitica: EXTRA, A, B e C. ln questo studio sono state prese in esame le due qualità con un maggiore contenuto di illite: EXTRA ed A. Le due argille sono state caratterizzate dal punto di vista chimico-fisico. Inoltre, è stato studiato ìl comportamento in temperatura. Alle variazioni osservate nelcomportamento dilatometrico è stato dato un significato in termini mineralogici e microstrutturali, potendo seguire le trasformazioni con diffrazione a Raggi X in situ e microscopia elettronica a scansione.Questo lavoro si inquadra in un progetto generale ai studio i argille illitiche nel campo dei ceramici tradizionali, che prende in esame argille con un diverso contenuto di illite dal 5 ai 70%; ottenendo importanti ìnformazioni su come l'impasto stesso modifichi le sue caratteristiche quando il minerale viene inserito in percentuali diverse. Dai confronti dì tutti i dati ottenuti ci si propone infatti dì valutare gli effetti della presenza di illite in impasto e come la variazione delle sue percentuali possa modificare le proprietà del prodotto finito, in modo tale da ottimizzare le condizioni di uso di questa importante nuova materia prima ceramica.

L. ESPOSITO; E. RAMBALDI; A. TUCCI; E. GAETTI; A. GUALTIERI ( 2005 ) - Riciclo di amianto inertizzato termicamente in impasti da grès porcellanato. ( Ecomondo 05 - - 26-29/10/2005) ( - Ecomondo 05 ) (MAGGIOLI Bologna ITA ) - n. volume - - pp. da 768 a 774 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Nella presente ricerca si è valutata la possibilità di riciclare amianto inertizzato termicamente con torcia al plasma, in impasti da grès porcellanato. Il materiale inertizzato, denominato INERTAM, è costituito per circa 50% da una fase amorfa. Il restante 50% è costituito da fasi cristalline fra le quali prevale la gehlenite-akermanite (ca. 36% del totale). Considerando il carattere refrattario dell'INERTAM, si è ritenuto opportuno sostituirlo ai materiali, quali le sabbie, che negli impasti ceramici svolgono una funzione smagrante e strutturale. Partendo da un impasto da grès porcellanato commerciale, scelto come riferimento, è stato preparato un nuovo impasto, sostituendo il 2.5% di sabbia feldspatica con l'1%di INERTAM.Il nuovo impasto ha messo in evidenza caratteristiche migliori rispetto al materiale standard, presentando a 1220°C, valori di assorbimento d'acqua inferiori, 0,82%, e un ritiro lineare di 7,9%. Le analisi al microscopio elettronico a scansione (SEM), dei provini sinterizzati, hanno evidenziato una microstruttura più omogenea e meno porosa rispetto a quella dell'impasto standard.

G. VENTRUTI; F. SCORDARI; E. SCHINGARO; A. GUALTIERI; C. MENEGHINI ( 2005 ) - The order-disorder character of FeOHSO4 obtained from the thermal decomposition of metahohmannite, Fe2(3+H2O)4[O(SO4)(2)] - AMERICAN MINERALOGIST - n. volume 90 - pp. da 679 a 686 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The iron sulfate FeOHSO4 studied was obtained as a dehydration product of metahohmannite Fe-2(H2O)(4)[O(SO4)(2)] during a synchrotron real-time powder diffraction experiment. As quoted in the literature, FeOHSO4 has iron atoms octahedrally coordinated with two hydroxyl groups and four sulfate O atoms, while each hydroxyl group is bonded to two iron atoms. This compound is commonly described in the orthorhombic system with space group Pnma, lattice parameters a(J) = 7.33, b(J) = 6.42, and c(J) = 7.14 angstrom (a(J), b(J), and c(J) are the Johansson lattice parameters), and Z = 4. However a preliminary Rietveld refinement of the pattern at about 220 degrees C using the structural model from the literature yielded a poor fit of the observed data and a final R-p value of about 23%. A careful analysis of the calculated powder diffraction pattern showed unexpected peaks, not observed in the experimental trace, for h = 2n + 1, while sharp reflections for h = 2n seemed to point to different lattice constants and space group. The recognition of the order-disorder character of the FeOHSO4 compound was the key to successfully interpreting the unexpected features of the experimental powder pattern and the misfit with respect to the calculated pattern. In fact, FeOHSO4 belongs to a family of OD structures formed by equivalent layers of symmetry Pbmm. Only two MDO (Maximum Degree of Order) polytypes are possible. MDO1 results from a regular alternation of stacking operators 2(1/2) and 2(-1/2), and yields an orthorhombic structure with space group Prima and lattice parameters a(J) = 7.33, b(J) = 6.42, and c(J) = 7.14 angstrom. MDO2 results from the 2(1/2)/2(1/2)/2(1/2)... sequence of symmetry operators and yields a monoclinic structure with space group P2(1)/c, a(M) = 7.33, b(M) = 7.14, c(M) = 7.39 angstrom, and = 119.7 degrees. The analysis of one-dimensional stacking disorder was performed by fitting the observed XRPD pattern with a calculated intensity curve generated by DIFFaX. The disorder model was investigated by taking into account a probability matrix for the occurrence of OD layer sequences. The best fit (R-P = 0.009) to the observed powder pattern was obtained with a 61:39 ratio of monoclinic and orthorhombic polytypes for a fully disordered OD layers sequence.

FERRARI S.; GALLI E.; GUALTIERI A.F. ( 2005 ) - Preliminary characterization of an unknown mineral from Mont Peylenc (Massif Central, France) ( - OXIDE BASED MATERIALS - New sources, novel phases, new application ) (ELSEVIER AMSTERDAM NLD ) - n. volume 155 - pp. da 261 a 269 ISBN: 9780444519757 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The discovery of a new natural zeolite phase is a rare event since only less than one hundred natural zeolites are known to date. We have been recently involved in a research project aimed at the investigation of a microscopic aggergate coming from the Massif Central (France) that appears to be anew zeolite species. The sample was collected more than 30 years ago by Professors Glauco Gottardi and Ermanno galli and since then, many unsuccesful attempts have been made to disclose the crystal chemistry of this new3 species. The quantity of available material is very limited, and single crystals are not available. For this reason, structure determination from powder diffraction data is attempted. This work represents the result of preliminary chemical, microscopy and minralogical charcterization of this apparently unknown mineral, mainly using X-ray podwer diffraction. All data point to a new zeolite species and the results will be hopefully integrated in the future with the crystal strcture solution by the powder methods.

L. ESPOSITO; A. SALEM; A. TUCCI; A. GUALTIERI; S.H. JAZAYERI ( 2004 ) - The use of nepheline-syenite in a body mix for porcelain stoneware tiles (Elsevier Applied Science:An Imprint of Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington Oxford OX5 1GB United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: nlinfo-f@elsevier.nl OR usinfo-f@elsevier.com OR forinfo-kyf04035@niftyserve.or.jp, INTERNET: http://www.elsevier.nl/, Fax: 011 44 1865 843010 ) - CERAMICS INTERNATIONAL - n. volume 31 - pp. da 233 a 240 ISSN: 0272-8842 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In the study, the possibility to use nepheline-syenite, as fluxing agent, in a body mix used for porcelain stoneware tile, was determined. Starting from the reference mix composition, different amounts, 5.0, 10.0 and 15.6 wt.%, of sodium feldspar were replaced with the same amounts of nepheline-syenite. Different sintering cycles were used to understand the role of the nepheline-syenite in the development of the final microstructure. The presence of nepheline-syenite strongly favours the sintering behaviour, by reducing the sintering time necessary to reach the water absorption values, requested by the International Standard. Furthermore, the microstructure results more homogeneous and the mechanical characteristics are increased. The better mechanical performances can also be attributed to the different mineralogical compositions, in particular with lower amount of glassy phase, higher flexural strength values are obtained.

M. MARIANI; P. PIZZOLI; R. SANTINI; P. CALICETI; S. FERRARI; A. GUALTIERI ( 2004 ) - Argille illitiche: composizione, struttura, microstruttura e comportamento negli impasti ceramici da grès porcellanato (Gruppo Editoriale Faenza Editrice:via Pier de Crescenzi 44, I 48018 Faenza Italy:011 39 0546 670111, EMAIL: info@faenza.com, Fax: 011 39 0546 660440 ) - CERAMICA INFORMAZIONE - n. volume 436 - pp. da 664 a 670 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

La relazione vuole raccogliere lo stato dei lavori che stiamo portando avanti nel nostro laboratorio riguardo alla ricerca e l'indagine sulle materie da impasto. Abbiamo posto l'attenzione sulla plasticità delle argille e sulle interconnessioni, alcune note e altre un po' meno, tra le caratteristiche tecniche di lavorabilità e le composizioni chimiche e mìneralogiche di questi materiali. Abbiamo preso in considerazione 7 argille diverse, utilizzate attualmente in impasti ceramici nazionali e non, aventi tenori di allumina dal 20 al 28%. Questo lavoro presenta la fase preliminare di un progetto più vasto in cui si intende raccogliere un numero molto più consistente di dati e creare un data base significativo in termini statistici.

M.PRUDENZIATI; B. MORTEN; A. F. GUALTIERI; M. LEONI ( 2004 ) - Dissolution Kinetectcs and diffusivity of silver in glassy layers for hybrid microelectronics (Kluwer Academic Publishers:Journals Department, PO Box 322, 3300 AH Dordrecht Netherlands:011 31 78 6576050, EMAIL: frontoffice@wkap.nl, kluweronline@wkap.nl, INTERNET: http://www.kluwerlaw.com, Fax: 011 31 78 6576254 ) - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS - n. volume 15 - pp. da 447 a 453 ISSN: 0957-4522 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silver and palladium/silver compositions are widely used in hybrid microelectronics, as electrodes for dielectric layers and multilayers, terminations of thick film resistors and interconnections. Interactions between Ag and the adjacent films are known to affect the microcircuit performances. The present study is aimed at collecting data on the behavior of Ag-based films in contact with glassy layers. Most experiments were performed with a glass with composition 68.2 PbO : 30.5 SiO2 : 1.3 Al2O3 wt %. Two different systems were analyzed. The first system consists of thick films prepared from a paste containing glass and either 3 or 15 wt % silver particles; both fine (spherical grains, 0.5–1 mgrm diameter) and coarse (flakes, 2–5 mgrm, <1 mgrm thick) Ag powders were used for these pastes. The distribution of Ag in the film was studied with X-ray diffraction, scanning electron microscopy and fluorescence analysis. The results show that Ag floats on the glassy layer. Diffraction of X-rays generated by a synchrotron radiation source allowed us to study the kinetics of silver dissolution in the glass; this phenomenon is consistent with the Avrami theory, with an apparent activation energy E dis=0.69±0.04 eV. The second system analyzed, Ag-based terminations of glass layers fired at various peak temperatures, enabled us to obtain quantitative values for both Ag solid solubility (about 2.5 wt %) and Ag diffusion coefficients D Ag(T ). Typical values of D Ag(850 °C) are 30.3±11.9 10–8 cm2/s; an apparent activation energy of the diffusion process is E a=0.6±0.1 eV.

Immovilli S; Morten B; Prudenziati M; Gualtieri A; Bersani M ( 1998 ) - Interactions between bismuth oxide and ceramic substrates for thick film technology - JOURNAL OF MATERIALS RESEARCH - n. volume 13 - pp. da 1865 a 1874 ISSN: 0884-2914 [Articolo in rivista (262) - Articolo su rivista]
Abstract

We investigated the interactions between screen printed and fired layers of Bi2O3 and ceramic substrates of alumina and beryllia. It was found that the reaction products are invariably crystalline in nature. Several transitions of Bi2O3 in its polymorphic phases were found to occur on BeO substrates, while newly formed compounds have been observed to grow on alumina substrates, i.e., Al4Bi2O9 on 99.9% Al2O3 and Bi12SiO20 On 96% Al2O3 Bismuth deeply penetrates in the ceramic interstices in all the cases. Until Bi2O3 is not completely reacted, this penetration is diffusion limited (penetration depth w approximate to t(d)(1/2), where t(d) is the reaction time) with values of the activation energy ranging from 3.7 +/- 0.6 eV (BeO substrate) to 1.4 +/- 0.06 eV (96% Al2O3 substrate). It is shown that these processes are notably different to those occurring in PbO/ceramic systems; moreover, they imply different adhesion phenomena of thick films on different substrates.

M. Bersani; B. Morten; M. Prudenziati; A. F. Gualtieri ( 1997 ) - Interactions between lead oxide and ceramic substrates for thick film technology - JOURNAL OF MATERIALS RESEARCH - n. volume 12 - pp. da 501 a 508 ISSN: 0884-2914 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper deals with the mechanisms and kinetics of interactions between screen printed and fired PbO layers and ceramic substrates: alumina and beryllia. The interaction with alumina occurs via two main processes: (i) a reaction between PbO and Al2O3 grains, which induces the formation of a crystalline phase, Pb2Al2O5; and (ii) an interdiffusion process involving Pb and the intergranular amorphous phase in the ceramic substrate. This latter process results in a compositional change of the intergranular phase at considerable depths inside the ceramic substrate, as well as in the formation of a high lead glass layer on the substrate surface. Since PbO is not completely reacted, the Pb penetration in the ceramic is diffusion limited (penetration depth w proportional to the quare root of td, where td is the reaction time) with an activation energy of 1.20 ±0.05 eV. The ceramic microstructure significantly affects the interaction processes.