Bologna, Italy
Bologna, Italy

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Sassoni E.,University of Bologna | Andreotti S.,University of Bologna | Bellini A.,University of Bologna | Mazzanti B.,Centro Ceramico Bologna | And 4 more authors.
Composites Part B: Engineering | Year: 2017

This paper aims at evaluating how the FRP/brick debonding force is influenced by brick mechanical properties (compressive, tensile and flexural strength) and physical-microstructural properties (surface roughness, porosity, pore size distribution, rate of water capillary suction). The depth of epoxy resin penetration into bricks and the thickness of brick layer detached at the end of bond test were also determined, in order to investigate the role of resin penetration into the brick on the FRP performance. All the tests were carried out on different brick surfaces (namely “bed” and “face”), to account for possible brick anisotropy. The results of the study point out that brick mechanical properties alone are not sufficient to accurately predict the maximum debonding force, but a better estimation can be achieved taking into account also brick surface roughness and resin penetration depth. If brick anisotropy is not considered, in some cases a remarkable overestimation of the maximum debonding force may be found. © 2016 Elsevier Ltd


Parente P.,Charles III University of Madrid | Ortega Y.,Complutense University of Madrid | Savoini B.,Charles III University of Madrid | Monge M.A.,Charles III University of Madrid | And 3 more authors.
Acta Materialia | Year: 2010

Positron annihilation spectroscopy (PAS), indentation, nanoindentation experiments and scanning electron microscopy (SEM) observations were performed on Al2O3-ZrO2 laminates samples to assess the effect of residual stresses on their mechanical and microstructural properties. Layered samples were implemented by slip-casting, constituted by two thin Al2O3 external layers and an intermediate thick one, consisting of a mixture of Al2O3 and monoclinic ZrO2 in the range 0-30 vol.%. In these systems residual tensile stresses fields were generated inside the external layers during cooling from the sintering temperature, by the expansion of the adjacent ZrO2-containing layer. SEM observations showed the microstructural effects due to the level of tension related to the zirconia content. A correlation between the PAS parameters and the microstructural changes caused by the presence of residual stresses was found. Nanoindentation measurements were used to trace the sign and magnitude of the residual stress gradient across the interface between the layers. © 2010 Acta Materialia Inc.


Rambaldi E.,Centro Ceramico Bologna | Prete F.,Centro Ceramico Bologna | Bignozzi M.C.,Centro Ceramico Bologna | Bignozzi M.C.,University of Bologna
Ceramics International | Year: 2015

Acoustic and thermal performances of floating floor and/or radiant floor can be improved by using ceramic tiles with tailored porosity and microstructure. Porcelain stonewares are still the most widespread typology of tiles, due to their high physical and mechanical performances coming from a very low level of open porosity and water absorption (≤0.5 wt%). However their closed porosity values, usually neglected, can be significantly different from one product to another. As a consequence, the properties directly dependent on the total porosity, such as thermal and acoustic ones, may be strongly diverse among commercial tiles. Several commercial porcelain stoneware tiles having different composition, microstructure and porosity, were selected for the present work. These tiles, alone or coupled with different types of resilient underlayer materials (glass fibre, cork and rubber), were studied on the basis of dynamic stiffness. Their acoustic and thermal properties were investigated in terms of thermal conductivity and walking noise reduction. ;copy 2015 Elsevier Ltd and Techna Group S.r.l.


Prete F.,University of Bologna | Prete F.,Centro Ceramico Bologna | Rizzuti A.,University of Modena and Reggio Emilia | Esposito L.,Centro Ceramico Bologna | And 2 more authors.
Journal of the American Ceramic Society | Year: 2011

Zirconia-doped alumina nanometric powder (5 mol%) was prepared by means of microwave hydro- and solvothermal syntheses, with the use of either bi-distilled water or diethylenic glycol as solvents, respectively. The as-obtained products were thermal treated at different temperatures (400°, 450°, and 500°C) to study the phase evolution. The experimental method allows synthesis of carbon-coated zirconia-dispersed alumina nanopowders with excellent characteristics, such as very fine size, high homogeneity, no phase separation, and narrow size distribution. © 2011 The American Ceramic Society.


Bernardo E.,University of Padua | Esposito L.,Centro Ceramico Bologna | Rambaldi E.,Centro Ceramico Bologna | Tucci A.,Centro Ceramico Bologna
Advances in Applied Ceramics | Year: 2011

Plasma vitrification is a safe technique for eliminating the environmental impact of asbestos containing materials. Additional advantages may arise from the obtainment of valuable ceramics from vitrified waste if low cost treatments, comparable to those applied to traditional ceramics, are feasible. In the present paper, the application of a fast heating rate (40°C min -1) to produce dense sinter crystallised materials from vitrified asbestos containing waste, having strength in excess of 100 MPa, is discussed. Sinter crystallisation, with fast heating processes, constituted also the basis of cellular glass ceramics and a new type of stoneware, with waste glass replacing conventional feldspar fluxes. © 2011 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute.


Mestre S.,Jaume I University | Chiva C.,Centro Ceramico Bologna | Palacios M.D.,Jaume I University | Amoros J.L.,Jaume I University
Journal of the European Ceramic Society | Year: 2012

In this study a yellow pigment was obtained for third-fire ceramic decorations, based on silver nanoparticles synthesised by the method of chemical reduction in aqueous phase, using silver nitrate and polyvinylpyrrolidone as raw materials. Monitoring of the nanoparticle synthesis reaction by UV-vis spectroscopy allowed optimum operating conditions to be defined in preparing these particles for use as chromophores. Under these conditions, a stable suspension of Ag nanoparticles, which were well dispersed and had an average diameter of 20-30. nm, was obtained. Polyvinyl alcohol and tetraethyl orthosilicate were then added to the nanoparticle suspension to obtain the pigment precursor. The pigment precursor was directly applied on to fired glazed ceramic tile. Subsequent thermal treatment at moderate temperature (700 °C) yielded a layer less than one micron thick, which generated an intense yellow colour. © 2011 Elsevier Ltd.


Bernardo E.,University of Padua | Dattoli A.,University of Padua | Bonomo E.,University of Padua | Esposito L.,Centro Ceramico Bologna | And 2 more authors.
International Journal of Applied Ceramic Technology | Year: 2011

Vitrified inorganic wastes are often converted into glass-ceramics; although these products exhibit interesting properties, the processing is quite complex and expensive. This paper reports an alternative approach, based on substituting traditional feldspar fluxes in stoneware with a CaO-Al 2O3-SiO2 glass, from industrial plasma vitrification of municipal solid waste incinerator fly ashes. The new materials feature low sintering temperatures, <1000°C, associated to a substantial crystallization. For an optimized balance between crystallization and densification (by introducing soda-lime glass as a sintering promoter), the products exhibit remarkable mechanical properties (e.g., bending strength exceeding 100 MPa), even superior to those of traditional porcelain stoneware. © 2010 The American Ceramic Society.


Salem A.,Sahand University of Technology | Jazayeri S.H.,Iran University of Science and Technology | Rastelli E.,Centro Ceramico Bologna | Timellini G.,Centro Ceramico Bologna
Thermochimica Acta | Year: 2010

The effect of nepheline syenite on porosity-soaking time relationship of porcelain stoneware bodies has been studied using the experimentally measured total porosity. A new kinetic model was applied to quantify porosity as function of temperature and soaking time. In the first part of work, the effect of nepheline syenite was evaluated on the kinetic parameters and the porosity variations were found to be related to surface tension/viscosity ratio of melted phase which influences the minimum porosity of ceramic body. The kinetic analysis of data indicated that the optimum soaking time to achieve minimum porosity in ceramic body is controlled by amount of nepheline syenite and milling time. The validity of presented theory to predict the experimental results was substantiated by computing total porosity at other temperatures and soaking times. The proposed model can be used to describe the sintering process of ceramic bodies that are sintered by diffusing melted phase. © 2010 Elsevier B.V. All rights reserved.


Tobaldi D.M.,Centro Ceramico Bologna | Tucci A.,Centro Ceramico Bologna | Skapin A.S.,Slovenian National Building And Civil Engineering Institute | Esposito L.,Centro Ceramico Bologna
Journal of the European Ceramic Society | Year: 2010

A series of TiO2-SiO2 mixtures - having the following stoichiometry Ti1-xSixO2, with x=0, 0.1, 0.3 and 0.5 atoms per formula unit - were prepared by using precursor oxides and fired at three temperatures (900, 1000 and 1200°C). The modifications in the structure and, consequently, on the photocatalytic activity, induced by the addition of SiO2 into the TiO2 powder, were thoroughly investigated by using various analytical techniques: X-ray powder diffraction, electron microscopy (FE-SEM and TEM), XPS, FT-IR, DRS and BET analysis. The results underlined as essentially no solid solution occurs between the two crystalline end-members. Nevertheless, silica addition caused a retarding effect on anatase-to-rutile phase transformation and on the crystallite growth.The photocatalytic activity of the powders was assessed in gas phase and the results were explained by taking into account the anatase and rutile relative amounts in the samples, their crystallite size, the surface hydroxyl groups adsorbed on the photocatalysts and the surface area of the mixtures. © 2010 Elsevier Ltd.


Rambaldi E.,Centro Ceramico Bologna | Esposito L.,Centro Ceramico Bologna | Andreola F.,University of Modena and Reggio Emilia | Barbieri L.,University of Modena and Reggio Emilia | And 2 more authors.
Ceramics International | Year: 2010

The possibility of recycling the Municipal Solid Wastes Incinerated (MSWI) bottom ash by its incorporation in ceramic tiles was investigated. The MSWI bottom ash was introduced both in untreated (previous deironization) and vitrified condition. The sintering of the different products was investigated by determining water absorption and linear shrinkage. To evaluate possible variations due to the presence of different amount of bottom ash, mineralogical and microstructural examinations by quantitative X-ray diffraction and scanning electron microscopy, were performed. While the untreated bottom ash, till an amount of 5 wt%, did not seem to affect the above characteristics of selected materials, the vitrified bottom ash, 5-10 wt%, as strong fluxing agent, promoted the sintering of porcelain stoneware. Leaching results allow to assert that the fired samples are not dangerous. © 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

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