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Castel Guelfo di Bologna, Italy

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

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. Source

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

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. Source

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

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. Source

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

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. Source

Timellini G.,Centro Ceramico Bologna | Resca R.,Centro Ceramico Bologna | Bignozzi M.C.,Centro Ceramico Bologna | Bignozzi M.C.,University of Bologna
Comprehensive Analytical Chemistry

The subject of this chapter, air quality associated to the ceramic tile industry, represents a very interesting 'real scenario' in the framework of the whole volume. The reasons can be summarised in this way: (1) the ceramic tile technology includes several significant pollutant emissions into the atmosphere and (2) ceramic industry has generated - although many years ago and in rather small industrial areas, characterised by large concentrations of factories - some air quality problems. The Ceramic District of Sassuolo, Italy, can be considered as a significant example of such industrial areas and represents the main reference adopted in this chapter. Another 'ceramic district' is that of Castellón, Spain, which however is quite different as regards significant factors influencing air quality: factors such as territory, orography, climate, meteorological conditions, urban and industrial settlements and density, road system and traffic, etc.With reference to the Italian ceramic tile industry, this chapter deals with the description and quantification of emissions into the atmosphere from ceramic industries and aims to document the approach adopted, the resources used and the knowledge developed, to drastically reduce the environmental impact of these emissions on air quality.This objective has been successfully achieved, at the point that, in particular, the Italian ceramic tile sector is still working, in the framework of a continuous improvement approach, on its environmental performances, as well as on the exploitation of the results achieved as competitiveness factors. © 2016 Elsevier B.V. Source

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