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Thuault A.,CNRS Crystallography and Material Science Laboratory | Savary E.,CNRS Crystallography and Material Science Laboratory | Savary E.,Laboratoire des Materiaux Ceramiques et Proce des Associes | Bazin J.,French National Center for Scientific Research | Marinel S.,CNRS Crystallography and Material Science Laboratory
Journal of Materials Processing Technology | Year: 2014

In this study, large size pieces of kaolin with a complex shape were successfully sintered in a microwave multimode cavity. The challenge was to obtain a sample homogeneously sintered on a large surface. For this purpose, prior to sintering, a finite element modelling study was carried out to determine the optimal experimental set-up configuration permitting to have an electromagnetic field as homogenous as possible around the sample. In this case, it was pointed out that the hybrid heating configuration (use of susceptors) was the most suitable configuration. The samples experimentally obtained were structurally and mechanically characterized. Therefore, it was highlighted that the microwave sintered samples present a microstructure and mechanical properties similar to those of samples conventionally processed for a lower sintering temperature. Finally, the microwave sintering permit to significantly reduce the energy consumption required for the production of sintered ceramic pieces, which is crucial for sustainable development. © 2013 Elsevier B.V.

Mercier C.,University of Lille Nord de France | Mercier C.,Laboratoire des Materiaux Ceramiques et Proce des Associes | Follet-Houttemane C.,University of Lille Nord de France | Follet-Houttemane C.,Laboratoire des Materiaux Ceramiques et Proce des Associes | And 5 more authors.
Journal of Non-Crystalline Solids | Year: 2011

29Si and 31P MAS-NMR has been used in order to study the influence of P2O5 content on the structure of SiO 2-Na2O-CaO-P2O5 bioglasses. The 29Si NMR spectra show many QSi n entities co-existing in the same glass. For all the glasses, the QSi n species are associated with Ca2+ and Na+. The glass network becomes more and more polymerized when the P2O 5 content increases. The 31P NMR spectra show that the phosphorus is present as monophosphate with or without diphosphate complexes associated with both Ca2+ and Na+. The increase in phosphorus content modifies the relative abundance of phosphate complexes and leads to changes in the chemical environment around phosphate indicating that the distribution of cations is not homogeneous. Indeed most phosphate complexes attract calcium. The percentage of diphosphate complexes increases with the P2O5 content as the silicate network repolymerizes. © 2011 Elsevier B.V. All Rights Reserved.

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