Optimization of the sintering schedule for multiphase materials obtained by reaction sintering of ZrO2- CaMg (CO3)2

FERNANDO BOOTH; LILIANA GARRIDO; ESTEBAN AGLIETTI; PILAR PENA; CARMEN BAUDÍN

Toledo

Congreso; Eurpean Cerámic Society Conference ECERS .; 2015

Instituto de cerámica y vídrio CSIC-ICV

Reaction sintering is a classic process for manufacturing multiphase advanced ceramic materials. This method is based on thermal treatment of mixtures of incompatible compounds. Reaction and sintering occur during the thermal treatment; such processes may or may not occur simultaneously. The fundamental problem is to adjust the thermal cycle in a way that the complete reaction of the components as well as high density is achieved. Adjusting the thermal cycling presents additional problems when part of components experience significant weight loss during the heat treatment.This work is a part of a larger study on the capability of multiphase materials based on CaZrO3, and ZrO2 for advanced structural applications. Ceramic and refractories based on MgO-CaZrO3-c-ZrO2 are also interesting materials for applications structural and in particular to have high resistance to corrosion attack, the process of reaction sintering of dolomite-zirconia mixtures is described and discussed.The optimization of the sintering schedule in this system is complex, because during the heat treatment decomposition processes (CaMg (CO3) 2), sintering (solid state and in the presence of a liquid phase) and reaction (formation of CaZrO3 and c-ZrO2) occur. The criterion used to design the heating cycle has been to maintain a constant rate of shrinkage of the compact during the heating step. A combination of DTA-TG and dynamic and isothermal sintering studies have been done to select the optimum schedule. Composites constituted by CaZrO3, MgO and c-ZrO2 with density higher than 99% of the theoretical density using maximum sintering temperatures between 1350 and 1450ºC have been obtained. The microstructures were analyzed as a function of the sintering conditions.