Preparation of ZrO₂/ZrW₂O₈ and SnO₂/ZrW₂O₈ Cosintered Ceramics with Controlled Thermal Expansion Coefficient

Abstract

Preparation of ceramics with controlled thermal expansion behavior by cosintering of various oxides and negative thermal expansion oxide, ZrW₂O₈, was examined. It was revealed that cosintering of ZrW₂O₈ with TiO₂ nor Y₂O₃ was impossible owing to chemical reaction at the sintering temperature. We have succeeded in cosintering of ZrW₂O₈ with ZrO₂ or SnO₂ and thermal expansion coefficient of cosintered ceramics could be controlled by compositional variation. SnO₂/ZrW₂O₈ cosintered ceramics showed higher bending strength than that of ZrO₂/ ZrW₂O₈. Sintering mechanism of the cosintered ceramics was investigated by means of thermomechanical analysis and secondary electron microscope. Different sintering mechanism was observed between cosintered body of ZrO₂ and ZrW₂O₈ system and SnO₂ and ZrW₂O₈ one. It was also revealed that Al₂O₃ could work as sintering aid of both SnO₂/ZrW₂O₈ system and ZrO₂/ ZrW₂O₈ one.