In-situ synthesis of Sc2W3O12/YSZ ceramic composites with controllable thermal expansion

Abstract

In this work, Sc2W3O12/ZrO2 ceramic-based composites with controlled coefficients of thermal expansion (CTEs) were successfully synthesized via an in-situ liquid phase sintering technique. The effects of Sc2W3O12 content, sintering temperature and crystal stabilizer on the crystalline structure, fracture morphology and thermal expansion properties were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal mechanical analyzer (TMA). The results indicated that the composites containing orthorhombic Sc2W3O12 and tetragonal ZrO2 can be prepared using low temperature sintering (800°C); however, the crystallization degree of Sc2W3O12 was poor. Increasing the sintering temperature can make the crystallinity of composites become better, but it also leaded to partial phase transformation of ZrO2. A small amount of crystal stabilizer (Y3+) can stabilize monoclinic ZrO2 as YSZ-matrix ceramics containing different ratio of Sc2W3O12. The CTEs of the Sc2W3O12/YSZ ceramics can be controlled from −2.03×10−6°C−1 to 7.60×10−6°C−1 and very low thermal expansion (1.04×10−6°C−1) was observed in the specimen with a Sc2W3O12/YSZ weight ratio of 1/1.