液相包覆制备Ce-TZP陶瓷的力学性能与稳定行为

采用XRD、SEM、TEM等分析手段对由液相包覆工艺制备的Ce—TZP陶瓷的微结构进行了研究，并和共沉淀粉体制备的Ce—TZP陶瓷进行了对比分析．力学性能表明，同共沉淀粉体制备的Ce—TZP陶瓷相比，由液相包覆工艺制备的Ce—TZP陶瓷虽硬度下降，但断裂韧性改善；液相添加少量Al2O3硬度随之增加、断裂韧性显著提高．电镜分析表明，液相包覆工艺制备的Ce—TZP陶瓷晶粒尺寸分布宽化，一部分晶粒尺寸较大但CeO2含量低、易发生马氏体相转变晶粒的存在是断裂韧性改善的主要原因．陶瓷体中单斜相大晶粒与四方相之间的残余应力、添加少量Al2O3在晶界上易形成薄的非晶包裹层，是增加可相变四方相数量，提高断裂韧性的其它机制。

Mechanical Properties and Stabilization Behavior of Ce-TZP Ceramics Prepared by Coating Process

The microstructure of Ce-TZP ceramics processed by a coating technique, compared to co-precipitated powder-based Ce-TZP, was analysed using a combination of XRD, SEM, TEM, etc. The results showed that CeO2-coated powder-based zirconia ceramics exhibited higher fracture toughness than co-precipitated powder-based zirconia ceramics in spite of a little decreasing hardness. Besides, a small amount of alumina addition can significantly improve the fracture toughness of CeO2-coated powder-based zirconia ceramics. In contrast with homogeneous grain size and stabilizer content distribution of co-precipitated powder-based Ce-TZP ceramics, SEM and EPMA analysis revealed that coating process resulted in wider grain size and stabilizer content distribution in this Ce-TZP ceramics. The superior fracture toughness of CeO2-coated Ce-TZP ceramics was mainly attributed to a fraction of highly transformable tetragonal ZrO2 grains with low ceria content. The residual stress existing between anisotropic monoclinic and tetragonal grains, and the thin glass films containing alumina and silica at grain boundary observed by TEM, were believed to benefit the preservation more tetragonal grains during sintering, contributing to the stress-induced martensitic phase transformation.