ZTA-SiC_W的显微结构与断裂特征

MICROSTRUCTURE AND FRACTURE FEATURE OF ZTA-SiC_w COMPOSITE

用溶胶-凝胶方法制备室温强度为935—1110MPa、断裂韧性9.7MPam^(1/2)的ZTA-SiC_W复合陶瓷。经X射线衍射分析、透射电子显微镜、扫描电子显微镜等手段研究其显微结构和断口特征。结果表明,晶须得到了很好的分散,基体有显著的织构特征,晶须与基体之间除了一部分常见的多晶相接型关系,还有大量的穿晶及穿晶相接型关系。断口上有相当数量与局域晶须群密切相关的二次裂纹。局域晶须群对扩展裂纹的协同阻挡形成二次裂纹可能是晶须群增强增韧的一种新方式。

A ZTA-SiC_W ceramic composite of room temperature strength 935-1110 MPa and fracture toughness 9.7MPa·m^(1/2) was prepared by the sol-gel process.Its microstructure and fracture feature have been examined by means of X-raydiffraction analysis and electron microscope observations. The results show that thewhiskers are well dispersed and the matrix has an obvious texture character. Betweenthe whisker and matrix, there is a great number of transcrystalline and trans-crystalline connective relation other than part of conventional polycrystalline connective ones. Certain secondary cracks closely related with local whisker groupare found on the fracture surface. It may be a new reinforcing and tougheningmechanism by whisker group, of which the whiskers in the local whisker grouparrest synergetically the crack propagation accompaning with the formation of se-condary cracks.