Processing and fracture behaviour of hot pressed silicon carbide whisker reinforced alumina

The improvement of mechanical properties of silicon carbide whisker reinforced alumina has been investigated with emphasis on the effects of the whisker type and content, the hot pressing temperature and the influence of an interfacial film between the whisker and the matrix. The introduction of silicon carbide whiskers significantly improves the fracture toughness, flexural strength and creep resistance of polycrystalline alumina. However, these properties are strongly dependent on the size and morphology of whiskers. Large diameter whiskers generate extensive micro-cracking which leads to a decrease in flexural strength. Also, the presence of carbon-coated SiC whiskers substantially increases the high temperature strain rate by promoting cavitation. A grain boundary glassy phase introduced by the carbon coating was also detected.