Effects of Carbon-Coated Whiskers on the Fracture Toughness of SiC Whisler/Si3N4 Ceramic Composite

초록

The effects of carbon-coated whiskers on the fracture toughness of SiC whisker/Si3N4 ceramic composite were investigated. The results obtained can be summarized as follows. (1) By the addition of carbon-coated SiC(w), the fracture toughness of SiC(w)/Si3N4 composites was increased, irrespective of an amount of sintering aids. The carbon-coated SiC(w)/ Si3N4 composite showed a high degree of crack deflection and pull-out in fracture surface. Therefore, carbon-coated layers were considered to form relatively weak interfacial bond with Si3N4 matrix. (2) The 꺬-Si3N4 acicular grains tended to be oriented more easily and vertically to hot-press direction by the addition of carbon-coated SiC(w). Thus, it is considered that weak interfacial bond and preferential orientation of 꺬-Si3N4 grains contribute to improvement in the KIC.