FABRICATION AND FRACTURE-BEHAVIOR OF NOVEL SIC CERAMICS HAVING RODLIKE GRAINS

A new type of silicon carbide having rodlike grains has been fabricated by hot-pressing or hot-pressing followed by hot isostatic pressing using SiC whiskers as the raw powder. Preliminary relationships between sintering conditions and microstructure and fracture toughness of the processed ceramics were established. Ceramics with relative density greater than 98% were prepared at temperatures of 2050-degrees-C or greater. The fracture toughness of these ceramics was better than that of ordinary SiC, and its maximum value was 7.3 MPa.m1/2. Grain pullout, grain bridging, and crack deflection were considered to be the main operative mechanisms which led to improved fracture toughness.