Sinterability,strength and oxidation of alpha silicon carbide powders

Pressureless sintering of commercially available -SiC powders was investigated at temperatures between 1900 and 2150° C for times of 10 to 240 min under one atmosphere of argon pressure. Alpha-SiC powder containing boron and carbon sintering aids was sinterable at 2150° C for a period of 30 min to a high final density greater than 96 per cent of theoretical. In contrast, a final density only about 80 per cent of theoretical was achieved in -SiC powder containing aluminium and carbon sintering aids. Room temperature and high temperature (1370° C) flexure strength and oxidation resistance were determined on sintered high density (>96% of theoretical) -SiC (boron, carbon) material. Both the strength and the oxidation resistance were found to be equivalent and comparable to those of Carborundum Company sintered -SiC, which is representative of the current state-of-the-art material.