HEAT-TREATMENT OF ULTRAFINE SIC POWDERS TO REDUCE OXIDATION SENSITIVITY AND GRAIN-GROWTH

Ultrafine SiC powders of 20 nm were synthesized by a CO2 laser induced reaction between silane and acetylene followed by heat treatment at d ifferent temperatures and in different atmospheres. These powders were examined by TGA, IR-spectroscopy, XRD and also densified by HIP. Resu lts of different oxidation behavior of the powders are presented. Dens ification of the different heat treated powders lead to different grai n sizes in the dense body. Heat treatment of ultrafine SiC in nitrogen improves oxidation resistance of the powders and reduces grain growth during densification significantly.