Preparation of Ultrafine SiC Powders by Carbothermal Reduction

SiC powder was synthesized by carbothermal reduction method using silica sol and amylum as reactants in closed and open graphite crucibles, respectively. The phase composition and morphology of the powders were characterized. Formation of phase-pure silicon carbide can be achieved at 1700°C for 1h. Increasing reaction temperature and extending holding time can greatly promote the production of SiC. The products synthesized in open graphite crucibles are mainly composed of equiaxial β-SiC particles while those synthesized in closed graphite crucibles are β-SiC particles and nanorods.