FORMATION OF FINE SILICON-CARBIDE POWDERS BY A VAPOR-PHASE METHOD

The formation of silicon carbide powders by the vapor phase reaction of SiCl4 + CH4 (1400-1500°C), CH3SiCl3 (800-1400°C) and (CH3)4Si (800-1400°C) was studied. The effectiveness of the silicon sources was in the sequence (CH3)4Si > CH3SiCl3 > SiCl4, in accordance with the thermodynamic parameters. Fine β-SiC powders were produced by the pyrolysis of (CH3)4Si in hydrogen above 900°C. The crystallinity of the products increased with increasing reaction temperature. The particles were spherical and had average sizes of 0.02-0.12μm which decreased with increasing reaction temperature and with decreasing (CH3)4Si concentration. A reaction process consisting of the formation of particles of organosilicon polymers and their subsequent decomposition was proposed for the formation of SiC particles by the pyrolysis of (CH3)4Si. © 1979.