SYNTHESIS OF SIC(BETA) ULTRAFINE PARTICLES FROM SI, SIO, OR SIO2 POWDER AND CH4

A process for synthesis of ultrafine ceramic particles using a high-te mperature flame is described, Thermodynamic calculations for the Si-C- O-H system were performed using a computer program for calculation of complex chemical equilibrium compositions. Possible synthesis of ultra fine SiC particles using Si, SiO2 and SiO2 powders (1.0-3.0 mu m) as S i sources was investigated using an electric furnace (5 kW) at 2,018 K . Particle products were characterized mainly by X-ray diffraction ana lysis, field emission scanning electron microscopy, and thermogravimet ry-differential thermal analysis. Ultrafine particles (18-29 nm) of cu bic SiC (beta-SiC) could be produced through Si + CH4, SiO + CH, and S iO2 + CH4 reaction systems, respectively. The effect of hydrogen addit ion on the synthesis of SiC was also investigated. Ultrafine particles of 96.0% SiC selectivity were obtained when H-2 was added to the SiO + CH4 reaction system, and the CH4/SiO molar ratio in this case was 2. 0.