SYNTHESIS OF SILICON-CARBIDE THROUGH THE SOL-GEL PROCESS FROM DIFFERENT PRECURSORS

Silicon carbide (SIC) was synthesised from silicon alkoxides and vario us carbon sources. Tetraethoxysilane (TEOS), methyltriethoxysilane (MT ES) and a mixture of TEOS and MTES were hydrolysed in the presence of phenolic resin, ethylcellulose, polyacrylonitrile (PAN) and starch to incorporate the gel into the carbon source in the silica network. The gel thus obtained was carbonized at 800 degrees C in an argon atmosphe re to obtain the mixture of silica and carbon which when heated to 155 0 degrees C in argon yielded silicon carbide. The characterization of the product by X-ray, FTIR and SEM showed it to be beta SiC with diffe rent crystallite and grain sizes. The difference in the crystallite an d grain sizes is attributed to the nature of the carbon source. The de nsity of the SiC obtained by the sol-gel process was found to be lower than the values reported for SiC and this is ascribed to the porous n ature of the products generally obtained by this process.