Synthesis and characterization of carbon-silicon carbide particulate composites by powder metallurgical route

Carbon-silicon carbide composites have been prepared using powder metallurgical route. Phenolic resin, cokes, silicon powder, and silicon carbide in varying amounts were dry mixed and co-ball milled. The co-ball milled powders were then compacted and cured simultaneously in hot press. The compacted blocks were carbonized at 1000 degrees C and further heat-treated at 1400 degrees C in an inert atmosphere. Silicon carbide was formed in carbon-ceramic composites due to the reaction of silicon with carbon matrix during heat treatment at 1400 degrees C. The densities of the final carbon-ceramic composites obtained were in the range of 1.66-1.83 gm/cm(3) with open porosities of 2-7%. Scanning electron microscopy and X-Ray diffraction were used to characterize the microstructures and compositions, respectively, of the composites processed at 1000 and 1400 degrees C. It is found that the sintered composites consist of beta-SiC with particle size varying from 1 to 5 mu m. Mechanical strengths of the composites were found to be highly dependent on the percentage of silicon carbide formed due to the reaction of silicon with carbon matrix at 1400 degrees C. Friction coefficient, measured by pin-on-disc method, was found to be higher for 1400 degrees C heat-treated composites as compared to 1000 degrees C heat-treated composites due to formation of SiC.