Effect of heat treatment on crystallite size and grain morphology of silicon carbide synthesized from carbon-silica hybrid precursors

Carbon-silica hybrid precursors for SiC with different carbon contents were prepared by firing hybrid gels consisting of crosslinked phenol resin and silica gel. The SiC precipitation processes in these precursors at 1873 K w ere traced in terms of X-ray diffraction and scanning electron microscope ( SEM) observation. Excess carbon in the system reduces the size of the forme d SiC crystallite during the heat treatment. The precursor with high carbon content yielded aggregated grains consisting of small SiC crystallite, whi le the precursor with low carbon content yielded coarse isolated grains of 100-200 nm after a long-term of heat treatment.