The effect of deposition temperature on microstructure and mechanical properties of SiC coatings on graphite

In this study, silicon carbide (SiC) coating was prepared by CVD using MTS-H2-Ar as precursors on graphite substrate in the temperature range of 1100–1300℃. The morphology of SiC coatings was observed by SEM, and the phase composition, preferred orientation, grain size and crystallinity of the SiC coating were analyzed by XRD. It was found that the rate of deposition was increased with increasing temperature under low temperature range and then was nearly consistent over 1200℃. It indicated that the structure changed from smooth featureless to highly faceted structures. The β-SiC was obtained at four different deposition temperatures. An increasing crystallinity and grain size were observed with increasing temperature. Hardness and Young’s modulus also increased with increasing temperature. It can be concluded that crystallinity has an important influence on both hardness and Young's modulus, while grain size has a greater influence on hardness but a smaller influence on Young's modulus.