Synthesis and Characterization of SiC Ceramics for High Temperature Resistant Coatings and Matrix

SiC ceramics are expected as oxidation resistant coating material for Carbon/Carbon (C/C) composites. In the present study, SiC ceramics were synthesized through Sol-Gel method with low environmental impact. The gels were synthesized from ethylalcohol, methyltriethoxysilane (MTES), hydrochloric acid (HCl) and purified water (H2O), and it was pyrolyzed at 1 000, 1 500 and 1 700◦C. The structures of gels after heat treatment were analyzed by X-ray diffraction (XRD). XRD results indicated that β-SiC were obtained in the present method and crystallization was increased with increasing heat treatment temperature. There was little weight change in synthesized SiC obtained at 1 000◦C in air, which results in lower weight changes in SiC coated C/C composites comparing with bare C/C composites. However, SiC coated C/C composites were also oxidized because of the generation of cracks during heat treatment at 1 000◦C. Residual tensile strength of SiC coated C/C composites were also higher than that of bare C/C composites after 5 minutes oxidation.