A C/SiC Graded Coating on C/C Composites by LPCVD in the Methyltrichlorosilane/Hydrogen System

Abstract

In order to improve the anti-oxidation of C/C composites, a C/SiC functionally graded coating for C/C composites was prepared by low pressure chemical vapor deposition (LPCVD) using methyltrichlorosilane (MTS, CH3SiCl3) and H2 as precursors. The relative amount of C and SiC in coatings was varied by controlling the input ratio of H2 to MTS. The phase composition and morphology were examined by scanning electron microscope (SEM) and X-ray diffraction (XRD), and the content distribution of C and SiC phases were investigated by energy dispersive spectroscopy (EDS). The isothermal oxidation test was evaluated at 900 °C and 1500 °C respectively. The results showed that the as-obtained coatings were possessed of a dense and uniform structure, and the SiC content in coatings increased with an increment of the molar ratio of H2 to MTS. The C/SiC coating had a good oxidation resistance.