Microstructures and mechanical properties of CVD-SiC coated PIP-C/SiC composites under high temperature

In order to improve the anti-oxidation performance of carbon fiber reinforced silicon carbide (C/SiC) composites, SiC coating was prepared by chemical vapor deposition (CVD). The effects of high-temperature annealing and the anti-oxidation properties of coated composites were investigated. The results showed that CVD-SiC coating, which was β-SiC phase, was fabricated successfully on the PIP-C/SiC with thickness of about 30 μm. It was clear that visible cracks existed and the ratio of weight loss increased with the annealing temperature increasing, while the flexural strength of coated composites greatly decreased with the elevation of the annealing temperature. Coated composites showed the best anti-oxidation ability at 1773 K (1.73 wt.%). During thermal cycle tests, the weight loss of coated sample was 0.68 wt.% and the percentage of remaining strength was 98.1%. The decrease of flexural strength during the tests was primarily due to the oxidation of the coated samples by oxygen or vapor.