Oxidation resistance of NITE-SiC/SiC composites with/without CVD-SiC environmental barrier coating

In this study, the oxidation resistance of nuclear grade graphite (IG-430U) and NITE-SiC/SiC composites with/without CVD-SiC outer coating were evaluated at various temperatures (400–1000 °C) under high oxygen contents (O2 1% and O2 21%). The effect of CVD-SiC outer coating on the oxidation of NITE-SiC/SiC composite was also investigated in the atmosphere of partial oxygen. The weight change of NITE-SiC/SiC composites was mainly dominated by the active oxidation at the interphase of PyC. The weight change speed of these materials significantly decreased with increasing the oxidation time. The oxygen concentration was not sensitive for the oxidation behavior of NITE-SiC/SiC composites, because these materials were affected by oxygen supply rate and CO2 gas evaporation rate through fine channels between fiber and matrix. The PyC interphase of NITE-SiC/SiC composites with a CVD-SiC outer coating remained after the oxidation test. It could be confirmed that the CVD-SiC environmental coating on the surface of NITE-SiC/SiC was very effective for the suppression of oxidation weight loss.