Oxidation behavior of SiC/SiC composites for helium cooled solid breeder blanket

In order to evaluate the oxidation behavior and mechanism of SiC/SiC composites with conventional pyrolitic graphite interface (PyC-SiC/SiC) and advanced multilayer interface (ML-SiC/SiC) in a HCSB blanket environment, a thermal gravimetric analysis (TGA) in He + O₂ environment at 1000 °C and 1200 °C was performed. The PyC-SiC/SiC at 1200 °C and the ML-SiC/SiC at 1000 °C and 1200 °C showed relatively smaller weight change during oxidation because SiO₂ formed on the SiC-matrix and SiC-fiber sealed the specimen surface before the PyC interface recession by gasification of graphite due to relatively high SiO₂ formation rate. While the PyC-SiC/SiC at 1000 °C showed significant weight loss because the specimen surface was not sealed by SiO₂ and significant PyC interface recession occurred due to relatively slow SiO₂ formation.