Long-term oxidation behavior of C/SiC-SiBCN composites in wet oxygen environment

Polymer derived SiBCN ceramic was introduced into carbon fiber reinforced SiC composites to prepare C/SiC-SiBCN composites. Weight change and flexural strength of the samples after oxidation at different temperatures and in different atmospheres were tested up to 100 h to investigate their wet oxidation behavior. It was found that the stable silicoboron glassy self-healing phase formed from the oxidation of SiBCN had favorable oxidation resistance in wet oxygen atmosphere. And the SiC-SiBCN matrix can provide about 50 h of protection for carbon fiber in wet oxygen. Besides, the influence of temperature on the oxidation behavior of C/SiC-SiBCN composites were much related to the release speed of gas products (B₂O₃, HBO₂ and Si(OH)₄). And the oxidation mechanism of SiC/SiC-SiBCN composites were further explained by the comparation with C/SiC-SiBCN composites.