Oxidation failure behavior and repair of the damaged SiC-ZrB₂/SiC coating of C/C composites

The impacts of damage on the thermal barrier performance of SiC-ZrB₂/SiC coating of C/C composites were investigated. The microstructure, chemical components, and thermal protection performance of the damaged coating before and after repair were analyzed, and the failure behavior of the damaged coated C/C composites was studied. After oxidation at 1500 °C for 360 min, the weight loss of the undamaged sample was −0.38 %, while that of the damaged sample reached 21.16 %. A repair method using polysiloxane and SiC-ZrB₂ powder as repair agent was employed to recover the oxidation resistance property of the damaged coating. The repair agent generated Si[sbnd]O[sbnd]C ceramics after high-temperature treatment, covering the damaged area and bonding well with the original coating. The weight loss of the repaired sample was 2.4 %, which was significantly improved compared to the damaged coating. This work offers a research foundation for the optimization of the repair of damaged silicon-based ceramic coatings.