Interfacial modification and cyclic ablation behaviors of a SiC/ZrB_2-SiC/SiC triple-layer coating for C/SiC composites at above 2000 °C

摘要

A SiC/ZrB2-SiC/SiC triple-layer coating was fabricated successively by chemical vapor deposition (CVD), slurry brushing-sintering and CVD for C/SiC composites. To enhance the cyclic ablation resistance, a pre-oxidation treatment on the inner SiC layer was performed. The bonding strength of the coating with pre-oxidation at 1600 degrees C is significantly improved to 32 MPa, 77.8 % greater than that of the untreated specimen. The coating can endure 5 ablation cycles from 2050 degrees C to room temperature without peeling off and displays a small spalling area of 18 mm(2) after 6 cycles. The cyclic ablation mechanisms are discussed in detail.