Interfacial modification and cyclic ablation behaviors of a SiC/ZrB2-SiC/SiC triple-layer coating for C/SiC composites at above 2000 °C

•To enhance the cyclic ablation resistance of the SiC/ZrB2-SiC/SiC multilayer coating for C/SiC composites, an interfacial modification process was carried out to improve the coating bonding strength.•The bonding strength was significantly improved from 18 MPa to 32 MPa by a pre-oxidation treatment at 1600 °C.•The modified coating endures 5 ablation cycles without peeling off and displays a small spalling area after 6 cycles.•The pre-oxidation treatment did not deteriorate the mechanical property of C/SiC. 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 °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 °C to room temperature without peeling off and displays a small spalling area of 18 mm2 after 6 cycles. The cyclic ablation mechanisms are discussed in detail.