Effect of pre-oxidation treatment on the bonding strength and thermal shock resistance of SiC coating for C/C-ZrC-SiC composites

To improve the bonding strength and thermal shock resistance of SiC coating for C/C-ZrC-SiC composites, a transition layer with mechanical interlocking structure was constructed at the interface by pre-oxidation treatment and chemical vapor deposition. For the coated specimens with pre-oxidation treatment at 1073 K for 5 min, the bonding strength increased from 2.0 to 4.0 N, and the mass loss percentage decreased by 52.5% after 12-time thermal cycling between 1773 K and room temperature in air. The transition interlocking structure can effectively alleviate the mismatch between the coefficients of thermal expansion of SiC coating and C/C-ZrC-SiC substrate, improving the bonding strength and thermal shock resistance. As the pre-oxidation time increases, a rugged and loose ZrO₂-SiO₂ layer will be formed at the interface, which is disadvantageous to the bonding strength and thermal shock resistance of SiC coating for C/C-ZrC-SiC composites, and results in the debonding and collapse of the coating.