Anti-ablation performance of plasma sprayed ZrB2/SiC coatings on C/C substrates and the influence of a chemical vapor deposited SiC interlayer

To address the industrial usage of carbon/carbon (C/C) substrates with plasma-sprayed ZrB2/SiC coatings, a continuous and dense chemical vapor deposition (CVD)-SiC interlayer of 150 µm was deposited on a C/C substrate. The integration of CVD-SiC with the C/C substrate and plasma sprayed (PS) ZrB2/SiC coatings results in a tight interface. The SiC interlayer significantly reducing thermal stress in the optimized composites up to 1828 Mpa, a decrease of approximately 60% compared to standard composites without CVD-SiC. Ablation tests conducted showed that the optimized composites displayed remarkable mass ablation rate of -11.7% after ablation for 600 s, with a notable increase of -3.5% even after ablation for 1800 s. After 600 s of ablation, the exposed SiO2 layer is approximately 500 µm in size. After 900 s of ablation, the exposed SiO2 layer is approximately 1500 µm. After 1800 s of ablation, the SiO2 is completely evaporated, exposing the C/C matrix, at which point the coating has failed. The SiC interlayer improve the ablation resistance due to the continuous SiO2 film formed by the self-sealing and O anti-diffusive properties.