Ablation behavior of CVD-ZrC coating under oxyacetylene torch environment with different heat fluxes

• The structure evolution and ablation behavior of the coating are investigated under ablation with different heat fluxes environments.
• The value of “y” in the chemical composition of ZrCxOy remains stable at 1~2 during the different heat fluxes of ablation environments.
• The oxidation progress from ZrC to ZrCxOy to ZrO2 is accelerated by the continuous diffusion of oxygen resulted from the increase of heat flux.

An ablation resistance ZrC coating composed of micrometer particles was prepared on carbon/carbon composites by chemical vapor deposition. The structure evolution, ablation property and behavior of the coating were investigated under an oxyacetylene torch environment with different heat fluxes. Results show that the ablation performance decreases with the increase of heat fluxes from 2380 to 4180 kW/m2. Oxidation erosion is proposed as the major ablation mechanism. The ablated coating consists of three layers (outer ZrO2 layer, transitional ZrCxOy layer and residual ZrC layer). An oxidation progress that the ZrC is oxidized into ZrCxOy firstly and then into ZrO2 is inferred and accelerated by the continuous diffusion of oxygen resulted from the increase of heat fluxes. During different heat flux environments, the coating exhibits efficacious mechanical denudation resistance and the formed transitional ZrCxOy and outer ZrO2 layers act as a good oxygen diffusion barrier, which could be the reason for its high ablation resistance at the temperature of 2000–3000 °C.

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