Ablation behaviour of the CVD-(ZrC/SiC)₃ alternate coating on C/C composites under oxyacetylene torch with different heat fluxes

The (ZrC/SiC)₃ alternate coating prepared on C/C composites by CVD were tested using an oxyacetylene torch with the heat fluxes of 2.38 and 4.18 MW/m². Results showed that the coating exhibited great ablation resistance under both low and high heat fluxes. Under heat flux of 2.38 MW/m², the ablation and oxidation occurred layer by layer, while the six layers of coating were reserved after ablation. The SiO₂ phase and transitional ZrC_xO_y layer were formed, providing an effective protection. As the heat flux increased to 4.18 MW/m², the ablation became more serious while the oxide layer still kept intact on C/C substrate after ablation. Dense and stable layered ZrO₂ layers covered on C/C composites after the rapid consumption of SiC layers, which could resist the flame scouring. The (ZrC/SiC)₃ alternate coating was demonstrated to have potential in applications under different ablation conditions.