Microstructure characteristics and ablation behavior of an Al1.92Cr0.08O3-SiC-ZrC anti-ablation coating

A novel oxide-carbide coating system was achieved on a C/C-ZrC-SiC composite surface by low-pressure plasma spraying and a slurry method, with Cr doping to improve the thermal stability of the coating. The phase compositions and microstructure characteristics of composites were characterized by XRD, SEM and EDS. The ablation properties were tested in an oxy-acetylene environment at temperatures up to 2500℃ for 120 s. The results show that the C/C-ZrC-SiC substrate coated with the Al1.92Cr0.08O3-SiC-ZrC coating exhibits a significant improvement in ablation resistance, with the mass and linear ablation rates decreased by 66% and 76% respectively. This is caused by the highly dense and stable protective structure formed during ablation. The pinning effect of the ZrO2 phase and the thermal-stability efficiency of Cr2O3 provide and explanation for the reduction of the volatilization of SiO2 and Al2O3 at high temperature. Continuous and robust multi-oxide scales on the surface comprised of ZrO2 grain skeletons and molten Al1.96Cr0.04O3-SiO2 cause the superior anti-ablation property.