Preparation and ablative mechanism of C/C-ZrC-SiC composites filled with Fe-based superalloy coating

The C/C-ZrC-SiC composites filled with Fe-based superalloy coating were prepared by low pressure suspension impregnation to improve the C/C-ZrC-SiC composites used in the field of hypersonic flight vehicle's thermal protective performance. The evolution rule of the surface microstructure of the C/C-ZrC-SiC composites filled with Fe-based superalloy before and after oxy-acetylene flame ablation was studied by means of XRD, SEM and EDS. And the effect of the Fe-based superalloy coating on the ablation behavior of the C/C-ZrC-SiC composites was clarified. The results show that the C/C-ZrC-SiC composites are infiltrated by low pressure suspension infiltration at 1 650℃ for 2 h, and a uniform, dense and tightly bonded Fe-based superalloy coating is formed on the surface. After the ablation at 2 500℃ for 180 s, the surface of the modified the C/C-ZrC-SiC composites generates a smaller ablation pit, and the mass and linear ablation rate are reduced by 8% and 35% respectively than the unmodified sample. And a uniform and dense protective layer of the Fe₂O₃-ZrO₂ composite oxides is formed on the surface, which greatly reduces the occurrence of surface cracks, holes and other defects, thereby reducing the diffusion rate of oxygen and the stress concentration caused by defects. The Fe-based superalloy coating improves the high temperature oxidation resistance and mechanical corrosion resistance of the C/C-ZrC-SiC composites.