Oxidation ablation resistance of ZrB₂-HfB₂-SiC-TaSi₂ coating prepared on C/C composite surface

In order to improve the oxidation and ablative properties of C/C composites, ZrB₂-SiC-HfB₂-TaSi₂ coating was prepared on the surface of C/C composites by atmospheric plasma spraying. By means of microstructure analysis and phase structure analysis, the difference of the spray powder before and after IPS treatment and the microstructure and oxidation ablation resistance of the coating were studied. The results show that the IPS treated powder has better fluidity and densification. In the coating, part of ZrB₂ and HfB₂ exist in the form of unmelted particles, another part exists in the form of intermediate solid solution (Zr, Hf)B₂, and TaSi₂ exists in the particle gap. The linear ablation rate and mass ablation rate of the coating are −1.513 × 10⁻⁴ mm/s and 2.842 × 10⁻⁴ g/s, respectively, measured under the condition of oxygen acetylene heat flux of 1.8 MW/m², 180 s were ablated. The coating has good ablative resistance, and TaSi₂ can form dense Zr-Ta-O and Hf-Ta-O oxides with Zr and Hf elements. The Ta-Si-O glass phase can effectively seal the holes of the coating to prevent oxygen penetration. During the ablation process, the oxidation of (Zr,Hf)B₂ also plays a certain role in the formation of densification zone on the coating surface.