TaSi₂-modified HfB₂–SiC coating: Preparation and ablation behavior

HfB₂–SiC coatings modified with TaSi₂ were prepared on carbon/carbon composites by slurry-dipping combined with gaseous silicon infiltration. The effects of TaSi₂ content on the microstructure and ablation performance were investigated. With 20 wt.% addition of TaSi₂, the HfB₂–SiC coating demonstrated the highest resistance to ablation under an oxyacetylene torch. The good ablation resistance was attributed to the formation of the Hf–Ta–Si–O compound phase, the Hf–Ta–O skeleton and the “sheet-like” clusters. During ablation, the Hf–Ta–Si–O compound phase healed the defects and inhibited penetration of oxygen. Meanwhile, both the Hf–Ta–O skeleton and the “sheet-like” clusters with good stability pinned the compound phase. They jointly enhanced the ablation performance of the coating.