A self-healing HfB2-SiC-TaSi2 coating with outstanding long-term ablation resistance above 2000 °C

To meet the service requirements of advanced aerospace vehicles, materials withstanding long-term (>2000 s) ablation resistance at ultra-high temperature (>2000°C) are in urgent demand. With this in mind, this paper prepared a self-healing HfB 2 -SiC-TaSi 2 coating that exhibited outstanding long-term ablation resistance. After ablation for 2160 s (24 cycles, 90 s per cycle) exceeding 2000°C, the thickness and mass loss rates of the coating were as low as 4.6×10 -5 mm/s and 5×10 -5 g/s, respectively, approaching near-zero ablation. The high performance resulted from the formation of a stable Hf-Ta-O oxide layer, as well as its defects generated during ablation were healed timely via “wound sutures” and “scab healing” patterns, enabled by precipitated Ta-rich particles and oxidation products from the internal coating. The proposed coating greatly extends the protection time in ultra-high temperature environments, providing valuable insights for the thermal protection design of advanced aerospace vehicles.