Design of stable oxide layers and heat transfer structure for SiC whiskers reinforced (Hf_0.5Zr_0.5)C ceramics with superior ablation resistance at 2500 °C

SiC whiskers (SiC_w) and Y₂O₃ reinforced (Hf_0.5Zr_0.5)C ceramics are designed to realize superior oxidation and ablation resistance at 2500 °C. MoSi₂, TaSi₂, and SiB₆ (with varying SiC_w contents) are further introduced as sintering aids and modifying components to enhance density and improve ablation resistance. The introduction of SiB₆ leads to higher oxidation and ablation resistance due to the in-situ formation of borides with high thermal conductivity. The borides and SiC jointly serve as rapid heat transfer pathways, facilitating the release and mitigation of thermal stresses during ablation. Meanwhile, an appropriate amount of SiC_w serves as toughening and high-temperature self-healing phases, while Y₂O₃ suppresses the crystalline transformation. Thus, a dense and stable oxide layer is developed during ablation. Therefore, the designed SiC_w-Y₂O₃-SiB₆-(Hf_0.5Zr_0.5)C exhibits near-zero damages under a 1050 s ablation at 2500 °C, with mass and linear ablation rates of −0.220 μm/s and −0.071 mg/(cm²·s), respectively.