High-Heat Design Boosts Thermal Protection in Ablation

ZrC has drawn wide attention as an anti-ablation coating material for lightweight C/C composites but is limited by the produced porous and loose ZrO₂ film. To address this issue, the second phase is introduced to improve the densification of the formed Zr-X-O film. Such as ZrC-SiC/TaC coating, the produced low-melting-point oxides, SiO₂ (T_m=1650 °C), Ta₂O₅ (T_m=1800 °C) and Zr₆Ta₂O₁₇ (T_m=1900 °C), helped to form a dense oxides film. However, the high service temperature causes heat accumulation and a large thermal stress gradient on the surface of the coatings, which will result in large local defects and accelerate the failure of the coating. To decrease the ablation heat accumulation, incorporating nanomaterials with high thermal conductivity is an effective strategy but is limited in practical applications due to the agglomeration. A core–shell structure is advantageous because it can endow the outer carbon shell with good dispersion and a thermal conduction network. However, achieving a uniformly dispersed core–shell structure within a dense coating remains challenging due to structural retention difficulty that is limited by complex preparation processes.