Novel high‐entropy ultra‐high temperature ceramics with enhanced ablation resistance
Pan Zhang, Xiongjun Liu, Guangyu He, Fu‐Kuo Chiang, Hui Wang, Yuan Wu, Suihe Jiang, Xiaobin Zhang, Zhaoping Lü
Abstract
Abstract Ultra‐high temperature ceramics (UHTCs) offer great potential for applications in extreme service environments, such as hypersonic vehicles, rockets and re‐entry spacecraft. However, the severe ablation caused by high‐speed heat flow scouring and high‐temperature oxidation limits the engineering application of UHTCs. In this work, we report a novel high‐entropy UHTC (Ti 0.2 Zr 0.2 V 0.2 Nb 0.2 Cr 0.2 )(C 0.5 N 0.5 ), which exhibits superior ablation resistance and light weight compared with traditional UHTCs. Specifically, at a temperature of 2650 K, the mass ablation rate of the material was measured as 1.025 × 10 −2 g·s −1 , and the density was calculated to be 6.7 g·cm −3 . The impressive ablation resistance of (Ti 0.2 Zr 0.2 V 0.2 Nb 0.2 Cr 0.2 )(C 0.5 N 0.5 ) is attributed to the incorporation of a self‐healing mechanism, which is associated with the in‐situ formation of a medium‐entropy oxide (TiVCr)O 2 during the ablation process. The medium‐entropy oxide can seal pores and cracks to retard oxygen diffusion and prevent the material from fragmentation, thereby resulting in outstanding ablation resistance.