With the rapid development of high-speed aircraft, the demanding for light, strong, reliable and high temperature resistive thermal protection material (TPM) is becoming urgent. High temperature material interface, such as silicon carbide (SiC) ceramic matrix composite, has received strong interest recently due to its high mechanical and thermochemical stability. For reactive interface development with nano-roughness under extremely hyperthermal non-equilibrium flow conditions for TPM applications, however, has not been reported yet. This work performs a systematic reactive molecular dynamics (RMD) study of the SiC surface morphology effect withstanding hyperthermal atomic oxygen (AO) impact via a gas–solid interface reaction model. The results show that a self-healing trend of the defect-rich silicon carbide surface with original nano-roughness is revealed towards a flatter interface accompanying with the oxidation process. The surface catalytic recombination coefficient is more sensitivity to the surface defects when wall temperature > 500 K. Nano-roughness structure can also vary the main thermochemical reaction path at the thermochemical reactive interface: For the nano-groove surface model, the thermal oxidation reaction becomes dominant, while more pronounced surface catalytic recombination characteristics are revealed for the flat surface model. The mechanisms of roughness effect, surface temperature and gas impacting angle on the surface catalytic recombination, surface oxidation, and interface evolution are revealed, which advance our microscopic understanding of SiC interfacial performance with nano-roughness under non-equilibrium flow conditions.

中文翻译：

---

非平衡流动下纳米粗糙度对碳化硅基材料界面热氧化和表面催化复合特性的影响


随着高速飞行器的快速发展，对轻质、坚固、可靠、耐高温的热防护材料（TPM）的需求日益迫切。高温材料界面，例如碳化硅（SiC）陶瓷基复合材料，由于其高机械和热化学稳定性，最近受到了人们的广泛关注。然而，对于 TPM 应用的极端高温非平衡流动条件下的纳米粗糙度反应界面开发尚未有报道。这项工作通过气固界面反应模型对承受高温原子氧 (AO) 影响的 SiC 表面形貌效应进行了系统的反应分子动力学 (RMD) 研究。结果表明，具有原始纳米粗糙度的富含缺陷的碳化硅表面随着氧化过程呈现出向更平坦界面的自修复趋势。当壁温 > 500 K 时，表面催化复合系数对表面缺陷更加敏感。纳米粗糙结构还可以改变热化学反应界面处的主要热化学反应路径：对于纳米凹槽表面模型，热氧化反应变为占主导地位，而平坦表面模型则揭示了更明显的表面催化复合特征。揭示了粗糙度效应、表面温度和气体冲击角度对表面催化复合、表面氧化和界面演化的影响机制，推进了我们对非平衡流动条件下纳米粗糙度SiC界面性能的微观理解。