SiC界面热化学反应演化响应机理研究

Evolution and response mechanisms of interfacial thermochemical reactions for silicon carbide materials

超高温陶瓷是保障飞行器在极端热环境下安全服役的理想热防护材料之一,其中SiC组分由于其优异的力热性能已成为陶瓷基体或抗氧化涂层领域的研究热点。但由于目前尚未能清晰认知其在高温边界层内界面热响应演化的复杂机理,限制了其热防护性能设计的进一步提升。为在微观尺度上研究SiC复杂界面演化及热响应机制提供新的可能,采用基于反应力场的反应分子动力学模拟方法,模拟了SiC界面的高温演化过程,并探究了界面在温度和压强变化下的热响应机理,包括热氧化反应及升华等;计算了典型工况下SiC界面的氧化反应速率、升华速率及烧蚀速率,并将计算获得的烧蚀后退速率结果与文献实验结果进行了对比,发现误差在10%以内,进一步验证了该方法在材料界面热化学反应定量计算方面应用的可行性。

Ultra-high temperature ceramics are one of the ideal potential materials for thermal protection in extremely high-temperature environments.Silicon carbide,owing to its exceptional mechanical and thermal performance,becomes a research hotspot in the area of ceramic matrix or oxidation-resistant coatings,significantly enhancing the oxidation and ablation resistance of thermal protection materials.However,the complex mechanisms of thermal response and evolution for the silicon carbide interface in the high-temperature boundary layer remain unclear,limiting its further modification in thermal protection system design.Reactive molecular dynamics(RMD)simulation method based on the reactive force field,provides new possibilities for investigating the complex interface evolution and thermal response mechanisms of silicon carbide at the atomic scale.In this study,the interfacial evolution of silicon carbide is investigated by employing the RMD simulation method,and the thermal response mechanism is explored under various temperature and pressure conditions,including the oxidation and sublimation phenomena,etc.Moreover,the oxidation rate,sublimation rate and material ablation rates are further calculated under typical operating conditions.Through comparing the calculated ablation recession rate with experimental results from literatures,a relative error within 10% is revealed,verifying the feasibility of applying RMD method in quantitative calculation of thermochemical reactions at the material interface.