MoSi2涂层高温富氧火焰冲刷失效机理-中国材料进展

文章信息/Info

Title:: Study on Failure Mechanism of MoSi2 Coating under High-Temperature Oxygen-Enriched Flame Erosion

Author(s):: LUO Jingchuan1; ZHU Changfa2; LIU Kun2; WANG Yuesong3; XU Xiangyi4; YANG Guanjun1; CHEN Lin1; 1. State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 710049, China 2. Xi’an Aero Engine Corporation in CASC, Xian 710065, China 3. The Second Military Representative of Equipment Department of the PLA Rocket Force Office in Xi’an, Xian 710065, China 4. The 8th Military Representative of Equipment Department of the Air Force Office in Xi’an, Xian 710065, China

Keywords:: MoSi2 coating; oxide film; grain boundary; vertical cracks; transverse spallation

摘要:: MoSi2高温氧化时表面可生成保护性SiO2，有望用于推力室喷管内表面抗高温氧化涂层材料。然而，在1800 ℃超高温火焰冲刷考核条件下，MoSi2涂层发生损伤失效。为揭示MoSi2涂层超高温冲刷失效机理，系统研究了不同位置涂层的氧化行为和损伤规律。结果表明：涂层损伤分为个特征区域，分别为前缘、喉部、过渡段、中部和尾部，其中喉部发生整个涂层剥落，尾部涂层仍保持完整。MoSi2涂层的主要失效形式为：超高温下MoSi2涂层晶界快速氧化和，产生晶界裂纹，晶界裂纹合并形成网状、贯穿性、大尺度的纵向裂纹，将MoSi2涂层分割成岛状区域。在热冲击载荷作用下，岛状区域MoSi2涂层发生剥落失效。MoSi2涂层冲刷腐蚀机理，为发展推力室喷管超高温、长寿命MoSi2抗氧化涂层提供了理论方向。

Abstract:: MoSi2 can generate protective SiO2 on the surface during high temperature oxidation, which is expected to be used as a high-temperature oxidation-resistant coating on the inner surface of the thrust chamber nozzle. However, the MoSi2 coatings failed under the flame erosion at ≥1800 ℃. In order to reveal the failure mechanism of MoSi2 coatings, the oxidation behavior of coating on various locations of the thrust chamber nozzle specimen after the flame erosion was clarified. The results show that the coating can be divided into five characteristic regions, namely the leading edge, the throat, the transition section, the middle and the tail. Among them, the entire coating peels off at the throat, and the coating remains intact at the tail. The main failure mode of the MoSi2 coatings are: rapid oxidation and corrosion at the grain boundaries (GB) of the MoSi2 coatings result in the formation of penetrating GB cracks, the coalescence of penetrating GB cracks causes the connected and large-scale vertical cracks, dividing the coatings into island-shaped regions. Under the action of thermal shock, island-shaped coatings peel off. This research analyzes the erosion behavior of coating, and provides the reference for the development of ultra-high temperature and long-life MoSi2 anti-oxidation coatings for thrust chamber nozzles