【摘要】 钼是一种优异的高温结构材料,通常在其表面制备MoSi₂涂层来防止氧化。MoSi₂/Mo涂层在高温使用过程中通常反复加热冷却,不可避免的出现裂纹,裂纹引起严重的应力集中,使涂层结合强度明显减弱,导致涂层剥落。而振动往往是导致材料失效的主要环境因素,若材料经受热震和振动的叠加作用,对涂层会产生更大的损伤破坏。本文利用Abaqus软件计算了MoSi₂/Mo涂层在800℃热震30次后界面应力分布和裂纹扩展情况,再对热震之后的MoSi₂/Mo涂层施加声波振动,分析了声波幅值和超声波频率对涂层裂纹扩展的影响规律。基于涂层损伤力学,总结了热震次数以及超声波幅值和频率对于裂纹扩展的影响。更多还原

【Abstract】 Molybdenum is an excellent high-temperature structural material,and MoSi₂ coating is usually prepared on its surface to prevent Mo oxidation. MoSi₂/Mo coating is usually heated and cooled repeatedly during high-temperature service,and cracks inevitably appear. The cracks cause severe stress concentration,which significantly weakens the bonding strength of the coating and causes the coating to peel off. Vibration is often the main environmental factor leading to material failure. If the material is subjected to the superimposition of thermal shock and vibration,it will cause greater damage to the coating. This paper uses Abaqus software to calculate the interfacial stress distribution and crack growth of the MoSi₂/Mo coating after 30 thermal shocks at 800 ℃,and then applies ultrasonic vibration to the MoSi₂/Mo coating after thermal shock,and analyzes the effects of ultrasonic amplitude and ultrasonic frequency on the crack growth. Based on the damage mechanics of the coating,it summarizes the effects of the number of thermal shocks and the amplitude and frequency of ultrasonic waves on crack propagation.更多还原