涡轮转子叶片热障涂层损伤失效的实时检测与分析

Real-time Detection and Analysis of Damage and Failure of Thermal Barrier Coatings on Turbine Rotor Blades

在地面台或核心机上开展热障涂层试车需耗费巨大的人力物力,且无法捕捉涂层损伤演化的关键信息。通过研制高速旋转涡轮叶片热障涂层动态服役环境模拟与测试装置,并在转子叶片热障涂层表面敷设高温电阻应变计与热电偶可实现服役过程中的应变损伤与温度场的实时检测。敷设方法选择陶瓷棒火焰喷涂,应变计的温度补偿通过高温升降炉来实现,同时也开展了静态热冲击考核对比实验。结果表明转速6000 r/min、服役温度1000℃时涡轮叶片截面温差为103℃,提高转速后热障涂层温度降低但主应变显著提高,吸力面主应变大于压力面,在平行于缘板方向应变梯度最大。在动态热冲击循环测试中涂层失效前测点主应变为0.23%~0.82%,高于静态测试的0.04%~0.67%,各测点均为拉伸变形。高速旋转热障涂层经历128次热循环剥落失效,失效原因为应变损伤的累积以及离心载荷作用下裂纹的迅速扩展。

Carrying out the thermal barrier coatings test on the ground table or core machine requires huge manpower and material resources,and cannot capture the key information of damage evolution.By developing a dynamic environment simulator for turbine blades,high-temperature resistance strain gauges and thermocouples were installed on the surface of the thermal barrier coatings to collect the strain damage and temperature field during service in real time.The laying method was flame spraying,and the temperature compensation of the strain gauges was realized by the lifting furnace.At the same time,a comparative experiment was carried out with the static thermal shock assessment.The results show that the temperature difference of the dynamic test section is 103℃when the rotating speed is 6000 r/min and the temperature is 1000℃.After increasing the rotating speed,the temperature of the thermal barrier coating decreases but the principal strain increases significantly.The principal strain of the suction surface is greater than that of the pressure surface,and the strain gradient parallel to the edge plate direction maximum.In the dynamic thermal shock cycle test,the principal strain varies from 0.23%to 0.82%,which is higher than that of the static test(0.04%~0.67%).High-speed rotating thermal barrier coating fails after 128 thermal cycles,which is caused by the accumulation of strain damage and the rapid expansion of cracks under centrifugal loading.