摘要
目的研究退火过程中LaMgAl_(11)O_(19)热障涂层内部残余热应力的分布情况及其对热障涂层热稳定性的影响机理。方法基于等离子喷涂制备的LaMgAl_(11)O_(19)/YSZ双热障涂层物理模型,采用Abaqus建立数值仿真模型,通过温度位移耦合计算,系统分析不同退火温度下LaMgAl_(11)O_(19)热障涂层内部残余热应力的分布情况。通过扫描电镜,观察退火前后涂层表面及断面的微观组织形貌。根据数值模拟结果及涂层SEM图像,分析残余热应力对LaMgAl_(11)O_(19)热障涂层热稳定性的影响,探究引起涂层裂纹损伤失效的影响因素。结果数值模拟结果显示,LaMgAl_(11)O_(19)热障涂层内部的残余热应力以径向应力为主,其值远大于轴向应力及剪切应力。退火中,径向残余热应力在径向距离0~2.4 mm内缓慢增长到最大值,而在x=2.4 mm至径向边缘范围内急剧降低。退火后,在涂层径向边缘位置出现应力集中,在径向距离x=2.6 mm处达到最大拉应力,并迅速减小为压应力。900、1000、1100、1200℃退火中径向残余热应力梯度分别为0.334、0.369、0.389、0.391 GPa。退火后径向残余热应力梯度分别为0.104、0.148、0.203、0.260 MPa。从退火后涂层表面及断面扫描电镜图像观察到,LaMgAl_(11)O_(19)热障涂层内部裂纹损伤以轴向裂纹为主。结论LaMgAl_(11)O_(19)热障涂层退火过程中内部径向残余热应力在径向边缘位置存在拉压应力突变,应力梯度随退火温度的升高而增大。LaMgAl_(11)O_(19)热障涂层在退火过程中存在较大的径向残余热应力,其应力值占主导地位,是引起涂层轴向裂纹产生及扩展的主要原因。
This work aims to explore the distribution of residual thermal stress in LaMgAl_(11)O_(19) thermal barrier coating during annealing and its effect on the thermal stability of thermal barrier coating.Based on the physical model of LaMgAl_(11)O_(19)/YSZ double thermal barrier coating prepared by plasma spraying,the numerical simulation model was established by Abaqus.Through the coupled calculation of temperature displacement,the distribution of residual thermal stress in LaMgAl_(11)O_(19) thermal barrier coating at different annealing temperatures was systematically analyzed.The microstructure of the coating surface and section before and after annealing was observed by SEM experiment.According to the results of numerical simulation and SEM image of the coating,the influence of residual thermal stress on the thermal stability of LaMgAl_(11)O_(19) thermal barrier coating was analyzed,and the influencing factors of coating crack damage and failure were explored.The numerical simulation results show that the residual thermal stress in LaMgAl_(11)O_(19) thermal barrier coating is mainly radial stress,which is much larger than the axial stress and shear stress.During annealing,the radial residual thermal stress increases slowly to the maximum in the range of 0~2.4 mm,but decreases sharply in the range of x=2.4 mm to the radial edge.After annealing,the concentrated stress appears at the radial edge of the coating,reaches the maximum tensile stress at the radial distance x=2.6 mm,and decreases rapidly to compressive stress.The radial residual thermal stress gradients are 0.334 GPa,0.369 GPa,0.389 GPa and 0.391 GPa at 900℃,1000℃,1100℃and 1200℃,respectively.The radial residual thermal stress gradients are 0.104 MPa,0.148 MPa,0.203 MPa and 0.260 MPa after annealing,respectively.From the SEM images of the surface and cross section of the annealed coating,it is found that the main damage of the internal crack of LaMgAl_(11)O_(19) thermal barrier coating is axial crack.During the annealing process,the radial residual t
作者
胡帅
冯永军
李伟汉
胡素影
宫雪
解志文
HU Shuai;FENG Yong-jun;LI Wei-han;HU Su-ying;GONG Xue;XIE Zhi-wen(School of Mechanical Engineering and Automation,University of Science and Technology Liaoning,Liaoning Anshan 114051,China;College of Aerospace Engineering,Shenyang Aerospace University,Shenyang 110136,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2022年第6期275-282,共8页
Surface Technology
基金
国家自然科学基金青年科学基金项目(52001217)
辽宁省教育厅科学研究经费项目(JYT19035)。
关键词
热障涂层
退火
残余热应力
应力梯度
热稳定性
数值模拟
thermal barrier coating
annealing
residual thermal stress
stress gradient
thermal stability
numerical simulation
