ZrO_2陶瓷热障涂层显微结构及隔热性能研究

Investigation of the Microstructures and Thermal Barrier Properties of YSZ Thermal Barrier Coatings

用电子束物理气相沉积法(EB-PVD)在DZ125高温合金上制备Y2O3部分稳定化的ZrO2(YSZ)陶瓷热障涂层,并用扫描电镜(SEM)观察涂层显微结构。采用激光脉冲法对EB-PVD热障涂层的热扩散系数进行测试。为防止热扩散系数测试时激光穿透ZrO2陶瓷层,在试样表面制备不同材料的遮挡层。结果表明,EB-PVD热障涂层呈明显的柱状晶结构,柱状晶垂直于涂层/基体界面。基体的热扩散系数随温度的升高而急剧增加,陶瓷热障涂层的热扩散系数随温度的升高呈下降趋势,但变化幅度不大。室温下陶瓷层的热扩散系数小于基体的1/3,1200℃时约为基体的1/67。试样的激光遮挡层很好解决了激光脉冲法测试涂层热扩散系数时的不稳定性和激光穿透问题。在满足遮挡要求的条件下,遮挡层材料种类对热扩散系数测试无明显影响。

Thermal barrier coatings （TBCs） with Y2O3 paritally stablized zireonia （YSZ） ceramic top layer were deposited on the DZ125 superalloy substrates by using electron beam-physical vapor deposition （EB-PVD） technology. The mierostruetures of the EBPVD TBCs were investigated by scanning electron microscopy （ SEM ） , and laser pulse method was used to evaluate their thermal diffusion coefficients. Prior to the coefficient measurement, several thin sheltered layers on the surface of TBCs were adopted to prevent laser beam from penetrating the ceramic top layer. It was found that EB-PVD TBCs presented a typical columnar morphological features perpendicular to the substrate/eoating interface. The thermal diffusion coefficient of the EB-PVD ceramic top layer slowly decreased with the elevation of the testing temperature, whereas the coefficient of the substrate increased rapidly. The coefficient value of the ceramic top layer was less than one third of the value of substrate at room temperature, and was about one sixty-seventh at 1200℃. With proper shelter layers, the instability and penetration issues in thermal diffusion coefficient measurement were resolved perfectly. If the sheltering requirement was satisfied, the variance of the shelter layer materials did not affect the measuring results in this study.