Mahade Satyapal, Curry Nicholas, Björklund Stefan, Markocsan Nicolaie, Joshi Shrikant
Department of Engineering Science, University West, 46186 Trollhattan, Sweden.
Treibacher Industrie AG, Auer von Welsbachstr, 1, A-9330 Althofen, Austria.
Materials (Basel). 2019 Jul 11;12(14):2238. doi: 10.3390/ma12142238.
Higher durability in thermal barrier coatings (TBCs) is constantly sought to enhance the service life of gas turbine engine components such as blades and vanes. In this study, three double layered gadolinium zirconate (GZ)-on-yttria stabilized zirconia (YSZ) TBC variants with varying individual layer thickness but identical total thickness produced by suspension plasma spray (SPS) process were evaluated. The objective was to investigate the role of YSZ layer thickness on the durability of GZ/YSZ double-layered TBCs under different thermal cyclic test conditions i.e., thermal cyclic fatigue (TCF) at 1100 °C and a burner rig test (BRT) at a surface temperature of 1400 °C, respectively. Microstructural characterization was performed using SEM (Scanning Electron Microscopy) and porosity content was measured using image analysis technique. Results reveal that the durability of double-layered TBCs decreased with YSZ thickness under both TCF and BRT test conditions. The TBCs were analyzed by SEM to investigate microstructural evolution as well as failure modes during TCF and BRT test conditions. It was observed that the failure modes varied with test conditions, with all the three double-layered TBC variants showing failure in the TGO (thermally grown oxide) during the TCF test and in the ceramic GZ top coat close to the GZ/YSZ interface during BRT. Furthermore, porosity analysis of the as-sprayed and TCF failed TBCs revealed differences in sintering behavior for GZ and YSZ. The findings from this work provide new insights into the mechanisms responsible for failure of SPS processed double-layered TBCs under different thermal cyclic test conditions.
人们一直在寻求提高热障涂层（TBCs）的耐久性，以延长燃气涡轮发动机部件（如叶片和导向叶片）的使用寿命。在本研究中，评估了通过悬浮等离子喷涂（SPS）工艺制备的三种双层钆锆酸盐（GZ）/氧化钇稳定氧化锆（YSZ）热障涂层变体，它们的各层厚度不同，但总厚度相同。目的是研究YSZ层厚度在不同热循环测试条件下，即分别在1100°C的热循环疲劳（TCF）和表面温度为1400°C的燃烧器试验台测试（BRT）中，对GZ/YSZ双层热障涂层耐久性的影响。使用扫描电子显微镜（SEM）进行微观结构表征，并使用图像分析技术测量孔隙率。结果表明，在TCF和BRT测试条件下，双层热障涂层的耐久性均随YSZ厚度的增加而降低。通过SEM对热障涂层进行分析，以研究在TCF和BRT测试条件下的微观结构演变以及失效模式。观察到失效模式随测试条件而变化，所有三种双层热障涂层变体在TCF测试期间均在热生长氧化物（TGO）中失效，而在BRT测试期间则在靠近GZ/YSZ界面的陶瓷GZ顶层涂层中失效。此外，对喷涂态和TCF失效后的热障涂层进行孔隙率分析，揭示了GZ和YSZ在烧结行为上的差异。这项工作的研究结果为理解SPS处理的双层热障涂层在不同热循环测试条件下的失效机制提供了新的见解。
