Multi-scale failure mechanisms of thermal barrier coating systems
Multi-scale failure mechanisms of thermal barrier coating systems
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DOI：
10.1016/j.commatsci.2013.04.028
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发表时间：
2013-12
影响因子：
3.3
通讯作者：
P. Seiler;M. Bäker;J. Rösler
中科院分区：
文献类型：
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作者：
P. Seiler;M. Bäker;J. Rösler
热障涂层系统在目前的燃气涡轮机部件的顶部上是完善的。它们由不同的涂层组成：粘合涂层（BC），热障涂层（TBC）和在操作过程中形成的热生长氧化物（TGO）。涂层系统的复杂失效机制尚未完全了解。因此，本文分析了一个简化的模型系统，重点研究了粘结层蠕变和分段裂纹对脱层形成和扩展的影响。本文讨论了两种有限元（FE）模型，并与实验结果进行了比较：（i）微尺度模型描述初始分层的形成，以及（ii）采用分段裂纹模型从细观尺度上分析了分层与分段裂纹的相互作用，发现初始分层主要发生在TGO/TBC界面的微凸谷中，在快速和慢速蠕变粘合涂层材料中均是如此。从第一次热循环开始，在涂层系统中可以发现分段裂纹。它们促进了两个分段裂纹之间分层的发展。分层的扩展在TBC中没有停止，分层与分段裂纹一起生长。最后，提出了分析模型系统中TBC失效的可能情况。
Thermal barrier coating systems are well-established on top of present gas turbine components. They consist of different coating layers: the bond-coat (BC), the thermal barrier coating (TBC), and the thermally grown oxide (TGO), which is formed during operation. The complex failure mechanisms of the coating systems are not fully understood, yet. Therefore, a simplified model system is analysed to focus on the influence of bond-coat creep and segmentation cracks on the formation and propagation of delaminations.Two finite element (FE) models are discussed in this paper and compared to experimental results: (i) a micro-scale model describes the formation of initial delaminations and (ii) a segmentation crack model analyses the interaction between delaminations and segmentation cracks on the meso-scale.It was found that initial delaminations develop mainly in the valley of asperities at the TGO/TBC interface, both in fast and slow creeping bond-coat materials. Segmentation cracks can be found in the coating system from the first thermal cycle. They promote the development of delaminations between two segmentation cracks. The propagation of delaminations is not stopped in the TBC and the delaminations grow together with the segmentation cracks. In conclusion, a possible scenario of TBC failure in the analysed model system is presented.