Thermal barrier coating toughness: Measurement and identification of a bridging mechanism enabled by segmented microstructure
Thermal barrier coating toughness: Measurement and identification of a bridging mechanism enabled by segmented microstructure
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DOI：
10.1016/j.msea.2012.11.126
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发表时间：
2013-03
期刊：
影响因子：
6.4
通讯作者：
Erin M. Donohue;N. Philips;M. Begley;C. Levi
中科院分区：
文献类型：
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作者：
Erin M. Donohue;N. Philips;M. Begley;C. Levi
热障涂层的失效机制通常涉及顶层涂层中分层裂纹的扩展。本文提出的工作有两个主要贡献：第一，一个简单的测试几何形状和分析方法的发展，使这些涂层的模式I断裂韧性的准确测定，第二，该方法的应用技术相关的涂层产生新的见解的影响致密的垂直裂纹（DVC）微观结构的韧性。通过在改进的双悬臂梁结构中对独立涂层进行拉伸来测量空气等离子喷涂的8wt%氧化钇稳定的氧化锆DVC热障涂层的I型韧性。数字图像相关测量和有限元分析提供了一种快速准确地从位移数据中提取韧性值的途径。结果显示R曲线行为和出乎意料的高稳态韧性值Gss为300- 400 J/m2。这种高韧性的观察可以通过与TBC的起始微观结构和断裂表面特征一致的裂纹桥接模型来合理化。
Failure mechanisms in thermal barrier coatings (TBCs) often involve the propagation of delamination cracks within the top coating. The work presented in this paper makes two principal contributions: first, the development of a straightforward testing geometry and analysis approach enables the accurate determination of the mode I fracture toughness of these coatings and second, the application of the approach to technologically relevant coatings produces new insights into the impact of the dense vertically cracked (DVC) microstructure on the toughness. Mode I toughness of air plasma-sprayed 8wt% yttria-stabilized zirconia DVC TBCs is measured by sandwiching the freestanding coatings in a modified double cantilever beam configuration. Digital image correlation measurements and finite element analysis provide a pathway to quickly and accurately extract toughness values from displacement data alone. Results show R-curve behavior and unexpectedly high steady-state toughness values of Gss≈300–400J/m2. The observation of this elevated toughness can be rationalized by a crack bridging model that is consistent with the TBC's starting microstructure and features of the fracture surfaces.