Miniaturized bend tests on partially stabilized EB-PVD ZrO2 thermal barrier coatings
Miniaturized bend tests on partially stabilized EB-PVD ZrO2 thermal barrier coatings
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DOI：
10.1016/j.surfcoat.2010.11.047
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发表时间：
2011-02
影响因子：
5.4
通讯作者：
C. Pfeiffer;E. Affeldt;M. Göken
中科院分区：
文献类型：
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作者：
C. Pfeiffer;E. Affeldt;M. Göken
热障涂层 (TBC) 的弹性特性对于模拟这些涂层的寿命非常重要。开发出一种新的测试装置，可通过小型弯曲测试来测量电子束增强物理气相沉积 (EB-PVD) TBC 涂层的系统模量。由于面漆的脆性、刚度低、厚度小以及其复杂的微观结构，很难通过标准的力学测试来测量其杨氏模量。为此，我们准备了一种特殊的样品材料，其中包含 1 毫米厚的 EB-PVD TBC 层。该材料在 950°C、1100°C 和 1200°C 下进行不同时间的等温热处理，然后在专门开发的小型弯曲测试中进行测试。弯曲测试装置允许以高分辨率进行应力和应变机械测试，其中应变通过数字图像相关性进行测量。因此，可以高精度测量独立式 TBC 样品的刚度，并可以确定 EB-PVD TBC 的烧结行为以及随之而来的杨氏模量的上升。结果表明，随着涂层烧结引起的热处理时间和温度的增加，系统模量显着增加。该过程的活化能已确定为 220kJ/mol。此外，通过纳米压痕测试材料，以测量局部尺度的杨氏模量，并通过定量图像分析确定样品的孔隙率。
The elastic properties of thermal barrier coatings (TBCs) are important for modelling the lifetime of these coatings. A new test setup has been developed to measure the system modulus of electron-beam enhanced physical vapour deposited (EB-PVD) TBC coatings by miniaturized bend tests. Due to the brittleness, low stiffness and small thickness of the top coat and its complex microstructure, it is difficult to measure its Young's modulus by standard mechanical testing. For this reason, a special sample material has been prepared which consists of a 1mm thick layer of EB-PVD TBC. This material was isothermally heat treated for different times at 950°C, 1100°C and 1200°C and then tested in a specially developed miniaturized bend test. The bend test setup permits mechanical tests with a high resolution in stress and strain, where the strain is measured by digital image correlation. So the stiffness of the free-standing TBC samples could be measured with a high accuracy and the sintering behaviour of the EB-PVD TBC and the consequent rise of Young's modulus could be determined. The results show a significant increase of the system modulus with heat treatment time and temperature caused by sintering of the coating. An activation energy of 220kJ/mol for the process has been determined. In addition, the material was tested by nanoindentation in order to measure Young's modulus on a local scale, and the porosity of the samples was determined by quantitative image analysis.