Sintering-induced delamination of thermal barrier coatings by gradient thermal cyclic test
Sintering-induced delamination of thermal barrier coatings by gradient thermal cyclic test
复制标题
梯度热循环试验导致热障涂层烧结分层
DOI：
10.1111/jace.14713
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发表时间：
2017
影响因子：
3.9
通讯作者：
Li Chang-Jiu
中科院分区：
文献类型：
--
作者：
Cheng Bo;Zhang Yu-Ming;Yang Ning;Zhang Meng;Chen Lin;Yang Guan-Jun;Li Cheng-Xin;Li Chang-Jiu
寿命是先进热障涂层应用的关键，为了准确、有效地预测热障涂层的使用寿命，需要开发合适的寿命评估方法。在这项研究中，等离子喷涂YSZ热障涂层在不同的表面温度下进行梯度热循环试验，目的是阐明涂层表面温度和热循环寿命之间的相关性。结果表明，热障涂层的热循环寿命随表面温度的升高而降低。然而，这些经受热循环测试的热障涂层的失效模式与不同的表面/热障涂层温度无关，即，烧结引起的顶层分层。热生长氧化物（TGO）的厚度明显小于临界TGO厚度，导致热障涂层通过顶层分层失效。涂层失效后没有发生相变。与此相反，在关于失效试样的顶涂层表面的情况下，尽管各种热循环条件下，由于烧结，弹性模量和显微硬度增加到相当的水平。因此，可以得出结论，接受梯度热循环测试的TBC失效主要是由高温暴露期间的烧结引起的。开发了具有多层飞溅的分层模型，以帮助理解热障涂层通过烧结诱导的顶层分层的失效机制。基于上述结果，本研究应有助于通过在实验室条件下在较高温度下进行加速热循环试验，对在相对较低温度下服役的热障涂层进行寿命评估。
Lifetime is crucial to the application of advanced thermal barrier coatings (TBCs), and proper lifetime evaluation methods should be developed to predict the service lifetime of TBCs precisely and efficiently. In this study, plasma‐sprayed YSZ TBCs were subjected to gradient thermal cyclic tests under different surface temperatures, with the aim of elucidating the correlation between the coating surface temperature and the thermal cyclic lifetime. Results showed that the thermal cyclic lifetime of TBCs decreased with the increasing of surface temperatures. However, the failure modes of these TBCs subjected to thermal cyclic tests were irrespective of different surface/BC temperatures, that is, sintering‐induced delamination of the top coat. The thickness of thermally grown oxide (TGO) was significantly less than the critical TGO thickness to result in the failure of TBCs through the delamination of top coat. There was no phase transformation of the top coat after failure. In contrast, in the case concerning the top coat surface of the failure specimens, the elastic modulus and microhardness increased to a comparable level due to sintering despite of the various thermal cyclic conditions. Consequently, it is conclusive that the failure of TBCs subjected to gradient thermal cyclic test was primarily induced by sintering during high‐temperature exposure. A delamination model with multilayer splats was developed to assist in understanding the failure mechanism of TBCs through sintering‐induced delamination of the top coat. Based on the above‐described results, this study should aid in facilitating the lifetime evaluation of the TBCs, which are on active service at relatively lower temperatures, by an accelerated thermal cyclic test at higher temperatures in laboratory conditions.