Mechanics and Mechanisms on Adhesion of Thermal Barrier Coating : Towards Improvement and Design of Thermal Fatigue Endurance.

高性能热障涂层（tbc）对于在极高温度下运行的下一代先进燃气轮机至关重要。为了提高tbc的热疲劳性能和设计tbc的热疲劳耐久性，开展了一系列的实验工作，对以下文章有了基本的认识：如何评估tbc中陶瓷面涂层的力学性能，特别是弹性模量；过程变量有什么影响？陶瓷面漆与镍基高温合金基体的结合强度有多高，应如何评价；以及tbc的残余应力有多高以及应该如何评估。采用宏观、微观和纳米压痕法测量了先进燃气轮机热障涂层（TBC）系统中常用的空气等离子喷涂YSZ （； ZrO2由8 wt. pct. Y2O3稳定）面涂层试样的弹性刚度。采用oliver - farr法测量弹性刚度。结果表明，喷涂条件对YSZ的弹性刚度和微观组织有显著影响。特别是陶瓷粉末的大小被发现有最显著的影响。弹性刚度表现出显著的尺寸效应，即宏观、微观和纳米压痕方法的弹性刚度存在显著差异。讨论了上述尺寸效应，并将其与压痕过程中的一些相关现象：裂纹、下沉、堆积和剥落联系起来；并与喷涂面漆特有的显微组织相结合。在此基础上，着重讨论了开发高性能tbc应控制哪种类型的微观结构以及如何通过控制喷涂工艺变量来实现这一目标。

Thermal barrier coatings (TBCs) with high performance have been essential for next generation advanced gas turbines operating at extremely high temperatures. Towards improvement and design of thermal fatigue endurance of TBCs, a series of experimental works have been carried out to get basic understandings on the following articles : how the mechanical properties of ceramic top coat film in TBCs, especially elastic moduli, should be evaluated ; what effect(s) the process variables have ; how high is the adhesion strength of ceramic top coat with Ni-based superalloys substrate and how it should be evaluated ; and how high is the residual stress in TBCs and how it should be evaluated. Elastic stiffness of air plasma sprayed (APSed) YSZ (; ZrO2 stabilized by 8 wt. pct. Y2O3) top coat specimen, which is frequently used for thermal barrier coating (TBC) system for advanced gas turbines, was measured by employing the macro-, micro-, and nano-indentation methods. The elastic stiffness was measured, following the Oliver-Pharr method. It was shown that the elastic stiffness of the YSZ, as well as the microstructure, were significantly influenced by the spraying conditions employed. Especially the size of ceramic powders used were found to have the most pronounced effect. It was also shown that the elastic stiffness revealed significant size effect : that is, there were significant differences in elastic stiffness between the macro-, micro-, and nano-indentation methods. The above size effect was discussed, correlating with some relating phenomena during the indentation process : crackings, sink-in, pile-up and spalling ; as well as with the characteristic microstructures of the sprayed top coat. Based on these knowledge, special discussions have been made on which type of microstructure should be controlled to develop high performance TBCs and how it can be realized through a control of spraying process variables.