Effect of oxide growth on the stress development in double-ceramic-layer thermal barrier coatings
Effect of oxide growth on the stress development in double-ceramic-layer thermal barrier coatings
复制标题
氧化物生长对双层陶瓷层热障涂层应力发展的影响
DOI：
10.1016/j.ceramint.2017.07.218
复制
发表时间：
2017
影响因子：
5.2
通讯作者：
Wang T. J.
中科院分区：
文献类型：
--
作者：
Li Biao;Fan Xueling;Zhou Kun;Wang T. J.
通过数值模拟研究了氧化物生长对等离子喷涂双层陶瓷热障涂层内部应力发展的影响。氧化物的形态，生长速率和氧化时间的作用进行了讨论。建立了二维周期性单胞模型，考虑了涂层间不同的界面粗糙度。在高温期间施加热梯度条件，以表示整个涂层厚度上的非均匀温度分布。结果表明，陶瓷层界面附近区域的应力主要是由热膨胀失配和温度场不均匀引起的，其中氧化物生长对应力的影响可以忽略不计。逐渐增厚的热生长氧化物（TGO）主要贡献于其附近区域的应力和非弹性应变演化的变化。涂层中的残余应力场几乎不受氧化物厚度的影响后，运行足够长的时间。在长期运行过程中，大的非弹性变形被认为是TGO附近开裂的内在原因。
A numerical study is conducted to investigate the effect of oxide growth on the stress development within the plasma sprayed double-ceramic-layer thermal barrier coatings. The roles of oxide morphology, growth rate, and oxidation duration are discussed. A two-dimensional periodical unit-cell model is developed, taking into account the different interfacial roughnesses among the coatings layers. Thermal gradient conditions are imposed during the high-temperature period to represent the non-uniform temperature distributions throughout the coatings thickness. It is found that stresses in the regions that close to the interface of the ceramic layers result from the thermal expansion mismatch and the non-uniform temperature field, in which the oxide growth reveals negligible influence on the development of the stresses. The gradually thickening thermally grown oxide (TGO) mainly contributes to the variations of stress and inelastic strain evolutions in its nearby regions. The residual stress fields in the coatings are almost unaffected by the oxide thickness after operating for a sufficiently long time. During long-term operation, the large inelastic deformation is found to be the intrinsic reason responsible for the cracking in the vicinity of TGO.