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建立了一种预测多层复合梯度热障涂层热应力的理论模型,并通过有限元方法分析了梯度涂层分布指数n、热循环过程中热氧化物的生长对涂层热应力大小及分布的影响。结果表明,通过控制梯度涂层的成分分布指数可以显著降低热应力和改善应力分布。当n=1时,涂层热应力较小且变化平缓,结合性能优异。与双层非梯度涂层的热应力对比可知,功能梯度涂层能显著地缓和涂层系统的热应力和消除应力集中。另外,热循环过程中梯度热障涂层与基体界面附近生长的热氧化物急剧地提升了界面附近的热应力,复杂而又集中的热应力对梯度涂层有很大的破坏。同时采用了一种方法来抑制热氧化物的生长,结果显示该方法能较好地优化涂层的热应力和改善涂层质量。
A theoretical model for predicting the thermal stress of multi-layer composite gradient thermal barrier coatings was established. The distribution index n of gradient coating was analyzed by finite element method. The thermal stress on the coating was related to the size and distribution of thermal stress Impact. The results show that by controlling the composition distribution index of the gradient coating, the thermal stress and the stress distribution can be significantly reduced. When n = 1, the thermal stress of the coating is smaller and changes gently, and the bonding performance is excellent. Compared with the thermal stress of the two-layer non-gradient coating, it can be seen that the functionally graded coating can significantly reduce the thermal stress and eliminate the stress concentration in the coating system. In addition, the thermal oxide growing near the interface between the gradient thermal barrier coating and the substrate rapidly increases the thermal stress near the interface during thermal cycling, and the complex and concentrated thermal stress greatly damages the gradient coating. At the same time, a method is used to suppress the growth of thermal oxide. The results show that this method can better optimize the thermal stress and improve the coating quality.