基于真实TGO三维结构的热障涂层热应力分析

Thermal Stress Analysis on Thermal Barrier Coatings Based on Real three-dimensional Structure of Thermally Grown Oxide

摘要:

本文采用三维X射线显微镜对高温热循环后的双层结构热障涂层样品进行了分辨率0.5 μm的高分辨率CT (Computed Tomography)重建，实现了热生长氧化物 (Thermally Grown Oxide，TGO)三维结构分割与可视化，建立了基于真实TGO微结构的热障涂层三维有限元模型，研究了蠕变及热循环次数对热障涂层热应力的影响。有限元分析结果表明：恒温阶段受蠕变的影响，应力大幅度减小，高温蠕变对热障涂层热应力具有释放作用。三维热应力分布结果表明粘结层与TGO界面处应力最大。热障涂层的应力随着热循环次数的增加而增大，但在15个循环之后，应力趋于稳定。

Abstract:

Using X-ray microscope, thermal barrier coatings (TBCs) were imaged with a high resolution of 0.5 μm after high temperature cycles. Three-dimensional segmentation and extraction of thermally grown oxide (TGO) was performed. A finite element analysis model of thermal barrier coatings was established based on real three-dimensional (3D) structure of thermally grown oxide, and the effect of creep and thermal cycles on the stress distribution of thermal barrier coatings were researched. The results of finite element analysis show that the stress decreases greatly due to the influence of creep at the keeping stage. The results of three-dimensional thermal stress distribution shows that the thermal stress at the interface between the bond coat and the TGO is the maximum. The stress of thermal barrier coating increases with the increase of thermal cycle number, but the stress tends to be stable after 15 thermal cycles.