热障涂层的残余应力分析

建立了热障涂层结构的残余应力计算公式,分析了陶瓷层和氧化层弹性模量、热膨胀系数及其厚度的变化对残余应力的影响.结果表明:陶瓷层和氧化层的面内残余应力均为压应力,其数值与温降成正比;自身弹性模量越高或热膨胀系数越小,陶瓷层或氧化层的残余应力越大;厚度变化对残余应力的影响很小;典型情况下陶瓷层的室温残余应力接近300 MPa,明显低于大块陶瓷材料的抗压强度.这些结果对分析热障涂层结构的失效机制有指导意义. 

Residual stress analysis of thermal barrier coatings

An expression for calculating residual stresses in a thermal barrier coating structure was developed. Effects of Young's modulus, coefficients of thermal expansion (CTE) and thicknesses of the ceramic coating and thermally grown oxide (TGO) were analyzed based on the expression. The main results are as follows: compressive in-plane residual stresses are generated with lowering temperature in both ceramic coating and TGO, which exhibits a linear relationship with the temperature drop. And the greater the Young's modulus or the less the CTE, the greater the residual stress in ceramic coating or in TGO. While the influence of thickness on residual stress is negligible. The maximum residual stress in ceramic coating is about 300 MPa, much less than the compressive strength of bulk ceramic material. On the above results, it is suggested that buckling of delaminated ceramic coating should be responsible for its final spallation.