界面粗糙度对热障涂层残余应力和裂纹演化的影响

Effects of Interface Roughness on Residual Stress Distribution and Crack Nucleation and Propagation in Thermal Barrier Coatings

摘要:

由于残余应力的作用是造成热障涂层失效剥落的主要因素之一，本工作采用不同幅值的正弦曲线来模拟粗糙度对陶瓷层 (TBC)-结合层 (BC) 界面处残余应力分布的影响；以内聚力模型模拟TBC-BC界面，研究了在外加机械载荷作用下粗糙度对界面裂纹萌生和扩展的影响。结果表明，粗糙度对残余应力分布以及裂纹的形核与扩展有很大的影响。随着粗糙度的增大，陶瓷层和结合层靠近界面的波峰波谷处最大拉/压应力也增大。当施加一定拉伸位移载荷时，最大损伤与裂纹首先在幅值最小的波峰波谷处产生。

Abstract:

The residual stress is one of the main factors to cause the failure of thermal barrier coatings. In this paper, a sinusoid curve with different amplitudes was used to model the roughness of interface between ceramic top coat (TBC) and bond coat (BC) in thermal barrier coatings and the effect of interface roughness on residual stress distribution was analyzed. Besides, the effect of roughness on interfacial crack nucleation and propagation under load was simulated with cohesive zone model. Results show that the interface roughness has a significant effect on residual stress distribution and crack nucleation and propagation. With the increase of interfacial roughness, the maximum tensile/compressive stress near the interface also increases in the TBC/BC. When applying a certain tensile displacement load, the maximum damage and crack firstly take place in the peak and valley of minimum amplitude.