Numerical Analysis of Interface Morphology Effects on Stress Behaviors in Thermal Barrier Coatings with Varied Thicknesses

Abstract

Designing thermal barrier coatings (TBCs) with varied thicknesses on surface of a turbine vane has practical significance. The present study focused on reducing the residual stress levels through optimally designing the interface morphology in TBC at the junction between zones with different coating thicknesses. The two-dimensional FEM was employed to estimate the interface stress level. The combined influences of the internal interface morphology parameters and the external geometrical parameters of TBCs on the interface stress behaviors were discussed deeply. The TBC with unchanged thickness was chosen as the reference. The comparisons revealed that the maximum increment in harmful tensile stress level due to the variation of thickness can reach 60%. Relative to the other phases, the interface morphology featuring zero phase can acquire a higher harmful stress level and larger high-stress region. The proposed interface with nonuniform morphologies can reduce the harmful stress by about 60%. The criteria in the amplitude variations and the location of each period with the external geometrical parameters were acquired. The thickened thermally grown oxide can reduce properly the benefits of the modifications of interface morphology on the reduction of stress; however, the maximum decrement can be controlled below 15%.