Simulating the effect of roughness of the bond coat surface on stress distribution in EB-PVD thermal barrier coatings with finite element method

Thermal barrier coatings are widely used in gas turbine motors in air and ground sections (electricity generation). One of the challenges in developing these coatings is the fracture occurring around the interface of the ceramic layer with thermally grown oxide layer. These fractures result from the accumulation of energy around this area. Important parameters influencing stress distribution and fracture of thermal barrier are the roughness of the bond coat layer, the thickness of the coating and the mechanical properties of the coating components. In this paper, the effect of the roughness of the bond coat surface on stress distribution in different parts of thermal barrier coatings resulting from electron beam physical vapor deposition (EB-PVD) process was studied. The results indicated increase in roughness enhanced the curvature area, premature degradation of coating system led to thermal barrier.