Fracture Characteristics of Thermal Barrier Coating in Tension and Bending Tests(Student Poster Session)

Abstract

In the present paper, a method for determining the fracture characteristic of the ceramic coat layer/bond coat interface was developed. The uniaxial tension and four point bending tests were conducted on plasma-sprayed rectangular specimens of two-layer system and functionally gradient material (FGM) layer. The top coat layer was yttria-partially-stabilized zirconia (YSZ) and the bond coat layer was MCrAlY, both of which were deposited by plasma-spraying technique. FGM consisted of 5 layers: 100% YSZ, 80%YSZ+20%NiCrAlY, 60%YSZ+40%NiCrAlY, 40%YSZ+60%NiCrAlY, 20%YSZ+80%NiCrAlY. The detailed fracture process in the thermal barrier coating system was examined by using scanning electron microscopy (SEM). It was shown that vertical multiple cracking preceded in the top coat followed by the propagation of interface crack between top coat and bond coat. A shear lag model was used to evaluate the interface strength. The experimental results show that FGM specimens have higher interface strength than non-FGM specimens.