Study on the bonding strength and thermal shock resistance of thermal barrier coatings regulated by interface texture

Abstract

Regulating the microstructure of thermal barrier coating interfaces is an effective approach to enhance the thermal stability of the coatings. In this study, high-energy beam laser was used to texture the interface between the bond coat and the ceramic coat (circumferential type, Class C; Kagome type, Class K). The tensile bonding strength and strain capacity of the textured thermal barrier coatings were higher than those of the non-textured coatings. Texturing increases the unit contact area ratio (U) at the interface between the bond coat and the ceramic layer, which helps the coating resist thermal stress impact, reduces the spallation area ratio (Sar) and the spallation rate. Among them, Class C texture can effectively delay the rate of microcrack propagation, while Class K texture has a dual effect of circumferential restraint and suppression of inelastic deformation at the interface. The Kagome-type (Class K) textured coatings have a lower spallation rate than the circumferential-type (Class C) textured coatings. The coating with K2 interface texture exhibits the best thermal shock resistance, with a surface spallation area ratio of only 9.38 % after 120 thermal shock cycles; whereas the non-textured coating has a spallation area of about 13.7 % after the same number of thermal shock cycles. This research provides potential application value for the regulation of interface stability in thermal barrier coatings.