Effects of texture spacing and bulges of bionic sinusoidal texture on the adhesion properties and fracture mechanism of plasma-sprayed coatings

Abstract Ni based MoS2 coatings were prepared on grit-blasted and bionic sinusoidal laser-textured surfaces by using an atmospheric plasma spray. The effects of bionic sinusoidal textures with different texture spacing and bulges on the adhesion strength of the coatings were investigated using the ASTM 633 adhesion test. The cross-sectional microstructure of the coatings and the fracture morphology were characterized to investigate the coating deposition and fracture mechanism. Results showed that the texture spacing and bulge significantly affect coating adhesion. Thus, the decrease in texture spacing and the existence of texture bulges significantly increased the adhesion strength. The comparison of textured surfaces with and without bulges showed that the exposed plain areas were harmful to the improvement of coating adhesion. An optimal texture spacing for coating adhesion improvement was observed for the textured surfaces with bulges. Fracture analysis showed that the mix failure mode mainly occurred without bulges, and adhesive failure occurred in almost all plain areas. With the existence of bulges, the adhesive failure only dominated when the texture spacing was very large or very small, otherwise, the fracture mechanism was dominated by cohesive failure.