Parameter-Dependent Bonding Properties of Sinusoidal-Texture-Modified Plasma-Sprayed Coatings

Abstract

Laser surface texturing is widely acknowledged as an effective technique for enhancing coating bonding strength. However, the influence of texture parameters, particularly those of a novel sinusoidal configuration, on coating adhesion has been insufficiently explored. This gap in research underscores the necessity for a comprehensive investigation into the effects of these parameters. In this work, sinusoidal textures with varying width–depth ratios, sinusoidal amplitude, and sinusoidal wave number were engineered using nanosecond laser technology. Thereafter, Ni-based MoS₂ coatings were deposited on these sinusoidal-textured surfaces. The coating bonding strength was subsequently evaluated using adhesion test in accordance with ASTM 633 standard. Concurrently, the fracture morphology, the relative adhesion area, and the surface roughness were characterized to investigate the fracture mechanisms. The experimental findings revealed a positive correlation between the coating bonding strength and the reduction in texture width–depth ratio, as well as the augmentation of sinusoidal amplitude and wave number. Notably, a reduced width–depth ratio may result in incomplete filling and large holes at the coating-substrate interface, which is detrimental to the coating adhesion strength. Optimal adhesion is achieved with a texture width–depth ratio ranging from 0.52 to 2.09, an sinusoidal amplitude exceeding 0.1 mm, and an wave number surpassing 10 rad/mm. It can be inferred that the judicious design of texture parameters is imperative to attain the desired level of coating adhesion.