Adhesion-Related Phenomena of Stellite 6 HVOF Sprayed Coating Deposited on Laser-Textured Substrates

Abstract

One of the key factors for a successful application of thermal spraying is appropriate surface preparation prior to thermalspraying. Conventional surface roughening methods such as corundum grit blasting are used to achieve the desiredadhesion. In recent years, efforts to find a suitable alternative, both from an economic and an ecological point of view,have been increasingly developed. A potentially suitable alternative appears to be surface preparation by laser texturing.The experimental part of the paper focuses on the thermal spraying of Stellite 6 coating by High Velocity Oxygen Fuel(HVOF) technology on laser textured substrates. The thermal spraying of this coating was deposited both on conventionalsubstrate material (low carbon steel) and on substrates that had been previously heat treated (nitrided steel). The study includes analysis of laser produced textures on substrates, analysis of the coating – substrate interface, adhesion strength tests by tensile testing, and the effect of laser texture geometry on resulting adhesion. The results showed on the usability of laser texturing in the case of carbon steel, comparable or even better than traditional grit blasting. For nitrided steel, the problem remains the hardness and brittleness of the nitrided layer, which allows the propagation of brittle cracks near the interface and thus reduces the adhesion strength.