Adhesion of HVOF Sprayed Coatings on Laser Textured Steel and Ceramics substrates

Abstract

In thermal spraying, one of the fundamental elements to achieving good bonding strength of the applied coating is surface preparation. Traditionally grit blasting using hard particles such as corundum is used to achieve suitable roughness on the substrate. Lately, there is an effort to find a suitable alternative from ecological and economical aspects. A promising possibility is laser texturing which enables the preparation of defined structures on the surface. Within a research project, procedures are developed to texture various substrates to direct application of HVOF coatings. The main goal is to achieve speeds of texturing comparable to grit blasting – more than 500 mm2/s while ensuring good bonding strength of the applied coating. This study focuses on HVOF spraying of Stellite 6 and WC-CoCr Coating. Selected substrates are steel, and then materials that cannot be traditionally grit blasted – nitrided steel and alumina ceramics. The study presents the analysis of laser textures on substrates, analysis of coating substrate-coating interface, and adhesion tests by tensile test. The most suitable textures – regarding the processing speed and achieved adhesion are selected.