Improving corrosion and wear performance of HVOF-sprayed Inconel 625 and WC-Inconel 625 coatings by high power diode laser treatments

This paper reports an investigation of the effects of laser surface treatment on the corrosion and wear performance for Inconel 625, and Inconel 625-based WC HVOF-sprayed MMC coatings. Examination of the laser-treated surface was conducted in terms of microstructural morphology, chemical composition and phase analysis. Corrosion resistance using potentiodynamic polarisation in 3.5% NaCl solution and dry sliding wear behavior of the various coatings before and after laser treatment was evaluated. The results indicated that significant improvement of corrosion and wear resistance can be achieved after laser treatment as a result of the elimination of discrete splat-structure, microcrevice and porosity, and also the reduction of microgalvanic driving force between the WC and the metal matrix. In addition, the formation of faceted dendritic structure of the WC phase was considered to be beneficial for the wear performance.