Wear and Corrosion Behavior of HVOF-Sprayed WC-CoCr Coatings on Al Alloys

In this study, WC-CoCr coatings were deposited on an aluminum substrate by HVOF spraying. Layer thicknesses between 50 and 150 μm were achieved by stepwise increase of the number of torch scans. The stepwise method is shown to make the coatings not only thicker, but also denser due to peening effects and changes in the splat formation mechanism. It also explains the incremental improvement in coating hardness and corrosion and wear resistance observed over the first few torch scans, the largest of which occurs between the second and third scans. The coatings are also compared to anodized films and were found to have superior wear and impact resistance but less resistance to corrosion.