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

WC-CoCr coatings were HVOF-sprayed onto an AA6082T6 substrate. Thickness values between 50 and150 lm were produced by stepwise increase of the number of torch scans. This increase made thecoatings not only thicker but also denser. This was due both to peening effects and by modifications tothe splat formation mechanism, investigated by focused ion beam technique. Thanks to such densification,the hardness, the wear and impact resistance, and the corrosion protectiveness of the layersincreased with the number of torch scans. The largest improvement occurred from 2 to 3 torch scans.These coatings were also compared to anodized films: cermets had superior wear and impact resistancebut offered less corrosion protection.