Some comments on mapping the combined effects of slurry concentration, impact velocity and electrochemical potential on the erosion-corrosion of WC/Co-Cr coatings

Materials exposed to aqueous slurry environments must not only resist the impact of solid particles and the flowing environment but also the degradation caused by electrochemical corrosion. In this study, the combined effects of slurry particle concentration and velocity on the erosion-corrosion of a WC/Co-Cr coating were assessed at a range of electrochemical potentials in a synthetic sea water solution containing sand particles and compared to the performance of a mild steel exposed to similar conditions. The erosion and corrosion contributions and their interactions were evaluated for the materials. The results indicated that the erosion-corrosion mechanism of the coating and the mild steel showed significant differences when particle velocity and concentration were increased at various potentials. For both materials, degradation mechanisms were identified and superimposed on erosion-corrosion maps. Maps indicating levels of wastage, extent of synergy between the processes and the optimum material performance were also generated as part of this study. Scanning electron microscopy was used to confirm the degradation regimes and mechanisms of material removal during the erosion-corrosion process. (c) 2007 Elsevier B.V. All rights reserved.