Assessment of the corrosion rates and mechanisms of a WC–Co–Cr HVOF coating in static and liquid–solid impingement saline environments

The corrosion behaviour of a WC–Co–Cr high-velocity oxy-fuel (HVOF)-sprayed coating has been examined in static saline conditions and under the influence of an impinging jet of liquid free from solids and containing solids. The corrosion behaviour in static conditions is neither passive nor active, and its complexity results from the composite ceramic/metal nature of the coating surface. The influence of exposure to the impinging jet free from solids is to slightly increase the corrosion rate, and a further increase in corrosion rate is observed when solid particles are added to the liquid stream. This paper assesses the corrosion behaviour of this cermet system and discusses the factors controlling the electrochemical material loss.