Electrochemical and mechanical interactions during erosion-corrosion of a high-velocity oxy-fuel coating and a stainless steel

This paper describes the results of a study of the erosion-corrosion behaviour of a thermally sprayed Ni-Cr-Si-B-C cermet coating in saline solution in the presence and absence of solid particles. The water, at ambient temperature, impinged perpendicularly onto the specimen surface at a velocity of 17 m/s. Emphasis was placed on the assessment of the contribution of corrosion processes to the overall erosion-corrosion deterioration. For comparison purposes in terms of performance and degradation mechanisms, parallel tests were carried out on a standard stainless steel alloy (UNS S31603). The study provided clear evidence of the crucial role of corrosion processes in governing the extent (totalling about 30% in solid/liquid impingement) and mechanisms of erosion-corrosion of the cermet material. The cermet coating was found to undergo less weight loss than the stainless steel in solid/liquid conditions but vice-versa during solid-free impingement and this was attributed to the relative influences of erosion and corrosion.