Velocity effects on the erosion-corrosion of Nb/CrN superlattice PVDcoatings

摘要

Although there has been much progress in the study of erosion-corrosion in recentrnyears, there are still many materials that have received little attention in this area. Inrnparticular, the area of thin coatings has received little interest despite the applications ofrnsuch coatings to environments where erosion-corrosion may occur. In addition, there isrnstill confusion on the mechanism of erosion-corrosion of the coatings, particularly whenrnpin holes (through which the corrosion process is driven) may vary significantly fromrnone specimen to another.rnIn this paper, the effects of velocity were assessed for a CrN/NbN superlatice coating.rnThe tests were carried out in an impinging jet apparatus. SEM and AFM were used torncharacterize the transitions between the erosion-corrosion regimes.rnThe results showed that increases in velocity had a significant effect on the erosioncorrosionrnrates of the coating. Such effects were dependent on the solution chemistry.rnMechanisms of erosion-corrosion of superlattice coatings were proposed based on thesernobservations.