Three-body tribocorrosion of high-chromium cast irons in neutral and alkaline environments

Two high-chromium cast irons (HCCIs) with different microstructure and Cr:C ratio of 9 and 6 were tested using a new three-body abrasion–corrosion rig incorporating electrochemical techniques. Coarse garnet particles acted as abrasive grits and the effect of mechanical parameters (i.e. load, sliding distance) was investigated. Electrolytes with different pH, neutral and alkaline were used and the effects of chloride ions and elevated temperature were also tested. SEM and optical profilometry were used to analyse the extent of abrasion–corrosion damage and the surface morphology. In the corrosion-only tests it was found that the corrosion rate increased with increasing pH, and both the chloride ions and elevated temperature had a detrimental effect. Increasing alkalinity has shifted the anodic behaviour from the matrix to the carbides. The influence of key alloying elements on the corrosion behaviour is also addressed.