THE CORROSIVE WEAR OF CAST-IRON UNDER POTENTIOSTATICALLY-CONTROLLED CONDITIONS IN SULFURIC-ACID-SOLUTIONS

An investigation has been made of the sliding wear of cast iron held under potential control in 60°/v sulphuric acid solutions. Tests were performed at different applied potentials, covering the region from complete cathodic protection to anodic protection and showed that the extents of wear and resulting surface morphologies can be influenced markedly by varying the potential. Sliding at potentials held in the passivation range or in the sulphation range give relatively high wear rates, due to rapid dissolution of the metal matrix following breakdown of the protective passive or sulphate films. The more corrosion-resistant hard phases in the cast iron increase the wear rate by acting as abrasives between the contacting surfaces. Sliding under cathodic protection conditions results in relatively low wear rates. In such situations, corrosion does not occur and the damage is due to mechanical action only. The results indicate that corrosion makes a large contribution to the wear of cast iron in this environment. © 1990.