NATURE OF CORROSIVE AND ABRASIVE WEAR OF CHROMIUM-BEARING CAST-IRON GRINDING MEDIA

Electrochemical aspects of grinding media wear in quartzite grinding under nitrogen and oxygen atmospheres were examined with respect to the abrasive/corrosive wear and passivation behavior of chromium-bearing cast irons. Potentiostatic and potentiodynamic polarization measurements, as well as marked ball wear tests, were used to study the electrochemical and wear behaviors of various cast iron grinding media. Corrosion currents estimated from polarization curves for cast iron ball materials under abrasion were correlated with corrosive wear obtained from marked ball wear tests by applying Faraday's laws. The anodic currents were observed to increase with increasing rotation speed and decreasing chromium content. The passivation rates were estimated for high chromium cast iron and austenitic stainless steel balls. The passivation rates increased as a more positive potential was applied.