The effects of an electric current on the sliding wear of cast iron

Abstract

Dry sliding wear tests were carried out to clarify the influence of an electric current on friction and wear of cast iron. Some carbon steels were also examined for comparison. A ball-on-plate type tribotester was used with a high-carbon chromium bearing steel as a fixed ball. It was found that changes in the friction coefficient, due to an increase in electric current, were completely different for cast irons than for carbon steels. The friction coefficient of cast iron is lower than that of carbon steel under zero current conditions, but with an increase in applied current the coefficient increases. In contrast, the friction of steels decreases under a high electric current. A further increase in current produced an inversion of the friction coefficient between cast irons and steels. The direction of the current affects the amount of wear: the anode of the couple always experiences heavier wear than the cathode, in the case of both cast irons and carbon steels. The wear of cast iron increased with an increase in electric current under all tested contact loads. However, the wear of the carbon steel showed little increase (with increasing electric current) under high contact load. These differences in the tribological behavior under electric current of both cast iron and carbon steel are attributed to the difference in melting point of the materials, which changes the transition of wear mode from adhesion to fusion.