Effects of oxidation layer and roughness on the fretting wear behavior of copper under electrical contact

Bulk pure copper samples with varying roughness were prepared, heated and oxidized at different temperatures in air by using an ordinary box-type heat treatment sintering furnace to form different oxide layers. Electrical contact fretting wear tests were conducted on pure and treated copper in contact with a brass ball to investigate the effects of surface roughness and oxidation layers on electrical contact fretting wear properties. Test results showed that the roughness of the samples increased after oxidation and became prominent after oxidation at 400 degrees C. The friction coefficient and contact resistance of the samples oxidized at 200 degrees C were lower than those of the samples oxidized at room temperature and 400 degrees C. The adhesion and transfer in the wear process decreased with the increase in oxidation temperature, whereas the oxidation of copper increased with the increase in temperature. A competitive relationship was observed between adhesion and oxidation, and this relation increased the electrical contact resistance. A low oxidation treatment temperature corresponded to serious adhesion. A high the oxidation treatment temperature resulted in intensified oxidation and reduced adhesion. Adhesion accumulation and oxidation increase the contact resistance of the samples. The samples oxidized at 200 degrees C, 400 degrees C and RT had lowest, moderate, and worst contact resistance, respectively.