Electrical sliding friction and wear behavior of Cu-Nb in situ composites

The sliding friction and wear behavior of Cu-Nb in situ composites was studied in the presence of electrical load. Electrical sliding was performed between a Cu-Nb composite pin and a flat surface of a hardened tool steel disk in ambient atmosphere. The effects of Nb proportion, electrical current density, sliding speed, and Nb-filament orientation on the friction and wear behavior were investigated. It was found that the coefficient of friction decreased with increasing Nb proportion and Cu-20 vol.%Nb has the best wear resistance. Both the coefficient of friction and wear rate increased as a small electrical current was applied and then decreased as the current density increased. With increase in sliding speed, the coefficient of friction and wear on the Cu-Nb composite decreased. The composite with Nb-filaments perpendicular to sliding direction was found to have higher wear resistance than that of parallel orientation. The deformation layer and oxide film of the composite are much thicker at electrical sliding than nonelectrical sliding. The surface oxide played a key role in governing the sliding friction and wear behavior of the Cu-Nb composites under electrical current