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 pe rformed 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 tha t the coefficient of friction decreased with increasing Nb proportion and Cu-20vol.%Nb has the best wear resistance. Both the coefficient of friction and wear rate increased as a small electrical current was ap plied and then decreased as the current density increased. With increa se 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 c omposite are much thicker at electrical sliding than nonelectrical sli ding. The surface oxide played a key role in governing the sliding fri ction and wear behavior of the Cu-Nb composites under electrical curre nt.