Electrotribological behavior of Cu-15 vol.% Cr in situ composites under dry sliding

The Cu-15 vol.% Cr in situ composite i a promising material for the electrical contacts in high current devices, since it has an excellent combination of mechanical strength and electrical/thermal conductivity. The electrotribological behavior of Cu-15 vol.% Cr was studied using a modified pin-on-disk tester with an electrical current applied across the sliding interface. The Cu-15 vol.% Cr pins were slid against a hardened AISI 52100 steel disk under dry ambient conditions. Coefficient of friction, wear rate and bulk temperature of the composite pins were evaluated as a function of electrical current, normal pressure and sliding speed. The microstructural change in the composite due to electrical sliding was related to the electrotribological behavior. Within the studied range of electrical current, normal pressure and sliding speed, the coefficient of friction and the wear rate decreased with increasing electrical current, whereas the bulk temperature increased. A deformed subsurface layer was identified in the composite after electrical sliding. The thickness of the subsurface layer decreased with increasing electrical current. The surface layer, containing refined structure, wear debris and back transferred materials from the steel disk, had a high level of microhardness.