Synergetic effect of NbSe2 and Cr2Nb on the tribological and electrical behavior of Cu-based electrical contact composites

Abstract

The Cu-based electrical contact composites containing reinforcement (Cr₂Nb particles) and solid lubricants (NbSe₂ particles) were fabricated by a powder metallurgy method, and their mechanical and electrical properties were investigated. The wear tests of Cu-based composites were performed on a ball on disc under dry sliding conditions in a laboratory atmosphere and the worn surface of the Cu-based composites was observed by using scanning electron microscopy. Experimental results indicated that Cu-based composite materials containing Cr₂Nb and NbSe₂ nanofibers possessed lower electrical resistivity and better prominent tribological properties than Cu/NbSe₂ and Cu/Cr₂Nb composites, and that the friction coefficient and wear rate of the composites gradually decreased with the increase of NbSe₂ nanofiber content. The lubricating effect of the Cu-based composites containing 25 wt% NbSe₂ nanofibers and 10 wt% Cr₂Nb particles was outstanding with a friction coefficient close to 0.15. The tribological properties of Cu-based composites were affected by the size and morphology of NbSe₂ particles, and Cu-based composites with NbSe₂ nanofibers have been proven to be more effective to reduce friction and wear compared to Cu-based composites containing commercially available NbSe₂ micro-particles under dry sliding conditions. Furthermore, the addition of Cr₂Nb could improve the hardness and oxidation resistance of composites, and consequently enhance wear resistance and conductivity of Cu-based composites.