Research on synergistic lubrication effect of silver modified Cu–Ni-graphite composite

Abstract

Cu–Ni-graphite composite is intended to be used as switch slide baseplates in the high-speed railways., The composite is modified by silver element to enhance the tribological properties. Pin-on-disk wear tests were conducted to evaluate the tribological properties. The synergistic lubrication effect generated when the silver-modified Cu–Ni-graphite composite slide against U75V steel. The results showed that the silver-modified Cu–Ni-graphite composite consists of α-Cu, graphite, and a silver phase. The higher graphite content in the composite corresponds to lower coefficient of friction and wear weight loss. Both the coefficient of friction and wear weight loss of the silver-modified composite are much lower than those of the unmodified Cu–Ni-graphite composite. The synergistic lubrication effect of graphite and silver in the composite decrease the friction coefficients and wear weight loss. Compared with the single graphite lubrication, the introduction of the silver phase efficiently enhances the lubricating property and decreases the microcutting and deformation effects. The wear mechanism of silver-modified Cu–Ni-graphite composite with 1–6 wt% graphite content consists of microcutting, oxidation wear, and adhesion wear. The delamination and fatigue wear are resisted at the higher graphite contents by the addition of the silver phase.