Abstract

The rapid development of high-speed railways necessitates the development of new materials for switch slide baseplates. In this study, a Cu-Ni-graphite composite, containing 1 wt.% to 6 wt.% graphite and prepared by powder metallurgy, was used as a potential material. Pin-on-disk wear tests were conducted to measure the sliding friction of the Cu-Ni-graphite composite against U75V steel. The results showed that the friction coefficients gradually decreased when the graphite content in the composite ranged from 1 wt.% ~ 4 wt.% in the composite. When the graphite content was 4 wt.%, the friction coefficient reached the minimum value (0.153). When the graphite content was low (1 wt.% to 4 wt.%), the primary wear mechanism was microcutting. An increased graphite content facilitated the generation of lubricating films and decreased the wear damage. As the graphite content increased from 4 wt.% to 6 wt.%, the friction coefficients also increased. The variation in the wear volume rate had the same tendency as the friction coefficient. When the graphite content exceeded 4 wt.%, the primary wear mechanism was delamination and fatigue wear. Due to the tendency to form cracks on the subsurface and the plentiful generation of spalled pits, the graphite fragments could not completely form lubricating films but separated as wear debris. The lubricating films existing on the U75V steel were in proportion to the graphite content in the composite. The wear weight loss of the U75V steel exhibited a reduction with increasing graphite content.

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