Enhanced mechanical and current-carrying wear performances of copper/carbon-matrix composites via interfacial reaction of chromium.

The copper/carbon-matrix (Cu/C) composites have a wide application prospect in high-speed railway pantograph sliders due to both the self-lubrication of carbon and the good conductivity of copper. However, the poor wettability between copper and carbon affects the interface bonding strength. In this work, the carbonizable element chromium powder was added into the composite system, and the Cr-Cu/C composites were fabricated by hot pressing and sintering process. The interface phase of Cr3C2 between copper and the carbon matrix was determined, which results from the interface reaction between chromium and carbon, leading to the improvement of the bonding of copper and carbon. Meanwhile, the mechanical and current-carrying wear performances can be enhanced significantly with the addition of chromium. The results demonstrate that the Cr-Cu/C composite with 0.48wt% Cr has the best comprehensive performance, which includes the compressive strength of 62.82 MPa, the flexural strength of 26.72 MPa, the impact strength of 0.17 J cm−2 and the electrical resistivity of 31.28 μΩ m, respectively, and this composite has the lowest wear rate and friction coefficient. It is also found that with the alteration of current density change from 5 A cm−2 to 10 A cm−2, the wear mechanism changes from abrasive wear to adhesive wear. With the introduction of chromium, a certain thickness of Cr3C2 layer is formed at the interface between copper and carbon, which can improve the wettability of copper and carbon obviously, enhancing bonding effect and reducing pores. Therefore, the novel copper/carbon-matrix composites have excellent mechanical and current-carrying wear performances at current densities of 5 A cm−2 and 10 A cm−2. [ABSTRACT FROM AUTHOR]