Influence of Electric Current on the Temperature Rise and Wear Mechanism of Copper–Graphite Current-Carrying Friction Pair

Abstract In order to study the influence of current on the temperature rise and wear mechanism of the copper–graphite friction pair, the pin-disc current-carrying friction experiments were carried out under different current conditions. The friction coefficient, temperature, and wear topography were measured, and the energy dispersive spectroscopy (EDS) analysis was conducted as well. The results show that the temperature of the friction pair rises rapidly at first, then the rising speed slows down, and finally reaches dynamic thermal equilibrium in the process of test. The temperature rise at the stable stage increases with the current. The main wear mechanism under low current is material spalling, and it turns to melt ejection and arc erosion under high current. The change of the lubricating film causes the complex wear behavior. With the increase of the current, the amount of transferred graphite increases, but the arc ablation becomes severe, and the graphite lubrication film gradually ruptures, which in turn increases the friction coefficient and makes the wear more severe. The results have a great significance for the anti-friction and wear-resistant design of the current-carrying friction pair.