The effect of temperature on the current-carrying tribological behevior of C/Cu contact pairs in high humidity environments

Abstract

The environmental temperature alters the frictional behaviour by changing the state of the current-carrying contact interface, which makes the electrical contact invalid. In this work, the effects of three different temperatures (-20 ℃, 0, 20 ℃) on the current-carrying tribological behaviour of C-Cu tribo-pairs in high humidity environment (85%) were discussed. The evolution laws of friction coefficient, wear volume, contact surface properties, and contact resistance of C-Cu contact pairs under the coupling effect of temperature and current were studied, and the current- carrying wear mechanism of C-Cu at low temperature was analyzed in depth. The friction coefficient at each temperature exhibits a similar changing rule before and after current-carrying, demonstrating that the friction coefficient increases as temperature falls. However, the average friction coefficient at each temperature is lower than that without current. Although it will hasten the material surface's oxidation, a drop in ambient temperature will effectively lessen the transfer behavior of copper to carbon surface and reduce the wear volume of carbon material. The amount of copper transferred increases as current rises. Compared with the current, the change of temperature has a greater impact on the damage of tribo-pairs. At room temperature, the contact resistance under high current is greater than that of low current, the low temperature is just the opposite. In addition, at 0℃, although the contact resistance of low current (5 A) decreases significantly in the early stage of friction, its average resistance and fluctuation amplitude are the largest. As the temperature decreases, the current-carrying wear mechanism of C-Cu contact pairs gradually changes from adhesive wear to fatigue wear.