Electrical Sliding Behaviour of Solid Lubricant-Reinforced Copper Composites for Slip Ring Applications

Adhesive wear is a dominant problem for copper in electrical sliding contacts due to the low relative hardness difference between the contacting bodies materials and their high mutual solubility. These adhesive islands are responsible for intermittent electrical contact during sliding, eventually leading to a loss of reliability and performance in electromechanical systems such as electric drives, slip-ring assemblies and current collectors. To mitigate this issue, a solid lubricant reinforcement approach and powder metallurgy route were adopted. Layered materials were reinforced into the copper matrix and processed using the spark plasma sintering technique. The processed composites were tested under electrical sliding conditions. The obtained results were statistically analysed using response surface methodology to identify the most influential parameters affecting tribological performance. This was followed by worn surface analysis, which revealed reinforcement-specific wear signatures. The influence of electric current was evident by the dominance of electrical arc erosion mechanisms. This research addresses the combined effects of electric current and mechanical load on the coefficient of friction, electrical contact resistance, and wear as key performance indicators for different composites. The stability of electrical contact resistance was found to be strongly influenced by the size of wear debris. SEM-based debris analysis revealed molten and sintered debris on the wear tracks, which were subsequently oxidised under ambient air conditions.