Effects of electrical current on the sliding damage behaviors of Au-plated Cu alloy pairs

Failure mechanisms of high-power electrical connectors operating under hot-swap conditions at currents spanning tens to hundreds of amperes (interfacial current densities spanning 10 1 –10 3 A/mm 2 ) have remained elusive. To address this problem, reciprocating sliding tests were performed on comparative Cu pairs and Au-plated Cu pairs under electrical currents ranging from 0 A to 20 A (interfacial current density spanning 0–2.0×10 3 A/mm 2 ). At low currents (0–10 A), the Au-plated layer reduced average COF from ∼0.6 (Cu pairs) to ∼0.2 (Au-plated Cu pairs), representing a 70% reduction. And surface resistance was lowered from ∼7 mΩ·mm 2 in Cu pairs to ∼0.6 mΩ·mm 2 in Au-plated Cu pairs, a 90% decrease. The wear rate of Au-plated Cu pairs (∼10 -5 mm 3 ·N -1 ·m -1 ) was an order of magnitude lower than that of Cu pairs (∼10 -4 mm 3 ·N -1 ·m -1 ), demonstrating excellent anti-wear performance. But at high currents (15–20 A), the COF and surface resistance of Au-plated Cu pairs became comparable to those of Cu pairs. This was primarily attributed to wear-induced degradation of the Au plating, where the Au content dropped below 5%, diminishing its protective effect. Notably, at 20 A, arcing occurred in Cu pairs, but no arcing was observed in Au-plated Cu pairs. This indicates that the Au-plated layer effectively suppressed arc generation even at high currents. Interfacial temperatures generated by Joule and arc heating could explain the observed wear behaviors. These results offer valuable references for designing damage-tolerant high-power electrical connectors, where Au plating can be strategically used to enhance reliability under varying current conditions.