Sliding wear and friction of electroplated and clad connector contact materials: effect of surface roughness

A modeling study with bench apparatus was conducted with connector contact materials consisting of electroplated hard gold and gold flashed palladium on nickel underplatings mated to a clad noble metal. The clad metal contact was the "rider", i.e., had the smaller surface involved in sliding compared to the plated "flat" surface. This configuration is consistent with good engineering practice in commercial products. It was found that although a lubricant could reduce friction significantly and virtually eliminate adhesive transfer of metal, a requirement for negligible wear, i.e., the absence of loose particles, was that the plated surface be very smooth. If this contact was rough, such as might occur due to it having a nodular nickel underplate, tool marks, or burrs, abrasive wear of the cladding occurred in proportion to the magnitude of roughness, However, when both contacts were plated, lubricated wear was low and surface roughness was not a significant factor. Unlubricated plated contacts wore severely with high friction by the prow formation adhesive wear mechanism regardless of their surface roughness.