Comparison of coefficient of friction and contact resistance during sliding wear on clad gold-nickel surfaces

This paper presents analysis of experimental sliding wear data for four hard-gold flash over gold-diffused nickel material systems (GF-DGNi). The surface hardness of the DGNi material was altered by varying both the gold surface concentration and the amount of gold reduction after the diffusion anneal. These material systems were evaluated for unlubricated and lubricated sliding wear durability. The lubricant used was a 6-ring polyphenyl ether, OS-138, that was applied by dipping the specimens in a 2.50% solution of OS-138 in a propylene glycol monomethyl ether carrier. A gold flash palladium connector pin and a strip of metal that had been clad with the gold-nickel material system were mated to form a pseudo-crossed-rod configuration for each of these sliding wear experiments. Sliding wear experiments were conducted at 50 g and 150 g normal load. The amplitude of the motion was 1.14 mm with a velocity of 1 mm/s. Each experiment was conducted for a minimum of 2000 wear cycles and five replications were made for each experimental test condition. A new sliding wear test machine and software program were developed for this test series to appropriately handle the clad metal samples and to allow simultaneous measurement of coefficient of friction and electrical contact resistance during each wear cycle.