Effect of Hardness on Wear and Abrasion Resistance of Silver Plating on Copper Alloy

摘要

This study is aimed at clarifying the mechanism of wear process for Ag plating with different hardness. The samples of Ag plating on Cu alloys were prepared as coupon and embossment specimens, which simulated terminal contacts. During the sliding test, the contact resistance and the friction coefficient versus sliding distance were measured. The surface observation, surface roughness and worn volume of the Ag films after wear tests were investigated. As results, the hard Ag plating film (120 Hv) exhibited higher contact resistance comparing to the soft Ag plating film (80 Hv). The soft Ag film delivered a larger wear scar on embossment and wider wear trace on coupon specimens compared to the hard one. The overall worn volume of hard Ag film was less than that of soft Ag film, which can be attributed to the fine crystalline structure on hard Ag. Moreover, the observation of tribofilms formed on the Ag films after wear tests suggested that a mixed-type of adhesive and abrasive wears occurred for both of soft and hard Ag films. Furthermore, the hard Ag plating exhibited longer stable region of friction coefficient than the soft one in a linear oscillating fretting test, indicating an enhanced fretting corrosion resistance.