Fretting property of asymmetrical metal contact pairs

Au-Au plated contact pairs have long been the most frequently used in electrical and telecommunication system due to their outstanding electrical, physical and chemical properties. However, the increasingly high cost of gold plated connectors forces the manufacturers to seek some inexpensive substitution due to serious global competition. Non-noble metals Ni and/or PdNi alloy are frequently chosen to make contact pairs. In this paper, asymmetrical metal contact pairs, including Au(probe)-Ni(coupon), Au-PdNi and Ni-PdNi are conducted fretting tests at the condition of 200 μm fretting amplitude, 1 Hz fretting cycle rate, from 0.5 to 1.5N normal forces and from 2000 to 20000 fretting cycles. Contact resistance of each contact pair during fretting test is measured at constant DC current 100 mA and limited voltage 1V. Morphology and element composition of fretting wear track are observed and analyzed to study the fretting process and mechanism of asymmetrical metal contact pairs.