Fretting corrosion of Tin-plated copper alloy

The rise in contact resistance of a tin-plated copper alloy under cyclical minute motion has been studied for both dry circuit and with electrical loads. In the range of circuit voltage and current investigated, the electrical conduction through slightly corroded contacts is shown not to be affected by the electrical load. For moderately corroded contacts, the resistance characteristic shows a sustained plateau near the melting voltage of Sn; and for severely corroded contacts, plateau occurs in the resistance range corresponding to the voltage range of the melting, sublimation, and decomposition of the oxides and the vaporization of tin. Based on our observation, a consistent picture of fretting corrosion and electrical conduction through such contacts is presented.