Fretting in copper-to-copper contacts under AC and DC current conditions

The effect of fretting on the contact resistance behavior of copper-to-copp er wire-plate combinations under ac and dc current carrying conditions was investigated. The fretting conditions were as follows: frequency 1 Hz, slip amplitude 100 mum and load 400 g (4N). The current level in both ac and dc conditions was 50 mA. In addition to contact resistance measurements, SEM and EDX were used to examine the surface damage in the fretted contact zone s. The results indicate that the overall contact resistance behavior of cop per-to-copper wire-plate couples subjected to the same fretting conditions but under ac and dc currents was practically the same. The characteristic f eature of the samples under ac current conditions is a pronounced distortio n of the waveforms of the contact voltage. The results of SEM surface analy sis of the contact zones indicates that the surface damage resulting from f retting under ac current conditions was different from that under dc curren t conditions.