Correlation between Wear Resistance and Lifetime of Electrical Contacts

Abstract

Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.

Research on fretting Regimes of gold-plated copper alloy electrical contact material under different vibration amplitude and frequency combinations

“…There is a slight increase followed by a great fluctuation between 50 and 300 mΩ in the contact resistance from 20,000 to 82,000 cycles, followed by a sharp decrease from 82,000 to 90,000 cycles. The relationship between the contact resistance and fretting cycles correlates well with the findings of other researchers [5,6,10,11].…”

“…The number of cycles to the rapid increase of contact resistance was used in ever study as lifetime, since it has the strongest impact on the behavior of electrical contacts. The number of cycles which leads to a 300% increase of contact resistance was defined as lifetime [11], meanwhile several researchers also used 100 mΩ and 300 mΩ as the lifetime limit [5][6][7]11,27]. It is proved that the occurrence of 100 mΩ corresponds to the damage on gold plating and the contacts can normally still work properly.…”

“…Because gold does not oxidize when exposed to air, connectors with gold coatings would be guarded against fretting corrosion [10][11][12][13][14], unless the gold coating is worn out and followed by the corrosion of the substrate material. Therefore, the connectors with goldcoatings appear to be a preference for aircraft applications.…”

“…This provides more fresh metal for oxidation and generates more accumulation of oxide wear debris at the contact zone [3]. However, the fretting frequency is mainly focused on 1 Hz [11,[17][18][19] [22] and 100 Hz [9], [23]. Vingsbo and Soderberg [24] first presented fretting maps and according to the slip amplitude, categorized contact surface damage into these regimes: stick, mixed stick-slip and gross slip.…”

Degradation of contact materials — Effects of time, temperature and wear

“…Many authors have therefore also carried out various tribological investigations on electrical contacts [18][19][20][21].…”