Investigation on contact surface damage of an automotive connector by fretting corrosion

Abstract

The main cause of electrical contact resistance degradation by corrosion is the vibration of contact interfaces. The purpose of this article is to analyse the change of contact resistance under vibration testing for uncoated sphere/plane contact made of new high-copper alloys. The influence of electrical and mechanical properties of materials and mainly the hardness on contact resistance was studied in this work. During the fretting test, the contact point was submitted to 16,000 vibration cycles under a fretting amplitude of 50 µm and 1 Hz frequency. The spherical part was fixed, while the plane part was submitted to a relative motion. At the end of the test, the fretted surfaces and the wear debris were analysed by scanning electron microscope and energy dispersive X-ray spectroscopy to evaluate damage, oxidation and elemental composition present in the wear surfaces. In addition, the measurement of the wear track profile using a 3D surface scanning system was introduced. Increases in contact resistance and contact temperature have been examined during the fretting test. The results showed that the contact resistance for the harder alloy was higher than that obtained for the other materials. In addition, topographic measurement showed that the small wear track corresponds to the harder material. Finally, depending on the hardness and the resistivity, these uncoated materials influence fretting appearance and its level.