Abstract
Key words:
Fretting corrosion, mechanical wear, contact resistance.
Abstract
It is well known that vibration of contact interfaces is the main cause of contact degradation by the so called fretting corrosion phenomena. In fact the process of generated particles by mechanical wear produce the increase of contact voltage frequently assimilated as high contact resistance in low power and signal connector. In high power connector, this degradation is expected to be accentuated by thermal effect generate by increasing contact voltage to melting and arcing voltage. The main objective of this work is to examine conjointly the wear amount and electrical behaviour of connector terminal under vibration and higher current stress. The spring lamellas of an automotive connector are submitted to high number of vibrations (103 to 106) whereas the pin is firmly attached to a fixed support. High frequency oscillation (100Hz) with amplitude of 50μm is used. The contact is made with copper alloy and coated with 2μm of tin. The contact is inserted in resistive circuit supplied by 20V and 3A. The contact voltage is measured with fast sampling oscilloscope and the voltage histogram is built in real time. So, the removed mass in the track are evaluated by micro weight (1μg). The main results show that at low level of wear observed during the earlier stage of fretting corresponds to pure constriction voltage <20mV. However after this initiation period as the wear is increased, the contact voltage is increased and reaches few hundred millivolts (melting and fritting voltage). Finally in later stage of degradation, arcing voltage due to bounce phenomena is detected close 12V. This short arc, observed for the first time in fretting area under power could accentuate the wear and the degradation process by erosion and mass transfer.