Einfluss der Mikrohärte der Ober- flächenschutzschicht auf den Verschleiß und die Lebensdauer von elektrischen Kontakten bei Reibverschleißbelastung

Abstract

The lifetime of electrical contacts is influenced by various factors. Micromotions due to fluctuations in temperature and vibration in the field lead to fretting wear and fretting corrosion of electrical contacts. In case of the contacts with noble coatings, the fretting wear results in the wear through of the coating causing the exposure of the underlying non-noble metal to the surrounding atmosphere which in turn leads to fretting corrosion. These degradation mechanisms lead to an increase in electrical contact resistance and eventual failure of the system. In this study, the extent of contact degradation due to fretting war of galvanically silver-plated electrical contacts is investigated. To compare the extent of war occurring at different stages of the contacts’ lifetime, the fretting tests are conducted up to predefined fretting cycles. XRF measurements of the coating thickness before after the tests are performed and the wear depth after the given fretting cycles is determined via confocal microscopy. The results of two different types of silver plating are compared. Based on this, a prognosis regarding the wear behavior and expected lifetime of different coating systems can be made possible.