Failure Mechanism of Sliding Electrical Contacts with Various Plated Materials

Sliding performance of electrical contacts depends on the friction and wear of contact materials, the oxidation of base metals and application conditions. Since the multi-layer coatings on electrical contacts have more combinations with various materials and plating thickness, the sliding life of electrical contacts will be influenced by the interaction of materials performances and application conditions. In this paper, the failure mechanism of both gold plated contacts and silver plated contacts was analyzed by detecting the contact resistance and element compositions on contact interfaces. Orthogonal experimental design and range analysis were used to study the influencing extent and trends of plating thickness, plating combinations and normal force on the sliding life. A modified sliding model was supposed to show the relationship between sliding life and various factors, such as the materials hardness, normal force, plating thickness and sliding amplitude. The difference of failure mechanism and sliding life between gold and silver plated contacts was compared based on the wear characters and the influencing factors.