Fretting corrosion of tin coated electrical contacts: The influence of normal force, coating thickness and geometry of sample configuration

Coating thickness, normal force and the geometry of sample configuration are important design parameters for contacts. The influence of these parameters on the fretting behavior of the tin coated electrical contacts has been recently studied. It was concluded by some researchers that the tin coating thickness and load have a larger effect on contact resistance, while the other parameters, namely temperature, humidity, amplitude, frequency, geometry of sample configuration and aged/brand-new samples, are less critical [1]. However, according to our experiments, the geometry of sample configuration, namely the radius of the sphere part at the sphere/plane configuration, also has great influence on the fretting behavior reflected by the change of contact resistance. In this paper, a further investigation was conducted on some of the parameters in [1]. It was found that the radius of the sphere parts at the sphere/plane configuration is also a critical parameter with regard to the fretting corrosion. The fretting behavior is complicated under a lower level force, since increasing force on the one hand assists the penetration of the oxide layer, and on the other hand increases the wear. At the high level force of 4 N, a longer lifetime can be obtained.