THE INFLUENCE OF BOUNCE PARAMETERS ON THE MAKE EROSION OF SILVER METAL-OXIDE CONTACT MATERIALS

Make erosion of contacts made from powder metallurgically produced Ag/CdO and three differently produced Ag/SnO2 materials was investigated employing both a commercial contactor and a new bounce model switch. Additional tests were executed in a fixed gap arrangement in order to study separately the influence of the thermal stress due to the bounce arc only. The bounce model switch was developed to simulate contact bounces at well-defined and reproducible but independently variable values of bounce duration, bounce height, and contact force. The influence of the bounce parameters (bounce arc duration, bounce height and static contact force, current and magnetic induction) on the make only erosion was investigated by systematic variation of each single parameter value in the bounce model switch. The Ag/SnO2 materials suffered either three times higher or about 50% lower erosion losses than powder metallurgically produced Ag/CdO, depending on the manufacturing process (internally oxidized, powder metallurgically produced) and/or the additives of the materials, and therefore on the structure of the materials rather than on the kind of the main metal oxide component (CdO or SnO2). The different make erosion rates of the materials investigated have been correlated with the micro structure of their stressed surfaces.