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. A dditional tests were executed in a fixed gap arrangement in order to s tudy separately the influence of the thermal stress due to the bounce arc only. The bounce model switch was developed to simulate contact bo unces at well-defined and reproducible but independently variable valu es of bounce duration, bounce height, and contact force. The influence of the bounce parameters (bounce arc duration, bounce height and stat ic contact force, current and magnetic induction) on the make only ero sion was investigated by systematic variation of each single parameter value in the bounce model switch. The Ag/SnO2 materials suffered eith er three times higher or about 50% lower erosion losses than powder me tallurgically produced Ag/CdO, depending on the manufacturing process (internally oxidized, powder metallurgically produced) and/or the addi tives of the materials, and therefore on the structure of the material s rather than on the kind of the main metal oxide component (CdO or Sn O2). The different make erosion rates of the materials investigated ha ve been correlated with the micro structure of their stressed surfaces .