Effect of Arcing on the Microstructure and Morphology of Ag-CdO Contacts

The changes in the microstructure, the composition, and the morphology of internally oxidized Ag-CdO contacts after high current arcing were investigated. The contacts were always opened on the same half cycle (60 Hz ac); thus one electrode was always the cathode, the other always the anode. Qualitative spectra of the arc at its midpoint were also taken, The results indicate that during arcing, there is a much higher concentration of Cd vapor than of Ag vapor in the interelectrode region. It is also found that the erosion of the cathode is more severe, and that the metal in the interior of the cathode craters is depleted of CdO, while a layer of Ag-Cdo is built up in the anode craters.