The effects of CdO on the static gap arc erosion of silver-based contacts

A series of homopolar static gap electrical tests made to evaluate the effects of adding cadmium, as a metal to form an alloy or as an oxide to form a composite, on the erosion behavior of silver-based contacts is discussed. Pure silver tends to have anode dominated erosion with little cathode disruption. Adding cadmium as either a metal or as oxide particles causes the cathodic disruption to become substantial, with the cathodic weight loss exceeding the anodic weight loss for materials with higher cadmium concentrations. The cadmium tends to transfer from the cathode to the anode surface, where it agglomerates largely in the form of an oxide regardless of its initial form. It is concluded that the material deposited on the anode, with its CdO agglomerates and porosity, provides a weld-inhibiting interface between the contacts