Influence of Oxides on Material Transfer Behavior of Silver Base Contacts Containing Various Metal Oxides

Abstract

Silver base contacts containing magnesium, aluminium, manganese, zirconium, lanthanum and cadmium oxides are prepared by internal oxidation. The material transfer or erosion characteristics of these contacts are investigated in the range of applied voltages from 40 to 212 V and currents from 6.4 to 80.1 A in direct current, alternating current and rectified full sinusoidal wave current circuits.
The characteristics of the material transfer or erosion for switching contacts in direct current and alternating current can be clarified in many respects by a switching test of rectified full sinusoidal wave current. In the switching of rectified full sinusoidal wave current, the direction of the material transfer depends on the value of the testing current. In the range of lower current than the transition one the material transfer occurs in a direction from cathode to anode, and in the higher current range from anode to cathode. The direction of the material transfer and the amount of erosion are affected remarkably by the kind of containing oxides, and particularly by the materials of the electrode in which erosion occurs. In the range of material transfer from cathode to anode in direct current and rectified full sinusoidal wave current, the amount of cathode erosion is approximately proportional to the arc energy in contact breaking at a constant applied voltage. Moreover, the ratio of the amount of material transfer to the arc energy varies with the oxides contained.