Characteristics for Electrical Contact of Silver Base Alloys Containing Magnesium, Manganese and Lanthanum Oxides

Abstract

Silver base alloys containing magnesium-, manganese- and lanthanum-oxides were prepared by internal oxidation in air at 650°C. The characteristics of erosion resistance, welding adhesion resistance, and contact resistance of these contacts have been measured under an applied voltage of 100 V and testing currents from 10 to 50 A in alternating current.The addition of lanthanum oxide is very effective in improving the above characteristics. The contacts containing lanthanum oxide (0.5 at%La) have higher welding resistance and lower contact resistance than silver-12 wt% cadmium oxide contacts, and both contacts are equal in erosion resistance. On the other hand, although additions of magnesium and manganese oxides are not so effective as that of lanthanum oxide, the erosion resistance of magnesium oxide (1.0 at%Mg) and manganese oxide (3.2 at%Mn) contacts are comparable to that of 12 wt% cadmium oxide contacts in the high current region over 30 A. Furthermore, the change in the amount of erosion with current becomes small for magnesium-and manganese-oxide contacts.