Characteristics for Electrical Contact of Silver Base Alloys Containing Two Kinds of Oxides in Magnesium, Manganese, Lanthanum and Zirconium Oxides

Abstract

Four silver base alloys containing two kinds of oxides, viz. manganese and zirconium oxides, magnesium and zirconium oxides, magnesium and lanthanum oxides and lanthanum and zirconium oxides, were prepared by the internal oxidation in the air at 650°C. For these contacts the characteristics of erosion resistance, welding resistance and contacts resistance were measured under the conditions of an applied voltage of 100 volts and circuit currents from 10 to 50 amperes in alternating current.
The coexistence of zirconium oxide with others is very effective to improve the welding resistance. As compared with the characteristics of silver-12 wt% cadmium oxide contacts which are used very frequently, the contacts containing lanthanum and zirconium oxides (0.40 at%La and 0.49 at%Zr) have higher welding resistance, but their erosion resistance is a little lower. It is also shown that magnesium and zirconium oxide contacts (0.49 at%Mg and 0.50 at%Zr) have almost the same erosion resistance and welding resistance. Furthermore, both contacts are comparable in contact resistance. On the other hand, the erosion resitance of manganese and zirconium oxides (2.0 at%Mn and 0.96%Zr), magnesium and zirconium oxides (0.49 at%Mg and 0.50 at%Zr) and magnesium and lanthanum oxides (0.49 at%Mg and 0.36 at%La) is improved in the high current region, because the circuit current dependency of the amount of erosion is less than that of other contacts.