Non-Welding Contact Materials for Heavy Current Applications

Abstract

The authors observed the welding tendency of electrical contact materials by means of measuring the strength of welding which was caused at the contact by passing a large current through the stationary contact to be tested. The critical welding current of a contact material was defined as one below which no welding occurred. Further an attempt was made to find materials having a high critical welding current, other wise, materials having a small welding strength when welding cannot be avoided. The results of experiments were summarized as follows.
(1) Assuming the critical welding current of copper contact as 1, the value of Cu-Pb or Cu-Bi alloys contact was as high as 1.2 to 2.0. Thus, it was concluded that copper alloys alloyed with low melting point elements possessed an excellent non-welding tendency.
(2) Sintered silver-carbon and silver-carbon-cobalt materials showed a high critical welding current. A large value of the critical welding was obtained by use of a pair of contacts being composed of different kinds of alloys, e.g. silver and cobalt-carbon alloy.