Metal oxide on the surface of contacts having excellent contact performance

Abstract

AbstractPreviously, a substance identified as ammonium sulfate was found on the speech path contacts of XS‐type crossbar switches in the electronic switching system of NTT. On the basis of this finding, the contacts of 99% Au/1 % Ni alloy in contact with Pd were developed by the author's group more than ten years ago for the pushbutton dial contacts of telephone sets. These contacts showed excellent performance and are still in use at the present. This development depends on the hypothesis that some metal oxides have the effect of preserving contact performance against the influence of air pollution.In this paper, the hypothesis, experimental results in the investigation of the properties of the Au‐Ni alloy surface, and applications of this alloy for electrical contacts are described. The experimental results are as follows: by heating the Au‐Ni (Ni 1%) alloy, it was confirmed that nickel oxide was accumulated on the alloy surface; by measuring the contact angle of a water droplet on the Au‐Ni alloy, the relationship between the angle and accumulation of nickel oxide was obtained; and by operating the contacts combined with Au−1 % Ni and Pd which are similar to the actual use of contacts, the characteristics and the size of the formed powder were evaluated.