A Study on the Polishing of Electric Contacts (Succeeding Report)

Abstract

In the last paper concering the same problem, the authors reported on the performances of sintered Ag-W alloy contact polished by a machine based on lapping and also on the mechanism of plane contact of metal pieces. In this paper, the results of the experiments on the polishing of sintered W contacts and the influences of different roughness of contact surfaces and applied load on the electrical contact resistance are discribed. Also the relationships between the applied load and the size of true contact area are deduced by assuming a simple model which represents the profile curve of metal surface. The results of this investigation may be summarized as follows : (1) For sintered alloy contacts mechanical polishing is effective. (2) The contact resistance is proportional to 3/5∼3/4th power of load and 1/5∼1/4th power of surface roughness. (3) True contact areas are presumed to order of 10^-4∼10⁵cm² at range of 0.01∼0.1kg in load, 0.01∼0.1μ in roughness and it is independent of apparent contact area.