A Study on the Thickness of Rhodium Oxide Film Produced by the Surface Deactivation Treatment of Rhodium-Plated Contact Reed Switches

Surface deactivation treatment, i.e., oxygen treatment at high temperatures, was invented to prevent adsorption and catalysis of rhodium-plated contact surfaces. This oxygen treatment was also found to be effective to inhibit soft sticking, a kind of locking phenomena that is one of the most serious problems in the field of electrical contacts. So far, oxygen on rhodium-plated contact surfaces treated with oxygen at 450°C or above is found to be present in the state of rhodium oxide (Rh203). However, research on the thickness of rhodium oxide film remained to be carried out. This time the rhodium-plated contact surfaces are examined precisely to obtain information about the thickness of rhodium oxide film produced by oxygen treatment at 450°C or above, by utilizing ellipsometry and Auger electron spectroscopy. As a result of these investigations, it is found that the thickness of rhodium oxide film by oxygen treatment at 450°C is about 60 A and that the thickness of rhodium oxide film increases as the oxygen treatment temperature rises.