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 (Rh
2
0
3
). 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.