Tarnish-Resistant Contact Material

This paper suggests how tarnish-resistant contact material may be obtained. Of particular interest are those alloys made up of transition and nontransition metals that are able to resist corrosive gases and inhibit the formation of organic polymers. Such alloys can be identified by their physical properties, for example, magnetic susceptibility. The d electronic bands of transition metals are not normally entirely filled, having high magnetic susceptibility. Therefore, those contact materials, especially of the platinum family, cause the formation of organic polymers. When metals such as silver, copper, tin, and antimony are added to these metals, their valence electrons in the high-energy bands, which cause them to corrode, are absorbed into the unfilled d bands of transition metals. It follows that the alloys made up of transition and nontransition metals are inactive for both corrosive gases and unsaturated organic vapors at a composition that loses high magnetic susceptibility. This inactivity is also experimentally verified for palladium alloys.