Vacuum switch contact materials

Abstract

A material is described which is useful in electrical current switching devices and is especially adapted to form the contact surface of the electrodes of electrical current switching devices which are employed in a vacuum environment. The contact material comprises a major component which is characterized by a melting point in excess of 1250.degree. C and a boiling point of less than 3500.degree. C. A small but effective amount of an element which provides antiwelding characteristics and in which said element has only minimum solubility within the major component. The balance is a minor constituent for providing a low resistance path for the electrical current to flow from one electrode to the other. Typical compositions includes a chromium matrix material which comprises in excess of 50% by weight of the contact material, up to about 1.5% of an antiwelding element for example bismuth and the balance essentially a high electrical and thermal conductivity element notably copper or silver. These ingredients are compounded and are formed into the shape of a contact material which is attached to the electrodes in electrical current switching devices.

Dependencies are inferred from the claim text.