Switching behavior of silver/graphite contact material in different atmospheres with regard to contact erosion

Silver graphite contact materials with graphite contents of 3 and 5% by weight were examined with regard to contact erosion behavior. Tests have been carried out in a model switch, applying different gases as switching atmospheres: ambient air and pure gases such as oxygen, nitrogen and argon. It was found that the contact erosion is mainly influenced not only by the reaction of graphite with oxygen, but also by the reaction of graphite with nitrogen. In argon atmosphere, no reaction occurs and in consequence the contact erosion is reduced substantially.