Study on electrical contact properties of Ag-SnO2 contact material

As forbidden of the heavy metal Cd, Ag-SnO₂ is the most promising contact material to take the place of Ag-CdO. In this paper, the electrical contact properties of Ag-SnO₂ contact material and the reasons of failure for Ag-SnO₂ contact material were studied in DC level. It was found that under the action of arc, as the Ag sputter and evaporate, SnO₂ gathered on the surface of the contact. It makes the surface of the welding brittleness. So the two contacts easily separate to each other. At the same time, the contact resistance becomes more and more larger with the Ag loss, then the contacts temperature increase. Asymmetric use was studied in this paper also. It can be found that contact material transfer is effectively prevented when AgSnO₂ was used as anode material and Ag-Ce was used as cathode material as match.