Influence of Bi to AgSnO2 material's contact resistance

AgSnO2 is the most likely contact material to replace of AgCdO contact material. But AgSnO2 exists defect of high contact resistance in the process of use. How to reduce the contact resistance of AgSnO2 is the key issues in the paper. Firstly, AgSnO2 and AgSnO2Bi2O3 contact materials are prepared by powder metallurgy. Arc tests are carried on the two kinds of contact materials. The structure and shape on arc-melted surface of AgSnO2Bi2O3 and AgSnO2 are observed and analyzed by scanning electron microscopy. Then, by wetting test, the wetting angle of AgSnO2Bi2O3 and AgSnO2 are measured. The results show that the wettability of liquid Ag on the SnO2 is improved by adding Bi elements. And the wetting angle decreased. So, river-like tissue formed on the surface of AgSnO2Bi2O3 after arc erosion. The SnO2 is avoided concentration to forms insulating layer on contact surface. Finally, it is verified that the AgSnO2Bi2O3 contact resistance is smaller than that of AgSnO2 by electrical property tests. Through the tests, it is proved that the AgSnO2 contact resistance is reduced by adding Bi.