Effects of pressing pressure on the physical and electrical contact properties of silver based contact materials

The Ag/SnO2, Ag/ZnO, Ag/Ni and Ag/W materials were prepared by powder metallurgy method. The effects of pressing pressure on the physical and electrical contact properties of different silver-based contact materials were systematically studied. The results showed that the relative densities of the Ag/SnO2 and Ag/ZnO materials significantly increased with the increase of pressing pressure. While, the densities of Ag/Ni and Ag/W alloys obviously decreased. When pressing pressure reached 600 MPa, the electrical conductivity of the Ag/SnO2 material could be increased from 35.2 to 52.6 %IACS. The electrical contact properties of the Ag based contact materials were greatly affected by pressing pressure. The Ag/SnO2 and Ag/ZnO materials prepared under 600 MPa showed the lower arcing energy and contact resistance. Especially, the Ag/ZnO material exhibited the best arc erosion resistance, and the contact resistance was less affected by pressing pressure. Although the conductivity of Ag/W alloy was up to 93% IACS, the mass loss of its anode was larger after arc erosion. The surface of cathode was rough and the obvious cracks were generated. In addition, the contact resistance was greatly affected by pressing pressure. In contrast, the mass loss of Ag/Ni alloy was lower and mainly occurred at cathode, resulting in a good arc erosion resistance.