Effect of pressing force on physical and electrical contact properties of silver-based contact materials

Ag/SnO₂, Ag/ZnO, Ag/Ni, and Ag/W silver-based contact materials were prepared by powder metallurgy method. The effects of pressing force on the physical and electrical contact properties of the different silver-based contact materials were systematically studied. The results show that the relative density of the Ag/SnO₂ and Ag/ZnO materials significantly increases with the increase of pressing force, while the relative density of the Ag/Ni and Ag/W alloys obviously decreases. When the pressing force reaches 600 MPa, the electrical conductivity of the Ag/SnO₂ materials can be increased from 35.2% IACS to 52.6% IACS. The electrical contact properties of the silver-based contact materials are greatly affected by pressing force. The Ag/SnO₂ and Ag/ZnO materials prepared under 600 MPa show the lower arc energy and contact resistance. Especially, the Ag/ZnO materials exhibit the best arc erosion resistance, and the contact resistance is less affected by pressing force. Although the conductivity of the Ag/W alloys is up to 93.0% IACS, the anode mass loss is great after arc erosion, the cathode surface is rough, the obvious cracks appear, and the contact resistance is greatly affected by the pressing force. In contrast, the mass loss of the Ag/Ni alloys is lower, which mainly occurs at the cathode, showing the better arc erosion resistance.