The effect of microstructure on the electrical performance of Ag-WC-C contact materials

Silver-tungsten carbide-graphite contacts of varying microstructures were investigated to determine the effect on contact erosion, sticking, resistance, and current interruption. The parameters examined were graphite particle size and silver particle size. Statistically significant results were weld strength after contact bounce at 400 amperes peak, weight loss after 10,000 operations at 141 amperes peak, and weight loss and resistance after interruption at 1,920 amperes peak. For the Ag-WC-C composition tested, the use of fine graphite and fine silver powders led to enhanced electrical performance.