Comparison of Reignition Properties of Several Ag/W, Ag/WC, and Ag/Mo Electrical Contact Materials

The reignition properties of several Ag/W, Ag/WC, and Ag/Mo electrical contacts were compared in a static gap discharge system. The effects of refractory particle size, composition, and processing method were studied. Silver-molybdenum was found to have the least tendency to restrike. Silver-tungsten carbide contacts generally restruck more frequently than Ag/Mo and Ag/W and the number of restrikes increased with the refractory content. Restrike in silver-tungsten contacts was not as sensitive to the refractory content; however, the use of coarse tungsten increased the tendency to restrike. The processing method had a significant influence on the number of restrikes of Ag/W contacts. In particular the press-sinter contacts processed at below the melting temperature of silver showed a high probability of reignition.