Investigation on arc behavior of AgNi electrical contact material with three-dimensional network structure

To clarify the arc characteristics of Ag–Ni contact material, the Ag-8wt.%Ni contact material with three-dimensional network structure was prepared by powder metallurgy, and the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. The electrical contact tests were performed for different operations, the arc motion behavior, arc-preferred characteristics and surface morphology evolution were investigated, and arc erosion mechanism was discussed. The results show that serious arc erosion prefers to occur on the Ni-rich phase at the eroded anode surface. However, at the cathode region of the arc-eroded surface, the reticulate Ni phase restrains the expansion of molten pool and decreases arc erosion at the early stage of electrical contact tests. The difference in the arc-erosion behaviors of anode and cathode can be attributed to the changes in the mean free path of free electrons and cations in the contacting bodies. With the increased use of electrical contacts, the floatation, dissolution and subsequent precipitation of Ni cause the formation of fine Ag-rich and Ni-rich phase, which not only disperses the thermal energy and reduces the splash, but also decreases the fluctuations of arc duration and arc energy. In addition, the break-arc-energy presents larger fluctuation than make-arc-energy.