Two new Cu-Cr alloy contact materials

Two new contact materials, vacuum casting Cu-25Cr alloy and a laser refining Cu-50Cr surface alloy, have been developed. Examined by the backscattered electron imaging of scanning electron microscopy and attached energy dispersive X-ray spectrometer, it is shown that both alloys are uniform and have very fine Cr-dendrites surrounded by Cu-matrix, homogeneous composition distribution, good cohesive interface between Cu and Cr phases and high mutual solubility of Cr and Cu phases at room temperature. Meanwhile, the relative density, Vickers hardness and electrical conductivity of the two alloy contact materials were measured. The results of standard vacuum interruption test at 38 kV 25 kA and then overfulfilled test at 38 kV 31.5 kA, have shown that the vacuum interruption performance of the interrupter contacts made from the two new alloy materials are superior to that of the powder metallurgy contacts with the same composition. Therefore, it is expected that high performance, energy saving and minimum size of the vacuum interrupters will be realized if the two new Cu-Cr alloy materials are adopted to make the contacts in practice.