Method for producing electrode material for vacuum circuit breaker, electrode material for vacuum circuit breaker and electrode for vacuum circuit breaker

The electrode material for a vacuum circuit breaker is produced by a method comprising a mixing step, a press sintering step, and a Cu infiltration step. In the mixing step, an Mo powder having a particle diameter of 0.8 to 6 μm is homogeneously mixed with a thermite Cr powder having a particle diameter of 40 to 300 μm in such a manner as giving a mixing ratio (Mo:Cr) of 1:1 to 9:1 and satisfying the weight relation Mo≧Cr. In the press sintering step, the resultant mixture is pressure molded under a press pressure of 1 to 4 t/cm 2 to give a molded article. Next, said molded article is sintered by maintaining the same at a temperature of 1100 to 1200° C. for 1 to 2 hours in an heating furnace to give a partially sintered article. In the Cu infiltration step, a thin Cu plate is placed on said partially sintered article and maintained at a temperature of 1100 to 1200° C. for 1-2 hours in a heating furnace so that Cu is liquid-phase sintered and infiltrated into the partially sintered article. A contact material of an electrode for a vacuum circuit breaker has an integral structure consisting of a central member and a Cu—Cr outer peripheral member, said central member having been produced as described above and comprising 30 to 50 wt % of Cu of a particle diameter of 20 to 150 μm and 50 to 70 wt % of Mo—Cr of a particle diameter of 1 to 5 μm, while said outer peripheral member being formed of a material, which is highly compatible with the central member, shows excellent interruption performance and has high withstand voltage, and being provided outside the central member and fixed thereto.