| Cu-Cr alloy is the dominant contact material for use in high-power vacuum interrupters because of its high-strength and hardness, good electric conductivity as well as endurance and resistance to arc erosion. Cu-W alloy is widely used as electrical contact material in various voltage interrupters and as electrode material for electrical discharge machining, due to its advantages of high strength, excellent resistance to arc erosion and welding. However, with the development of interrupters to fit high-power, high capability and miniaturization, Cu-Cr alloy can not meet the demand of high-voltage, high-current interrupters. Recently, the main method to develop new contact materials is to improve the preparation craft of old contact materials and to add some additives to Cu-Cr alloy and Cu-W alloy to enhance some single property. Through investigation of microstructure and properties, it is expected that the alloy can be used in the high-voltage, high-current vacuum interrupters. CuWCr composite material were prepared by powder metallurgy- infiltration. The effect of sintering temperature, CrW mass proportion and heat treatment on the the microstructure, hardness, electric conductivity and some vacuum breakdown properties such as breakdown strength, chopping current and the life of vacuum arc were investigated. From those investigations, the following conclusions can be drawn:1.With increase of sintering temperature, the solid solubility increased gradually. When the sintering temperature reach 1450℃,Cr and W can formed CrW solid solution;2.With increase of sintering temperature, the hardness of CuWCr composite material increases and the electric conductivity decreases. After the vacuum electric breakdown of CuWCr composite material, the results show that the area of breakdown pit become smaller and shallower with increase of sintering temperature. Meanwhile, the breakdown strengthincreases, the arc life prolongs and the chopping current decreases obviously. So the 1450℃is the best sintering temperature;3.When the ratio of Cr mass fraction to the W mass fraction is approximately 1:3.5, Cr and W will form CrW solid solution with 1:1 atom ratio. When the ratio of Cr mass fraction to the W mass fraction is above 1:3.5, CrW solid solution with high Cr content is formed. In the contrary, CrW solid solution with high W content is formed. With increase of Cr/W mass fraction, the hardness of CuWCr composite increases, whereas the electrical conductivity decreases. The vacuum electrical breakdown experimental results show that the breakdown area gradually increases, and breakdown pit becomes shallower. The breakdown strength gradually increases, the arc life increases and chopping current decreases;4.The hardness of CuWCr composite material increases with increase of solution temperature, the electrical conductivity decreases. Subsequent aging treatment shows that, compared with those of CuWCr composite material with only solution treatment, both the hardness and electrical conductivity increase significantly. The CuWCr composite material after solid solution treatment has the biggest breakdown strength, the longest arc life and the lowest chopping current. However, those counterpart values have the total opposite results after solid solution + aging treatment;5.The maximum hardness and electrical conductivity of CuWCr composite material can be obtained at 1000℃solution, holding for 2h and 500℃aging, holding for 3h.
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