Traditional manufacturing method of copper-tungsten alloy contacts

    The traditional preparation and processing technology of precision copper-tungsten alloy contact raw materials includes infiltration method, high-efficiency liquid phase sintering method, powder injection molding, vacuum pump electric smelting and so on.

    The mechanism of the infiltration method is that the copper liquid and tungsten have excellent lubricity at high temperature. Under the effect of capillary force, the copper liquid can fill the gap of the tungsten skeleton to obtain a composite material with excellent relative density. The general process of the infiltration method is tungsten powder green embryo suppression, tungsten skeleton pre-firing and copper liquid infiltration, in which pre-firing and infiltration need to be carried out in a vacuum pump or an oxidizing atmosphere to avoid air oxidation. When preparing CuW raw materials by infiltration method, the powder particle size distribution and the addition of inducers during skeleton pre-sintering are very harmful to the arrangement of CuW composite materials. Research by Ning Chao et al. showed that if the particle size distribution of tungsten powder is too large, the porosity of the skeleton will be uneven, and if the particle size distribution of tungsten powder is too small, it is very easy to produce reunion, which will lead to the blockage of the pores in the skeleton, so that the copper liquid cannot penetrate. When the particle size of tungsten powder is 5~9um, the obtained green embryo porosity is uniform in size. Appropriate addition of 2.5%~3.5% of induced copper chips can improve the balance of porosity during skeleton pre-sintering, and improve the wetting between copper and tungsten during infiltration, but too much entry will cause copper aggregation during infiltration. The high-efficiency liquid phase sintering method is another way to prepare CuW composite materials. The basic processing technology is: mix the Cu powder and the W powder evenly, press the compact, and maintain it in an oxidizing atmosphere at an ambient temperature higher than the melting point of Cu. Carry out sintering molding, and finally carry out high-density processing such as final pressing and hot forging to obtain products. The relative density of the raw materials obtained after high-efficiency liquid phase sintering is not high, and a high-density post-processing process is usually required. In addition, high-efficiency liquid phase sintering also has the defects of a lot of copper evaporation and high power and energy costs. The addition of active elements such as Co and Fe to the precision copper-based alloy contacts during the sintering process can improve the sintering characteristics and reduce the sintering temperature, but the addition of active elements is not conducive to the electrical conductivity and heat transfer of the raw materials, and it is not suitable for precision silver Manufacture of base alloy contact raw materials.