Copper / Tungsten Copper Welding Contacts

Due to excellent thermal and electrical conductivity, copper / tungsten copper has been widely used in electric motor and electronics fields. Since the electrical contacts manufactured by single pure copper has lower hardness and in the case of heated prone to softening (melting point of copper is low), especially in some high-voltage, high-load switch contacts can not ensure the operation stable. So in order to ensure the electrical contact reliability and durability, the relevant researchers found that copper electrode coated with a layer of tungsten copper can effectively improve the overall properties, such as the density, the hardness, the anti-ablation, the thermal shock resistance, heat dissipation and the service life.

At present, there are many processes to connect copper and copper alloy, such as vacuum brazing, vacuum diffusion welding, vacuum electron beam welding, resistance welding, inert gas welding and friction welding and so on. Here we mainly introduce vacuum brazing and vacuum diffusion welding. In general, vacuum brazing in air and vacuum furnace, the solder and flux sequentially sandwiched between copper and tungsten copper, heated to 780 ℃, held 20min, and cooled; it should be noticed that the controlling the degree of vacuum, pressure welding, soldering temperature and holding time. Viewed from micro structure, vacuum diffusion welding contacts, copper and tungsten-copper-binding capacity is good, the interface is relatively smooth transition. And by brazing process, filler metal substrate with good bond, and the role of the liquid solder and copper tungsten alloy between the copper is not so intense. In terms of resistivity, vacuum brazing contact resistivity lowest close resistivity tungsten copper base material, when brazing in air contacts prone to oxidation, impurities and porosity and other weld defects, uniformity of can not be effectively guaranteed, and so the electrical resistivity is higher.

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