Tungsten based composites are strong refractory metal materials manufactured by a strictly controlled process involving pressing, sintering and infiltrating with copper or silver. They are highly resistant to heat, electric arc, wear and deformation at high temperature welding, flash butt and spot welding. They also have excellent electrical and thermal conductivity. The properties of Tungsten composites are related to the copper/silver-to-Tungsten ratio. If the Tungsten content improves, the electric arc and wear resistance will increase while the thermal and electrical conductivity, on the contrary, reduce.
Due to their unique properties, Tungsten based composites are widely used where the combination of good electrical and/or thermal conductivity and low thermal deformation is necessary, for example:
In electric resistance welding as electrical contacts or heat sinks.
In electrodes for electrical discharge machining (EDM) and electrochemical machining (ECM).
CuW50 and CuW55 have the lowest Tungsten contents. They are both good switching and contact materials for oil filled devices. CuW55 is also used for arcing contacts in oil circuit breakers and arcing edges of selectors and switchblades in transformer tap changers.
CuW65 and CuW70 are used as contact materials in severe arcing applications including gas, oil and some air circuit breakers. They are also used for arcing edges on selectors and reversing switch blades.
CuW75 and CuW80 are used as contact materials under extreme arcing conditions. Applications include arcing contacts in gas and oil circuit breakers, contactors and transformer tap changers, arcing plates and arc runners in power switching equipment.
CuW85 and CuW90 have the highest Tungsten content. They are used as contact materials where resistance to contact welding, sticking and arc erosion are critical. They also provide satisfactory heat and current interruption capabilities. Typical applications are power vacuum switches and high power spark gap electrodes, etc..
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