Since tungsten (W) has good electron emission function, a class of composites such as tungsten alloy and W-Cu is good electrode materials, which have been widely used in EDM, electric locomotive guide block, ultra-high voltage switch and welding in the electric power industry. The tungsten-rhenium alloy has replaced platinum as a temperature thermocouple on many occasions, and the high-performance tungsten-rhenium wire is also used as the electron material for display tube launching into thousands of households. Moreover, chromium, vanadium and other materials have been widely used in electron microscopy and coated the glass.
Tungsten has high hardness and the highest melting point among all metals, copper (Cu) has excellent electrical and thermal conductivity, while the W-Cu composite has good electrical and thermal conductivity, low thermal expansion coefficient and high resistance to arc corrosion, so they have been widely used as electric contacts, EDM, resistance welding and plasma electrode materials for a long time. With the development of microelectronic information technology, W-Cu composite material has been widely used in large-scale integrated circuits and high power microwave devices.
Due to the melting point of W (3390 ~ 3430 ℃) is much higher than the boiling point of Cu (2350 ~ 2600 ℃), the Cu in tungsten-copper can cool down and maintain integrity of the tungsten skeleton through "sweat" heat dissipation under the action of high-temperature arc when used as an electric contact, thus ensuring good breaking function of the electric contact. The W-Cu composite material has excellent resistance to arc corrosion, fusion welding, and voltage resistance, making it especially suitable for use as high voltage and UHV open and close contacts, such as in vacuum switch appliances and new high voltage appliances with SF6 as arc extinguishing medium.
Keywords: W-Cu composite,tungsten alloy,tungsten