Tungsten Copper Applications

Tungsten copper are used where the combination of high heat resistance, high electrical and thermal conductivity, and low thermal expansion are needed. Some of the applications are in electric resistance welding, as electrical contacts, and as heat sinks. As contact material, the composite is resistant to erosion by electric arc. Tungsten copper alloys are also used in electrodes for electrical discharge machining and electrochemical machining.

The CuW75 composite, with 75% tungsten, is widely used in chip carriers, substrates, flanges, and frames for power semiconductor devices. The high thermal conductivity of copper together with the low thermal expansion of tungsten allows thermal expansion matching to silicon, gallium arsenide, and some ceramics. Other materials for this applications are CuMo alloy, AlSiC, and Dymalloy.

Tungsten copper composites with 70–90% of tungsten are used in liners of some specialty shaped charges. The penetration is enhanced by factor 1.3 against copper for homogeneous steel target, as both the density and the break-up time are increased. Tungsten powder based shaped charge liners are especially suitable for oil well completion. Other ductile metals can be used as a binder in place of copper as well. Graphite can be added as lubricant to the powder.

Tungsten Copper Parts Picture

Tungsten copper can also be used as a contact material in a vacuum. When the contact is very fine grained (VFG) the electrical conductivity is much higher than a normal piece of copper tungsten. Copper tungsten is a good choice for a vacuum contact due to its low cost, resistance to arc erosion, good conductivity, and resistance to mechanical wear and contact welding. Tungsten copper is usually a contact for vacuum, oil, and gas systems. It is not a good contact for air since the surface will oxidize when exposed. Tungsten copper is less likely to erode in air when the concentration of copper is higher in the material. The uses of tungsten copper in the air are as an arc tip, arc plate, and an arc runner.

Copper tungsten materials are often used for arcing contacts in SF6 circuit breakers that require medium and high voltages. The copper tungsten used in these circuit breakers is subject to temperatures above 20,000K, which is reached during arcing. Copper tungsten arc contacts resist arc erosion.

The spark erosion (EDM) process calls for copper tungsten. Usually, this process is used with graphite, but tungsten has a high melting point (3420 0C). This allows the CuW electrodes to have a longer service life than the graphite electrodes. This is crucial when the electrodes have been processed with complex machining. Since the electrodes are susceptible to wear the electrodes provide more geometrical accuracy than the other electrodes. These properties also let the rods and tubes manufactured for spark erosion be made smaller in diameter and have a longer length since the material is less likely to chip and warp.

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