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Contact Materials

Copper Refractory
Like silver tungsten, copper tungsten is used in applications where extensive arcing is experienced.

High voltage circuit breakers, switchgear, and transformer tap changers are typical applications where copper tungsten might be required. One benefit of copper tungsten is that it exhibits very low contact erosion rates. The refractory component (W) provides the necessary durability to withstand arcing, while the copper component provides high electrical conductivity. As the refractory content increases, the resistance to erosion increases, although conductivity will go down. Like silver refractory materials, high contact pressures are required to ensure sufficiently low contact resistance. Copper tungsten experiences increasing contact resistance as the service life progresses. The arc mobility of copper tungsten materials is poor, much like silver tungsten. 


Copper tungsten contact materials are dual phase materials produced through powder metallurgy processes. Their compositions range from 25% to 50% copper. They are produced through unit compaction techniques and therefore the fabrication costs are relatively high. Discrete contacts are available, usually supplied with a solder flush applied. Contact assemblies are also supplied. Where high volumes are required, furnace brazing is the most economical method of attachment. Where volumes are lower, resistance brazing or torch brazing techniques are more economical. 

The compositions listed are generally considered the industry standards. The listed values represent the typical properties of these materials. Modifications to meet special applications may be possible.

Composition Hardness Density Conductivity
(weight %) (R'well) (g/cc) (IACS %)
CT50PSI Cu50/W50 B70 12.1 63
CT60PSI Cu40/W60 B81 13.1 58
CT70PSI Cu30/W70 B90 14.1 53
CT75PSI Cu25/W75 B100 14.8 47

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