TECHNICAL DATA SHEET
COPPER REFRACTORY CONTACT MATERIALS

OVERVIEW
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. The materials exhibit 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 tungsten content increases the resistance to erosion increases, however, the resistivity of the material increases also. Like silver refractory materials, high contact pressures are required. The materials experience increasing contact resistance as the service life progresses. The arc mobility of copper-tungsten materials is poor, much like silver-tungsten.

AVAILABILITY
Copper-tungsten contact materials are dual phase materials and are produced through powder metallurgy processes. Compositions range from a low of 25% copper, to a high of 50% copper. The materials 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.

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