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Contact Materials

Silver Refractory
These contact materials are used extensively in applications where high voltages generate considerable arcing, such as circuit breakers and switchgear.

The refractory component (W, WC, Mo) provides durability to the contact, while the silver provides excellent thermal and electrical conductivity. Relative to many other contact materials, silver refractory materials are more electrically resistive due to the refractory component. As a result, high contact pressures are typically required to overcome this resistance. When selecting these materials, consideration must be given to the increasing contact resistances that are experienced during service life. The correct selection of compositions, refractory components, and particle sizes can often help to overcome this phenomenon.


These dual phase materials are produced exclusively through powder metallurgy techniques, primarily through unit compaction. Compositions can range from 10% to 90% silver. Unit compaction is commonly required to form these contacts due to the low ductility of these materials. Consequently, silver refractory tends to involve more fabrication than many other contact materials. Refractory contact materials are supplied as discrete contacts with or without brazing alloys flushed to the attachment side. They are also available as furnace, torch, or resistance brazed contact assemblies.  

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 %)
ST50PSI Ag50/W50 B65 13.2 62
ST65PSI Ag35/W65 B85 14.6 50
ST75PSI Ag25/W75 B95 15.4 45
STC50PSI Ag50/WC50 B80 12.1 47
STC65PSI Ag35/WC65 B98 12.8 36
SM50PSI Ag50/Mo50 B75 10.1 50
SM60PSI Ag40/Mo60 B82 10.1 43
SM65PSI Ag35/Mo65 B87 10.0 40

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