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Contact Materials

Silver Metal Oxide
Overview
Silver metal oxide contact materials like silver tin oxide and silver cadmium oxide are widely used in low and medium power applications.

Relays, contactors, switches, and low voltage circuit breakers all employ silver metal oxide contact materials, primarily due to their relatively high and stable conductivity, their anti-welding, and their arc quenching properties. These materials are produced through powder metallurgy techniques as well as traditional wrought metallurgy techniques. The main difference that results from choosing one of these processes over the other lies in the distribution of the metal oxide component within the silver matrix. The metal oxide distribution and particle size significantly affect contact performance.

Availability

Silver cadmium oxide and silver tin oxide are produced in sheet and wire products. Consequently, they are available as discrete contacts, contact rivets, clad contacts, and contact tapes, as well as in the complete range of clad strips and their by-products. When welding or brazing either of these materials, it is typical to employ a pure silver backing. This assists in the bonding of the contact to the adjacent metal substrate.  

Note
The asterisks (*) in this table represent the fully annealed condition. 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 %)
SCDO10 Ag90/CdO10 F 45* 10.1 75
SCDO15 Ag85/CdO15 F 50* 10.01 55
WCDO1-10 Ag90/CdO10 F 45* 10.15 82
WCDO1-15 Ag85/CdO15 F 55* 10.1 70
WCDO2-10 Ag90/CdO10 F 50* 10.2 70
WCDO2-15 Ag85/CdO15 F 50* 10.1 60
WSNO1-10 Ag90/SnO10 F 55* 9.8 75
WSNO1-12 Ag88/SnO12 F 60* 9.7 70