Silver Metal Oxide Contact Materials


OVERVIEW

Silver Metal Oxide

Silver metal oxide contact materials are used widely to serve low and medium power applications. Relays, contactors, switches and low voltage circuit breakers all employ silver metal oxide contact materials. Silver cadmium oxide and silver tin oxide are utilized 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 differences in the two processes entail differences principally in the distribution of the metal oxide component inside the silver matrix. The metal oxide distribution and particle size significantly affects 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, and in clad contacts and contact tapes and in the complete range of clad strips and their by-products. When welding or brazing attaching 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. 

MATERIALS

Composition

Hardness

Density

Conductivity

(weight %)

(R'well)

(g/cc)

(IAS %)

Silver-Cadmium Oxide

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 45*

10.2

70

WCDO2-15 Ag85/CdO15

F 50*

10.1

60

Silver-Tin Oxide

WSNO1-10 Ag90/SnO10

F 55*

9.8

75

WSNO1-12 Ag88/SnO12

F 60*

9.7

70



Note
The asterisk (*) indicates the fully annealed condition. 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.