Silver Tungsten Bar

Silver tungsten bar is used for electrical contacts. Typically they are used in heavy duty devices subject to high currents. The presence of the refractory material tungsten reduces the chances of welding and improves resistance to arc erosion. Optimal compositions are found by balancing conductivity and non-welding properties.

Silver tungsten bar Physical and Mechanical Properties:

Composites	Nominal Composition (% Weight)	Density (g/cm3=)	Electrical Resistivity (20°C, µΩ•cm, =)	Electrical Conductivity (IACS%, ≥)	Hardness (HB, ≥)	Bending Strength ( MPa )
AgW50	50 Silver 50 Tungsten	13.15	3.0	57	105	---
AgW55	45 Silver 55 Tungsten	13.55	3.2	54	115	---
AgW60	40 Silver 60 Tungsten	14.00	3.4	51	125	---
AgW65	35 Silver 65 Tungsten	14.50	3.6	48	135	---
AgW70	30 Silver 70 Tungsten	14.90	3.8	45	150	657
AgW75	25 Silver 75Tungsten	15.40	4.2	41	165	686
AgW80	20 Silver 80 Tungsten	16.10	4.6	37	180	726

Silver tungsten bar-AgW75 is one of the high refractory content tungsten-silver materials made by press-sinter-infiltration and normally a high resistance to arc erosion. It is generally used as arcing contacts in large air and oil circuit breakers, line disconnects, re-closures, and in high current switches and contactors. Contact resistance is low enough to protect the higher conductivity current carrying contacts from arc damage. Its resistance to welding makes it a good shorting contact for bimetal protection in circuit breakers.

Silver tungsten bar AgW70 and Silver tungsten bar-AgW50 have more silver than Silver tungsten bar-AgW75, which provides higher conductivity and a lower contact resistance. They are used extensively in a large variety of circuit breakers. In this application, a single pair of contacts provides the dual function of carrying the current without overheating, and interrupting the current without excessive arc erosion. They are also used in high current contactors where resistance to contact welding and arc erosion are required. In a variety of DC applications, they offer resistance to metal transfer.  

Silver tungsten bar-AgW50 has the highest silver content of the press-sinter-repress Tungsten-silver materials. It exhibits good resistance to contact welding and is used for current carrying contacts in power circuit breakers that encounter high momentary currents.