Silver wire

Silver and pure silver possess very high electric and thermal conductivity, low and

stable contact resistance and good processing and welding performance. Because

of a little nickel added into silver, pure silver has higher intensity and thermal

resistant performance than silver under same contact resistance. Therefore

its fusion resistance and arc burning resistance are better than that of silver.

Under the same application condition, pure silver can take the place of silver.

AgNi material with 10-40% of high melting-point metal nickel has high electric

conductivity, low contact resistance and little burning loss. This material has little

transfer when connecting and breaking direct current. To be widely used in AC and

DC low-voltage devices, such as relays, instruction switches, can switches, breaker

assisting contactors. Instrument switches, optical control switches, temperature

controller and washing machine timers.

AgZnO has higher thermal stability than AgCdO, therefore, has better fusion

resistance and arc burning resistance. But its contact resistance is high. Since

AgZnO is innoxiously and has no pollution to the environment. It is one of the ideal

materials to substitute AgCdO at present.

AgCdO is the most commonly used contact material at present. CdO obviously

increase the fusion resistance or cohesive resistance of the contacts at the moment

of getting through big current. The sublimation of CdO cools the contact surface

and lowers the arc energy and extinguishes the arc. Therefore AgCdO can meet the

main requirements of low-voltage apparatus to contacts. Such as arc burning

resistance at big-current switching-on, low and stable contact resistance under

various loads and good arc extinguishing performance. Since Cd pollutes the

environment, other materials are substituting it. It is used to low-voltage

apparatus with medium or high load, typically used to micro switches, relays

protection switches, contactors and auto-switches.

AgSnO2 and AgSnO2 In2O3 are the ideal environment-protective materials for

substituting AgCdO. Since SnO2 has better thermal stability and higher hardness

than CdO, AgSbO2 ABD AgSnO2 In2O3 is higher and it is more difficult to processing

these two materials. It is used to substitute AgCdO material in the low-voltage

apparatus field, such as breakers, contactors and relays, etc. Especially being used

to DC apparatus for automobiles, such contactors, starters and photo switches.

The AgC contact material containing 3-5% graphite bears the highest fusion

resistance, low contact resistance and small temperature rise in switching on short

circuit current. It is self-lubricated when being used as a sliding contact .The

AgC contact material manufactured by sintering and extrusion process not only has

high density, but also has a lower burning loss rate under arc action due to the

fiber-oriented graphite particles. It is usually used with Cu or AgNi in pairs.

AgW is a W-based sintered contact material containing silver. The good thermal

and electric conductivities of silver and the high melting point and burning-loss

resistance of tungsten are combined together for AgW. And besides, the hardness

of AgW is high. Therefore the mechanical wear of AgW in the make and break process

is small and its fusion resistance when making current is good. But the oxide

produced in the make and break process makes its contact resistance high.

AgWC contact material containing 12-65% high-65% high-melting-point and high

hardness WC has high hardness, high wear resistance, small fusion tendency, and

stable contact resistance which however, is higher than AgW. Since when electric

arc is in action, the dissociated carbons or AgWC have the function of deoxidization

which preventing the contact surface from forming an oxidized layer. AgWC is used

with AgNi in asymmetrical pairs sometimes.