Electrical Contact

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-resistance 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, etc.

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 used contact material at present. CdO obviously increased 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. 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. To be used to low-0voltage apparatus with medium or high load, typically use to micro switches, relays, protection switches, contactors and auto-switches, etc.

AgSnO2 and AgSnO2 In2O3 are the ideal environment-protecting 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. To be 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. and 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

Application
To be used to the switch devices with high current loads, such as breakers and leakage protection switches etc