Why So Many Precision Mold Engineers to Use Silver Tungsten Alloy

Update:19 Jan 2018
Summary:

Silver Tungsten Alloy is silver and tungsten alloy, so […]

Silver Tungsten Alloy is silver and tungsten alloy, so the price of tungsten silver is much higher than the tungsten-copper alloy. Even so, why are there still many EDM engineers still having to choose silver-tungsten alloy? From a technical point of view, when the silver tungsten alloy tungsten tungsten tungsten content is not much difference when their conductivity, hardness is about the same. However, the thermal conductivity of tungsten silver (410-420 W / m.K) is much higher than that of copper-tungsten alloy (210-220 W / m.K), even higher than pure copper (390 W / m.K). The high thermal conductivity means that the electrode heat dissipation is not easy to produce high temperature resulting in spark discharge oil carbonization. This discharge processing of the workpiece, the surface is smooth, less burr, so even if the higher prices, silver tungsten is still welcome.

Silver tungsten alloy is tungsten, silver element consisting mainly of a two-phase structure of pseudo-alloy, is a metal matrix composites. Due to the large differences between physical properties of metallic silver and tungsten, they can not be produced by the melting casting method, and are generally obtained by the powder alloy technique. Process for the ingredients mixed - pressing molding - sintering infiltration - cold processing. Tungsten silver alloy combines the advantages of metal tungsten and silver, including high melting point of tungsten (tungsten melting point of 3410 ℃), high density (tungsten density of 19.34g / cm3); silver conductive thermal conductivity superior performance, tungsten silver alloy (composition of the general range WCu7 ~ WCu50) uniform microstructure, high temperature, high strength, resistance to arc erosion, density.

Widely used in high temperature materials, high voltage switchgear alloy, electrical processing electrodes, microelectronic materials, as components and components widely used in aerospace, aviation, electronics, power, metallurgy, machinery, sports equipment and other industries.

Silver tungsten material has good welding and corrosion resistance, it is widely used in industrial and domestic circuit breakers. Various types of silver-tungsten provide higher silver with higher electrical conductivity, and higher tungsten makes it more aggressive and solderable.

Silver tungsten materials are made of higher tungsten content, burned contacts for large low voltage circuit breakers, and carry a stable line current molded case circuit breaker contacts and a variety of protective circuit breaker equipment. These contacts can also be used for high current contact resistance welding and arc erosion. Silver tungsten electrode is generally used for aluminum, magnesium alloy AC welding.

Preparation of silver tungsten powder metallurgy, more than 60% of the tungsten alloy after immersion greater capacity. Mainly used for low voltage power switch, lifting switch, switch locomotive, high current switch contacts, heavy duty relays, air circuit breakers and other cobalt. These can improve wet silver tungsten, in order to reduce the ability to contact resistance.

The tungsten silver alloy into dilute nitric acid to make it fully reacted, as silver can dissolve dilute nitric acid to produce silver nitrate, but tungsten can not dissolve into dilute nitric acid, so filtering can remove tungsten, and then the filtrate evaporation crystallization of silver nitrate crystals Finally, the silver nitrate crystals are heated to obtain silver (powder may be obtained). The last two steps should be carried out in a closed vessel because the filtrate may contain unreacted nitric acid which can decompose toxic nitrogen dioxide gas when heated, The last step will decompose when heated nitrogen dioxide, exhaust gas absorption lye.