How to develop silver tungsten alloy contacts?

    Silver-tungsten electrical contact raw materials have been widely used in control switches and their large-space isolation switches and molded case circuit breakers since their introduction in 1935. It has the advantages of excellent thermal and electrical conductivity deafness and arc corrosion resistance, and the development trend of arc welding for metal material transfer is small. The primary defect is that the contact resistance is unstable. Therefore, in recent years, overseas scientific research on silver tungsten has been mainly focused on improving its contact resistance. Recent studies have shown that the contact resistance of high-quality alloy contacts is unstable because the surface of the contact is converted into tungsten trioxide (WO3), silver tungstate (AgWO3) and some other non-conductive chemicals during the whole process of breaking. The tungsten content of the silver-tungsten contact surface gradually increases and other factors are caused. The processing method can be considered from two aspects: one is the innovation of raw material composition. It is improved according to the addition of metal materials copper, zinc, magnesium, aluminum oxide and iron group elements to the raw materials of silver-tungsten contacts. The actual effect of adding drills to improve the contact resistance of silver-tungsten is more significant. The contact resistance The value is 1/3~1/2 lower than the original silver-tungsten aluminum alloy, but the wear amount is enlarged, and the arc corrosion resistance is reduced to a certain extent.

    In addition, high-quality silver-nickel alloy contacts are beneficial for alleviating damage. Since the nickel content is less than 13%, the strength can be improved, and the arc corrosion resistance can also be increased. The second is to start with manufacturing technology. The composition of silver-tungsten, the particle size distribution of tungsten powder, and the manufacturing method are all harmful to the characteristics of silver-tungsten contacts. In silver-tungsten aluminum alloys with high silver content, the higher the tungsten content, the greater the contact resistance, the coarser the tungsten particles, and the stronger the strength. The lower it is, the worse the arc corrosion resistance is, but the contact cracking is reduced under the arc effect, and the raw material consumption is reduced. In addition, the contact resistance of the silver-tungsten contact material formed by the calcination extrusion method is lower than that of the calcination extrusion method, which is also because the calcination extrusion method produces fine cracks in the material.