Tungsten Wire Production Processes

Tungsten wire resistivity is 5.3 * 10 ^ -8, which has a high melting point, high resistivity, good strength, low vapor pressure and other excellent performance. Tungsten wire has many different species, including black tungsten wire, white tungsten wire, stranded tungsten wire, doped tungsten wire, tungsten rhenium wire and tungsten filament and so on. It is widely used in the field of electric light sources, the main application is used for create filament and high-speed cutting steel. On the other hand, it also can be used in the field of optical and chemical instruments.

Tungsten production processes are as follows:

1. ammonium paratungstate (APT) as a raw material, which was calcined in air at about 500 ℃ to obtain tungsten trioxide.

2. Doped a certain amount of potassium oxide hydroxide, silicon oxide and aluminum oxide into tungsten trioxide, wherein the total amount of the three types doped oxide is not more than 1%, then the powder is mixed uniformly.

3. Proceeded two-steps reduction, the first step is at about 630 ℃ restore tungsten oxide to tungsten dioxide, and then at about 820 ℃ restore tungsten dioxide to tungsten powder. The purpose two-step reduction is to make potassium which is doped into tungsten powder can fully play its role, but also two-step reduction can better control the particle size of the powder.

4. Placed restored doped tungsten powder in a special mold pressed into elongate square bars. The square bars are placed in hydrogen to electrify which is using and is using resistance heating method for sintering.

5. Swaging processing, sintered tungsten bar after swaging processing become about 3mm diameter tungsten rod, then drawing by wire-drawing die so its diameter becomes finer. Tungsten rods are drawing and lubrication by tungsten carbide wire-drawing die or diamond wire-drawing die, eventually processed into different thickness of the tungsten wire.

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