Tungsten wire, tungsten strip after forging, drawing made of fine wire.
Tungsten filament is mainly used in incandescent lamp, halogen tungsten lamp and other electric light sources. Tungstenwire, a tungstenwire used in light bulbs, also requires the addition of small amounts of potassium, silicon, and aluminum oxides in the smelting process. Such tungstenwire is called DopedTungstenWire, also known as 218 tungsten wires or Non-sagTungstenWire.
Ammonium paratungstate (APT) is used as raw material in the production of tungsten wire. The general process is to roast ammonium paratungstate into tungsten trioxide in air at about 500℃, or slightly reduce to blue tungsten oxide in hydrogen gas at about 450℃. To make tungsten filament for incandescent lamps, it is necessary to mix tungsten trioxide or blue tungsten oxide with a small amount of potassium oxide, silicon oxide and alumina, less than 1% of the total. This is the tungsten-wire doping process invented by Bartz in 1922. The doped tungsten oxide is reduced to metallic tungsten powder with hydrogen gas. The reduction process is generally carried out in two steps: the first step is reduced to tungsten dioxide (brown tungsten oxide) at around 630 ° C and the second step is reduced to metallic tungsten powder at around 820 ° C. The purpose of two-step reduction is to give full play to the added potassium and control the powder size. The doped tungsten powder thus obtained is then pressed into thin square strips in a special mould. The density of the sintered tungsten strip can reach more than 85% of the theoretical value after it is energized in hydrogen and sintered by self-resistance heating (the temperature is about 3000℃). The strip can then be spun into a tungsten rod with a diameter of about 3mm, and then molded into tungsten wires of various thicknesses. For example, the diameter of tungsten wire for 220V and 15W incandescent lamps is about 15µm, while the diameter of tungsten wire for 10000W bromo-tungsten lamps is about 1.25mm. More fine tungsten wire such as 220V, 10W incandescent lamp tungsten wire diameter is about 12µm, it should be made by electrolytic corrosion method.
Model number | Tungsten content | Impurity element content | manufacturer | |
total | each | |||
WAL1, WAL2 | ≥99.95% | ≤0.05% | ≤0.01% | CHAOLONGTI |
W1 | ≥99.95% | ≤0.05% | ≤0.01% | |
W2 | ≥99.92% | ≤0.08% | ≤0.01% | |
Note: Potassium is not included in the impurity content。 | ||||
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