Tungsten wire, a fine wire made by forging and drawing tungsten bars。
Tungsten filament is a heating element with high melting point, good corrosion resistance and long evaporation life, which is made of tungsten wire and can be leveled, cleaned and polished automatically. It can be used to make semiconductor devices, imaging tubes and heating elements of vacuum furnace and other components by vacuum spraying. Vacuum coating for mirror, plastic, metal matrix and various decorative surface; also can be evaporated metal wire and tungsten strand together, so that the product has more convenient and fast characteristics.
Tungsten wire is also mainly used in incandescent lamp, halogen tungsten lamp and other electric light sources. Tungsten wire used as various luminescent materials in light bulbs.Because of its high melting point, high resistivity, good strength and low vapor pressure, tungsten filament is the material for making incandescent filament in all pure metals.
The working temperature of tungsten filament for incandescent lamp is usually between 2300 and 2800 C. The higher the power of bulb, the higher the working temperature of filament. It can be seen that the working temperature of filament is much higher than the recrystallization temperature of tungsten filament. At this time, under the action of self-weight of filament, the filament segment between the two hooks will sag. When serious, the lamp will sag. The filament can hang down to touch the glass shell of the light bulb.
The sag of incandescent filament is related not only to the content of additive elements in doped tungsten filament and the processing technology, but also to the processing technology in the filament manufacturing process. Tungsten filament retains a lot of internal stress when it is drawn into finished filament. When it is wound into filament, new non-uniform internal stress is produced on the cross section of tungsten filament. These internal stresses must be eliminated before the filament rack enters the bulb shell. Otherwise, the lamp will twist, deform and sag the filament at the beginning of the ignition point. The sagging of the filament will seriously reduce the luminosity of the bulb.
