Tungsten wire is a fine wire made by forging and drawing tungsten bars.
Tungsten wires are mainly used in electric light sources such as incandescent lamps and halogen tungsten lamps. Tungsten wires used as various luminaries in bulbs also need to be doped with a small amount of potassium, silicon and aluminum oxides in the smelting process. This kind of tungsten wire is called dopedtungstenwire, also known as 218 tungsten wire or non sagtungstenwire.
Tungsten wire is usually drawn by various wire drawing dies. It is mainly used for manufacturing filament and high-speed cutting alloy steel, as well as optical instruments, chemical instruments and other functions.
The resistivity of tungsten filament is 5.3 * 10 ^-8. Tungsten has high melting point, high resistivity, good strength and low vapor pressure. It is the best material for making incandescent filament among all pure metals. However, tungsten is hard and brittle, which is difficult to process. When the current is heated to a certain temperature through the tungsten wire, the resistance value of the tungsten wire also increases to a certain value (generally, the resistance value of the metal wire increases with the increase of temperature). In 1909, Coolidge invented the processing technology of tungsten wire, which played a decisive role in the production and promotion of incandescent bulbs. Its basic principle has been used until today.