Tungsten is the most widely used refractory metal. As a filament form, its high temperature properties are critical to the production of lighting products as well as other products. Because its melting point is 3410°C, it still has good electrical and thermal conductivity under conditions of low thermal expansion, low vapor pressure and high temperature.
The resistivity of tungsten wire is 5.3*10^-8. In addition to a small amount of tungsten wire being used as a heating material for high-temperature furnaces, as a heater for electron tubes, and as a reinforcing rib for composite materials, most of it is used to make filaments for various incandescent lamps and tungsten halogen lamps and electrodes for gas discharge lamps. Main applications include the production of coiled incandescent lamp filaments, cathodes and support structures for power tubes, heating elements for high-temperature furnaces and evaporation sources for metallization processes. Thick tungsten wire is surface-treated after straightening and cut into rod shapes. It is widely used in glass-to-metal sealing components in the lighting and electronic industries.
