In addition to a small amount of heating materials used in high-temperature furnaces, thermosets of electronic tubes and reinforcement of composite materials, most of them are used to make various tungsten wire.
Filament for incandescent and halogen tungsten lamps and electrodes for gas discharge lamps. For the tungsten wire or tungsten rod used as the cathode of gas discharge lamps, 0.5 ~ 3% thorium must be added to reduce the electron escaping work, which is called thorium wire. Because thorium is a radioactive element, polluting the environment, cerium is used instead of thorium to make tungsten cerium wire or tungsten cerium pole. But the cerium has a high evaporation rate, so the tungsten wire or pole can only be used for low-power gas discharge lamps.
Once recrystallized at high temperatures, tungsten becomes brittle and easily breaks under impact or vibration. In some electric light source products requiring high reliability, 3 ~ 5% rhenium is often added into the doping tungsten wire to prevent the fracture of filament, which is called tungsten rhenium wire. It can make the transition temperature of tungsten brittle drop to room temperature or below room temperature. This is a curious rhenium effect, and no element has been found to replace rhenium, producing the same effect in tungsten.
Tungsten has good acid and alkali resistance at room temperature, but is easy to be oxidized in humid air, so the fine tungsten wire can not be stored in a humid environment for too long. In addition, tungsten reacts with carbon to form tungsten carbide around 1200℃. Therefore, attention should be paid to this problem in the hydrogen burning treatment of the filament; otherwise, tungsten reacts with graphite lubricant on the surface, and the filament will become brittle and fracture.