quality tungsten wire in bulb is mostly used to make filaments of various incandescent lamps and tungsten halogen lamps and gas discharge lamps, except for a small amount of heating materials for high-temperature furnaces, heating elements of electron tubes, and reinforcing ribs of composite materials. electrode. For the quality tungsten wire in bulb or tungsten rod used as the cathode of the gas discharge lamp, in order to reduce its electronic work function, 0.5 to 3% of thorium must be added, which is called tungsten thorium wire. Since thorium is a radioactive element that pollutes the environment, cerium is used instead of thorium to make tungsten-cerium wire or tungsten-cerium rod. However, the evaporation rate of cerium is high, so tungsten wire or tungsten rod can only be used for low-power gas discharge lamps.

quality tungsten wire in bulb becomes very brittle once it recrystallizes after being used at high temperature, and it is easy to break under the condition of impact or vibration. In some electric light source products that require high reliability, in order to prevent the filament from breaking, 3-5% rhenium is often added to the doped quality tungsten wire in bulb, which is called tungsten-rhenium wire, which can make the tungsten brittle transition The temperature drops to room temperature or below. This is a very peculiar rhenium effect. So far, no element has been found that can replace rhenium to produce the same effect in tungsten.