1. The high temperature performance: the working temperature of the incandescent lamp with tungsten wire is often between 2300 to 2800 degrees, the greater the bulb power is, the higher the working temperature of the filament also is. Thus we can see that the working temperature of the filament is more than the recrystallization temperature of the tungsten wire. At this time, the filament under the action of its gravity, will produce the phenomenon of sagging between two hooks in the wire. When it is serious, the filament can drop to collide with a glass bulb. In the metallurgy process of tungsten powder, it was mixed with doped tungsten wire, which includes small amounts of potassium, silicon and aluminum oxide. Although the content of silicon and aluminum in the final finished wire only is a few parts per million and the content of potassium is tens of parts per million, the degree of sagging can have greatly improved by using the filament with the doped tungsten wire. The reason is that there is big difference between doped tungsten wire and undoped tungsten wire’s crystal structure.
2. The room temperature performance: the performance of wire winding mainly manifests the room temperature performance of the tungsten wire. Owing to the length of its processes, tungsten wire is very easy to make itself produce many small cracks or local brittle if there is poor management of process so that the wire winding is easy to break.
3. The consistency of wire diameter: the consistency of wire diameter is an important reason to make the incandescent lighting’s photoelectric parameters become poor. It also can affect the service life of the bulb.
