Tungsten wire is often used in incandescent filament, because of its properties, such as high temperature performance, good room temperature performance and wire diameter consistency character.
High temperature performance
Tungsten has high temperature performance and tungsten filament operating temperature is between 2300 ~ 2800 ℃. Early, tungsten filament lamp life is short, and it is mainly for that the tungsten filament operating temperature exceeds its recrystallization temperature, resulting in filament sagging phenomenon, leading to lamp failure.
In order to solve this problem, doped a small amount of oxides such as silicon, potassium and aluminum in tungsten, the content of which is not more than 1%, can obtain a novel high temperature doped tungsten wire. This new type of high-temperature tungsten filament can improve filament sagging phenomenon. Besides, doped oxide in tungsten can also improve recrystallization temperature.
Room temperature performance
Tungsten wire room temperature performance refers to rolling properties. Tungsten wire rolling performance mainly depends on the processing after powder metallurgy. If the processing technology is unreasonable, it is easy to produce small cracks or cause local brittle in the tungsten wire, which is easy to break.
Wire diameter consistency characteristic
Tungsten wire diameter consistency characteristic can improve efficiency and service life of bulb. Poor diameter consistency will damage the optical parameters deterioration of incandescent bulb, and even affect the life of the bulb.
Most of the production raw materials of tungsten wire are ammonium tungstate. Firstly, the raw materials is roasted in the air at 500 ℃ to obtain tungsten trioxide, or at about 450 ℃ in hydrogen is reduced to blue tungsten oxide. And then the reduction tungsten powder was put into a specific mold to press into a slender square and the square after sintering, rotating can obtain required diameter tungsten rod. Finally, through the die drawing and other methods can obtain different sizes of tungsten wire.