Doping is that in order to prevent or control recrystallization or grain growth in sintering or using, adding a few other elements or compounds, making materials produce certain electrical, magnetic and optical properties.
Doped tungsten, also called non-sag tungsten, is a remarkable kind of dispersion strengthened material. The term non-sag refers to the resistance of the wire against deformation or sagging under its own weight at working temperature. The intentional simultaneous use of K-compounds, Si-compounds, and Al-compounds as dopes for tungsten is in order to obtain a well-defined internal interlocking structure.
Doped tungsten wire are products incorporating the silicon and aluminum oxide into the tungsten wires in the milling process. Doped tungsten wire are manufactured by the high tech of doping, acid washing, isostatic pressing, program control direct-sintering, swaging and auto feeding. The products are featured with minimum deformation at high temperatures, high recrystallization temperatures and excellent coil ability.
The Distinction of Doped Tungsten Wire and Undoped Tungsten Wire
Tungsten, means heavy stone in the Swedish, is use as materials for undoped and doped for filaments. It has the highest melting point of all metals at 3410 degrees C and is a copious emitter of electrons at temperatures above 2300 degrees.
The term undoped also refers to sag, pure or WUX and doped may refer to as non-sag, VM, or WK tungsten.Doped tungsten wire refer to industry standard doping of commercially pure tungsten wire with small amounts of aluminum, potassium and silicate. Filaments doped in this way have added strength to counteract operational stresses in unsupported applications.
1. In Chemistry
The table below shows us the distinction of undoped and doped tungsten wire in chemistry.
|Undoped tungsten wire
|Doped tungsten wire
2. In Properties
Doped tungsten wire have good resistance to drop ability, good resistance to high temperature and vibration and void reformation.
However, undoped tungsten wire have low ability to vibration resistance and reformation, the recrystallization temperature is lower than that of doped tungsten wire, and it is less resistant to sag at high temperatures.
3. In Application
Doped tungsten wire are suitable for coiled filaments and used as supports in all incandescent, infrared, and high-temperature halogen lamps. What is more, it is also used for electronic tube and heater applications as well as electric-furnace elements.It is available in the broadest range of standard process for the widest variety of applications.
While, undoped tungsten wire are used for lamp coils in which sag is not important item as in supported coils.