Ammonium Paratungstate Preparing Tungsten Rod 1/2

Tungsten Halogen Lamps is mainly applied in the lighting system of automotive, electronic and aerospace industry. Due to the special using environment in which the shock and vibration presence, thus the core materials-tungsten filaments is required to be with good recrystallized of dovetail joint structure, also the ratio of length and width is supposed to larger than 12, which means it has the good properties of sagging resistance at high temperature and deformation resistance. Therefore, improving the properties of tungsten bars which can improve the quality of Tungsten Halogen Lamps has become extremely urgent. A literature has proposed a method for preparing tungsten rod with good properties of sagging resistance at high temperature and deformation resistance which can applied in the production of Tungsten Halogen Lamps.

The specific steps are as follows:
1. Mix monoclinic and spherical ammonium paratungstate by the ratio of 3:1~1.5, as the raw materials;
2. Pre-reduction
Make the raw material going through a reducing furnace with four temperature zone, reduction to generate blue tungsten oxide at the hydrogen atmosphere;
3. High Potassium doping
Mix the blue tungsten oxide into a solution containing with potassium silicate and aluminum nitrate;
4. Reduction
1) Using Secondary-Reduction to generate fine grain tungsten powder with FSSS 2.0~2.6um from doped blue tungsten;
2) Generate coarse tungsten powder with FSSS 3.4~4.0um by One-Reduction method;
3) Generate medium grain tungsten powder with FSSS 2.7~3.3 um in a six temperature zone furnace by Secondary-Reduction method;

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