Ultra-fine ammonium paratungstate has received widespread attention around the world since the 1990s as it can be used to prepare ultrafine tungsten (W) powders, which a hot tungsten product to produce tungsten carbide powder and other down-stream products on tungsten. Compared with tungsten powder of conventional particle size, the sintering temperature of ultrafine W powder can be greatly reduced. And therefore, the preparation of ultrafine grain size APT has been researched a lot both in China and abroad.
The particle size of W powder obtained by APT hydrogen reduction under the selected process conditions has a “genetic relationship” with respect to the particle size and crystal morphology of the original ammonium paratungstate. Therefore, through an optimized traditional process, the ultrafine W powder may be prepared by using fine grain size APT as raw material.
The particle size of ammonium paratungstate prepared by traditional process is available between 25μm and 60μm currently. While it is difficult to meet the requirements for producing ultrafine W powder. But the ultra-fine APT may be prepared by evaporative crystallization method to produce ultra-fine W powder. The particle size of APT prepared by evaporative crystallization method can be reduced by adding ionic type active agent.
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http://www.ammonium-paratungstate.com/english/index.html
