Abstract In the temperature range of 900-1 100 ℃, the prepared W powder by hydrogen reduction of pure WO3 powder will have obvious crystal growth. In order to suppress the growth of W grains, the ultrafine tungsten powders were prepared by 10%-40% (mass fraction) nano-tungsten powder assisting hydrogen reduction of WO3. The effects of reaction temperature and the additive amount of nano-tungsten W(w(nano-W)) on the morphology and particle sizes of the products were studied, and the reaction mechanism of the two methods was also discussed. The results show that whether nano W is added or not, the particle size of W powder increases with the increase of reduction temperature. Without the addition of nano W powder, it is difficult to control the nucleation and growth of the product due to the chemical vapor transport (CVT) in the reaction process. The particle size of the reduced W powder is 2.10-2.78 μm. However, the addition of nano W can weaken the effect of CVT accompanied with nucleating agent in the reaction process, which makes the particle size of W powder decrease significantly. With the increase of w (nano-W) content, the particle size of reduced tungsten powder decreases gradually. When w (nano-W) is 40%, the particle size of reduced tungsten powder is 0.32-0.51 μm.
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2020, Vol. 25 
