Auxiliary carbon hydrogen reduction method in this paper is adding the carbon is a small amount of carbon and tungsten oxide volatilization inhibitor in the process of hydrogen reduction, which is using the reaction between carbon and water vapor to reduce the impact of water vapor on the volatilization of tungsten oxide, and the inhibition of inhibitors on tungsten oxide volatilizing, and finally to significantly reduce the particle size of tungsten oxide, to finally get nanometer tungsten powder. 

 

Ammonium metatungstate (AMT) is an excellent raw material for manufacturing tungsten powder since its very high solubility in water, thus the usage of aqueous solution ingredients method is possible, which will widen the range of particle size and shapes, and makes the possibility of obtaining the tungsten powder with high-performance. To a great extent, the performance of tungsten powder affects the tungsten products property, like the difficulty in preparing nanometer tungsten powder is becoming a big problem for manufacturing WC - Co cemented carbide with both high hardness and strength. And thus, a study is pointing out an auxiliary carbon hydrogen reduction method to prepare nanometer tungsten powder from the raw material of ammonium metatungstate, for overcoming this problem. 

 

The steps of auxiliary carbon hydrogen reduction method for manufacturing nanometer tungsten powder are like following: 

1. The aqueous solution ingredients method is used for obtaining precursor powder, which is dissolve the ammonium metatungstate, chromium nitrate and water soluble carbon source material (glucose, or sugar, or water soluble phenolic resin) in the hot deionized water with stirring to mix uniformly. Wherein, the weight percentage of water-soluble carbon source materials is 10 ~ 30%, 0.5 ~ 2% of chromium nitrate, the temperature of deionized water is 70 ℃ or even higher. Then carry out a spray drying to get precursor powder; 

2. Put the precursor powder obtained in step 1 in a tubular furnace to carry out a reduction in auxiliary carbon hydrogen reduction method, the reduction temperature is 710 ~ 850 °C, the heating rate is 10 ~ 15 °C /min, reaction time is 2 ~ 5 hours, then carry out the passivation treatment with inert gas after the reduction and before the nanometer tungsten powder leaves the furnace.

 

This process can obtain nanometer tungsten powder with particle size of 40 ~ 70 nm without obvious reunion phenomenon, which can generate the no reunion nanometer tungsten powder after broken, and thus effectively promote the development of nanocrystalline WC - Co cemented carbide.