Preparation Method of Ultra Coarse Tungsten Powder

Ultra coarse tungsten powder can not only be used to prepare high-toughness and high-density alloys, such as petroleum perforating bullets, heavy armor-piercing bullets and radiation protection materials, but also raw materials for the production of ultra-coarse tungsten carbide, which is mainly used for ultra-coarse-grained cemented carbide, then used for drill bits for oil drilling, mining, tunneling, hard coating spraying, etc. 

The steps of the new preparation method are as follows:

1) Prepare a mixed solution of sodium tungstate and ammonium tungstate in a certain ratio, the molar ratio of the former to the latter is between 1:100~140.

2) Heat the prepared solution to boiling, when the volume evaporates 80%~90%, stop heating, send it to a far infrared oven, and dry at 120~150°C for 2~10h to obtain ammonium paratungstate and sodium tungstate crystals mixed precursor.

3) Wipe the precursor through a sieve to prepare ~80 mesh powder, then add 10% to 20% of the precursor mass of the fine tungsten powder return material, and mix with a V-type mixer for 2 hours.

4) Feed hydrogen into the tubular reduction furnace for reduction to obtain ultra-coarse W powder with a particle size of 60~150μm, a reduction temperature of 800~1000°C, a reduction time of 1~2h, and a cross-sectional flow of hydrogen 0.01L/min*cm2.

5) The product obtained by reduction is cleaned and filtered with deionized water in an ultrasonic tank, dehydrated with industrial alcohol, and then dried in a vacuum drying oven at 80°C for 1~2h, and finally sieved to obtain the fine tungsten powder and is returned to the raw material for recycling.

The advantages of this production technology: (1) The prepared tungsten powder is approximately spherical, has good surface gloss, good formability, high purity, and coarse particle size (maximum particle size can reach 150μm); (2) Low reduction temperature, short time,high efficiency and low cost; (3) The equipment is simple, the investment is small, and the market is broad, which is suitable for rapid production of small and medium-sized enterprises.

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