Improvement of Ultra Coarse Tungsten Carbide Powder

Because of ultra coarse tungsten based alloys have good strength and toughness etc, so more and more widely used in the field of petroleum drilling, mining tools, stamping die, hard material etc.. The production of ultra coarse tungsten based cemented carbide needs high quality raw material of ultra coarse tungsten carbide powder.

The traditional production process is relatively complex, and it is difficult to solve two problems. First, the carbon and tungsten powder is not evenly distributed; the second is ball milling and crushing, which destroys coarse-grained structure of ultra coarse tungsten carbide powder. In order to improve the two methods, a new improvement scheme for the preparation of ultra coarse tungsten carbide powder is proposed. The contents are as follows:

(1)The concentration of 16.4 ~ 26.7g/L LiOH solution by 1: 55~60 ratio or the concentration is 24.6 ~ 34.6g/L Na₂CO₃ solution by 1: 60~75 ratio mixed with tungsten trioxide by means of atomized doping;

(2)The prepared raw materials into four tube reduction furnace, at a temperature of 950~1050 DEG C, hydrogen flow rate at 10 ~ 12M₃, push the boat speed in 30min/ boat under the condition of slow pushing speed reduction, the reduction process of gas phase deposition of tungsten using volatile alkali metal role, make tungsten powder grow after reduction sieve 80 mesh, removal of metal materials and crystal defects of coarse particles of tungsten powder, prepared Fisher particle size is 30 ~ 40um ultra coarse tungsten powder;

(3)The fine carbon powder of 24.5 ~ 25.5m²/g is obtained after the conventional carbon black is broken over the surface area of 11.5 ~ 12.5m²/g. In accordance with the proportion of carbon black in the total weight of 6 ~ 6.2% and the mixture of tungsten powder in the mixer 50 ~ 70min, the uniform WC powder was obtained by grinding 50 ~ 70min with 60kg stainless steel ball in the ball mill.

(4)The homogeneous mixed W+C is put into the high temperature carbon tube furnace, and the high temperature carbonization is 150 ~ 260min at the temperature of 2000~2200 ℃, and the bulk tungsten carbide is obtained.

(5)The bulk tungsten carbide was crushed by ball milling, the ratio of the ball material was 1.8, the crushing time was 3~10 minutes, and then the 120 mesh sieve was obtained, that is, the super coarse grained tungsten carbide of 30 ~ 40um.

The improved scheme effectively solves the two main problems of the traditional preparation method. The prepared ultra coarse tungsten carbide powder has the advantages of high carbon content, uniform total carbon, high feed particle size and ground state, and high pass rate of the product.

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