Ultra Coarse Tungsten Carbide Powder Improved Method

The production of ultra-thick tungsten-based hard alloys requires high-quality, ultra coarse tungsten carbide powder raw materials.

Traditional production methods are complex and difficult to solve two major problems. One is that carbon and tungsten powders are not uniformly mixed; the other is that ball milling breaks down the coarse-grained structure of ultra-thick tungsten carbide powders. The new ultra-tough tungsten carbide powder preparation scheme is as follows:

(1) The LiOH solution with a concentration of 16.4 to 26.7 g/L at a mass ratio of 1:55 to 60 or Na₂CO₃ solution having a concentration of 24.6 to 34.6 g/L at a mass ratio of 1:60 to 75 through the atomization doping method evenly mixed with tungsten trioxide.

(2) The prepared raw materials are put into a four-tube reduction furnace, and the slow-speed reduction is performed at a temperature of 950-1050°C, a hydrogen flow rate of 10-12M₃, and a boat speed of 30 minutes per boat. Make the use of alkali metals with vapor phase deposition during the reduction of tungsten to promote the growth of tungsten powder. After the reduction, 80 meshes are sieved to remove the iron skin material and the coarse grain crystal defect tungsten powder to obtain an ultra coarse tungsten powder with a Fisher particle size of 30-40um.

(3) After crushing conventional carbon black with a specific surface area of ​​11.5 to 12.5 m²/g, fine carbon powder of 24.5 to 25.5 m²/g is obtained, in accordance with the proportion of carbon black in the total weight of 6-6.2% mix with tungsten powder in the mixer for 50-70min, use the 60kg-stainless steel ball machine grinding for 50 ~ 70min, to obtain a uniform WC powder. Through the method of carbon distribute + ball milling, the broken carbon black is used to reduce the flow of carbon black, so that carbon black and tungsten powder can be uniformly mixed, and carbon black is evenly coated on the surface of tungsten powder to solve the segregation problem in carbonization process, without reducing the Fisher particle size.

(4) The uniformly mixed W+C was put into a high-temperature carbon tube furnace and carbonized at a temperature of 2000 to 2200°C for 150 to 260 minutes to obtain a bulk tungsten carbide.

(5) The obtained bulk tungsten carbide is ball milled, the ball material ratio is 1.8, the crushing time is 3 to 10 minutes, and then 120 mesh sieves are used to obtain 30 to 40um ultra-grained tungsten carbide.

The improved solution effectively solved the main problems of traditional preparation methods.
 

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