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What Is the Main Industrial Production Method of Tungsten Carbide Powder?

In large-scale industrial production, the main industrial production method of tungsten carbide powder is tungsten powder carbonization. With tungsten and carbon as raw materials, the average particle size is 3-5 μ M of tungsten powder and equivalent amount of carbon black are mixed dry with a ball mill, fully mixed, pressurized and shaped, and then put into a graphite plate, and then heated to 1400~1700 ℃ in a graphite resistance furnace or induction furnace, preferably controlled at 1550~1650 ℃. In the hydrogen gas stream, W2C is initially generated, and WC continues to be generated by reaction at high temperature. Alternatively, tungsten hexacarbonyl is first thermally decomposed into tungsten powder in the atmosphere of 650~1000 ℃ and CO, and then reacted with carbon monoxide at 1150 ℃ to obtain WC. The temperature above which can generate W2C. Chemical reaction formula:
W+C=WC
2W+C=W2C

Tungsten powder (average particle size 3-5) is prepared by hydrogenation reduction of tungsten trioxide WO3 μ m）。 Then press the mixture of tungsten powder and carbon black with equal molar ratio (dry mixing for about 10h with a ball mill) under a pressure of about 1t/cm2. Put the pressure-formed material block into a graphite plate or crucible, and use a graphite resistance furnace or induction furnace to heat it to 1400~1700 ℃ (preferably 1550~1650 ℃) in the hydrogen gas stream (using pure hydrogen with a dew point of - 35 ℃), so that it can be carburized to generate WC. The reaction starts from around the tungsten particles, because W2C is generated at the initial stage of the reaction. Because the reaction is incomplete (mainly due to the low reaction temperature), there are still unreacted W and intermediate product W2C in addition to WC. Therefore, it must be heated to the above high temperature. The maximum temperature should be determined according to the particle size of raw tungsten. If the average particle size is 150 μ Coarse particles of about m will react at a high temperature of 1550~1650 ℃.

Chemical reaction formula:
WO3+3H2=W + 3 H2O
2WO3+3C=2W+3CO2
W+C=WC
2W+C=W2C

Plasma technology is an ideal method to prepare high melting point powder materials. The high temperature of plasma is used as the heat source to melt and vaporize the raw powder, thus realizing the spheroidization process of irregular raw powder. This technology has many advantages:
1) The fluidity of powder can be effectively improved by changing the morphology of powder. The spheroidization rate of tungsten carbide powder prepared by this technology is more than 85%, and the powder has stable Hall fluidity. This will effectively reduce the segregation and agglomeration of powder, especially fine powder, and effectively control the process quality during powder mixing, charging and compacting in powder metallurgy process;
2) It can effectively improve the compaction density of powder;
3) Control and reduce the holes and defects in the powder particles;
4) It can effectively improve the morphology of the powder and make the microscopic morphology of the material be standard spherical;
5) The introduction of reducing atmosphere in the preparation process can greatly reduce the content of oxygen. The particle size of 0.7~5 can be continuously prepared by plasma method μ M tungsten carbide powder. The influence of the composition and properties of the powder before and after spheroidization and the plasma method on the properties of the fine tungsten carbide powder were analyzed and compared.

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