Preparation method of nano tungsten carbide

A technology of nanometer tungsten carbide and tungsten powder is applied in the field of nanocrystalline cemented carbide materials and preparation, which can solve the problems of accelerating the volatilization of tungsten oxide and obtaining nanometer tungsten carbide powder.

Active Publication Date: 2013-09-18
NANCHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the process of preparing tungsten carbide powder by carbon reduction / carbonization of tungsten oxide, although the influence of water vapor can be eliminated, the high temperature required for carbon reduction will also accelerate the volatilization of tungsten oxide, so nano-tungsten carbide powder cannot be obtained

Method used

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  • Preparation method of nano tungsten carbide
  • Preparation method of nano tungsten carbide

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Embodiment 1

[0017] Weigh 180g of ammonium metatungstate, 20g of anhydrous glucose, and 1.5g of chromium nitrate, and dissolve them in deionized water at 80°C. After the raw materials are fully mixed, the precursors required for reduction are prepared by spray drying. The precursor powder was put into a tube-type atmosphere furnace, and hydrogen gas was introduced for reduction. The reduction temperature was 780°C, the heating rate was 10°C / min, and the time was 2h. After the reduction, the tungsten powder is annealed at a high temperature in a hydrogen atmosphere, the annealing temperature is 1000°C, and the annealing time is 3h. The tungsten powder after high temperature annealing is carbonized, the carbon ratio is 6.21wt.%, mixed evenly in the coulter batcher, and then carbonized in the tube atmosphere furnace, the carbonization condition is hydrogen atmosphere protection, and the carbonization temperature is 1100 ℃, the carbonization time is 4h, and after the carbonization is completed...

Embodiment 2

[0019] Weigh 180g of ammonium metatungstate, 20g of anhydrous glucose, and 1.5g of chromium nitrate, and dissolve them in deionized water at 80 °C. After the raw materials are fully mixed, the precursors required for reduction are prepared by spray drying. The precursor powder was put into a tube-type atmosphere furnace, and hydrogen gas was introduced for reduction. The reduction temperature was 800 °C, the heating rate was 15 °C / min, and the time was 3 h. After the reduction, the tungsten powder is annealed at a high temperature in a hydrogen atmosphere, the annealing temperature is 1100°C, and the annealing time is 2.5h. The tungsten powder after high temperature annealing is carbonized, the carbon ratio is 6.21wt.%, and then carbonized in a tubular atmosphere furnace, the carbonization condition is hydrogen atmosphere protection, the carbonization temperature is 1200 °C, the carbonization time is 2h, and the carbonization is completed Finally, before the powder comes out o...

Embodiment 3

[0021] Weigh 170g of ammonium metatungstate, 30g of anhydrous glucose, and 2.5g of chromium nitrate, and dissolve them in deionized water at 80°C. After the raw materials are fully mixed, the precursors required for reduction are prepared by spray drying. The precursor powder was put into a tube-type atmosphere furnace, and hydrogen gas was introduced for reduction. The reduction temperature was 780°C, the heating rate was 10°C / min, and the time was 2h. After the reduction, the tungsten powder is annealed at a high temperature in a hydrogen atmosphere, the annealing temperature is 1300°C, and the annealing time is 1h. The tungsten powder after high temperature annealing is carbonized, the carbon ratio is 6.21wt.%, and then carbonized in a tubular atmosphere furnace, the carbonization condition is hydrogen atmosphere protection, the carbonization temperature is 1300 ° C, the carbonization time is 3h, and the carbonization is completed Finally, before the powder comes out of the...

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Abstract

A preparation method of nano tungsten carbide comprises the following steps: (1) dissolving ammonium metatungstate, chromium nitrate and a water-soluble carbon source substance into in heated deionized water, sufficiently mixing, and performing spray drying, wherein the weight percentage of the water-soluble carbon source substance is 10-30%, the weight percentage of the chromium nitrate is 0.5-2% and the temperature of the deionized water is 70 DEG C; (2) performing auxiliary hydrogen reduction on powdery carbon obtained in the step (1), and before discharging the powder out of a furnace, passivating the powder with an inert gas, wherein the temperature is 710-850 DEG C, the heating rate is 10-15 DEG C / min and the reaction time is 2-5h; (3) annealing tungsten powder obtained in the step (2) at high temperature, wherein the annealing temperature is 1000-1300 DEG C and the annealing time is 1-3h; and (4) carbonizing the tungsten powder obtained in the step (3), and before discharging the powder out of the furnace, passivating the powder with the inert gas, wherein the carbonizing ratio is 6.21wt.%, hydrogen is used as a protective atmosphere, the carbonizing temperature is 1100-1400 DEG C and the carbonizing time is 1-4h. The particle size of the prepared tungsten carbide is 60-90nm; after the prepared tungsten carbide is crushed, agglomeration-free nano tungsten carbide powder can be obtained; the environment is polluted; and the development of a nanocrystalline WC-Co hard alloy can be effectively promoted.

Description

technical field [0001] The invention belongs to the field of nanocrystalline hard alloy material and its preparation. Background technique [0002] Nanocrystalline WC-Co (tungsten carbide-cobalt) cemented carbide has become the development direction of cemented carbide due to its expected characteristics of high hardness and high strength (that is, both high wear resistance and high toughness). Two problems restricting the development of nanocrystalline WC-Co (tungsten carbide-cobalt) cemented carbide are the difficulty in the preparation of nano-tungsten carbide powder and the rapid growth of tungsten carbide particles during liquid phase sintering. [0003] The difficulty in the preparation of nano-tungsten carbide powder is actually the difficulty in controlling the "volatility-deposition" of tungsten oxide. At present, the preparation methods of tungsten carbide powder mainly include tungsten oxide hydrogen reduction / carbonization method and tungsten oxide carbon reduct...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/26B22F9/08
Inventor 唐建成叶楠卓海鸥
Owner NANCHANG UNIV
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