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Method for preparing tungsten carbide nano-powder

A tungsten carbide nano and tungsten nitride powder technology, applied in the direction of carbide, tungsten/molybdenum carbide, etc., can solve the problems of large WC grains, cumbersome process, high energy consumption, etc., to reduce the cost of raw materials and Energy consumption, cheap and easy-to-obtain raw materials, and the effect of reducing synthesis temperature

Inactive Publication Date: 2011-03-16
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these two methods still have defects in varying degrees: the sol-gel method, the raw material is easier to hydrolyze, the shrinkage is large during drying, the cost is high, the yield is low, and the process is cumbersome; the gaseous alkane cracking carbon encapsulation method requires high equipment requirements and consumes The energy is large, it is difficult to achieve carbon encapsulation in a monodisperse state, the prepared WC grains are too large, and the product purity is low, which also limits the application of these two methods to a certain extent.

Method used

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  • Method for preparing tungsten carbide nano-powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Weigh 10mmol of ammonium metatungstate and 50mmol of citric acid, dissolve them in 100ml of deionized water to obtain a clear mixed solution; perform complexation reaction in a water bath at 70°C for 5 hours; filter and dry at 120°C for 12 hours to obtain a tungsten oxide precursor body; calcined at 650°C for 3 hours in an air atmosphere to obtain WO 3 Powder.

[0032] The above WO 3 The powder is placed in a tube furnace, nitrogenated with ammonia gas, the flow rate of ammonia gas is controlled at 3L / min, the temperature is 700°C, the heating rate is 2°C / min, and the temperature is kept for 2 hours to obtain W 2 N powder.

[0033] Mix 10 grams of the obtained tungsten nitride powder with 0.62 g of carbon black, use ethanol as a solvent and tungsten carbide balls as a ball milling medium, mix on a roller ball mill for 24 hours, and dry by rotary evaporation to obtain W 2 N / C mixed powder, W 2 The N / C mixed powder is placed in a graphite crucible, heated to 1100°C in...

Embodiment 2

[0038] The difference between this example and Example 1 is that the obtained tungsten nitride powder is directly placed in a tube furnace, and then carbonized with a mixed gas of methane and hydrogen, and the volume ratio of methane to hydrogen is 1: 8. The flow rate of the mixed gas is 200ml / min, the carbonization temperature is 850°C, and the carbonization time is 3 hours, and the WC nanopowder is obtained with an average particle size of 40nm.

[0039] The rest of the content is exactly the same as described in Example 1.

[0040] The WC nano-powder prepared in this example was sintered by hot pressing at 1600-1700° C. / 1 h and 25 MPa, and the relative density was higher than 97%, indicating that the prepared WC nano-powder had good sintering activity.

Embodiment 3

[0042] The difference between this example and Example 1 is that: mix 10 grams of the obtained tungsten nitride powder with 0.62 g of carbon black, put them in a mixing tank, use ethanol as a solvent, and tungsten carbide balls as a ball milling medium , mixed on a roller mill for 24 hours, and then dried by rotary evaporation to obtain W 2 N / C mixed dry powder, W 2The N / C mixed dry powder is placed in a graphite crucible, and nitrogen gas is introduced into the sintering furnace, and the reactant is heated to 1200°C and kept for 2 hours to obtain WC nano-powder with an average particle size of 150nm.

[0043] The rest of the content is exactly the same as described in Example 1.

[0044] The WC nano-powder prepared in this example was sintered by hot pressing at 1600-1700° C. / 1 h and 25 MPa, and the relative density was higher than 97%, indicating that the prepared WC nano-powder had good sintering activity.

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Abstract

The invention discloses a method for preparing tungsten carbide nano-powder. The method comprises the following steps of: dissolving ammonium paratungstate and citric acid in deionized water, and performing complexation in water bath; filtering and drying to obtain a precursor of tungsten oxide, and calcining under air atmosphere to obtain tungsten oxide powder; putting the obtained tungsten oxide powder in a tube furnace, introducing ammonia and nitriding to obtain tungsten nitride powder; mixing the obtained tungsten nitride powder and carbon black, performing ball milling, performing rotary evaporation drying and performing heat treatment under the air pressure of less than 200 Pa or inert atmosphere; or putting the obtained tungsten nitride powder in the tube furnace, and introducing the mixed gas of methane and hydrogen and carbonizing to obtain the tungsten carbide nano-powder. The preparation process of the method is simple, practical, and high in controllability and can easily realize large-scale production; the particle size of the prepared powder is small, the particle size distribution is uniform and the aggregation degree is low; and the method has high sintering activity, and densification can be realized by performing hot pressing sintering at the temperature of 1,700 DEG C.

Description

technical field [0001] The invention relates to a preparation method of tungsten carbide nano powder, in particular to a method for preparing tungsten carbide nano powder based on a nitride conversion method, and belongs to the technical field of nano powder preparation. Background technique [0002] Tungsten carbide (WC) is one of the most important materials in transition metal carbides. It has excellent properties such as high melting point, hardness, thermal stability and mechanical stability. It is widely used in the production of cemented carbide materials, in cermets, There are important applications in mechanical processing, metallurgy and minerals, aerospace and other fields. In addition, since the surface electronic structure of WC is similar to that of Pt, it has good catalytic activity as a catalyst in some chemical reactions and is not affected by CO and H 2 Inactivated by poisoning under the influence of S, it has good stability and anti-poisoning performance,...

Claims

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Application Information

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IPC IPC(8): C01B31/34C01B32/949
Inventor 阚艳梅孙世宽张国军
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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