Preparation of micron/nano-scale high purity tungsten powder

Abstract

The invention relates to a preparation method of micro / nano-high-purity tungsten powder. Tungstate is dissolved in deionized water, excessive dilute nitric acid or hydrochloric acid is added to allow the mixture to fully generate yellow precipitation, dilute ammonia water is added to fully convert the yellow precipitation to transparent colloid under the stirring condition, a surfactant is added and is evenly dissolved by strong stirring; the hydrothermal reaction is carried out, a product after the hydrothermal reaction uses the deionized water or ethanol for cleaning and filtering, precursor powder is obtained by drying; and the precursor powder is carried out the reduction to obtain the high-purity micro / nano-tungsten powder. The micro / nano-tungsten powder which is prepared by using the invention is characterized by fine particle size, even distribution of the components and high purity, the specific surface particle size and the powder morphology analyzing particle size after the diffusion are less than 80nm, the tungsten particle size of the powder is 20 to 30nm, the powder is spherical or nearly spherical, the oxygen content is lower than 0.18 percent, the tungsten content is more than 99.5 percent, and the powder has good formability and sintering activity.

Description

technical field [0001] The invention relates to a method for preparing micro / nano-level high-purity tungsten powder, which belongs to the technical field of powder metallurgy. Background technique [0002] As the most important thermal emission and field emission materials, tungsten and tungsten alloys are widely used as cathode materials in X-ray tubes and radio tubes; and in electron microscopes, ion generators, electron guns, arc welding machines, and gas discharge tubes. Electrode materials; joints in circuit boards, heat sinks and packaging electronic materials in radar and various microelectronics; micro-drills and computer printing needles for integrated circuit boards in the electronics industry, as well as thermal ion energy conversion systems and cesium ion engines (for Alternative materials for key components in space probes). In addition, tungsten heavy alloys are widely used as kinetic energy armor-piercing projectiles, substitute materials for radioactive depl...

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Problems solved by technology

[0003] Magnusson M H and Deppert K. reported in J. Mater. Res. (2000, 15 (7): 1564-1569) that single crystal nano-tungsten powder can be obtained by thermally decomposing tungsten carbonyl. Experts in Japan and the United States also reported that gas evaporation and Plasma method is used to prepare high-purity nano-tungsten powder with particle size less than 30nm, but the instruments and equipment used in these methods are expensive, the cost of raw materials is high, and the process is not easy to control, so it is not suitable for large-scale production

Li Qiang et al. reported in "Rare Metal Materials and Engineering" (2004, 33(1): 70-74) that metal tungsten powder with a grain size of less than 20nm and a powder particle size of 10-80nm can be prepared by high-energy ball milling. The preparation of nano metal tungsten powder by this method has the advantages of high output, simple process equipment, and fine grain size of the produced powder, but the disadvantage is that the ball milling process will introduce impurities to pollute the tungsten powder, the powder sphericity is not good, and the obtained powder is easy to agglomerate And it is not easy to disperse, the energy consumption of the ball mill is high, and the noise is large

Chinese patent CN03150230.X discloses a method of preparing nano-scale WO by low-temperature ultrasonic spray heat transfer method. 3 The oxide powder is reduced to ultra-fine tungsten powder in the last two stages, and then crushed by a high-speed shear pulverizer and dried in a vacuum dryer to obtain nano-tungsten powder with an average particle size of ≤80nm. This method has complicated procedures, and the spray heat conversion method Particles are easy to agglomerate, pyrolysis gas pollutes the air, equipment is noisy, and high-speed shearing pulverizers are more likely to introduce impurities