Method for preparing nearly-spherical tungsten powder

Abstract

The invention provides a method for preparing nearly-spherical tungsten powder, which comprises the steps of drying at a temperature of 50 to 100 DEG C, oxidation at a temperature of 450 to 520 DEG C, alkaline washing by alkaline solution of which the OH<-> concentration is 3 to 8mol / L, cleaning, drying, and the like. In the invention, the oxidation treatment is performed on tungsten powder subjected to drying process. Because the area of sharp corners and edges of projecting parts of the tungsten powder is lager than the superficial area of the tungsten powder, the activity thereof is bigger, and the oxidation rate thereof in the process of oxidation is significantly higher than that of the flat surface of the tungsten powder. After removing the sharp corners and edges of projecting parts of the tungsten powder subjected to partial preferential re-oxidation by alkaline solution, nearly-spherical particles with surfaces smoother than that of original tungsten powder particles are formed. The nearly-spherical tungsten powder prepared by using the method of the invention has the advantage of good shape distribution uniformity; and meanwhile, the method of the invention is simple in process, low in production cost, and suitable for industrial production.

Description

technical field [0001] The invention relates to a preparation method of nearly spherical tungsten powder. Background technique [0002] Metal tungsten has a series of excellent properties such as high hardness, high strength, low vapor pressure, good corrosion resistance and high temperature corrosion resistance. The tungsten porous body made of it has particularly excellent dimensional stability and durable life, and has been more and more widely used in electronics, aviation, weapons and other application fields. With the development of the electronics and aviation fields, the requirements for the morphology and structure of tungsten materials are required to be spherical and compact. For example, when preparing high-emissivity tungsten-based cathode materials for electric vacuum devices, Cronin J L pointed out in 1981 that in order to meet the higher requirements for the quality and performance of reserve cathode materials, polygonal tungsten powders that are currently u...

AI Technical Summary

Problems solved by technology

[0003] At present, the main methods for preparing spherical tungsten powder are: 1. Plasma chemical vapor phase synthesis method (Journal of Refractory Metals & Hard Materials 27 (2009) 149–154), which uses hydrogen thermal plasma to vaporize and decompose tungsten salt Reduction can prepare spherical tungsten powder, but because it is solidified by gaseous state, it is generally nano-scale particles, the equipment is very expensive, complicated, and the production capacity is low; 2. Plasma spheroidization method (Nonferrous Metals, 2008, 60 (1): 41 -42), this method uses the high temperature of the plasma to melt the surface or the whole of the polygonal tungsten powder, forms spherical particles due to surface tension, and solidifies at a very high cooling rate to prepare micron-sized spherical tungsten powder. The equipment is expensive, the preparation cost is high, and the prepared powder is obviously coarsened; 3. The tungstate precipitation reduction method (Chinese patent 200810239760.2), this method uses concentrated sulfuric acid as the precipitant and dispersant of ammonium tungstate to obtain Precipitate with tungstic acid, then dry the precipitate and reduce spherical tungsten particles. Due to the use of concentrated sulfuric acid in this method, the requirements for equipment are extremely high, and the pollution of the production environment is serious. At the same time, the particle size distribution of the prepared spherical tungsten powder is limited to 1.2 ~2.8 microns