The current methods for preparingmacro crystal tungsten carbide (WC) powder mainly include: high-temperature reduction, high-temperature carbonization, high-temperature carbonization with the addition of alkaline earth metals or alkali metal elements, high-temperature carbonization of ultra-fine tungsten powder, mixed carbonization of coarse and fine tungsten powder, Thermite method, etc. However, if they do not have the problem of harsh reaction conditions, they have the disadvantage of poor product performance. In order to make up for the shortcomings of the existing technology, the following will provide you with a new preparation method ofmacro crystal WC. The specific steps are as follows:
The WC powder is mixed with cobalt powder and graphite powder, then treated at high temperature and crushed, then acid leaching is used to remove cobalt, flotation to remove free carbon, and finally the product can be obtained by drying.
Notes for this method:
(1) The tungsten carbide powder should meet the requirements of GB/T4295-2008; specifically, it includes 16 grades of FWC tungsten carbide powder in GB/T4295-2008, with an average particle size below 35.0 μm.
(2) The mass ratio of tungsten carbide powder, cobalt powder and graphite powder is (60—80):(15—40):(5—10), and after mixing (before high temperature treatment), ball milling should be carried out. The milling time is 1-3 hours.
(3) The high-temperature treatment is carried out under the protection of vacuum and inert gas. The vacuum degree should be less than 50 Pa, and the temperature should be 1450-1550°C. The inert gas can be nitrogen or argon, and the oxygen content is less than 0.005%.
(4) The acid is hydrochloric acid or dilute sulfuric acid; 1:1 hydrochloric acid is used to remove excess cobalt, and a mixture of graphite and coarse-crystalline WC is obtained after drying.
(5) The step of removing cobalt by acid leaching includes: leaching the crushed materials after high-temperature treatment with 1:1 hydrochloric acid. Generally, 1 kg of crushed materials consumes 0.8L of hydrochloric acid; after drying, they are ground, sieved, and the particle size is less than 74 μm. ; Use 1:1 hydrochloric acid for the second leaching, generally 1kg of sieved material consumes 0.5L of the hydrochloric acid.
(6) The step of removing free carbon by flotation includes: using kerosene as a collector and No. 2 oil as a foaming agent to remove free carbon. Taking advantage of the large density difference between tungsten carbide and graphite, kerosene flotation is used to remove free carbon, and tungsten carbide is obtained after drying.
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