Preparation of nanometer tungsten carbide composite powder

Tungsten carbide is a black gray crystalline powder. Relative density 15.6(18/4℃), melting point 2600℃, boiling point 6000℃, Mohs hardness 9. Tungsten carbide insoluble in water, hydrochloric acid or sulfuric acid, soluble in nitric acid and hydrofluoric acid mixture. Tungsten carbide reacts strongly with fluorine at room temperature and is oxidized to tungsten oxide when heated in air. At 1550 ~ 1650℃, the metal tungsten powder can be directly combined with carbon black, or at 1150℃, the tungsten powder can be reacted with carbon monoxide.
WC is an important part of hard alloy and cermet, with high hardness, high wear resistance and excellent fracture toughness. Known as the “industrial tooth”, WC has been widely used in drilling tools, cutting tools, precision molds, mining tools, printing needles, armor-piercing ammunition and other fields.
CN200810147889.0 reported a nano-sized tungsten carbide composite powder preparation methods, the preparation method of the implementation of the scheme is: with powdery ammonium tungstate, carbonaceous reductant and inhibitors as raw materials, including inhibitors of chromium, oxalic acid, ammonium salt, acetate, acetate in at least one or vanadium, oxalic acid, ammonium salt, acetate, acetate in at least one; The above material according to the in the weight of the WC, 81% ~ 90% of ammonium tungstate, carbonaceous reductant was 16% ~ 20%, inhibitors of 0.5% ~ 1.2% proportion of dissolved in deionized water or distilled water, and stir well, the obtained solution, then heating the solution, drying, finally get the precursor powder, put precursor powder at high temperature in the reactor, under the condition of vacuum, argon gas or hydrogen atmosphere protection, in 1000 ~ 1200 ℃, 30 ~ 60 min under the condition of average particle size carbide < 100 nm, uniform particle size distribution of tungsten carbide composite powder.
Compared with the existing preparation technology, the present invention has the following advantages:
(1) The unbonded tungsten carbide composite powder was prepared for the first time. A tungsten carbide composite powder containing vanadium carbide or/and chromium carbide grain growth inhibitor is prepared by a new in-situ synthesis process.
(2) The invention adopts carbon reducing agent, which is abundant in source and low in price and saves cost.
(3) Short reaction time and energy saving. The invention can prepare nano-tungsten carbide composite powder under the condition of 1000 ~ 1200℃ and 30 ~ 60min, which greatly saves energy.
(4) Simple process. The invention can be finished by carbonization once, has simple process and convenient operation, and is suitable for industrial production.
(5) Uniform and fine particle size. The particle size of the tungsten carbide composite powder generated by the reaction is less than 100nm, the particle size distribution range is narrow, and the impurity content is low.
[1] Dictionary of Chemical Substances
[2][Invention of China, Authorization of Invention of China]CN200810147889.0 a nanometer tungsten carbide composite powder and preparation method thereof

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