Preparation method of boron carbide superfine powder

A technology of ultra-fine powder and boron carbide, which is applied in chemical instruments and methods, carbon compounds, inorganic chemistry, etc., can solve problems such as difficult to remove, unsuitable for large-scale promotion and development, and achieve labor cost saving, process stability, The effect of prolonging the reaction time

Active Publication Date: 2018-03-06
QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI +1
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Problems solved by technology

2) Self-propagating high-temperature synthesis method: mix a certain proportion of magnesium powder (or aluminum powder), carbon powder and boron oxide powder, press it into a green body, ignite it in a protective gas, and pickle and dry it to obtain the product after the reaction. The reaction is a strong exothermic reaction, and the reaction temperature is generally between 1273K and 1473K. It is ignited under a protective atmosphere and a certain pressure, and the reaction can be continued by self-sustaining combustion, so it is also called self-propagating high-temperature reduction synthesis (SHS); such as a The preparation method of boron carbide powder, which mixes the raw organic carbon source with boric anhydride and metal magnesium powder according to a certain ratio, and after combustion reaction, the obtained product is added with concentrated hydrochloric acid and stirred and soaked, then suction filtered, washed with water until neutral, and washed with water After drying the obtained filter cake, ultrafine boron carbide polycrystalline powder can be obtained. This method has the advantages of low reaction temperature, energy saving, rapid reaction and easy control, so the purity of the synthesized boron carbide powder is high and the original powder The particle size is finer, and generally does not require crushing treatment. It is the best method for synthesizing boron carbide powder at present, but the residual MgO in the reactant must be washed away by additional processes, and it is extremely difficult to remove completely.
Currently only applicable to special industry needs, not suitable for large-scale promotion and development

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  • Preparation method of boron carbide superfine powder
  • Preparation method of boron carbide superfine powder
  • Preparation method of boron carbide superfine powder

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preparation example Construction

[0030] The invention discloses a preparation method of boron carbide ultrafine powder, which is based on a boron carbide smelting device.

[0031] Specifically, the boron carbide smelting device includes a smelting furnace body made of refractory bricks and a sunken cover plate made of high-temperature-resistant materials; the smelting furnace body includes a bottom plate and side walls surrounding the bottom plate, smelting There is an opening on the top of the furnace body opposite to the bottom plate, and the sunken cover plate is fastened on the opening; ".

[0032] More specifically, vent holes are opened on the sunken cover plate to remove the gas generated during the smelting process inside the smelting furnace body; positive electrodes and The negative pole, the positive pole and the negative pole all penetrate the inside of the smelting furnace body and the ends of the two are opposite; the inside of the smelting furnace body is filled with smelting raw materials, an...

Embodiment 1

[0052] Ultrafine boron anhydride and ultrafine graphite are used as raw materials, wherein the main content of ultrafine boron anhydride is 99.51%, the average particle size is 8 μm, and the average particle size of ultrafine graphite is 6 μm. 50kg of ultra-fine boron anhydride and 12kg of ultra-fine graphite are fully mixed through a ball mill, and then pressed into strips by an extruder to obtain smelting raw materials.

[0053] The smelting raw materials are placed in a boron carbide smelting device for sintering. The sintering process is as follows: 1000KVA transformer (rectifier), 15 gears of on-load tap changers, and power transmission in series. Starting from gear 1, the gears are gradually increased. Observe For the rise of the primary and secondary currents, adjust the interval between upshifts as appropriate. Whenever the primary current reaches 70A, downgrade by one gear. According to the furnace resistance and voltage conditions, adjust to parallel connection and en...

Embodiment 2

[0059] Recovered boric anhydride (dust collected in electric arc smelting), domestic ultra-fine boron oxide, ultra-fine graphite and ultra-fine carbon powder are used as raw materials, and the recovered boron anhydride is pretreated first, including removal of abnormally large particles and impurities, to obtain the main The content is 98.01%, and the average particle size is 12 μm ultrafine boric anhydride, and the particle size of the rest of the raw materials are all within 10 μm. Stir and mix 40kg ultrafine boric anhydride, 10kg domestic ultrafine boron oxide, 8kg ultrafine graphite and 4kg ultrafine carbon powder, grind them with a ball mill and press them into 8cm-12cm long squares with a compacted density of about 1.24g / cm 3 , to obtain smelting raw materials.

[0060] The smelting raw materials are placed in a boron carbide smelting device for sintering. The sintering process is as follows: 1000KVA transformer (rectifier), 15 gears of on-load tap changers, and power t...

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Abstract

The invention discloses a preparation method of boron carbide superfine powder. The preparation method is based on a boron carbide smelting device which comprises a smelting furnace body built with refractory bricks and a sunken cover plate buckled at a top opening of the smelting furnace body, wherein a positive pole and a negative pole communicating a power supply are inserted into the side wallof the smelting furnace body. The preparation method comprises the following steps: S1, mixing a boron source with a carbon source fully to obtain a smelting raw material; S2, fully filling the smelting furnace body with the smelting raw material and covering the furnace with the sunken cover plate; and S3, applying a voltage to heat the smelting raw material to 1500-1900 DEG C and keeping the temperature for 24-48h to obtain the boron carbide superfine powder. Boron carbide is prepared by means of a nearly closed high-temperature treatment method according to the preparation method disclosedby the invention, so that impurity pollution is reduced, the product is good in crystallinity, the primary content of the obtained boron carbide superfine powder is greater than 96%, and the productgraded meets the demand of an abrasive material, and meets the quality demand on boron carbide powder in the field of grinding industry or engineering ceramics.

Description

technical field [0001] The invention belongs to the technical field of ceramic material preparation, and in particular relates to a preparation method of boron carbide ultrafine powder. Background technique [0002] The lattice of boron carbide belongs to the R3m space lattice, and the lattice constant is α=66°18′, also commonly known as hexagonal lattice. The rhombohedral structure of boron carbide can be regarded as a regular icosahedron formed by elongating a cubic cell from the diagonal in space. The diagonal line parallel to the space becomes the C-axis of the hexagonal logo, and three boron atoms are connected with adjacent icosahedrons to form a linear chain. Thus, the unit cell contains 12 icosahedral sites, three of which are on a linear chain. The chemical formula is B 12 C 3 , namely B 4 c. Boron carbide has a stable structure, a relative density of 2.508-2.512, a melting point of 2350°C, and a boiling point of 3500°C. It is a compound with high hardness. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B32/991C04B35/563C04B35/626
CPCC01P2002/72C01P2006/80C04B35/563C04B35/626C04B2235/3409C04B2235/425C04B2235/96
Inventor 彭正军祝增虎王成春臧东营孙庆超李法强上官雪慧杨国威吴康
Owner QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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