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A kind of preparation method of boron carbide ultrafine 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 the problems that are not suitable for large-scale promotion and development, and difficult to remove, so as to save labor costs and reduce energy consumption , the effect of process stability

Active Publication Date: 2020-07-21
QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI +1
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  • Application Information

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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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  • A kind of preparation method of boron carbide ultrafine powder
  • A kind of preparation method of boron carbide ultrafine powder
  • A kind of preparation method of boron carbide ultrafine powder

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preparation example Construction

[0030] The invention discloses a preparation method of boron carbide superfine powder. The preparation method 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. The top of the furnace body opposite to the bottom plate has an opening, and the sinking cover plate is fastened on the opening; that is, the smelting furnace body is a "box-shaped body made of refractory bricks with an opening at the top ".

[0032] More specifically, the sunken cover plate is provided with vent holes to remove the gas generated during the smelting process inside the smelting furnace body; the two opposite side walls of the smelting furnace body are respectively inserted with positive electrodes and The negative electrode, the positiv...

Embodiment 1

[0052] Ultra-fine boron anhydride and ultra-fine graphite are used as raw materials. The main content of ultra-fine boron anhydride is 99.51%, the average particle size is 8 μm, and the average particle size of ultra-fine graphite is 6 μm. 50kg of superfine boric anhydride and 12kg of superfine graphite are thoroughly mixed through a ball mill, and then pressed into a long strip with an extruder to obtain raw materials for smelting.

[0053] The smelting raw materials are placed in a boron carbide smelting device for sintering. The specific sintering process is: 1000KVA transformer (rectifier), a total of 15 on-load voltage regulating switches, and the furnace is turned on in series. The gears are gradually increased from gear 1. Observe Regarding the rise of primary and secondary currents, adjust the interval of upshifts as appropriate. When the primary current reaches 70A, it will drop one gear. According to the furnace resistance and voltage, it should be adjusted in parallel a...

Embodiment 2

[0059] Taking recycled boron anhydride (that is, dust collected in arc smelting), domestically produced ultrafine boron oxide, ultrafine graphite and ultrafine carbon powder as raw materials, the recycled boron anhydride is pretreated first, including the removal of abnormally large particles and impurities, to obtain the main The content of ultrafine boric anhydride with a content of 98.01% and an average particle size of 12μm, and the particle size of the remaining raw materials are all within 10μm. Stir 40kg ultra-fine boron anhydride, 10kg domestic ultra-fine boron oxide, 8kg ultra-fine graphite and 4kg ultra-fine carbon powder. After stirring and mixing, they are ground by a ball mill and pressed into a block with a length of 8cm-12cm with a block molding machine. The compacted density is about 1.24g / cm 3 , Obtain smelting raw materials.

[0060] The smelting raw materials are placed in a boron carbide smelting device for sintering. The specific sintering process is: 1000KVA...

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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 specifically 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', usually also called hexagonal lattice. The rhombohedral structure of boron carbide can be regarded as a cubic unit cell elongated from a diagonal in space to form a regular icosahedron. The diagonal line parallel to the space becomes the C axis of the hexagonal sign, and three boron atoms are connected to the adjacent icosahedron to form a linear chain. Therefore, the unit cell contains 12 icosahedral positions and three positions are in 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 to 2.512, a melting point of 2350°C, and a boiling point of 3500°C. It is a compound with high hardne...

Claims

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Application Information

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Patent Type & Authority Patents(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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