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A method for synthesizing boron carbide powder at low temperature with high yield

A boron carbide powder, high-yield technology, applied in chemical instruments and methods, carbon compounds, inorganic chemistry, etc., can solve problems such as low yield, and achieve lower reaction temperature, controllable morphology and structure, and reduce the yield of B4C. Effect

Active Publication Date: 2017-05-03
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] For existing synthesis B 4 The low yield of C powder sol-gel system, the object of the present invention is to provide a method for synthesizing boron carbide powder at low temperature with high yield

Method used

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  • A method for synthesizing boron carbide powder at low temperature with high yield
  • A method for synthesizing boron carbide powder at low temperature with high yield
  • A method for synthesizing boron carbide powder at low temperature with high yield

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Experimental program
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Effect test

Embodiment 1

[0056] A boric acid solution with a concentration of 8.0 mol / L and a polyvinyl alcohol solution with a concentration of 2.0 mol / L were prepared respectively. Use ammonia water to adjust the pH value of the boric acid solution to 4, slowly add an appropriate amount of boric acid solution to the polyvinyl alcohol solution according to the molar ratio of boric acid / polyvinyl alcohol = 4 / 10, and stir at 85°C until the solvent is completely Evaporate to dryness to obtain a gel; place the obtained gel in a drying oven, raise the temperature to 80°C at a rate of 1°C / min, keep it warm for 12 hours, and then raise the temperature to 120°C and keep it for 16 hours to obtain a dry gel, of which 800-120°C The temperature rise rate in the temperature interval is 0.5°C / min. Put the obtained xerogel in a tube furnace for pyrolysis. The furnace is an argon atmosphere. The pyrolysis system is as follows: the heating rate is 2°C / min below 350°C, the temperature is kept at 350°C for 2 hours, and...

Embodiment 2

[0059] Molar ratio boric acid / polyvinyl alcohol=5 / 10, the pH value of boric acid solution is adjusted to be 5, other conditions are identical with embodiment 1, have made the B of particle diameter 1-2 μm 4 C powder, B 4 The yield of C was 13.5‰.

Embodiment 3

[0061]The molar ratio of boric acid / polyvinyl alcohol=6 / 10, the pH value of the boric acid solution is adjusted to 6, and other conditions are the same as in Example 1, and B with a particle size of 2-3 μm is obtained 4 C powder, B 4 The yield of C was 11.3‰.

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Abstract

The invention relates to a method for synthesizing boron carbide powder in high yield at low temperature. The method comprises the following steps: respectively measuring boric acid and polyvinyl alcohol according to a molar ratio of (4 to 7) : 10, mixing and stirring the boric acid and glycerol to be completely dissolved, adding alkali, adjusting the pH to 4 to 6, and obtaining a boric acid solution; mixing and stirring the polyvinyl alcohol and water to be completely dissolved, and obtaining a polyvinyl alcohol solution; mixing and stirring the obtained boric acid solution and the obtained polyvinyl alcohol solution, and heating and evaporating a solvent to completely form gel; drying the obtained gel to obtain dry gel; preserving the heat of the dry gel for 2 to 4 hours in a vacuum or inert atmosphere at the temperature of 500 to 700 DEG C, and carrying out the dissociation; preserving the heat of a dissociation product in a vacuum or inert atmosphere at the temperature of 1300 to 1500 DEG C for 3 to 5 hours, and carrying out the carbon thermal reduction for the dissociation product, and obtaining boron carbide powder. By adopting the method, the problems that B2O3 is severely volatilized and lost and the concentration of boric acid in a boric acid-polyvinyl alcohol system is extremely low in the subsequent process of gel of a boric acid-glycerol system are simultaneously overcome.

Description

technical field [0001] The present invention relates to boron carbide (B 4 C) the preparation method of powder, be specifically related to a kind of sol-gel method synthetic B 4 The method of C powder belongs to the field of inorganic non-metallic powder materials. Background technique [0002] Boron carbide (B 4 C) It has excellent mechanical properties, especially high hardness, high modulus and good wear resistance, making it widely used in the fields of abrasive tools, cutting tools and wear-resistant structural parts. [0003] Currently, the industrial preparation of B 4 The method of C powder mainly utilizes boric acid or boron oxide (B 2 o 3 ) powder and carbon black undergo carbothermal reduction reaction at 2000-3000°C to generate B 4 C. The disadvantage of this method is that the energy consumption is large, the high temperature seriously damages the equipment, the yield is very low, and B 4 The purity of C is poor. In recent years, self-propagating combus...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B32/991
Inventor 董绍明陈小武阚艳梅周海军胡建宝王震
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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