Low pressure combustion process of synthesizing alpha-phase silicon nitride powder

A technology of phase silicon nitride powder and low pressure combustion is applied in the field of low pressure combustion synthesis of high alpha phase silicon nitride powder, which can solve the problems of inability to meet the requirements of fine structure ceramics, high impurities such as iron in products, and increased probability of accidents. To achieve the effect of easy subsequent treatment, high content of α phase, and promotion of nitrogen permeation

Inactive Publication Date: 2004-11-03
SHENZHEN BORNSUN INDAL
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  • Summary
  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

Such as "a kind of preparation of high α phase Si" invented by Russia Merzhanov et al. 3 N 4 Powder method" (US Patent US5032370), the required nitrogen pressure is too high (4-30Mpa), the requirements for equipment are more stringent, the probability of accidents increases, and it is not conducive to large-scale production
The "preparation method of self-propagating high-temperature synthesis of ferrosilicon nitride powder" (Chinese Patent Publication No. CN1275526) invented by Jiang Guojian in China also has the disadvantages of high reaction pressure and strict requirements on equipment.
Moreover, due to the use of low-purity ferrosilicon powder and ferrosilicon nitride powder as raw materials, the product contains too many impurities such as iron, and is basically refractory grade β-phase silicon nitride with low commercial value, which cannot meet the needs of fine structure ceramics.
[0004] The above two patents also have the disadvantages of high nitrogen pressure (up to 30MPa), strict requirements on equipment, and increased accident probability

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The Si with an average particle size of 250 mesh was pickled with diluted HCl and dried under a protective atmosphere. Metal Si is 50.0% by weight, amorphous Si is 5.0%, Si 3 N 4 28.9%, NH 4 F is 12.3%, NH 4 Cl is 3.8%, the raw material powder is ball-milled on a rolling ball mill for 24 hours to make it fully mixed, the mixed raw material is dried at 65°C, placed in a porous graphite container, put into a combustion synthesis reaction device, and pumped After vacuuming, nitrogen gas with a pressure of 0.9 MPa is blown from the bottom of the powder, and the nitrogen gas flow rate is 8 l / min to induce the combustion of the raw material powder. The igniter is pure titanium powder or a mixture of titanium powder and carbon black, and the molar ratio is 1: 1. After the combustion reaction lasts for 15 minutes, cool to room temperature, finely grind and classify to obtain a silicon nitride powder with an α-phase silicon nitride content of 87wt% and a residual Si content o...

Embodiment 2

[0024] The silicon powder with a particle size of 350 mesh was ultrasonically treated at a power of 300 watts for 3 hours. Si is 40.5% by weight, amorphous Si is 29.5%, Si 3 N 4 21.5%, NH 4 F is 5.0%, (NH 4 ) 2 CO 3 3.5%, the raw material powder was ball milled on a rolling ball mill for 20 hours to make it fully mixed, and the mixed raw material was dried at 60°C, placed in a porous graphite container, placed in a combustion synthesis reaction device, and vacuumized Finally, nitrogen gas with a pressure of 0.7MPa is blown from the bottom of the powder, and the nitrogen gas flow rate is 4l / min, and the ignition agent is ignited to induce the combustion of the raw material powder. The ignition agent is pure titanium powder or a mixture of titanium powder and carbon black, and the molar ratio The ratio is 1:1; after the combustion reaction lasts for 10 minutes, cool to room temperature, finely grind and classify to obtain a silicon nitride powder with an α-phase silicon nit...

Embodiment 3

[0026] Silicon powder with a particle size of 450 mesh was ball milled at room temperature and at a speed of 100 r / m for 4 hours at high speed. Si is 25.5% by weight, Si(NH) 2 11.5%, Si 3 N 4 51.5%, NH 4 F is 7.6%, NH 4Cl is 3.9%, the raw material powder is ball-milled on a rolling ball mill for 15 hours to make it fully mixed, the mixed raw material is dried at 60°C, placed in a porous graphite container, put into a combustion synthesis reaction device, and pumped After vacuuming, nitrogen gas with a pressure of 0.7MPa is blown from the bottom of the powder, and the nitrogen gas flow rate is 2l / min. The igniter is ignited to induce the combustion of the raw material powder. The igniter is pure titanium powder or a mixture of titanium powder and carbon black. The ratio is 1:1; after the combustion reaction lasts for 20 minutes, cool to room temperature, finely grind and classify to obtain silicon nitride powder with α-phase silicon nitride content of 89wt% and residual Si ...

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Abstract

The method for synthesizing high alpha-phase silicon nitride powder body by utilizing low-pressure combustion includes the following steps: firstly, pretreating raw material metal silicon powder, according to proportion adding activating agent, diluting agent and additive, ball grinding, fully mixing them, drying, placing them into low-pressure combustion synthesis reaction equipment, evacuating, blowing nitrogen gas into the reaction equipment from bottom, inducing to combustion to implement suspension nitrogenation at low pressure. The purity of said invented product is high, and its alpha-phase content is high.

Description

technical field [0001] The invention relates to a method for synthesizing high-α-phase silicon nitride powder by low-pressure combustion, which belongs to the technical field of inorganic non-metallic materials. Background technique [0002] Si 3 N 4 Ceramics have excellent comprehensive properties such as high hardness, wear resistance, large elastic modulus, high strength, high temperature resistance, small thermal expansion coefficient, high thermal conductivity, good thermal shock resistance, low density, and small specific gravity. In addition, it is also resistant to corrosion and oxidation, and has the characteristics of small surface friction coefficient and good electrical insulation performance. Therefore, Si 3 N 4 Ceramics have very broad application prospects in high-temperature structures and engineering, refractory materials, circuit substrates and other fields. Traditional preparation of Si 3 N 4 There are many methods, the most typical of which are sil...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B21/068C04B35/584C04B35/64
Inventor 陈克新周和平葛振斌
Owner SHENZHEN BORNSUN INDAL
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