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Preparation method of high-purity silicon nitride powder

A silicon nitride powder, high-purity technology, applied in the field of high-purity silicon nitride powder preparation, can solve the problems of low product purity, poor particle size uniformity, and high cost, achieve uniform particle size, refine particle size, improve The effect of compactness

Active Publication Date: 2017-06-09
HEBEI LIFU CHEM TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a preparation method of high-purity silicon nitride powder to solve the problems of high cost, low purity of the obtained product and poor particle size uniformity in the existing preparation method

Method used

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  • Preparation method of high-purity silicon nitride powder
  • Preparation method of high-purity silicon nitride powder

Examples

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preparation example Construction

[0022] The invention provides a method for preparing high-purity silicon nitride powder, comprising the following steps:

[0023] Weighing raw materials: Weigh water-soluble starch and silicon dioxide powder respectively according to the weight ratio of water-soluble starch: silicon dioxide powder = 0.8~1.2:1, then weigh nano-silicon nitride sintering aid, the amount of sintering aid It is 1-3wt% of the sum of the mass of water-soluble starch, silica powder and sintering aid; among them, the particle size of silica powder is 0.8-1.2μm, and the purity is 99.99%; the carbon content of water-soluble starch The particle size of the sintering aid is 0.8-2.0nm, and the purity is 99%.

[0024] Mixing: Disperse the water-soluble starch in water, heat it to 80°C, and keep it warm for 45 minutes to make the water-soluble starch gelatinize evenly to obtain a gelatinized product; cool the gelatinized product to 50°C, and then add silicon dioxide powder and sintering aid Add it to the gel...

Embodiment 1

[0029] Disperse 29.85g of water-soluble starch in 100mL of water, heat it to 80°C, and keep it warm for 45min to make it gelatinize into a uniform gelatinized product, cool the gelatinized product to 50°C, and then add 18.65g of carbon dioxide The silicon powder and 1.5 g of silicon nitride powder with a particle size of 1 nm were stirred for 24 hours to fully mix the three, and then filtered, dried, and sieved to obtain a uniformly mixed precursor powder.

[0030] The precursor powder is put into the reaction furnace, and the ammonia / hydrogen mixed gas is introduced after vacuum treatment, the volume percentage of hydrogen in the mixed gas is 40%, the flow rate of the mixed gas is 2.0L / min, and the reaction temperature is 1350°C. Reaction time 5h. The obtained sintered product was placed in a decarburization furnace, and air was introduced at a flow rate of 10 L / min, and kept for 2 hours to obtain gray high-purity silicon nitride powder. The nitrogen content in the synthesiz...

Embodiment 2～8、 comparative example 1

[0032] With reference to the preparation method of Example 1, change the weight ratio of water-soluble starch to silicon dioxide powder (abbreviated as weight ratio in the table), the particle diameter and the consumption of sintering aid, prepare silicon nitride powder, comparative example 1 uses fluorine Calcium oxide is used as a sintering aid to prepare silicon nitride powder. The obtained silicon nitride powder was tested for elements and particle size, and the results are shown in Table 1.

[0033] Table 1:

[0034]

[0035]

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Abstract

The invention provides a preparation method of high-purity silicon nitride powder. The method comprises the following steps: dispersing water-soluble starch into water; heating to reach the temperature of 80 DEG C; gelatinizing for 45 minutes to obtain a gelatinized product; cooling the gelatinized product to reach the temperature of 50 DEG C; adding silicon dioxide powder and a sintering additive which is nano silicon nitride to the gelatinized product; stirring to uniformly mix; filtering, drying and screening to obtain a precursor; feeding the precursor into a sintering furnace; exhausting air from the sintering furnace; charging ammonia / hydrogen mixed gas to form a reacting atmosphere; sintering for 5h at the temperature of 1350-1450 DEG C to obtain a sintered product; transferring the sintered product into a decarbonizing furnace; and maintaining the temperature for 2h under the air atmosphere at the temperature of 700 DEG C, so as to obtain the high-purity silicon nitride powder. According to the method, the high-purity silicon nitride powder can be prepared under low temperature and normal pressure; the prepared silicon nitride powder is high in purity; the nitrogen content is not less than 39.29%; the oxygen content is not greater than 0.71%; the particle size is uniform; and the K is 0.5-0.98.

Description

technical field [0001] The invention relates to a preparation method of silicon nitride powder, in particular to a preparation method of high-purity silicon nitride powder. Background technique [0002] Silicon nitride material is a new high thermal conductivity filler with application potential. It has high hardness, wear resistance, large elastic modulus, high strength, high temperature resistance, small thermal expansion coefficient, large thermal conductivity, and good thermal shock resistance. Low density, small specific gravity, anti-oxidation, anti-chemical corrosion, its performance can be compared with alloys, it has broad application prospects in chemical industry, textile, aerospace, metallurgy, machinery, petroleum, transportation and other fields. [0003] At present, the preparation methods of silicon nitride powder mainly include the following types: 1. Direct nitriding of silicon powder, using pure silicon powder to synthesize silicon nitride powder at high t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/626
CPCC04B35/584C04B35/62605C04B35/62645C04B2235/3418C04B2235/3873C04B2235/6582
Inventor 杨志平张银霞赵金鑫
Owner HEBEI LIFU CHEM TECH
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