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Single-phase alpha-Si3N4 micropowder and preparation method thereof

An ultrafine powder, single-phase technology, which is applied in the field of single-phase α-Si3N4 ultrafine powder and its preparation, can solve the problems of uneven particle size distribution, complicated process, and low degree of industrialization of powder, and achieve The process is easy to control, the synthesis process is simple, and the effect of low reaction temperature

Inactive Publication Date: 2015-06-03
WUHAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For example, the price of raw materials is high, the process is complicated, difficult to control, high energy consumption or low degree of industrialization; the prepared product has low purity, uneven particle size distribution of powder or low α phase content

Method used

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  • Single-phase alpha-Si3N4 micropowder and preparation method thereof
  • Single-phase alpha-Si3N4 micropowder and preparation method thereof
  • Single-phase alpha-Si3N4 micropowder and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0028] A single-phase α-Si 3 N 4 Ultrafine powder and its preparation method. First mix 10-20wt% elemental silicon powder, 15-30wt% solid nitrogen source and 60-75wt% halide powder to prepare a mixture; The heating rate was raised to 1200-1300°C at a rate of 2-5°C / min, and the temperature was kept for 2-4 hours; then the obtained product was repeatedly washed with deionized water until it was washed with AgNO 3 and Ca(NO 3 ) 2 Titrate the solution until no white precipitate appears; finally dry at 110°C for 10-24 hours to obtain single-phase α-Si 3 N 4 Ultrafine powder.

[0029]In this embodiment: the solid nitrogen source is melamine; the halide powder is a mixture of 70-90 wt% sodium chloride and 10-30 wt% sodium fluoride.

[0030] figure 1 It is a kind of single-phase α-Si prepared by the embodiment 3 N 4 XRD pattern of powder; figure 2 yes figure 1 The single-phase α-Si shown 3 N 4 SEM image of powder; image 3 yes figure 2 The EDS map of the location ind...

Embodiment 2

[0032] A single-phase α-Si 3 N 4 Ultrafine powder and its preparation method. First mix 10-20wt% elemental silicon powder, 15-30wt% solid nitrogen source and 60-75wt% halide powder to prepare a mixture; The temperature was raised to 1100-1200°C at a rate of 2-5°C / min, and kept for 2-4 hours; then the obtained product was repeatedly washed with deionized water until it was washed with AgNO 3 and Ca(NO 3 ) 2 Titrate the solution until no white precipitate appears; finally dry at 110°C for 10-24 hours to obtain single-phase α-Si 3 N 4 Ultrafine powder.

[0033] In this embodiment: the solid nitrogen source is a mixture of 50-70 wt% melamine and 30-50 wt% ammonium chloride; the halide powder is sodium fluoride.

[0034] The single-phase α-Si prepared in this example 3 N 4 The ultrafine powder has high purity, no particle agglomeration, and the particle size is 150-250nm.

Embodiment 3

[0036] A single-phase α-Si 3 N 4 Ultrafine powder and its preparation method. Firstly mix 5-15wt% elemental silicon powder, 10-25wt% solid nitrogen source and 70-80wt% halide powder to make a mixture; The heating rate was raised to 1000-1100°C at a rate of 5-10°C / min, and the temperature was kept for 4-6 hours; then the obtained product was washed repeatedly with deionized water until it was washed with AgNO 3 and Ca(NO 3 ) 2 Titrate the solution until no white precipitate appears; finally dry at 110°C for 10-24 hours to obtain single-phase α-Si 3 N 4 Ultrafine powder.

[0037] In this embodiment: the solid nitrogen source is urea; the halide powder is potassium fluoride.

[0038] The single-phase α-Si prepared in this example 3 N 4 The ultrafine powder has high purity, no particle agglomeration, and the particle size is 300-400nm.

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Abstract

The invention relates to a single-phase alpha-Si3N4 micropowder and a preparation method thereof. The technical scheme is as follows: the preparation method comprises the following steps: uniformly mixing 5-30 wt% of simple substance silicon powder, 15-45 wt% of solid nitrogen source and 40-80 wt% of halide powder to prepare a mixture; putting the mixture into an electric tube furnace, heating to 1000-1300 DEG C at the heating rate of 2-10 DEG C / minute in a nitrogen atmosphere, and keeping the temperature for 2-6 hours; repeatedly washing the product with deionized water until no white precipitate appears when respectively titrating with AgNO3 and Ca(NO3)2 solutions; and finally, drying at 110 DEG C for 10-24 hours to obtain the single-phase alpha-Si3N4 micropowder. The preparation method has the characteristics of low reaction temperature, low cost, simple synthesis technique, controllable process, high yield and wide industrialization prospects. The particle size of the prepared single-phase alpha-Si3N4 micropowder is 100-500nm; and the single-phase alpha-Si3N4 micropowder has the advantages of no impurity phase, high activity, small particle aggregation and uniform particle size distribution.

Description

technical field [0001] The present invention belongs to Si 3 N 4 Ultrafine powder technology field. Specifically related to a single-phase α-Si 3 N 4 Ultrafine powder and its preparation method. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramics and their composites, as functional materials with excellent performance, are widely used in various fields such as machinery, electrical / optical devices, and refractory materials. Si 3 N 4 There are mainly two common crystal structures: α phase and β phase, both of which belong to the hexagonal crystal system. The reason for the formation of two different variants is that [Si-N 4 ]hedral structures are stacked in different ways to form two two-dimensional network crystal forms: α-Si 3 N 4 The stacking order is ABCDAB…, β-Si 3 N 4 The stacking sequence is ABABAB.... α-Si 3 N 4 β-Si 3 N 4 It is long columnar. α-Si 3 N 4 It is a thermodynamically unstable phase. At 1300-1600 °C, α-Si 3 N 4 The te...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/626
Inventor 梁峰张海军张少伟李发亮鲁礼林段红娟刘江昊
Owner WUHAN UNIV OF SCI & TECH
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