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Method for preparing high-purity alpha-silicon nitride powder and high-purity alpha-silicon nitride powder

A silicon nitride powder and high-purity technology, which is applied in the field of high-purity α-silicon nitride powder and the preparation of high-purity α-silicon nitride powder, can solve the problem of reducing product purity, increasing content, and reducing α-phase in silicon nitride Content and other issues, to achieve the effect of ensuring purity and increasing the content of α phase

Active Publication Date: 2021-10-12
XINJIANG JINGSHUO NEW MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, on the one hand, the introduction of metal impurities needs to be mixed with a sufficient amount of impurity powder to contaminate the surface of all silicon powders, which reduces the purity of the product. On the other hand, more molten liquid phases will lead to β-Si 3 N 4 The corresponding increase in content reduces the content of α phase in silicon nitride

Method used

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  • Method for preparing high-purity alpha-silicon nitride powder and high-purity alpha-silicon nitride powder
  • Method for preparing high-purity alpha-silicon nitride powder and high-purity alpha-silicon nitride powder

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Embodiment 1

[0057] Such as figure 1 Shown, the present invention provides a kind of method for preparing high-purity α-silicon nitride powder, comprising:

[0058] Step S101: adding a catalyst to the fine silicon powder with a particle size below 100 microns, the catalyst is capable of generating a metal compound in a reversible reaction under the reaction conditions for preparing the silicon nitride powder, and allows the presence of a metal halide;

[0059] Step S102: Place the fine silicon powder added with the catalyst in a nitriding furnace, and keep it warm for 50-180 hours at a temperature of 1050°C-1400°C under a mixed atmosphere of nitrogen and argon to allow nitriding reaction to occur Silicon nitride powder was obtained.

[0060] The main reaction in the nitriding furnace

[0061] SiO 2 (s)+H 2 (g)←→SiO(g)+H 2 O(g)

[0062] Si(s)+H 2 O(g)←→SiO(g)+H 2 (g)

[0063] 6SiO(g)+4N 2 (g)←→2Si 3 N 4 (s)+3O 2 (g)

[0064] 3Si(s)+2N 2 (g)←→Si 3 N 4 (s)

[0065] The effec...

Embodiment 2

[0138] This embodiment discloses a method for preparing high-purity α-silicon nitride powder, which includes the following steps.

[0139] Electronic grade polysilicon powder with a size of 6-10mm is used as raw material, and the total content of Fe, Cr, Ni, Cu, Zn, Al, K, Na and other metal impurities in the raw material is ≤15ppb; mechanical crushing and airflow crushing are adopted successively to silicon The powder becomes superfine silicon powder with a particle size of D50=2.5 ​​μm and D90=8 μm, and the fine silicon powder with a particle size of 50-100 μm is obtained after coarsening by granulation.

[0140] Add ferric ammonium citrate to the above fine silicon powder, the specific addition amount is converted according to the metal content, adjust the total metal content to about 100ppm, and add 1% NH 4 Cl, mixed with airflow homogenization equipment, ammonium ferric citrate pyrolyzes in reducing atmosphere to produce elemental iron, which is finer than the direct addi...

Embodiment 3

[0154] This embodiment discloses a method for preparing high-purity α-silicon nitride powder, which includes the following steps.

[0155] 100-mesh high-purity coarse silicon powder is used as raw material, and the total content of Fe, Al, Ca, Cr, Ni, Cu, Zn and other impurities in the raw material matrix is ​​less than 50ppm; jet milling is used to obtain fine silicon powder with D50=12μm and D90=45μm.

[0156] Add Al with a molar ratio of 1:1 to the above fine silicon powder 2 o 3 and Fe 2 o 3 Powder, the specific addition amount is converted according to the metal content, adjusted to a total metal content of about 500ppm in the mixture, and mixed evenly with a V-type mixer.

[0157] Put the above mixture code into a nitriding furnace for nitriding, the total gas pressure is 0.4MPa, and the initial atmosphere volume ratio is 13% hydrogen, 2% chlorine, 40% nitrogen, and 45% argon; the volume ratio of hydrogen and chlorine is The total volume ratio of nitrogen and argon r...

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Abstract

The invention provides a method for preparing high-purity alpha-silicon nitride powder and high-purity alpha-silicon nitride powder. The method comprises the steps that: a catalyst is added into fine silicon powder with the particle size being 100 micrometers or below, and the catalyst can generate a metal compound through a reversible reaction under the reaction condition for preparing the silicon nitride powder, and a metal halide can exist; and the fine silicon powder added with the catalyst is putted into a nitriding furnace, and heat preservation is carried out for 50-180 hours at the temperature of 1050-1400 DEG C in a mixed atmosphere of nitrogen and argon so as to carry out nitriding reaction to obtain the silicon nitride powder. According to the method disclosed by the invention, through the special effects that the catalyst for forming the volatile metal halide through the reversible reaction is transported back and forth among the surfaces of the powder particles, repeatedly plays a catalytic role at a plurality of sites and fully catalyzes the surface reaction with fewer metal impurities, so that the purity of the product is guaranteed, and the alpha-phase content of the product is increased, and the requirements of high-purity silicon nitride powder are met.

Description

technical field [0001] The invention belongs to the technical field of inorganic non-metallic materials, and in particular relates to a method for preparing high-purity α-silicon nitride powder and a high-purity α-silicon nitride powder. Background technique [0002] Silicon nitride ceramic is an important engineering ceramic material and electronic ceramic material. It has excellent properties such as high hardness, high strength, high toughness, low thermal expansion coefficient, excellent thermal shock resistance and electrical insulation. It is used in light metal smelting and semiconductor manufacturing. , high-precision bearings, industrial cutting tools, power electronic devices and other fields have been widely used. [0003] However, the presence of transition metal impurities can reduce the hardness, strength, and especially high-temperature mechanical properties of silicon nitride ceramic materials. Therefore, high-purity high-quality silicon nitride powder is ve...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B21/068
CPCC01B21/068C01P2004/61C01P2006/80
Inventor 张耀华王思嘉李小东马海安宗鑫张吉武黄彬
Owner XINJIANG JINGSHUO NEW MATERIALS CO LTD
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