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Preparation method of Beta-Si3N4 single crystal

A -si3n4, single crystal technology, applied in the field of preparation of Si3N4 single crystal, can solve the problems of grain collision, equipment corrosion, product mixing, etc., and achieve the effect of increased aspect ratio, complete crystal form and good integrity

Inactive Publication Date: 2011-09-21
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the invention is to solve the problem of preparing β-Si in the prior art 3 N 4 The method of single crystal exists in the product mixed with impurities, β-Si 3 N 4 The size of the single crystal is not easy to control, the use of additives causes equipment corrosion, the exhaust gas is harmful to the environment, and the crystal grains will collide with each other during the preparation of dense materials. β-Si 3 N 4 Single crystal preparation method

Method used

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  • Preparation method of Beta-Si3N4 single crystal
  • Preparation method of Beta-Si3N4 single crystal
  • Preparation method of Beta-Si3N4 single crystal

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specific Embodiment approach 1

[0008] Specific implementation mode 1: this implementation mode β-Si 3 N 4 The preparation method of single crystal is carried out according to the following steps: 1. Take α-Si by weight ratio 20~99: 1~80 3 N 4 Powder and additives, after mixing, add polyvinyl alcohol aqueous solution with a concentration of 0.5% to 5% by weight, and ball mill and mix for 1 to 24 hours to obtain mud; 2. Pour the mud into an open graphite container, and then put 3. Place the graphite container containing the green body in a high-temperature furnace, and then heat-preserve and sinter it in a nitrogen atmosphere with a temperature of 1400-2200°C and a pressure of 0.1-10MPa for 0.1-10h to obtain Block; 4. Break the block, put it in 400℃ molten NaOH for 1-30min, collect the precipitate, and then wash it with water for 3-5 times to get β-Si 3 N 4 single crystal; wherein the structural formula of the additive in step 1 is: MO·mAl 2 o 3 · nSiO2 2 , M is one or more of Mg, Ca, Sr, Ba, m=0~2, n=...

specific Embodiment approach 2

[0018] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that α-Si in step 1 3 N4 The particle size of the powder is 0.1-10 μm, and the mass purity is greater than 99.5%. Other steps and parameters are the same as those in Embodiment 1.

specific Embodiment approach 3

[0019] Embodiment 3: This embodiment differs from Embodiment 2 in that in step 1, ball milling is mixed with zirconia, alumina or silicon nitride grinding balls, and the ball-to-material ratio is 5:1. Other steps and parameters are the same as in the second embodiment.

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Abstract

The invention provides a preparation method of Beta-Si3N4 single crystal, relating to the preparation method of Si3N4 single crystal. The method solves the problems of the prior art that the existing method for preparing the Beta-Si3N4 single crystal is prone to generate impurities in products, the size of the Beta-Si3N4 single crystal is not easy to control, use of the additives leads to corrosion to the equipment, the exhausted tail gas is harmful to the environment, and in the process of preparation, crystal grains collide with each other. The method comprises: 1. Alpha-Si3N4 powder and additives are weighed and blended before being added to aqueous polyvinyl alcohol solution, slurry is obtained after ball milling and blending; 2. the slurry is poured into a graphite container and dried to obtain a green body; 3. the graphite container is placed in a high temperature furnace for obtaining a block by atmosphere sintering; and 4. the block is smashed and placed in liquated NaOH, deposit is collected and washed, and the Beta-Si3N4 single crystal is obtained. The Beta-Si3N4 single crystal of the invention is of high purity and the diameter and length thereof can be controlled; moreover, the used additives do not corrode the equipment and no tail gas is generated.

Description

technical field [0001] The present invention relates to Si 3 N 4 Single crystal preparation method. Background technique [0002] β-Si 3 N 4 The tensile strength of single crystal is 30-50GPa, and it can withstand high temperature above 1400℃. Its crystal structure determines the β-Si 3 N 4 Single crystals can be grown into rod-shaped crystals with high aspect ratios, and as a reinforcing phase for ceramics, metals, and plastic-based composites, their strengthening and toughening effects are comparable to SiC whiskers. [0003] The name is "Method for preparing high-β-phase silicon nitride rod-shaped whiskers by self-propagating synthesis method (Chinese patent application number: 200710114558.2, application date: December 28, 2007, publication date: October 08, 2008)" and In the patent titled "Method for preparing β-silicon nitride whiskers by self-propagating high-temperature synthesis (Chinese patent number: ZL01126400.4, application date: August 3, 2001, publicatio...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B29/38
Inventor 叶枫刘利盟张海礁
Owner HARBIN INST OF TECH
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