Preparation method of silicon nitride ceramic

A technology of silicon nitride ceramics, -si3n4, applied in the field of preparation of silicon nitride ceramics, can solve the problems of difficulty in realizing industrialization, high cost, low self-diffusion coefficient, etc., and achieve easy industrial production, excellent performance, widen Effects in the field of application

Inactive Publication Date: 2009-10-14
SHANDONG GUIYUAN ADVANCED CERAMICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Since silicon nitride is a strong covalent bond compound, the self-diffusion coefficient is very low, and only when the sintering temperature is close to the decomposition temperature of silicon nitride, can there be sufficient ion migration speed, so it is difficult to obtain dense silicon nitride ceramics by solid phase sintering
Therefore, oxide sintering aids are often added, which react with the silicon dioxide and silicon nitride on the surface at high temperatures to form oxynitride liquid phases to promote sintering, but these liquid phases often form amorphous glass phases or crystals during cooling. Boundary precipitates exist between silicon nitride grains, which greatly affect the performance of silicon nitride ceramics. In order to obtain high-performance silicon nitride ceramic materials, hot pressing sintering process is often used, which consumes a lot of energy and costs high , and can only manufacture products with relatively simple shapes, it is difficult to realize industrialization, which limits the application field of silicon nitride ceramics

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The preparation method of silicon nitride ceramics of the present invention comprises batching, molding and firing, and its batching weight percentage is composed of:

[0022] α-Si 3 N 4 Powder 85%, AL 2 o 3 10%, ZrO 2 4% and Y 2 o 3 1%.

[0023] in:

[0024] α-Si 3 N 4 The α-phase content in it is 90%.

[0025] The particle size of the ingredients is controlled separately: α-Si 3 N 4 2-30μm, AL 2 o 3 1-3μm, ZrO 2 0.5-1μm and Y 2 o 3 1-2μm.

[0026] Mix the ingredients evenly by ball milling with water as the medium, then add 1.0% polyvinyl alcohol and mix for 2 hours to obtain the slurry, dry and granulate, the granulation is controlled between 60-120 mesh sieve, and isostatic pressing under 150Mpa pressure The molded green body is dried and then fired at 1650°C under the protection of a nitrogen atmosphere and kept for 3 hours.

[0027] The technical index of the obtained silicon nitride ceramic product is: density 3.05g / cm 3 , The bending s...

Embodiment 2

[0029] The preparation method of silicon nitride ceramics of the present invention comprises batching, molding and firing, and its batching weight percentage is composed of:

[0030] α-Si 3 N 4 Powder 86%, AL 2 o 3 8%, ZrO 2 4% and Y 2 o 3 2%.

[0031] in:

[0032] α-Si 3 N 4 The α-phase content in it is 89%.

[0033] The particle size of the ingredients is controlled separately: α-Si 3 N 4 2-30μm, AL 2 o 3 1-3μm, ZrO 2 0.5-1μm and Y 2 o 3 1-2μm.

[0034] Mix the ingredients evenly by ball milling with water as the medium, then add 1.1% polyvinyl alcohol and mix for 2.5 hours to obtain the slurry, dry and granulate, the granulation is controlled between 60-120 mesh sieve, and isostatic pressing under 150Mpa pressure The molded green body was dried and fired at 1700°C under the protection of nitrogen atmosphere for 3 hours.

[0035] The technical index of the obtained silicon nitride ceramic product is: density 3.09g / cm 3 , Room temperature flexural strength...

Embodiment 3

[0037] The preparation method of silicon nitride ceramics of the present invention comprises batching, molding and firing, and its batching weight percentage is composed of:

[0038] α-Si 3 N 4 Powder 88%, AL 2 o 3 6%, ZrO 2 5% and Y 2 o 3 1%.

[0039] in:

[0040] α-Si 3 N 4 The α-phase content in the product is 92%.

[0041] The particle size of the ingredients is controlled separately: α-Si 3 N 4 2-30μm, AL 2 o 3 1-3μm, ZrO 2 0.5-1μm and Y 2 o 3 1-2μm.

[0042] Mix the ingredients evenly by ball milling with water as the medium, then add 1.2% polyvinyl alcohol and mix for 2 hours to obtain a slurry, dry and granulate, and control the granulation between 60-120 mesh sieves, and press isostatically under a pressure of 160Mpa The molded green body was dried and fired at 1720°C under nitrogen atmosphere protection, and kept for 4 hours.

[0043] The technical index of the obtained silicon nitride ceramic product is: density 3.09g / cm 3 , The bending stre...

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Abstract

The invention relates to a preparation method of a silicon nitride ceramic, which belongs to the technical field of the special ceramic. The method comprises the following steps of blending, molding and burning and is characterized in that the silicon nitride ceramic comprises the following components of 82-88 percent of alpha-Si3N4 powder, 5-10 percent of AL2O3, 3-6 percent of ZrO2 and 1-3 percent of Y2O3 by weight; the components are evenly mixed by ball milling by taking water as the medium, then the polyvinyl alcohol with 0.8-1.2 percent of the total component weight is added in for mixing for 1-5-3 hours to obtain pulp, the pulp is dried for granulation, and the isostatic compaction is performed at the pressure of 110-180 MPa to obtain blank; the blank is loaded in a nitriding furnace and is protected in the nitrogen atmosphere, and the burnt temperature is controlled between 1550-1720 DEG C. The invention is low in cost, is easy for realization of the industrialization production and extends the application range.

Description

technical field [0001] The invention relates to a method for preparing silicon nitride ceramics, which belongs to the field of special ceramic bases. Background technique [0002] As a high-temperature structural ceramic, silicon nitride ceramics have excellent performance, and have special use value in high-temperature, high-speed, and strong corrosive media. growing. [0003] Since silicon nitride is a strong covalent bond compound, the self-diffusion coefficient is very low, and only when the sintering temperature is close to the decomposition temperature of silicon nitride, there is sufficient ion migration speed, so it is difficult to obtain dense silicon nitride ceramics by solid phase sintering . Therefore, oxide sintering aids are often added, which react with the silicon dioxide and silicon nitride on the surface at high temperatures to form oxynitride liquid phases to promote sintering, but these liquid phases often form amorphous glass phases or crystals during ...

Claims

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Application Information

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IPC IPC(8): C04B35/622C04B35/584C04B35/64
Inventor 高礼文樊震坤许业静刘天程范勇刘宝英刘德军
Owner SHANDONG GUIYUAN ADVANCED CERAMICS
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