Preparation method for high reliability large-scale silicon nitride ceramic material

A technology of silicon nitride ceramics and silicon nitride ceramic balls, which is applied in the field of preparation of silicon nitride ceramic materials, can solve the problems that cannot be used to prepare large-size bearing balls, reduce reliability, and be expensive, and achieve mass production , performance index improvement, and the effect of low production cost

Active Publication Date: 2009-09-23
BEIJING SINOMA SYNTHETIC CRYSTALS CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] There are various preparation techniques for silicon nitride bearing balls. R. L. Yeckley's invention patent "Silicon nitride bearing ball with high fatigue life" (public number CN1143944), Zhang Peizhi's invention patent "a large-size ceramic ball "Preparation method" (publication number CN101125755A) all adopt expensive hot isostatic pressing (HIP) sintering process, and the post-processing cost of bearing ball is high
Zhang Baolin's invention patent "Sialon ceramics for bearing balls and its preparation method" (publication number CN1270944) adopts air pressure sintering. Although it can reduce production costs and sinter silicon nitride bearing balls of close size, it uses more Y 2 o 3 、Al 2 o 3 , AlN causes the performance of silicon nitride material to decrease, the hardness is greater than 16.5GPa, and the room temperature fracture toughness is only 5.5-6.2MPa m 1 / 2 , the strength is only 607-756MPa, the reliability of silicon nitride ceramic balls used in a large load environment is reduced, and this invention mainly produces ceramic balls below 25.4mm, which cannot be used to prepare large-size bearing balls

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] According to the total weight of solid matter, Si with an average particle size of 0.8 μm 3 N 4 Micropowder is the main raw material (α-Si 3 N 4 Content is Si 3 N 4 95% of the total weight), adding 10% (weight) of silicon nitride nanopowder with an average particle diameter of 0.02 μm, 5% (weight) of MgO (purity 99.9%, average particle diameter of 0.5 μm), 2% (weight) of Ce 2 o 3 (purity 99.99%, average particle size 0.5 μ m), with silicon nitride grinding balls as the grinding medium, with absolute ethanol as the mixing medium in the stirring mill to stir for 6 hours, the solid phase content of the slurry is 45% of the weight of the slurry , preparing solid spherical particles with an average particle size of 50 μm by a closed circulation dryer.

[0021] After the granulated silicon nitride particles are cold isostatically pressed at 300 MPa into green spheres of Φ76 mm, they are put into an oven and dried at 60-80° C. for 24 hours. Under nitrogen or argon pres...

Embodiment 2

[0023] According to the total weight of solid matter, Si with an average particle size of 0.5 μm 3 N 4 Micropowder is the main raw material (α-Si 3 N 4 Content is Si 3 N 4 91% of the total weight), add 2% (weight) of Sm 2 o 3 (purity 99.99%, average particle size 0.8μm) and 2% (weight) of La 2 o 3 (purity 99.99%, average particle size 0.8 μm), using silicon nitride grinding balls as the grinding medium, gasoline as the mixing medium in a horizontal ball mill for 40 hours, the solid phase content of the slurry is 30% of the weight of the slurry. The slurry is dried at 100-120° C., pressed at 50 MPa, and then granulated to prepare silicon nitride particles with an average particle size of 100 μm.

[0024] After the granulated silicon nitride particles are cold isostatically pressed at 400 MPa into spheres of Φ128 mm, they are put into an oven and dried at 100-120° C. for 24 hours. Under nitrogen or argon pressure of 10MPa, heat preservation at 1850°C for 2 hours. The p...

Embodiment 3

[0026] According to the total weight of solid matter, Si with an average particle size of 0.5 μm 3 N 4 Micropowder is the main raw material (α-Si 3 N 4 Content is Si 3 N 4 95% of the total weight), adding 4.5% (weight) of MgO (purity 99.99%, average particle size 1 μm), 1% (weight) of La 2 o 3(purity 99.99%, average particle size 0.8 μ m), with silicon nitride grinding balls as grinding media, with isopropanol as the mixing medium in a horizontal ball mill to stir for 30 hours, the solid phase content of the slurry is 45% of the slurry weight %. The slurry is dried at 100-110° C., pressed at 100 MPa and then granulated to prepare silicon nitride particles with an average particle size of 100 μm.

[0027] After the granulated silicon nitride particles are cold isostatically pressed at 200 MPa into green spheres of Φ54 mm, they are put into an oven and dried at 110-120° C. for 24 hours. Under nitrogen or argon pressure of 2 MPa, heat preservation at 1800°C for 2 hours. ...

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Abstract

The invention provides a preparation method for high reliability large-scale silicon nitride ceramic material, which comprises the following steps: a sintering aid is added into silicon nitride powder and well bended in medium to prepare a ground paste; the ground paste is dried and then formed by isostatic cool pressing; atmosphere pressure sintering is carried out. The density of the silicon nitride bearing ball prepared by atmosphere pressure sintering is larger than 98.5%, the strength is 700-900 MPa, the fracture toughness property is 8-9MPa-m<1/2>, and the hardness is larger than 15 GPa; after hot isosotatic pressing treatment, the density of the silicon nitride bearing ball is larger than 99%, the strength is 800-1000 MPa, the fracture toughness property is 8-10MPa-m<1/2>, and the hardness is larger than 15 GPa; compared with the large-scale silicon nitride products prepared by the existing atmospheric pressure sintering process, the performance indexes of the silicon nitride ceramic material can fully meet the requirement of high-power aerogenerator on the large-scale bearing ball; the large quantities of production can be realized with relatively low manufacture cost.

Description

technical field [0001] The invention relates to a method for preparing a silicon nitride ceramic material, in particular to a method for preparing a silicon nitride ceramic material with high reliability and large size. Background technique [0002] Silicon nitride ceramic materials have excellent properties such as high strength, high rigidity, light specific gravity, wear resistance, corrosion resistance, thermal shock resistance, self-lubrication, maintenance-free and electrical insulation, and are currently the first choice for the production of various types of precision ceramic bearings. . Silicon nitride ceramic balls can also be widely used as valve balls, measuring balls, and grinding balls in aviation, aerospace, machinery, and chemical industries. For large-size silicon nitride bearing balls, because of their performance stability, reliability, and good mechanical and thermal properties, they have been used in the bearings of wind turbines abroad, which reduces t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/622C04B35/63
Inventor 张伟儒孙峰茹敏超丁艳
Owner BEIJING SINOMA SYNTHETIC CRYSTALS CO LTD
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