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Large-size silicon nitride ceramic ball and preparation method thereof

A silicon nitride ceramic ball and silicon nitride powder technology, applied in the field of ceramic materials, can solve the problems affecting the uniformity of the density and mechanical properties of ceramic balls, the difference in density and microstructure of ceramic ball cores, and large-scale ceramics. Problems such as large volume of the ball, to achieve the effect of increased density, high sphericity, and uniform density

Active Publication Date: 2021-07-20
SINOMA ADVANCED NITRIDE CERAMICS CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the large volume of large-sized ceramic balls, it is easy to form a temperature gradient during the sintering process, resulting in differences in the density and microstructure of the surface and core of the ceramic balls, thus affecting the uniformity of the density and mechanical properties of the ceramic balls

Method used

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  • Large-size silicon nitride ceramic ball and preparation method thereof
  • Large-size silicon nitride ceramic ball and preparation method thereof
  • Large-size silicon nitride ceramic ball and preparation method thereof

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preparation example Construction

[0030] The invention provides a kind of preparation method of silicon nitride ceramic ball, comprises the following steps:

[0031] The silicon nitride powder, the sintering aid and the reinforcing phase are ball-milled and mixed in absolute ethanol, and then granulated to obtain granulated powder;

[0032] Mix ammonium acrylate monomer, crosslinking agent, dispersant and water to obtain a premix;

[0033] Dispersing the granulated powder in the premixed liquid, adding a catalyst and an initiator to the resulting slurry to obtain a gelling slurry;

[0034] Carrying out vacuum coagulation molding to the coagulation slurry, and obtaining a ceramic ball green body after microwave drying;

[0035] Carrying out debinding, cold isostatic pressing, air pressure sintering and processing the ceramic ball green body in sequence to obtain silicon nitride ceramic balls; the diameter of the silicon nitride ceramic balls is 20-200mm;

[0036] The air pressure sintering method is two-step ...

Embodiment 1

[0062] raw material:

[0063] Silicon nitride powder (α-Si 3 N 4 The content is 93%, the average particle size D 50 0.7μm): 44kg

[0064] Alumina (purity 99.9%, average particle size D 50 1μm): 2kg,

[0065] Yttrium oxide (purity 99.9%, average particle size D 50 1μm): 3kg,

[0066] Titanium carbide (purity 99%, average particle size D 50 0.5μm): 1kg.

[0067] 1. Powder preparation

[0068] Mix the above raw materials in proportion, use absolute ethanol as a solvent to obtain a slurry with a solid phase content of 40%, the grinding medium is silicon nitride balls, and perform wet ball milling. The ball milling device is a horizontal ball mill, and the mixing time is 24h. The uniformly mixed slurry is spray-dried and granulated by using a nitrogen-protected centrifugal spray granulator to obtain granulated powder with a particle size of 20-200 μm.

[0069] 2. Injection forming

[0070] 1) Prepare the premix:

[0071] Dissolve 1.5kg of ammonium acrylate, 0.19kg of N,...

Embodiment 2

[0085] raw material:

[0086] Silicon nitride powder (α-Si 3 N 4 The content is 93%, the average particle size D 50 0.7μm): 45kg

[0087] Alumina (purity 99.9%, average particle size D 50 1μm): 1.5kg,

[0088] Yttrium oxide (purity 99.9%, average particle size D 50 1μm): 2kg,

[0089] Titanium nitride (99% purity, average particle size D 50 0.5μm): 1.5kg.

[0090] 1. Powder preparation

[0091] Mix the above raw materials in proportion, use absolute ethanol as a solvent to obtain a slurry with a solid phase content of 40%, the grinding medium is silicon nitride balls, and perform wet ball milling. The ball milling device is a horizontal ball mill, and the mixing time is 24h. The uniformly mixed slurry is spray-dried and granulated by using a nitrogen-protected centrifugal spray granulator to obtain granulated powder with a particle size of 20-200 μm.

[0092] 2. Injection forming

[0093] 1) Prepare the premix:

[0094] Dissolve 1.8kg of ammonium acrylate, 0.18kg o...

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Abstract

The invention provides a silicon nitride ceramic ball and a preparation method thereof, and belongs to the technical field of ceramic materials. According to the invention, a vacuum injection-coagulation forming method is adopted, so that the forming of large-size and oversized silicon nitride ceramic balls with high sphericity degree and uniform density can be realized. Microwave drying is adopted, the drying speed is high, and deformation of a green body is small. According to the invention, the cold isostatic pressing treatment is carried out on the degummed ceramic balls, so that the compactness of the sintered ceramic balls is improved. A two-step air pressure sintering process is adopted, so that internal air holes of the ceramic ball can be removed, and the density can be further improved. According to the invention, the surfaces and the core parts of the large-size and oversized silicon nitride ceramic balls prepared by adopting the method of combining injection coagulation forming with cold isostatic pressing forming and two-step air pressure sintering have no obvious difference in properties such as relative density, Vickers hardness and fracture toughness. Homogenization of density and mechanical properties of large-size and oversized silicon nitride ceramic balls can be realized.

Description

technical field [0001] The invention relates to the technical field of ceramic materials, in particular to a large-size silicon nitride ceramic ball and a preparation method thereof. Background technique [0002] Silicon nitride ceramics have the advantages of high strength, high hardness, high toughness, high temperature resistance, corrosion resistance, wear resistance and self-lubrication, and are ideal materials for rolling elements of bearings. Bearings with silicon nitride as rolling elements are especially suitable for use in high-speed, high-low temperature, lean oil lubrication and other working conditions, such as precision machine tool electric spindle bearings, electric vehicle bearings and wind power bearings. [0003] The general process for preparing silicon nitride ceramic balls is powder preparation, forming, sintering and grinding. Forming is one of the key process steps in the preparation of silicon nitride ceramic balls. The purpose is to obtain a ball b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/622C04B35/64
CPCC04B35/584C04B35/622C04B35/64C04B2235/6023C04B2235/3217C04B2235/3224C04B2235/3225C04B2235/3227C04B2235/3843C04B2235/3847C04B2235/3826C04B2235/3839C04B2235/3886
Inventor 张伟儒王文雪张晶孙峰李柏恒宋健张明帅李晓天张峰梅
Owner SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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