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Corrosion-resistant silicon nitride ceramic and preparation method thereof

A technology of silicon nitride ceramics and corrosion resistance, applied in the field of silicon nitride ceramics, can solve the problems of poor corrosion resistance and low service life

Active Publication Date: 2020-11-27
SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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  • Abstract
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  • Application Information

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Problems solved by technology

[0003] Y 2 o 3 -Al 2 o 3 The system is the most commonly used sintering aid for silicon nitride ceramics, and the silicon nitride ceramics prepared with it as a sintering aid have high bending strength and fracture toughness, but Y 2 o 3 -Al 2 o 3 The corrosion resistance of the grain boundary phase formed during the sintering process of silicon nitride is relatively poor, which leads to the low service life of silicon nitride ceramics prepared by using it as a sintering aid in some highly corrosive environments

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  • Corrosion-resistant silicon nitride ceramic and preparation method thereof
  • Corrosion-resistant silicon nitride ceramic and preparation method thereof
  • Corrosion-resistant silicon nitride ceramic and preparation method thereof

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preparation example Construction

[0040] The invention provides a method for preparing the above-mentioned corrosion-resistant silicon nitride ceramics, comprising the following steps:

[0041] (1) Mix silicon nitride powder, calcium hexaaluminate powder, silicon carbide powder, chromium oxide powder, silicon dioxide powder with a solvent, and grind to obtain a mixed powder slurry;

[0042] (2) adding a binder to the mixed powder slurry, followed by stirring and mixing and spray drying to obtain granulated powder;

[0043] (3) performing dry pressing and cold isostatic pressing to the granulated powder successively to obtain ceramic samples;

[0044] (4) Debinding and gas pressure sintering are performed sequentially on the ceramic sample blocks to obtain silicon nitride ceramics with high corrosion resistance.

[0045]The invention mixes silicon nitride powder, calcium hexaaluminate powder, silicon carbide powder, chromium oxide powder and silicon dioxide powder with a solvent, grinds them, and obtains a mix...

Embodiment 1

[0054] (1) Silicon nitride powder (α-Si 3 N 4 content is 91%, oxygen content is 2%, particle size D50 is 5 μm), 5% calcium hexaaluminate powder (purity is 99.5%, particle size D50 is 20 μm), 5.5% silicon carbide powder (purity is 98.5% , particle size D50 is 5 μm), 2% chromium oxide powder (purity is 99.5%, particle size D50 is 1 μm), 0.5% silica powder (purity is 99.9%, particle size D50 is 0.5 μm) put into sand Grinding in the mill for 2 hours at a speed of 1000r / min, the grinding solvent is absolute ethanol, the grinding medium is silicon nitride balls, the ball-to-material ratio is 3:1, and a mixed powder slurry with a solid content of 45% is obtained after grinding , the particle size D50 of the mixed powder is 0.8 μm;

[0055] (2) Add 1% polyvinyl butyral (PVB) and 1.5% polyacrylic acid emulsion with a solid content of 50% to the slurry, stir for 4 hours, and spray dry under nitrogen protection pressure to obtain granules Granulated powder with a diameter D50 of 100 μ...

Embodiment 2

[0062] (1) Silicon nitride powder (α-Si 3 N 4 content is 91%, oxygen content is 2%, particle size D50 is 5μm), 6% silicon carbide powder (purity is 98.5%, particle size D50 is 5μm), 5% calcium hexaaluminate powder (purity is 99.5% , particle size D50 is 20 μm), 1% chromium oxide powder (purity is 99.5%, particle size D50 is 1 μm), 1% silica powder (purity is 99.9%, particle size D50 is 0.5 μm) put into sand Grinding in the mill for 2 hours at a speed of 1000r / min, the grinding solvent is absolute ethanol, the grinding medium is silicon nitride balls, the ball-to-material ratio is 3:1, and a mixed powder slurry with a solid content of 45% is obtained after grinding , the particle size D50 of the mixed powder is 0.8 μm;

[0063] (2) Add 1% PVB of mixed powder mass and 1.5% polyacrylic acid emulsion with a solid content of 50% to the slurry, stir for 4 hours, and obtain a granulated powder with a particle diameter D50 of 100 μm by spraying and drying under nitrogen protection p...

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Abstract

The invention provides corrosion-resistant silicon nitride ceramic as well as a preparation method and an application thereof, and belongs to the technical field of preparation of silicon nitride ceramic. The corrosion-resistant silicon nitride ceramic is prepared from the following raw materials in percentage by mass: 75-92% of silicon nitride powder; 2-10% of calcium hexaluminate powder; 3-15% of silicon carbide powder; 0.5-5% of chromium oxide powder; and 0.2-3% of silica powder. According to the invention, calcium hexaluminate is used as a main sintering aid; chromium oxide and silicon dioxide are used as auxiliary sintering aids, calcium hexaluminate has excellent corrosion resistance and can form a high-corrosion-resistance grain boundary phase in the sintering process, so that the corrosion resistance of the silicon nitride ceramic is improved, and the obtained silicon nitride ceramic has a low weight reduction rate and a low bending strength reduction rate in an acidic or alkaline environment.

Description

technical field [0001] The invention relates to the technical field of silicon nitride ceramics, in particular to a corrosion-resistant silicon nitride ceramic and a preparation method thereof. Background technique [0002] Silicon nitride ceramics have excellent comprehensive properties and are widely used as engineering ceramic materials in the fields of machinery, metallurgy, chemical industry, electronics and aerospace. Silicon nitride is a compound with strong covalent bonds, and its self-diffusion coefficient is very low. It needs to add a certain amount of sintering aids to achieve densification through liquid phase sintering. After the sintering is completed, the liquid phase formed by the sintering aid exists in the silicon nitride ceramics as a grain boundary phase, which has an important influence on the performance of the silicon nitride ceramics. [0003] Y 2 o 3 -Al 2 o 3 The system is the most commonly used sintering aid for silicon nitride ceramics, and ...

Claims

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Application Information

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IPC IPC(8): C04B35/596C04B35/622C04B35/626C04B35/634C04B35/638C04B35/64
CPCC04B35/587C04B35/622C04B35/6261C04B35/6342C04B35/63424C04B35/638C04B35/64C04B2235/3826C04B2235/3208C04B2235/3222C04B2235/3418C04B2235/3241C04B2235/5436C04B2235/5445C04B2235/658C04B2235/656C04B2235/6567C04B2235/9692
Inventor 张伟儒张晶孙峰袁磊李新刘新宇司尚进张宝存荆赫俆金梦李洪浩
Owner SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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