Preparation method of fiber toughened porous silicon nitride ceramics

A technology for toughening silicon nitride ceramics and fibers, which is applied in ceramic products, applications, household appliances, etc., can solve the undisclosed problems of strengthening porous silicon nitride ceramics, and achieve high toughness, high porosity, and simple preparation process Effect

Active Publication Date: 2019-08-09
XIAN AERONAUTICAL UNIV
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  • Abstract
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  • Claims
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Problems solved by technology

Existing research has not disclosed the method of preparing silicon nitride fiber reinforced porous silicon nitride ceramics by using melamine, tetraethyl orthosilicate and carbon quantum dots combined with molding process

Method used

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  • Preparation method of fiber toughened porous silicon nitride ceramics
  • Preparation method of fiber toughened porous silicon nitride ceramics
  • Preparation method of fiber toughened porous silicon nitride ceramics

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preparation example Construction

[0031] A method for preparing fiber-toughened porous silicon nitride ceramics of the present invention comprises the following steps:

[0032] S1, melamine is dissolved in formaldehyde and the first deionized water, by volume ratio, melamine: formaldehyde: the first deionized water=1: (2.5~3.5): (50~55), the water bath is heated to 60~ 75°C, and continue the reaction for 15-25 minutes to obtain a white transparent liquid of methylol melamine;

[0033] S2, dissolving ethyl orthosilicate in absolute ethanol and the second part of deionized water, ethyl orthosilicate: absolute ethanol: the quality of the second part of deionized water is 100: (25~30): (12 ~15), heated to 40~65°C under constant stirring, and continued to react for 20~30min to obtain a transparent solution.

[0034] S3. Mix the white transparent liquid obtained in step S1 with the transparent solution obtained in step S2, the volume ratio of white transparent liquid: transparent solution (1-2): 1, then heat to 60-...

Embodiment 1

[0042] (1) Heat the solution of melamine, formaldehyde and water with a volume ratio of 1:2.5:50 to 60°C in a water bath, and continue the reaction for 15 minutes to obtain a white transparent liquid of methylolmelamine;

[0043] (2) Heat a solution of tetraethyl orthosilicate, absolute ethanol, and deionized water at a mass ratio of 100:25:12 to 40° C. under constant stirring, and continue to react for 25 minutes to obtain a transparent solution.

[0044] (3) Mix the white transparent liquid of methylolmelamine obtained in step (1) and the transparent solution obtained in step (2) at a ratio of 1:1, then heat to 60°C, add nitric acid into the mixed transparent solution and keep stirring , adjust the pH value to 4 to form a gel;

[0045] (4) Dry the colloid obtained in step 3 in an oven at 70° C. for 24 hours to obtain xerogel powder.

[0046] (5) Mix and grind the dry gel powder prepared in step 4 and the carbon quantum dots according to the molar ratio of 1:2, and pass throug...

Embodiment 2

[0049] (1) Heat the solution of melamine, formaldehyde and water with a volume ratio of 1:3.5:55 to 65°C in a water bath, and continue the reaction for 15 minutes to obtain a white transparent liquid of methylolmelamine;

[0050] (2) Heat a solution of tetraethyl orthosilicate, absolute ethanol and deionized water at a mass ratio of 100:30:15 to 60° C. under constant stirring, and continue to react for 20 minutes to obtain a transparent solution.

[0051] (3) Mix the white transparent liquid of methylol melamine obtained in step (1) with the transparent solution obtained in step (2) at a ratio of 2:1, then heat to 75°C, add nitric acid into the mixed transparent solution and stir continuously, Adjust the pH value to 1 to form a gel;

[0052] (4) Dry the colloid obtained in step 3 in an oven at 80° C. for 18 hours to obtain xerogel powder.

[0053] (5) Mix and grind the dry gel powder prepared in step 4 and carbon quantum dots according to the molar ratio of 1:2.2, and pass th...

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Abstract

The invention discloses a preparation method of fiber toughened porous silicon nitride ceramics. The method comprises the steps that carbon quantum dots serving as carbon precursors, melamine and supramolecular gel of silicon dioxide serve as a carbon source, a nitrogen source and a silicon source. Melamine, formaldehyde, tetraethyl orthosilicate, anhydrous ethanol, acid and deionized water are prepared into gel, drying, grinding and sieving are conducted, compression molding is conducted to form a green body, the green body is subjected to first sintering in an argon atmosphere and second sintering in a nitrogen atmosphere, and then the fiber toughened porous silicon nitride ceramics are obtained. The preparation method has the advantages of being simple in preparation process, controllable in pore structure, high in porosity of prepared samples, high in fracture toughness of the prepared samples and the like; the method can be applied in various fields such as dust removal, purification, waste gas filtration and noise absorption, and technical support is provided for economic sustainable development of the country and regions.

Description

technical field [0001] The invention belongs to the technical field of preparation of fiber-toughened porous silicon nitride ceramics, and in particular relates to a preparation method of fiber-toughened porous silicon nitride ceramics. Background technique [0002] Porous silicon nitride ceramics have excellent electrical, thermal and mechanical properties. It not only highlights the advantages of hardness, heat resistance, wear resistance and corrosion resistance of general ceramic materials, but also has good thermal shock resistance, high temperature creep resistance, Good self-lubrication, chemical stability and other characteristics, [0003] However, due to the high brittleness and low impact resistance of porous silicon nitride ceramics, it is necessary to add some energy-absorbing mechanisms to the ceramic material to enhance the fracture toughness of the ceramic material. The main method to improve the toughness of ceramic materials is to introduce ceramic reinfor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B38/02C04B35/591C04B35/80C04B35/622
CPCC04B35/806C04B35/591C04B35/622C04B38/02C04B2235/422C04B2235/48C04B2235/524C04B2235/6562C04B2235/6567C04B2235/658C04B2235/96C04B38/0074
Inventor 于方丽张海鸿唐健江谢辉张阔程娅伊罗西希张亚龙
Owner XIAN AERONAUTICAL UNIV
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