Silicon nitride nanoribbon aerogel and preparation method thereof

A silicon nitride and nanobelt technology, applied in ceramic products, other household appliances, applications, etc., can solve the problems of long cycle, low output and high cost, and achieve the effect of increasing growth space and high purity

Active Publication Date: 2019-05-03
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the previous research process, we applied for a patent (application number: 201610566429.6) on "compressible and recoverable silicon nitride nanowire airgel and its preparation technology", which is to prepare nanowire paper by quasi-CVD method. After compounding, bulk aerogels are obtained. Although silicon nitride aerogels are prepared by this method, the output is low, the cycle is long, and the cost is high.

Method used

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  • Silicon nitride nanoribbon aerogel and preparation method thereof
  • Silicon nitride nanoribbon aerogel and preparation method thereof
  • Silicon nitride nanoribbon aerogel and preparation method thereof

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preparation example Construction

[0035] see figure 1 , is the process flow chart of the preparation method of the silicon nitride nanofiber airgel of the present invention, comprising the following steps:

[0036] 1) Using siloxane precursors, such as methyltrimethoxysilane and dimethyldimethoxysilane, as raw materials, water as a crosslinking agent, and absolute ethanol as a solvent, prepare a polysiloxane sol in a certain proportion;

[0037] 2) uniformly disperse a certain amount of chopped carbon fiber in the polysiloxane sol, so that the surface of the carbon fiber has a layer of siloxane sol;

[0038] 3) Forming: remove most of the silica sol, such as vacuum filtration or pressure filtration, so that the chopped carbon fibers form a three-dimensional porous carbon fiber skeleton bonded by polysiloxane sol;

[0039]4) Curing: place the three-dimensional porous carbon fiber skeleton in an environment of 80°C to 120°C for heat preservation for 4 to 8 hours;

[0040] 5) Cracking: Put the cured carbon fibe...

Embodiment 1

[0043] This embodiment has prepared the density is 5mg / cm 3 , and silicon nitride airgel with adjustable size and density, the specific steps are as follows:

[0044] 1) Prepare silica sol with methyltrimethoxysilane (mass fraction 10wt.%) and silica sol raw materials, water as crosslinking agent (mass fraction 30wt.%) and absolute ethanol as solvent (mass fraction 60wt.%) ;

[0045] 2) Disperse 2g of chopped carbon fibers (about 2mm in length) in 100ml of silica sol, and mechanically stir for 10min;

[0046] 3) The method of vacuum filtration is adopted to overlap the carbon fibers dispersed in the sol to form a three-dimensional porous carbon fiber skeleton;

[0047] 4) The porous carbon fiber skeleton is placed in an environment of 100 ° C, and heat preservation treatment is carried out for 4 hours;

[0048] 5) Raise the temperature to 1400°C in nitrogen with a pressure of 0.2Mpa, heat preservation treatment for 2 hours, and generate a large number of silicon nitride nan...

Embodiment 2

[0053] This embodiment has prepared the density is 15mg / cm 3 , and silicon nitride airgel with adjustable size and density, the specific steps are as follows:

[0054] 1) Using dimethyldimethoxysilane (mass fraction 40wt.%) as raw material, water as crosslinking agent (mass fraction 10wt.%) and absolute ethanol as solvent (mass fraction 50wt.%) to prepare polysilicon Oxygen sol;

[0055] 2) Disperse the chopped carbon fiber (about 1 mm in length) in the silica sol, and perform mechanical stirring for 10 minutes;

[0056] 3) The method of vacuum filtration is adopted to overlap the carbon fibers dispersed in the sol to form a three-dimensional porous carbon fiber skeleton;

[0057] 4) Place the porous carbon fiber skeleton in an oven at 70°C for 8 hours of heat preservation;

[0058] 5) Rise to 1550°C in nitrogen with a pressure of 0.5Mpa, heat preservation treatment for 2 hours, generate a large number of silicon nitride nanofibers in the carbon fiber skeleton, and cool wit...

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Abstract

The invention discloses a silicon nitride nanoribbon aerogel and a preparation method thereof, and the method comprises the following steps: 1) preparing polysiloxane sol; 2) preparing slurry; 3) constructing a three-dimensional porous carbon fiber framework formed by mutual lap joint of short-cut carbon fibers bonded by the siloxane sol; 4) curing and cracking, to be more specific, heating the three-dimensional porous carbon fiber framework to the curing temperature of the polysiloxane sol, carrying out heat preservation treatment, carrying out heating and heat preservation treatment in a nitrogen atmosphere, and cooling to the room temperature in a furnace so as to obtain a carbon fiber / silicon nitride nano fiber composite block body; and 5) decarbonizing, to be more specific, heating the carbon fiber / silicon nitride nano-fiber composite block to 400-1000 DEG C in air, and carrying out heat preservation treatment for 2-4 hours to obtain the silicon nitride nanoribbon aerogel. The silicon nitride nanoribbon aerogel prepared by the method has quite excellent high-temperature stability and thermal insulation performance, the brittleness problem of the traditional ceramic aerogel isovercome, expensive drying equipment and low-efficiency drying processes are not needed, and the silicon nitride nanoribbon aerogel is low in cost, high in efficiency and suitable for the fields of heat insulation, heat preservation, wave transmission and the like.

Description

technical field [0001] The invention belongs to the technical field of airgel preparation, and relates to a silicon nitride nanobelt airgel and a preparation method thereof. Background technique [0002] Airgel is the lightest solid known to human beings. It has ultra-high porosity, so it has excellent thermal insulation performance. It is considered to be the best new material to replace traditional thermal insulation materials. The service life of airgel is more than ten times that of traditional heat insulation materials, and airgel is used as heat insulation material, and the thickness of the required material is only one-fifth to one-half of traditional heat insulation materials , and the weight is lighter, which not only shows great application value in the civilian field, but also has unparalleled advantages in the field of military heat insulation. Up to now, the application of airgel in civil applications is mainly in the fields of thermal insulation of some indust...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/589C04B38/06
Inventor 王红洁于志明卢德苏磊李明主
Owner XI AN JIAOTONG UNIV
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