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Short SiC fiber/SiO2 aerogel composite material and preparation method thereof

A technology of silicon carbide fiber and composite material, which is applied in the field of short silicon carbide fiber/SiO2 airgel composite material and its preparation, can solve the problems of poor high temperature stability, low airgel strength, and high cost, and achieve low cost and thermal conductivity The effect of low coefficient and simple preparation method

Inactive Publication Date: 2015-06-10
金成
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to improve the current problems of low strength, poor high temperature stability and high cost of pure silicon-based and aluminum-based aerogels, the present invention provides a short silicon carbide fiber / SiO 2 Airgel composite thermal insulation material and preparation method thereof, the method adopts water glass which is environmentally friendly, non-toxic and low in cost as a precursor, ethanol as a solvent, hexamethyldisiloxane or hexamethyldisiloxane or hexamethyldisiloxane with low cost and low toxicity Using disiloxane as the surface modifier, ethylene glycol and methanol as the replacement solvent, finally prepared short silicon carbide fibers / SiO with high temperature resistance (temperature greater than 1000°C) and thermal conductivity of 0.020-0.035W / m·k 2 Airgel composite thermal insulation material

Method used

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  • Short SiC fiber/SiO2 aerogel composite material and preparation method thereof
  • Short SiC fiber/SiO2 aerogel composite material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 1) Cut and grind long SiC fibers into short fibers with a diameter of 8-15um and a length of less than 1mm;

[0022] 2) Mix silica sol, ethanol, water and hexamethyldisiloxane in a molar ratio of 1:4:6:0.05 and stir evenly, add 0.5mol / l hydrochloric acid to adjust the pH to 2.5, stir for 20min, then add 0.1 mol / l ammonia water, adjust the pH to 5.0, stir for 60 min, and mix evenly to obtain a silica sol.

[0023] 3), get the short SiC fiber in step 1) (accounting for SiO 2 The mass percentage of sol is 5%) adding SiO 2 The sol was mixed and stirred evenly, and after standing for 9 minutes, the gel was aged, and the surface was modified (hexamethyldisiloxane modifier) ​​and solvent exchanged with ethylene glycol and methanol (each 24 hours).

[0024] 4) Drying under normal pressure at 60°C (2h) and 80°C (2h) respectively to obtain short SiC fiber-composite silica airgel composite materials.

[0025] After testing, it was found that the density of the material is 0.2g / ...

Embodiment 2

[0027] 1) Cut and grind long SiC fibers into short fibers with a diameter of 8-15um and a length of less than 1mm;

[0028] 2) Mix silica sol, ethanol, water and hexamethyldisiloxane in a molar ratio of 1:2:8:0.03 and stir evenly, add 0.5mol / l hydrochloric acid to adjust the pH to 3.0, stir for 25min, then add 0.1 mol / l ammonia water, adjust the pH to 5.5, stir for 50 minutes, and mix evenly to obtain a silica sol.

[0029] 3), get the short SiC fiber in step 1) (accounting for SiO 2 The mass percent of sol is 8%) adding SiO 2 The sol was mixed and stirred evenly, and after standing for 8 minutes, the gel was aged, and the surface was modified (hexamethyldisiloxane modifier) ​​and solvent exchanged with ethylene glycol and methanol (each 24 hours).

[0030] 4) Drying under normal pressure at 60°C (2h), 80°C (2h), and 100°C (2h) respectively to obtain short SiC fiber-composite silica airgel composite materials.

[0031] After testing, it was found that the specific surface a...

Embodiment 3

[0033] 1) Cut and grind long SiC fibers into short fibers with a diameter of 8-15um and a length of less than 1mm;

[0034] 2) Mix silica sol, ethanol, water and hexamethyldisiloxane in a molar ratio of 1:6:6:0.04 and stir evenly, add 0.5mol / l hydrochloric acid to adjust the pH to 3.5, stir for 25min, then add 0.1mol / l ammonia water, adjust the pH to 6.5, stir for 50min, and mix evenly to obtain a silica sol.

[0035] 3), get the short SiC fiber in step 1) (accounting for SiO 2 The mass percent of sol is 10%) adding SiO 2 The sol was mixed and stirred evenly, and after standing for 7 minutes, the gel was aged, and the surface was modified (hexamethyldisiloxane modifier) ​​and solvent exchanged with ethylene glycol and methanol (each 24 hours).

[0036] 4) Drying under normal pressure at 60°C (2h) and 80°C (4h) respectively to obtain short SiC fiber-composite silica airgel composite materials.

[0037] After testing, it was found that the specific surface area of ​​the materia...

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Abstract

The invention provides a short SiC (Silicon Carbide) fiber / SiO2 (Silicon Dioxide) aerogel heat-insulation composite material and a preparation method thereof. The composite material is characterized by being prepared from a SiC fiber and SiO2 collosol. The preparation method comprises the following steps; adding the SiC fiber to the SiO2 collosol, mixing uniformly, standing to form a gel, and aging to form alcogel; soaking the alcogel in absolute ethyl alcohol; modifying the surface of the alcogel by hexamethyldisiloxane or hexamethyl disiloxane; replacing a solvent in the alcogel with glycol and methanol respectively; and performing atmospheric pressure drying on a gel at different temperatures, thereby obtaining the short SiC fiber / SiO2 aerogel composite material. The composite material prepared by the method has the characteristics of large specific surface area, low heat conductivity factor, high-temperature resistance and the like, and the preparation method is simple and low in cost, and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of airgel composite materials, and particularly provides a short silicon carbide fiber / SiO 2 Airgel composite material and method for its preparation. Background technique [0002] As one of the most potential thermal insulation materials at present, airgel has many unique properties, such as low density, low porosity, large specific surface area, low thermal conductivity, high visible light transmittance, low refractive index, dielectric constant Low and excellent properties, so it is expected to be used in thermal insulation, catalyst and carrier, optics, electricity, sound insulation and other fields through process adjustment and control. Airgel is a form of solid matter, the solid with the smallest density in the world, with a density of 3kg / m3, it is a mesoporous material with a three-dimensional network structure, the pore size is between 1-100nm, and the skeleton size is ten A few nanometers, the specific su...

Claims

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Application Information

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IPC IPC(8): C04B28/24C04B14/38
Inventor 金成
Owner 金成
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