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a cr 2 o 3 Doped silica airgel material and preparation method thereof

A silica and aerogel technology, which is applied in the field of Cr2O3 doped silica aerogel material and its preparation, can solve the problems of uneven distribution of doping ions, influence on thermal insulation stability, uneven distribution, etc. The effect of uniform dispersion, improved thermal insulation performance and stability, and improved complexing force

Active Publication Date: 2017-12-26
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Generally, powder doping and in-situ ion doping are used for doping. The powder doping method is easy to cause problems such as powder agglomeration and uneven distribution. After continuous technical research, in-situ ion doping effectively solves the problems of powder agglomeration. The dispersion uniformity of hetero ions has been greatly improved, but in the study of airgel doping modification, it is found that doped ions are easy to be hydrothermal and solvothermal in subsequent gel treatment due to their ionic radius. Migration of dopant ions occurs during the reaction, resulting in uneven distribution of dopant ions and affecting the thermal insulation stability of the final product

Method used

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  • a cr <sub>2</sub> o <sub>3</sub> Doped silica airgel material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] (1) Preparation of composite sol

[0041] Silica water sol, chromium chloride aqueous solution, and complexing agent are mixed in a molar ratio of 1:0.05:0.08, and an acid-base catalyst is added to form a composite sol.

[0042] (2) Dipping

[0043] Add the sol to a bulk density of 0.08g / cm 3 The mold of the mullite fiber felt relies on gravity impregnation.

[0044] (3) Gel and Aging

[0045] The mold was placed at 25° C. for 8 hours to form a gel, and then placed at 50° C. for 72 hours. After the mold was naturally cooled to room temperature, the mold was removed to obtain a fiber-reinforced wet gel.

[0046] (4) Solvent replacement

[0047] The wet gel is placed in absolute ethanol so that the water content is lower than 1% (mass ratio).

[0048] (5) Supercritical drying

[0049] Put the wet gel into the autoclave, inject 5MPa carbon dioxide, and keep it warm at 40°C for 15 hours; then raise the temperature to 50°C, and the carbon dioxide will bring the ethanol i...

Embodiment 2

[0054] The silicon dioxide hydrosol, the chromium acetate aqueous solution, and the complexing agent are mixed in a molar ratio of 1:0.10:0.08, and an acid-base catalyst is added to form a complex sol. Pre-impregnated with sol with a bulk density of 0.08g / cm 3 The quartz fiber felt is then loaded into the mold cavity, added with sol, and impregnated by pressure. The mold was placed at 40°C for 24 hours to form a gel, and then placed at 60°C for 48 hours. After the mold was naturally cooled to room temperature, the mold was removed to obtain a fiber-reinforced wet gel. The wet gel is placed in ethanol so that the water content is lower than 1% (mass ratio). Carry out supercritical drying according to the method described in Example 1. The obtained fiber-reinforced airgel thermal insulation material was subjected to high-temperature pretreatment under the air condition of 800°C, the heating rate was 8°C / min, and the holding time was 2 hours. After high-temperature pretreatment...

Embodiment 3

[0057] Methyl orthosilicate, chromium sulfate alcohol solution, and complexing agent are mixed in a molar ratio of 1:0.25:0.10, and a catalyst is added to form a composite sol. Directly pass the sol through a vacuum device and inject it into a device with a bulk density of 0.50g / cm 3 The glass fiber wool is impregnated in the mold cavity. The mold was placed at 40°C for 10 hours to form a gel, and then placed at 80°C for 96 hours. After the mold was naturally cooled to room temperature, the mold was removed to obtain a fiber-reinforced wet gel. The wet gel is placed in propanol so that the water content is lower than 1% (mass ratio). Carry out supercritical drying according to the method described in Example 1. The obtained fiber-reinforced airgel thermal insulation material is subjected to high-temperature pretreatment under the air condition of 600°C, the heating rate is 3°C / min, and the holding time is 2 hours. After high-temperature pretreatment, the airgel thermal insul...

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Abstract

The invention provides a Cr2O3 doped silicon dioxide aerogel material and a preparation method thereof. The preparation method of the Cr2O3 doped silicon dioxide aerogel material comprises the following steps: taking a silicon source as a precursor, adopting an inorganic compound containing the Cr element and an organic compound as doping ions, mixing the compounds with a solvent, a complexing agent and a catalyst to form a composite sol, conducting impregnation technology to be compounded with reinforced fibers, carrying out gelatinizing, ageing, solvent replacement, supercritical carbon dioxide drying, high-temperature pretreatment and other technologies to obtain the product. The preparation method disclosed by the invention is to conduct metal Cr doping and modification on the aerogel through a complexing-gelatinizing method, skillfully combine the complexing reaction with the gelatinizing reaction to increase the complexing force of the metal Cr doping ions in the gel system, effectively restrain the phenomenon that the Cr is not uniform in distribution as the Cr ions are migrated during the follow-up treatment process of the gel, so that the diffusion effect of the complexing-gelatinizing method is uniform and stable, and the complexing-gelatinizing method is better than the in-situ doping method. The aerogel obtained by the complexing-gelatinizing method is treated in advance at high temperature, so as to enable the internal reaction to be conducted thoroughly under high-temperature action, then transform the aerogel to be the Cr2O3 doped stable aerogel structure, and facilitate the pore structure and the heat-insulating property to be stable.

Description

technical field [0001] The present invention relates to a Cr 2 o 3 The invention relates to a doped silicon dioxide airgel material and a preparation method thereof, which belong to the technical field of aerospace heat protection. Background technique [0002] With the continuous advancement of aerospace and aviation technology, various types of aircraft will face various special aerodynamic and thermal environments. Aerodynamic heating is serious during flight. In order to solve the problem of heat protection and heat insulation, a heat protection and heat insulation system needs to be introduced into the structure of the projectile body, shell, hot air channel and engine to protect the normal service of various equipment and materials. At the same time It also needs to meet the requirements of light weight, high temperature resistance, and efficient heat insulation. All kinds of aircraft are on the road of new type, diversification, and speed, and the indicators of lig...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/78C04B35/82C04B35/14C04B35/622
Inventor 裴雨辰周玉贵李文静赵英民张丽娟刘斌詹万初黄娣苏力军邹军锋
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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