氧化铝气凝胶的合成与性能

doi:10.15541/jim20170180

摘要/Abstract

摘要：

氧化铝气凝胶具有大比表面积、高孔隙率以及比氧化硅气凝胶更优异的热稳定性, 在高温隔热和催化领域有广阔的应用前景, 但其复杂的合成工艺和较低的强度限制了其应用。本文首先介绍氧化铝气凝胶合成工艺, 指出溶胶-凝胶过程中存在的问题, 不同干燥方式的特点以及最新发展的干燥工艺; 然后介绍了近年来氧化铝气凝胶在比表面积、热稳定性、强度、导热系数等性能改善方面所取得的代表性研究成果; 最后介绍了氧化铝气凝胶在高温催化、隔热领域的应用, 并展望了未来氧化铝气凝胶的发展方向以及应关注的问题。

关键词: 氧化铝气凝胶, 合成, 性能, 比表面积, 热稳定性, 综述

Abstract:

Alumina aerogel has wide application prospect in high temperature thermal insulation and catalytic fields due to its high specific surface area, high porosity, and better thermal stability than silica aerogel. However, the complicated synthetic process and the low strength of alumina aerogel restrict their application. In this review, the synthetic process of alumina aerogel is firstly introduced. Some problems existed in the Sol-Gel process, the characteristics of various drying methods, and the latest drying methods developed by researchers are pointed out. Then, some representation achievements in the performance improvements on specific surface area, thermal stability, thermal conductivity and compressive strength of alumina aerogel in recent years are summarized. Finally, the development and application of alumina aerogel in high temperature catalytic and thermal insulation fields are introduced, their development tendency is prospected, and some issues on the study of alumina aerogel are highlighted.

Key words: alumina aerogel, synthesis, property, specific surface area, thermal stability, review

中图分类号:

TB332
O648

杨景锋, 王齐华, 王廷梅. 氧化铝气凝胶的合成与性能[J]. 无机材料学报, 2018, 33(3): 259-265.

YANG Jing-Feng, WANG Qi-Hua, WANG Ting-Mei. Synthesis and Property of Alumina Aerogel[J]. Journal of Inorganic Materials, 2018, 33(3): 259-265.

图/表 9

图1 乙酰乙酸乙酯的螯合机理[22]

Fig. 1 Ethyl acetoacetate chelating effect[22]

表1 几种干燥方式的特点

Table 1 Characteristics of several drying methods

Drying method	Characteristics
Drying method	Drying process	Alumina aerogel
Supercritical drying	Short drying period, high synthesis cost	Low density, high porosity and specific surface area, low volume shrinkage^[34,35]
Ambient pressure drying	Long drying period, inexpensive synthesis cost, complicated drying process	High volume shrinkage, large pore size, high density and low specific surface area^{[34,35,36,37]}
Freeze drying	Long drying period, inexpensive synthesis cost	High volume shrinkage, large pore size, high density and low specific surface area

图2 快速超临界干燥的模具装配示意图[6]

Fig. 2 Schematic diagram of the mold assembly used for RSCE[6]

图3 乙醇的相图[35]

Fig. 3 Phase diagram of ethanol[35]

图4 OSSD制备气凝胶的干燥机理示意图[39]

Fig. 4 Mechanism illustration of the formation of aerogels by OSSD[39]

图5 Al2O3气凝胶的应力应变曲线(a)和高温热处理前后Al2O3气凝胶(b)[48]

Fig. 5 Stress-strain curves of Al2O3 aerogels (a) and Al2O3 aerogels before and after heat treatment at high temperature (b)[48]

图6 C/Al2O3气凝胶不同温度热处理后的应力-应变曲线(a)和密度、导热系数变化(b)[50]

Fig. 6 Compressive stress-strain curves (a) and bulk densities and thermal conductivities (b) of C/Al2O3 aerogels heat treated at different temperatures[50]

图7 不同纤维素含量ACA的应力应变曲线(ACA0.5, ACA1, ACA2分别为纤维素含量0.5%, 1%, 2%)[51]

Fig. 7 Stress-strain curves of ACAs with different contents of cellulose (ACA0.5, ACA1 and ACA2 corresponding to the cellulose content of 0.5wt%, 1wt% and 2wt%, respectively)[51]

图8 不同前驱物浓度得到的SiC涂层的莫来石纤维/Al2O3- SiO2气凝胶的有效比消光系数[52]

Fig. 8 Effective specific extinction coefficient of Al2O3-SiO2 aerogel composites reinforced by SiC-coated mullite fibers prepared with different concentration of precursor[52]

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