Abstract:

Low-density alumina aerogel/silica fiber composites were prepared by sol-gel technology and an atmospheric pressure drying method with N,N'-dimethylformamide (DMF) as a drying control chemical additive. The variation of pore structure and specific surface area were compared with alumina aerogel without adding silica fiber based on the nitrogen adsorption-desorption method. The changes in phase structure during the heating process were characterized by X-ray diffraction. The micro-morphology of the alumina aerogel and its composites were studied in detail by scanning electron microscopy and transmission electron microscopy. The influence of DMF on the aerogel matrix is discussed. We found that the fabricated bulk composites are a close combination between alumina aerogel and silica fiber. The silica fiber improves the phase transition temperature of the alumina aerogel. An appropriate amount of DMF is helpful for the formation of a uniformgel network, thus decreasing the drying shrinkage pressure.

Key words: Composite, Silica fiber/alumina aerogel, Non-supercritical drying, Drying control chemical additive