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Process Considerations in Monolithic Aerogels

Published online by Cambridge University Press:  25 February 2011

Arlon J. Hunt  and
Kevin D. Lofftus
Arlon J. Hunt
Affiliation:
Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
Kevin D. Lofftus
Affiliation:
Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
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Abstract

This paper describes important process considerations in the preparation of super-critically evacuated alcogels called aerogels. Aerogels are fine grained, open pore, low density materials that possess a variety of unusual properties and have a number of diverse applications. Factors influencing the microstructure and uniformity of alcogel monoliths are discussed. The effects of hydrolysis rate, diffusion, condensation, dispersion medium, and electrostatic interactions on particle formation and gelling are outlined. These effects are illustrated with the preparation of zirconia, mullite precursors, and silica alcogels. A theoretical model of particle interaction based on the combination of van der Waals and electrostatic double layer forces is used to interpret gelation and homogeneity. Solvent substitution and supercritical drying processes are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 121: Symposium H – Better Ceramics Through Chemistry III , 1988 , 679
Copyright
Copyright © Materials Research Society 1988

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References

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