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In-Situ Pore Structure Analysis During Aging and Drying of Gels

Published online by Cambridge University Press:  28 February 2011

Douglas M. Smith ,
Pamela J. Davis  and
C. Jeffrey Brinker
Douglas M. Smith
Affiliation:
Unm/Nsf Center For Micro-Engineered Ceramics,University of New Mexico,Albuquerque,NM, 87131,
Pamela J. Davis
Affiliation:
Unm/Nsf Center For Micro-Engineered Ceramics,University of New Mexico,Albuquerque,NM, 87131,
C. Jeffrey Brinker
Affiliation:
Division 1846,Sandia National Laboratories,Albuquerque,NM,87185
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Abstract

The use of NMR relaxation measurements for the in-situ study of pore structure evolution during gel aging and drying is illustrated. The change in the pore size distribution and surface area of both wet and dried gels is examined as a function of aging conditions including temporal aging, thermal aging, changing pH, and changing pore fluid. The effect of pore fluid pH on dissolution/reprecipitation in ordered packings of monodisperse silica spheres is also examined as a model system for particulate gels. As expected, the pore size distribution narrows with increasing time of treatment in high pH pore fluids. Interpretation of high pH results for the wet state is complicated by a microporous layer which forms on colloidal silica resulting in significantly larger wet surface area as compared to the final dried material. Narrowing of the pore size distribution, which is of interest for maximizing drying rates, is maximized in the least time by using either high pH or repeated ethanol washes for the base-catalyzed gel (B2) used.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 180: Symposium A – Better Ceramics Through Chemistry IV , 1990 , 235
Copyright
Copyright © Materials Research Society 1990

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References

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