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Investigation of the Effect of Dimethylformamide Addition on Alumina Sol-Gel Formation by 27Al NMR and Rheology Measurements

Published online by Cambridge University Press:  25 February 2011

L. F. Nazar ,
L. C. Klein  and
D. Napier
L. F. Nazar
Affiliation:
Department of Chemistry, University of Waterloo, Waterloo, Canada
L. C. Klein
Affiliation:
Department of Ceramics, Rutgers- The State University of New Jersey, Piscataway, N.J.
D. Napier
Affiliation:
Department of Chemistry, University of Waterloo, Waterloo, Canada
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Abstract

The role of dimethylformamide (DMF) in the sol-gel processing of alumina at high acid/Al ratios was studied at different hydrolysis and aging temperatures by 27A1 NMR and rheology measurements. The composition of sols in which aluminum sec-butoxide was hydrolyzed in 50/50 mixtures of DMF and H2O was similar to those hydrolyzed without DMF, although the DMF sols contained a slightly lower concentration of mobile alumina species. The Al13O4 (OH)24(H2O)12 7+ cation predominated in both DMF and aqueous sols hydrolyzed at room temperatures at acid/Al ratios between 0.4 and 0.6. However, aging the room temperature DMF sols at 90°C for 24 hrs was found to cause rapid gelation whereas a similar treatment of the aqueous sols resulted in a decrease in viscosity. This gelation process was correlated with a more rapid decay of the Al13 and A1(H2O)6 3+ cations in the DMF sols. In contrast, DMF sols hydrolyzed at 90°C were found to be less viscous than their aqueous counterparts at high acid ratios.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 121: Symposium H – Better Ceramics Through Chemistry III , 1988 , 133
Copyright
Copyright © Materials Research Society 1988

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References

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