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Production of Sols from Aggregated Titania Precipitates

Published online by Cambridge University Press:  25 February 2011

John. R Bartlett  and
James L. Woolfrey
John. R Bartlett
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1 Menai N. S. W. 2234., Australia
James L. Woolfrey
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1 Menai N. S. W. 2234., Australia
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Abstract

Titania and titania/zirconia sols, with solids loadings exceeding 1000 g dm3, have been prepared on a 10 kg scale by chemical methods involving the hydrolysis of an appropriate mixture of alkoxides, followed by peptisation with dilute nitric acid. The rate of peptisation of the hydrolysates was determined by static light-scattering and photon-correlation spectroscopy, enabling the hydrodynamic radius, the radius of gyration and the fractal dimension of colloidal species to be monitored as a function of peptisation time.

The peptisation kinetics were influenced by a range of factors including the initial solids loading, the acid concentration, the reaction temperature and the age of the alkoxide hydrolysate. Hydrolysate peptisation is first order with respect to concentration of acid and exhibited a non-integer reaction rate order (complex mechanism) with respect to solids concentration. Sols produced from freshly-precipitated hydrolysate peptised at a faster rate than aged precipitates but slowly re-aggregated after peptising, yielding “equilibrium” aggregate sizes often exceeding 100 nm. This effect was not observed in sols produced from aged hydrolysate. These differences are interpreted using DLVO theory.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 271: Symposium N – Better Ceramics Through Chemistry V , 1992 , 309
Copyright
Copyright © Materials Research Society 1992

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References

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