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Particle aggregation in alumina aerogels

Published online by Cambridge University Press:  31 January 2011

S. Keysar ,
Y. De Hazan ,
Y. Cohen ,
T. Aboud  and
G. S. Grader
S. Keysar
Affiliation:
Chemical Engineering Department, Technion, Haifa 32000, Israel
Y. De Hazan
Affiliation:
Chemical Engineering Department, Technion, Haifa 32000, Israel
Y. Cohen
Affiliation:
Chemical Engineering Department, Technion, Haifa 32000, Israel
T. Aboud
Affiliation:
Materials Engineering Department, Technion, Haifa 32000, Israel
G. S. Grader*
Affiliation:
Chemical Engineering Department, Technion, Haifa 32000, Israel
*
a)Author correspondence to this author.
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Abstract

Alumina aerogels were synthesized by low temperature CO2 supercritical drying (SCD) of gels via the Yoldas process. The aerogels have a surface area of ˜425 m2/gr, similar to that obtained under high pressure/temperature SCD. The surface area and the cluster size of the aerogels are strongly influenced by the amount of acid during gelation. Gels and aerogels were studied by small angle x-rays scattering (SAXS), and the data were analyzed using the Fisher–Burford equation. The SAXS results along with TEM observations support the existence of a hierarchical aggregation at the gelation stage, having a mass fractal dimension of Dm = 2.6−2.8. During the SCD the morphology collapses to form a structure with surface fractal dimension Ds = 2.6−2.9.

Type
Articles
Information
Journal of Materials Research , Volume 12 , Issue 2 , February 1997 , pp. 430 - 433
Copyright
Copyright © Materials Research Society 1997

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