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Proceedings Paper

Accelerated subcritical drying of large alkoxide silica gels
Author(s): Shiho Wang; Fikret Kirkbir; S. Ray Chaudhuri; Arnab Sarkar
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Paper Abstract

Fracture during drying has been the key hurdle in fabrication of large monolithic silica glass from alkoxide gels. Although existing literature suggests pore enlargement, aging, chemical additives, supercritical drying and freeze drying as helpful in avoiding fracture during drying, successful accelerated sub-critical drying of large silica monoliths from alkoxide gels has not yet been reported. In the present approach, acid catalyzed sols of TEOS, ethanol and water (pH equals 2) were cast as cylindrical rods in plastic molds of 8.0 and 10.0 cm diameter with volumes of 2000 cc and 3000 cc respectively. The resultant gels were aged for about 7 days and dried in a specially designed chamber under sub-critical conditions of the pore field. We have obtained monolithic dry gels in drying times of 3 - 7 days for sizes of 2000 - 3000 cc. The dry gels have narrow unimodal pore size distributions, with average pore radius of about 20 angstroms as measured by BET. Although capillary stress during drying increases with reduction of pore size, it was found that in this approach it is easier to dry gels of smaller pore size.

Paper Details

Date Published: 7 December 1992
PDF: 12 pages
Proc. SPIE 1758, Sol-Gel Optics II, (7 December 1992); doi: 10.1117/12.132006
Show Author Affiliations
Shiho Wang, YTC America Inc. (United States)
Fikret Kirkbir, YTC America Inc. (United States)
S. Ray Chaudhuri, YTC America Inc. (United States)
Arnab Sarkar, YTC America Inc. (United States)

Published in SPIE Proceedings Vol. 1758:
Sol-Gel Optics II
John D. Mackenzie, Editor(s)

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