Improvement of the silica aerogel strengthening process for scaling-up monolithic tile production

Previously published results have shown that washing and aging treatments (respectively in water/ethanol and water/polyethoxydisiloxane solutions) of silica gels (synthesized from polyethoxydisiloxane precursors through HF catalysis) significantly enhance both the permeability and mechanical propert...

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Veröffentlicht in:Journal of non-crystalline solids 2004-12, Vol.350 (Complete), p.196-201
Hauptverfasser: Rigacci, Arnaud, Einarsrud, Mari-Ann, Nilsen, Elin, Pirard, René, Ehrburger-Dolle, Françoise, Chevalier, Bruno
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Sprache:eng
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Zusammenfassung:Previously published results have shown that washing and aging treatments (respectively in water/ethanol and water/polyethoxydisiloxane solutions) of silica gels (synthesized from polyethoxydisiloxane precursors through HF catalysis) significantly enhance both the permeability and mechanical properties of the wet gels. Unfortunately, scaling-up the process induces severe cracks during supercritical drying. This phenomenon has been related to a pore-size distribution gradient between the surface and the bulk of the gel that appears after aging of thick gels. We report efforts to optimize the aging step. Aging in less-concentrated polyethoxydisiloxane solutions yields gels with a more homogeneous pore-size distribution and has enabled us to obtain large monolithic and crack-free aerogels that remain light and transparent.
ISSN:0022-3093
1873-4812
DOI:10.1016/j.jnoncrysol.2004.06.042