ISSN:
1573-4846
Keywords:
silica
;
monolith
;
sol-gel
;
pore size
;
strength
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract This review article summarizes the development of drying and sintering techniques for the production of sol-gel derived, large silica glass components. Gels may be synthesized using particulate or metal alkoxide precursors, or both in combination. Rapid fracture-free drying has been achieved easily with particulate gels because of their large pore size (100–6000 Å). Alkoxide gels, which generally have small pores (〈200 Å), were initially difficult to dry without cracking. However, recent studies have shown that large alkoxide gel monoliths can also be dried in reasonably short times (〈10 days). During subsequent heat treatment, alkoxide gels tend to have high shrinkage rates, which may cause trapping of hydroxyl ions or organic groups remaining on the gel surface. Although the removal of these species is easier for particulate gels, their large pore size necessitates heating above 1400°C to achieve full consolidation. Sintering at such temperatures was observed to deteriorate glass quality, through crystallization, warping, and/or sagging. Extensive optimization of the entire process has shown that on a laboratory scale, high-optical-quality glass can be produced from both alkoxide and particulate gels. It remains to be seen whether sol-gel process will be feasible for the manufacture of high-quality glass products on a commercial scale.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00402691
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