Transparent, transparency aerogels

One of the most promising applications of SiOa aerogels is their use as transparent thermal insulation. Extensive studies of transparent aerogels have shown that the thermal resistance as well as the solar transmission are sufficiently high to make these materials most suitable for passive solar usage [72]. However,... 

The first two methods yield a highly porous (porosity above 0.9) and transparent aerogel the other methods produce less perfect and more dense porous solids called xerogels. The principles and practice of these methods are summarized in the following sections. 

Tewari, P.H., Hunt, A.J., and Lofftus, K.D., Ambient-temperature supercritical drying of transparent aerogels. Materials Letters, 3, 363-367, 1985. 

Schneider F, Gertner G, Use of transparent aerogels for efficient thermal insulation . Intelligent Glass Solutions, Issue 1, S 39-42, Intelligent Publications Limited (IPL), Beijing, London, Munich, New Delhi, 2007... 

Sol-gel processing is an attractive route for the production of porous ceramics and glasses because the characteristic properties of gels such as high surface area, high porosity, and small pore size are not easily attainable by more conventional methods. In addition to the transparent aerogel applications mentioned above, these unique properties are exploited in a variety of applications, which include filtration, separation, catalysis, and chromatography (1,61,71). 

Hrubesh L.W. Aerogel apphcations. J. Non-Cryst. Solids 1998 225 335-342 Hunt A.J., Tewari P.H. Process for forming transparent aerogel insulating arrays. US Patent US 4610863 (1986)... 

Analogous aerogels are also used in space research as a capture medium for cosmic dusts. These hypervelocity particles enter the fine structure of the aerogel which dissipates their kinetic energy. Consequently particles having a few micron size can be captured intact and easily located within the transparent aerogel (Tsou, 1995). 

Figure 23.3 Schematic of the synthetic procedure of MSQ gels. Aerogel/xerogel can be obtained after washing and supercritical drying/ambient pressure drying. The bottom part shows typical appearances of transparent aerogel and xerogel of MSQ.

Kanamori, K., Kodera, Y., Hayase, G., Nakanishi, K., and Hanada, T. (2011) Transition from transparent aerogels to hierarchically porous monoliths in polymethylsilsesquioxane sol-gel system. 

For a more extensive analysis of aerogel synthesis and recent developments, readers are recommended to refer to Ref. [41]. In addition. Ref. [15] may be referred to for a recent life cycle assessment (LCA) of transparent aerogel made by supercritical drying. 

Figure 45.10 Four optimized transparent aerogel prototypes joined in a test frame for hot box measurements (a), and cross-section of two different approaches for application of the foil rim seal solution (b) for a monolithic aerogel-based evacuated glazing [20].

Jensen, K.I. and Schultz, J.M. (2007) Transparent aerogel windows results from an EU FP5 project. Proceedings of the 8th International Vacuum Insulation Symposium, ZAEBayern/UniWue, Wurzburg, September 18-19,2007. 

Thermal Insulation. In addition to their low thermal conductivity, as discussed in the section above, siUca aerogels can be prepared to be highly transparent in the visible spectmm region. Thus, they are promising materials as superinsulating window-spacer. To take further advantage of its... 

Fig. 6. Schematic diagram showing the use of transparent silica aerogel in passive solar collection. Reproduced from Ref. 53.

Silica aerogels, a newly developing type of material, also have been produced as thermal insulations with superinsulation characteristics. The nanometer-size cells limit the gas phase conduction that can take place. The aerogels are transparent to visible light, so they have potential as window insulation. The use of superinsulations at present is limited by cost and the need to have a design that protects the evacuated packets or aerogels from mechanical damage. 

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