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Thermal. Acoustical and Structural Properties of Silica Aerogels

Published online by Cambridge University Press:  28 February 2011

J. Fricke
Affiliation:
Physikalisches Institut der Universität, Am Hubland, D-8700 Wülrzburg, Federal Republic of Germany
G. Reichenauer
Affiliation:
Physikalisches Institut der Universität, Am Hubland, D-8700 Wülrzburg, Federal Republic of Germany
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Abstract

Silica aerogels either in monolithic or in granular form provide excellent thermal insulation and thus may be used as superinsulating spacer in all kinds of window systems. Highly porous aerogels also are exciting acoustic materials with sound velocities in the order of 100 m/s and acoustic impedances between 104 and 105 kg/(m2·s). Silica aerogels produced from TMOS seem to consist of massive primary particles (ø ≅ 1 nm, ρ ≅ 2000 kg/m3) which form secondary particles (ø ≅ 5 to 6 nm, ρ ≅800 kg/in 3) displaying fractal properties (D≅ 2). The further buildup creates the highly porous low-density structure which is responsible for the special thermal, acoustical and optical properties of aerogels. Above about 100 nm, transparent aerogels should be homogeneous.

Type
Articles
Copyright
Copyright © Materials Research Society 1986

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References

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