Densification kinetics and structural evolution during sintering of silica aerogel

George W. Scherer, Sylvie Calas, Robert Sempéré

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

A silica aerogel was sintered at 1050°C, and the effect of densification on the pore structure was determined by nitrogen sorption. Based on the initial pore size distribution (psd) of the aerogel, the kinetics of densification and the evolution of the psd were calculated using the theory of viscous sintering. If the psd is ignored, and the sintering behavior is predicted using the average pore size, then the agreement with measurements is not very good. However, when the actual psd is used in the calculation, then the predictions are excellent for density versus time, surface area and mean pore size versus density, and psd versus time. The quality of the fit depends on the constitutive laws describing the response of the porous material to stresses; the best results are obtained using the laws originally derived for the cylinder model. The power-laws that describe the density dependence of the elastic modulus of aerogels do not seem to apply to the viscosity; reasons for this dependence are discussed.

Original languageEnglish (US)
Pages (from-to)118-130
Number of pages13
JournalJournal of Non-Crystalline Solids
Volume240
Issue number1-3
DOIs
StatePublished - Oct 2 1998

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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