Aerogel sintering

Sempere R, Bourret D, WoignierT, Phalippou J, JuUien R (1993) Scaling theory and numerical applications of aerogel sintering. Phys Rev Lett 71 3307-3312... 

F. Placin, M. Feder, and F. Leal-Calderon Viscous Sintering Phenomena in Liquid-Liquid Dispersions Application to the Preparation of Sdicone Macroporous Aerogels. J. Phys. Chem. B 107, 9179 (2003). 

Since both aerogels and xerogels have high surface areas and small pore diameters they are used as ultrafiltration media, antireflective coatings, and catalysts supports. Final densi-fication is carried out by viscous sintering. 

Sherer, G.W., Calas, S., and Sempere, R., Densification kinetics and structural evolution during sintering of silica aerogel, J. Non-Crystl. Solids, 240, 118, 1998. 

Table 3 shows the properties of these aerogels. It can be seen that the yttria-doped silica exhibits a very good resistance towards sintering by comparison with pure silica even at relatively low temperature (300 °C). Pure silica transformed into cristobalite at 900 °C... 

Four silica samples, Aerogel S, Santocel C, a Davison xerogel, and Linde silica have been subjected to vacuum sintering treatments. 

Figure 5 Scaling of the elastic modulus cii of aerogels versus density p. Materials Si02 (triangles) sintered Si02 (dots) carbon (diamonds) MF (circles) RF (squares). Open symbols denote evacuated aerogels filled symbols denote aerogels in air.

NMR imaging of gas adsorption/desorption in nanoporous solids, such as Y-AI2O3 and ZnO powders and partially sintered ceramics of these materials, as well as Vycor porous glass was analysed using Brunauer-Emmett-Teller (BET) theory. Visualization of gaseous xenon and methane in the void spaces of aerogels offered unique information and insights into the pore structure and molecular diffusivities of occluded sorbates. ... 

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