Small angle X-ray scattering (SAXS) experiments performed on silica gels dr
ied by different methods show that for some of them, intensity oscillations
occur around the Porod law. These oscillations have been analysed to give
a chord length distribution of the solid network of the gels. Primary solid
particles are rough in xerogels and CO2 evacuated aerogels. Aerogels obtai
ned by methanol supercritical drying show a smooth surface with a well defi
nited chord length distribution curve. These features are explained by sili
ca dissolution-redeposition reactions occurring during the supercritical dr
ying treatment in methanol. (C) 2000 Elsevier Science B.V. All rights reser
ved.