Heat Treatment of Alumina Aerogels

Abstract

The phase conversions and morphological changes of alumina aerogel films and monoliths during heat treatment were investigated by TGA/DTA, BET, XRD, and image analysis of SEM micrographs. A preliminary model explaining the structural evolution of the film during heat treatment is proposed.

Monolithic copper oxide aerogel via dispersed inorganic sol–gel method

“…A mature and common method is classical sol-gel process which uses metal alkoxides as precursors. This method has been applied successfully to prepare several kinds of aerogels [1,[11][12][13], such as SiO 2 , Al 2 O 3 and TiO 2 . But it is not very suitable for preparing many other kinds of metal oxide aerogels, just like ZrO 2 , Nb 2 O 5 and RuO 2 [14,15], because many metal alkoxides (the precursor of those aerogels) are rare or difficult to synthesize.…”

Relationship between Crystallite Size and Bond Lengths in Boehmite

“…Aluminas are commonly obtained from four precursors: two hydroxides, gibbsite (11) and bayerite (12); and two oxyhydroxides, diaspore (13) and boehmite. Although this last phase has been widely used for preparing aluminas, a detailed characterization of boehmite is lacking.…”

The formation of Cr(VI) compound at the interface between metal and heat-insulating material and the approach to prevent the formation by sol–gel process

“…Clear crystal phases were not detected and it was suggested that the coating film consisted of amorphous phase. Yamaguchi et al reported that alkoxide-derived boehmite gel heat-treated at 803 K showed an amorphous phase and changed to £-Al 2 O 3 at 1008 K. 23) On the other hand, Keysar et al investigated the heat-treatment change of alkoxide-derived boehmite aerogel and concluded that the aerogel heat-treated at 873 K showed ©-Al 2 O 3 and changed to ª-Al 2 O 3 at 1473 K. 24) It is possible that the presence of SiO 2 prevented the crystallization of Al 2 O 3 in our experiment.…”