Spatial arrangement of fibrils in concentrated aqueous sols of fibrillar pseudoboehmite

摘要: Abstract The particle size, aggregation state and spatial arrangements of the particles in concentrated sols boehmite fibrillar pseudoboehmite are important parameters for determining final properties powders γ-Al2O3 use as catalysts, adsorbents, coatings alumina derived materials desired porosity mechanical strength. However, these very difficult to evaluate, even qualitatively, especially by conventional transmission electron microscopy. In this paper, we report freeze-etching critical point drying methods applied scanning microscopy describe organization fibrils aqueous pseudoboehmite. For purpose, a series mono-, two- three-layer containing 70 g/l AlOOH were produced reaction aluminum powder with solution acetic acid. A three-dimensional interwoven short, single was observed mono-layer sol. Similar arrangement seen upper layer or sols, although long aggregate-forming thin bundles. bottom layer, aggregated thick bundles aligned parallel their lengths forming plates ordered inside whole layer. third macroscopically constituted white precipitates, structure stacking fibril observed. model is proposed according aging time at 90 °C.