Nanocorundum - Advanced synthesis and processing

Inorganic and organic approaches for the synthesis of nanocorundum powders and products are described on a scale of 50 g batches. The median particle size of the volume distribution of redispersed powders is about 50 nm after calcination at T < 950 degrees C. A key issue of advanced processing is the preparation of dense sintered bodies at a sintering temperature < 1300 degrees C with a submicrometer grain size; the bodies are large enough to enable the measurement of a Vickers macrohardness > 21 GPa at a testing load of 10 kg. Porous sintered corundum bodies with an average pore size between 15 and 60 nm and a porosity of about 40-55% have been produced within the framework of the described synthesis by both powder or sol/gel technologies for the use as chemically highly stable filtration membranes or as catalyst supports. Other applications are amorphous or crystalline nanoporous products with average pore sizes of about 1 nm. (C) 2000 Acta Metallurgica Inc.