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 th e preparation of dense sintered bodies at a sintering temperature < 1300 de grees C with a submicrometer grain size; the bodies are large enough to ena ble the measurement of a Vickers macrohardness > 21 GPa at a testing load o f 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 f ramework 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 produ cts with average pore sizes of about 1 nm. (C) 2000 Acta Metallurgica Inc.