Patent ID: 6841497
Filing Date: 2005-01-11
Classification: B01D,B82Y,C01F,C01P,C04B,C23C,C25D

Abstract:
1. A process for producing redispersible nanocorundum with an average particle size D 50 <100 nm with addition of nuclei that promote transformation to corundum in subsequent annealing, comprising: (a) dissolving in a liquid medium or processing in a liquid medium to a sol, as starting materials, chlorine-free inorganic precursors; (b) hydrolyzing the solution or the sol of (a) through the addition of a base in a mole ratio of base:precursor of 1 to 3; (c) aging the hydrolyzed solution or sol of (b) at temperatures between 60 and 98° C. for 1 to 72 hours; (d) subsequently drying the aged solution or sol of (c) followed by calcination at temperatures between 350 and 650° C. for converting hydrolyzed precursor into a semiamorphous intermediate phase and ultimately into transitional aluminum oxides; and (e) performing annealing by increasing temperature to ≦950° C. for converting product of (d) into corundum phase.