Preparation and sintering of nanosized α-Al2O3 powder

Results of highly intensive mechanical comminution of alpha-Al2O3 in planetary ball mill with the use of a substance preventing the formation of hard aggregates and growth of crystallites are presented. Depending on experimental conditions mean size of the ground particles ranged from 18 to 40 nm., findings of different methods of particle size determination being consistent with each other. The powders exhibit unexpectedly good formability allowing to achieve 60-65% green density by simple uniaxial dry pressing. Compacts made of the powder show enhanced sintering kinetics resulting in dense material with fine microstructure at low temperatures. (C)1999 Acta Metallurgica Inc.