PREPARATION, COMPACTION AND SINTERING OF NANOSIZED α-AL₂O₃ POWDER

Results of highly intensive mechanical comminution of α-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 40nm., findings of different methods of particle size determination being consistent with each other. The powders exhibit unexpectedly good formability allowing achievement 60-65% green density by uniaxial dry pressing. The powder compacts show enhanced sintering kinetics resulting in dense material with fine microstructure at low temperatures.