MECHANOCHEMICAL EFFECTS FOR SOME AL2O3 POWDERS OF DRY GRINDING

Three kinds of Al2O3 Powders, i.e. two kinds of low-soda Al2O3 with average particle sizes of 3.9 and 0.6-mu-m and an electrofused Al2O3 with an average particle size of 21.8-mu-m, were ground for up to 300 h in a dry vibration ball mill. Variations in particle-size distribution, specific surface area, crystallite size, lattice strain, effective temperature factor and lattice constant were examined against milling time. The mechanism of grinding was found to differ between low-soda Al2O3 and electrofused Al2O3. The mechanochemical effects on these Al2O3 powders occurred in the order decrease of crystallite size --> increase of effective temperature factor --> increase of lattice strain. The length of the a-axis was clearly increased by a prolonged grinding. The difference in the ground state of three specimens was attributed to differences in the physical state of particles originating from the preparation methods, and also to particle size.