Preparation of Sphere-like α-Al2O3 from Commercial Al(OH)3 with a Mechanical Ball Milling Process

In comparison to the typically worm-like α-Al2O3 powders of 20–30 μm size from unmilled Al(OH)3 precursor fired at 1450 °C, almost-spheri-cal α-Al2O3 powders of ~0.5 μm size were synthesized from 9 h-milled Al(OH)3 precursor with the same heat treatment. The effect of the commercial Al(OH)3 precursor milling treatment on phase transformation and morphology of α-Al2O3 was studied by XRD and SEM. It was found that the milling treatment of the commercial Al(OH)3 precursor not only led to an acceleration of α-transformation during calcination, but also changed the morphology and particle size distribution of the α-Al2O3 powders. As the Al(OH)3 precursors were broken into irregularly shaped pieces with a ≤1 μm size range by the milling treatment, the resulting sharp corners with high vapor pressure would alter the evaporation-con-densation mechanism into one that is mainly based on diffusion in the α-Al2O3 calcination process and promotes the tendency to form spherical α-Al2O3 powders. © 2016, Springer Vieweg. All rights reserved.