Preparation of Sphere-like α-$ Al_{2} %$ O_{3} $ from Commercial Al(OH)3 with a Mechanical Ball Milling Process

Abstract In comparison to the typically worm-like α-$ Al_{2} %$ O_{3} $ powders of 20–30 µm size from unmilled Al(OH)3 precursor fired at 1450°C, almost-spherical α-$ Al_{2} %$ O_{3} $ powders of ∼0.5 µm size were synthesized from 9 h-milled Al(OH)3 precursor with the same heat treatment. The effect...
Ausführliche Beschreibung

Abstract In comparison to the typically worm-like α-$ Al_{2} %$ O_{3} $ powders of 20–30 µm size from unmilled Al(OH)3 precursor fired at 1450°C, almost-spherical α-$ Al_{2} %$ O_{3} $ 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-$ Al_{2} %$ O_{3} $ was studied by XRD and SEM. It was found that the milling treatment of the commercial Al(OH)3 precursor not only led ho an accleration of α-transformation during calcination, but also changed the morphology and particle size distribution of the α-$ Al_{2} %$ O_{3} $ 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-condensation mechanism into one that is mainly based on diffusion in the α-$ Al_{2} %$ O_{3} $ calcination process and promotes the tendency to form spherical α-$ Al_{2} %$ O_{3} $ powders. Ausführliche Beschreibung