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Influence of high-energy ball milling and additives on the formation of sphere-like α-Al2O3 powder by high-temperature calcination B A journal of chemical sciences

Li, Sai, Zhu, Lingling, Liu, Luoqiang, Chen, Liugang, Li, Hongxia, Sun, Chunhui
Zeitschrift für Naturforschung 2018 v.73 no.8 pp. 589-596
additives, aluminum hydroxide, aluminum oxide, milling, powders, raw materials
In comparison with the typically worm-like α-Al₂O₃ powders formed from an unground Al(OH)₃ precursor calcined at 1450°C, spherical α-Al₂O₃ powders with ~1 μm in size were prepared by the calcination of a ground Al(OH)₃ precursor with 5 wt.% [NH₄]⁺BF₄⁻ under the same calcination conditions. The influence of a high-energy ball milling pretreatment as well as of the additives on the morphological evolution of α-Al₂O₃ powders was studied using the commercial precursor Al(OH)₃ as raw material. The results indicate that the morphology of α-Al₂O₃ powders is closely related to the morphology of the Al(OH)₃ precursor and to the introduction of different additives. The refinement of the Al(OH)₃ precursor in aggregate size and of the primary crystal size by high-energy ball milling has effectively suppressed the neck growth of α-Al₂O₃ grains. In contrast to the findings made previously with the introduction of 5 wt.% [NH₄]⁺Cl⁻, the morphology of the α-Al₂O₃ particles could be significantly improved from a ground Al(OH)₃ precursor with the addition of 5 wt.% [NH₄]⁺BF₄⁻, which resulted in the formation of spherical α-Al₂O₃ powders with 1 μm size at 1450°C.