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AssigneeSumitomo Chemical Company, Limited
InventorsMasahide Mohri, Yoshio Uchida, Yoshinari Sawabe, Hisashi Watanabe
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A process for producing .alpha.-alumina powder comprising the step of calcining at least one of transition alumina and a transition alumina precursor capable of becoming transition alumina on heating, in a gas atmosphere containing (1) a hydrogen halide, (2) a component prepared from a halogen and steam or (3) a halogen, in the presence of at least one of a seed crystal and a shape-controlling agent. The .alpha.-alumina powder is particularly useful as a raw material for abrasives, fillers, sinters or spacers which comprises .alpha.-alumina particles having a substantially octahedral or eicosahedral shape, a specific structure, and a narrow primary particle size distribution.
A process for producing .alpha.-alumina powder comprising the step of calcining under atmospheric pressure at least one of transition alumina or a transition alumina precursor capable of being converted to transition alumina on heating, in a gas atmosphere containing a hydrogen halide selected from the group consisting of hydrogen chloride, hydrogen bromide and hydrogen iodide, in the presence of a shape-controlling agent and optionally a seed crystal;
A process for producing .alpha.-alumina powder comprising the step of calcining under atmospheric pressure at least one of transition alumina or a transition alumina precursor capable of being converted to transition alumina on heating, in a gas atmosphere containing steam and a halogen selected from the group consisting of chlorine, bromine, and iodine, in the presence of a shape-controlling agent and optionally a seed crystal;
A process for producing .alpha.-alumina powder comprising the step of calcining under atmospheric pressure at least one of transition alumina or a transition alumina precursor capable of being converted to transition alumina on heating, in a gas atmosphere containing a halogen selected from the group consisting of chlorine, bromine, and iodine, in the presence of a shape-controlling agent and optionally a seed crystal;
Dependencies are inferred from the claim text.