METHOD OF PRODUCING ALPHA-ALUMINA (VERSIONS) Russian patent published in 1999 - IPC

FIELD: industrial inorganic synthesis. SUBSTANCE: according to the first version, at least one transitory aluminum oxide and material precursor of transitory aluminum oxide capable of undergoing conversion upon heating is fired under gas atmosphere containing at least ca. 5 vol % halogen. According to the second version, gas atmosphere, instead of halogen, contains at least ca. 1 vol % hydrogen fluoride, hydrogen bromide, or hydrogen iodide. In the third version, gas atmosphere contains at least ca. 1 vol % gaseous fluorine, bromine, or iodine and at least ca. 0.1 vol % water steam. Alpha-alumina powder thus obtained contains high-purity homogeneous monocrystalline particles with narrow granulometric distribution and having octahedral and higher polyhedral forms. EFFECT: increased purity and homogeneity of product. 24 cl, 5 dwg, 2 tbl, 11 ex