| 摘要 |
A process for producing .alpha.-alumina comprising .alpha.-alumina single crystal particles characterized in that transition alumina and/or an alumina raw material capable of being converted to transition alumina on heating is calcined in an atmosphere containing at least 1% by volume of hydrogen chloride at a temperature of not less than 600.degree.C, preferably from 600 to 1,400.degree.C, and more preferably from 800 to 1,200.degree.C. Aluminum hydroxide, alum, aluminum sulfate, etc. are used as the alumina raw material capable of being converted to transition alumina on heating. .alpha.-Alumina comprising octahedral or higher polyhedral .alpha.-alumina single crystal particles which have a high alumina purity above a given level, are fine and homogeneous, have a narrow particle size distribution, and are not agglomerated particles can be obtained from raw materials of various kinds, purities, shapes, sizes, and compositions. |
