| 摘要 |
PROBLEM TO BE SOLVED: To obtain anα-alumina particle suitable for a polishing material a raw material for single crystals and a filler and having >30 and <=1,000μm average primary particle diameter, a narrow distribution of particle size, a polyhedral form of a uniform shape and >=99.9 mass % purity, and to provide a method for producing theα-alumina particle. SOLUTION: This method for producing theα-alumina particle comprises baking aluminum hydroxide having >=99.9 mass % purity and >=450 deg.C dehydrating temperature in an atmosphere containing at least one kind of gas selected from (a) hydrogen chloride, (b) a component prepared from molecular chlorine and water vapor and (3) molecular chlorine at a temperature within the range of >=800 and <=1,200 deg.C. The resultantα-alumina particle has the polyhedral form, <=3 aspect ratio, <=5 D90/D10 when the particle diameters of cumulative 10% and 90% are D10 and D90 from the fine particle side of a cumulative particle size distribution of theα-alumina particle, >30 and <=1,000μm average primary particle diameter and >=99.9 mass % purity.
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