| 摘要 |
PROBLEM TO BE SOLVED: To easily obtain alumina powder having good binder removing ability and giving a high density sintered body by pulverizing alumina having a specified average primary particle diameter and a specified specific surface area with an air stream pulverizer. SOLUTION: Alumina having 0.5-5 μm average primary particle diameter, <=2 m2/g BET specific surface area and <=9,500 cm2/g Blain specific surface area is pulverized with an air stream pulverizer. The average particle diameter of secondary particles formed by the aggregation of primary particles is about 30-100 μm. The alumina is obtained, e.g. by firing aluminum hydroxide (gibbsite) obtained by the Bayer process in a rotary kiln, a tunnel kiln or the like. The air stream pulverizer is, e.g. an air stream impact pulverizer, an air stream collision pulverizer, a counter air stream pulverizer or the like. The air stream impact pulverizer is preferably used because the occurrence of fine particles is suppressed. The pressure of pulverization air is usually about >=5 kg/cm2. |
