| 摘要 |
PROBLEM TO BE SOLVED: To obtain alumina powder reduced in coarse particles with high-level sieving treatment in coarse particle sieving process by incorporating alumina powder with a specific amount of fine inorganic powder with each specified average particle size, bulk density and difference angle. SOLUTION: This alumina powder is obtained by incorporating 100 pts.wt. of alumina powder with >=0.01 wt.% of fine inorganic powder with an average particle size of <1 μm, bulk density of 0.01-1.0 g/cm3 and difference angle of 15-30 deg. followed by sieving the resultant mixture with a relevant machine; wherein the original alumina powder, although there is no limitation particular to mention, is pref. α-alumina singly in terms of crystal form; the fine inorganic powder is normally of at least one kind selected from the group consisting of silicon oxide, alumina, titanium oxide and zirconium oxide, pref. being of silicon oxide or alumina; and it is preferable that the original alumina powder to be used is <=0.1 wt.% in moisture content and <=0.4 wt.% in Na2O content. |
