| 摘要 |
PROBLEM TO BE SOLVED: To produce calcined ferrite powder for a high performance ferrite magnet having a small particle diameter and almost uniform narrow particle size distribution by granulating starting material giving a specified compsn. after calcination to a specified particle diameter range and carrying out calcination at a specified temp. in a fluidized bed. SOLUTION: An aq. PVA soln. having 0.1-10 wt.% concn. is added by 0.1-1 wt.% to a slurry of an Fe2 O3 -MO mixture giving a basic compsn. represented by the formula MO.nFe2 O3 [where M is one or more kinds of metals selected from among Ba, Sr and Pb and (n) is 5-6] after calcination and the mixture is granulated to 20-10O μm particle diameter by a granulating means such as spray drying. The granulated mixture is fed into a fluidized bed and calcined at 1,000-1,200 deg.C under fluidization to obtain the objective calcined ferrite powder. This powder is pulverized to 0.5-1 μm average particle diameter, further wet- pulverized to 0.3-0.8 μm average particle diameter, concentrated, kneaded, wet- molded in a magnetic field and sintered to obtain the objective ferrite magnet. |
