| 摘要 |
PURPOSE:To improve characteristics in remanence (Br) and coercive force (Hc), by a method wherein value of (n) in an oxide permanent magnet represented by formula SrO.nFe2O3 is determined in specified region. CONSTITUTION:Fe2O3 and SrCO3 are measured at molar ratio 6.0-6.5 and mixed well. In this case, variation of the molar ratio is preferably less than 0.02 in delta. The mixture is calcined to be converted into ferrite. The calcination temperature is preferably 1,300-1,350 deg.C so as to produce ferrite fully. After the calcination, the product is crushed into powders having diameter less than the critical diameter (0.7-0.9mu) and the powders are oriented in the magnetic field and molded and then secondary calcination is performed. In this case, the magnetic field intensity during the molding in the magnetic field is preferably not less than 6 KOe at wet process. Relation between molar ratio and magnetic property of Fe2O3 and SrCO3 is in that maximum of Br is obtained at molar ratio 6.2-6.4 and maximum of BHC is obtained at ratio 6.0-6.2 and (BH)max becomes 4.0M.G.Oe at molar ratio 6.0-6.5. Moreover one of CaO, Bi2O3, B2O3 is combined with SiO2 thereby property of the magnet is further improved. |
