| 摘要 |
PURPOSE:To enhance coercive force, angle ratio and surface smoothness, by fixing on a mean particle diameter, a degree of orientation (Br/4pils) and an oil absorption based on Fischer-Subsieve sizer method. CONSTITUTION:A magnet-plumbite type ferrite granular powder has a mean particle diameter of 0.20-0.70mum, a degree of orientation more than 0.92, and an oil absorption less than 14.0ml/100g. The mixture of compound of such ferrite (Fe2O3/MO(M: Ba and/or Sr)=5.6-6.1) granular powder and barium and/or strontium, and iron oxide are fired and powdered in turn to obtain ferrite granular powder which has the mole ratio of Fe2O3/MO(M: Ba and/or Sr)=5.6-6.1. That is, 0.05-3.00wt.% Al2O3, 0.10-3.00wt.% SiO2 and 0.95-25.00wt.% BaCl2 and/or 0.25-1.55wt.% Bi2O3, by weight percentage to Fe2O3 particle, are added to the mixture of the compound of barium and/or strontium, the Fe2O3 powder with mean particle diameter of 0.20-0.60mum as the iron oxide to mix them. The obtained mixture is then fired at temperature between 800 deg.C and 1100 deg.C, powdering being performed thereafter. |
