| 摘要 |
PURPOSE:To improve the temperature characteristics of the coercive force of magnetic powder effectively by using hexagonal system ferrite, mean grain size and coercive force thereof each take specified values and which contains bivalent atoms and Sn atoms. CONSTITUTION:Substituted ingredients containing at lest Sn atoms and glass formation ingredients of ingredients constituting substances such as B2O3.BaO glass and substituted Ba ferrite compositions, the hexagonal system ferrite of BaO, Fe2O3, SnO2, CoO, B2O3, etc., are mixed at predetermined ratios. The mixture is melted at a temperature such as 1,300 deg.C or more, and rolled and quenched, thus manufacturing an amorphous body. The amorphous body is thermally treated for a fixed time at a temperature such as approximately 800 deg.C, thus precipitating the crystal of hexagonal system ferrite. Hexagonal system ferrite particulates having specific mean grain size of 0.02-0.2mum and coercive force of 200-2,000Oe and containing bivalent atoms and Sn atoms are acquired through crushing, washing and drying. The particulates are used as a medium for magnetic recording. |
