| 摘要 |
PURPOSE:To extract the particulates of hexagonal system ferrite in an excellent dispersible manner by a method wherein a glass forming substance is infiltrated into the sintered body obtained by heat-treating the amorphous material containing hexagonal system ferrite and glass forming substance, and a heat treatment is performed again. CONSTITUTION:In order to obtain the magnetic coercive force required for the magnetic powder to be used for a magnetic recording medium, a part of the Fe<3+> ions contained in a magnetic crystal such as magnet plumbite type barium ferrite is replaced with Co<2+> or Ti<4+> ions, and BaFe10.4Ti0.8Co0.8O19 is formed. The raw materials of H3BO3, BaCO3, Fe2O3, TiO2, and CoO are weighed, after they are sufficiently mixed and melted by heating them up to 1,350 deg.C, the melted material is poured on a water-cooling twin roll, cooled quickly, and an amorphous substance is formed. This amorphous substance is placed in the prescribed container, put in an electric furnace and crystallized under a suitable temperature condition. After the sintered body formed as above is pulverized, it is mixed with boracic acid (H3BO3 or B2O3), and a heat treatment is performed again at 100-300 deg.C for 1-2hr. After the heat-treated substance is repulverized, it is treated with an acetic acid solution, a rinsing is repeated, and when the pH in water becomes 6 or above, the rinsing process is finished. |
