| 摘要 |
PURPOSE:To produce ferromagnetic iron oxide powder wherein coersive force and saturation magnetization are improved by calcining acicular iron oxyhydroxide deposited with specified salt on the surface. CONSTITUTION:After adding Co<2+> salt (e.g. CoSO4) and salt of Zn<2+>, Cd<2+> or Ba<2+> (e.g. ZnSO4) and, if necessary, Fe<2+> salt (e.g. FeSO4N7H2O) to an aq. suspen sion of acicular iron oxyhydroxide grain (e.g. alpha-FeOOH) and making the mixture alkaline by NaOH or the like it is stirred under heating at <=100 deg.C and allowed to react and Co<2+> salt and Zn<2+>, Cd<2+> or Ba<2+> salt and, if necessary Fe<2+> salt are deposited on the surface of iron oxyhydroxide grain. Then after washing this mixture with water and filtering and drying it, it is calcined at 800-830 deg.C for 30min-2hr in air. |
