| 摘要 |
PURPOSE:To provide fine powder of iron oxide particles having holding power and to realize electrical and chemical stability by coating magnetic iron oxide particles containing ferrous iron with a double layer whose lower layer is Zn compound and upper layer is Si compound. CONSTITUTION:Magnetic iron oxide particle powders are formed by magnetic iron oxide particles containing ferrous iron which is covered with a double layer whose upper layer is a Zn compound layer and upper layer is an Si compound layer. The magnetic iron oxide particle powders containing ferrous iron are Co-coated magnetic particle powders and Co-coated magnetic particle powers whose magnetic particle powders and particle surface are coated or modified with Co and Fe (II). The Zn compound is zinc sulfate, zinc nitrate, zinc chloride, zinc acetate, oxide of zinc, hydroxide, etc. The amount of Zn compound on the surface of particle is 0.1 to 5wt.% in terms of Zn against magnetic iron oxide particles. As Si compound, water glass, colloidal silica, etc., can be used in an amount of 0.1 to 5wt.% converted in terms SiO2. |
