| 摘要 |
PURPOSE:To make large the axial ratio of the particles of magnetic particle powder and to equipoise the particle size of the particles by a method wherein water-soluble aluminium salt is kept added to either of a ferrous salt aqueous solution and an alkali hydroxide aqueous solution before an iron hydroxide is formed and at the same time, the water-soluble aluminium salt is properly added in the middle of an oxidation reaction. CONSTITUTION:Water-soluble cobalt salt is kept added to a ferrous salt aqueous solution in a ratio of 0.1 to 10.0 atomic % expressed in terms of Co to Fe, water-soluble aluminium salt is kept added to either of the ferrous salt aqueous solution and an alkali hydroxide aqueous solution in a ratio of 0.5 to 5.0 atomic % expressed in terms of Al to the Fe and the ferrous salt aqueous solution is reacted with this alkali hydroxide aqueous solution to obtain an alkaline suspension having an iron hydroxide-including pH value of 11 or more. Then, while oxygen-containing gas is passed in this suspension, a water-soluble aluminium salt aqueous solution is further added, thereby magnetic particle powder containing iron, which makes needle-like goethite particles containing Co and Al form, as its main component is manufactured. |
