| 摘要 |
PURPOSE:To obtain magnetic powder having high coercive force and improved electromagnetic conversion characteristics, by adding a ferrous salt to an alkali suspension containing gamma-Fe2O3, adding a cobalt salt to the suspension, followed by dehydration and drying. CONSTITUTION:A ferrous salt is added to an alkali suspension containing gamma-Fe2O3 particles, and stirred at <=the boiling temperature for 30min. A cobalt salt is added to the alkali suspension, stirred at <=the boiling temperature, dehydrated and dried. Sodium hydroxide potassium hydroxide, lithium hydroxide, etc. may be cited as the alkali used, and ferrous chloride, ferrous sulfate, etc. may be cited as the ferrous salt used. An amount of the aqueous solution of the ferrous salt added is preferably an amount to give a ratio Fe<2+>/Fe<3+> of ferrous ion Fe<2+> added to Fe<3+> to constitute gamma-Fe2O3 of 2-20atom%. |
