| 摘要 |
PURPOSE:To produce iron oxide for polycrystalline ferrite base metal having improved growth property of single crystals, by keeping a solution of ferrous hydroxide at a specific temperature to oxidize the ferrous hydroxide, forming magnetite, aging the magnetite and roasting the aged magnetite at a specific temperature. CONSTITUTION:An aqueous solution of ferrous sulfate is adjusted to 1.0-2.0pH and heated at >=65 deg.C and ammonia is then added to form ferrous hydroxide. The resultant solution is then kept at 7-9pH and >=65 deg.C temperature and an oxidizing gas is blown thereinto to form magnetite. The resultant suspension is then kept and aged at >=65 deg.C for a period of 0.5-3 times based on that required for the magnetite forming reaction while feeding the oxidizing gas into the suspension. The magnetite is then separated from the suspension and roasted at 450-750 deg.C. According to this method, occurrence of crystals of different kinds of orientation is suppressed to provide the aimed iron oxide raw material for polycrystalline ferrite base metal having improved growth property of single crystals.
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