| 摘要 |
PURPOSE:To industrially and stably manufacture metallic magnetic powder for magnetic recording by heating under condition of the specific atmosphere and temp. after coating combining the specific Al compound and B compound on surface of fine ferrous oxide. CONSTITUTION:Powder of water containing iron oxide of extremely fine FeOOH, etc., having >=55m<2>/g specific surface area or iron oxide of fine Fe2O3, Fe3O4, etc., having >=40m<2>/g specific surface area, is charged into suspension of B compound of boric acid, ammonium borate, etc., and Al(OH)3 to form mixed coating layer of the B compound and Al(OH)3 on the surface of water containing iron oxide and iron oxide particles. After heating this at 550-900 deg.C in the air, this is heated and reduced under reducing atmosphere of hydrogen gas stream, etc., and successively, cooled in N2 gas and after dipping this in toluene, the toluene is vaporized at the room temp. to manufacture the ferrous fine powder being suitable to the magnetic recording. |
