| 摘要 |
PURPOSE: To obtain metallic iron powder for magnetic recording which contains little amount of alkali and has an excellent magnetic characteristic by specifying the water-soluble alkali content and bulk density of the powder. CONSTITUTION: The water-soluble alkali content of metallic iron powder for magnetic recording is adjusted to <=50ppm expressed in terms of metal and the bulk density of the powder is adjusted to 0.55-1.0g/ml. It is preferable to adjust the coercive force and saturation magnetic flux density of the powder to 1,500-2,400Oe and 120-150emu/g, respectively. It is also preferable to adjust the major axis, minor axis, and acicular ratio of each particle of the powder to 0.05-0.2μm, 0.01-0.04μm, and >=6. Moreover, aluminum, rare-earth elements, nickel, etc., can be added to the powder as the other additive than cobalt. This power can be manufactured by washing and drying metallic iron powder obtained by reducing a raw material composed mainly of goethite or α-ferric oxide with hydrogen after oxidizing the surface of the powder. |
