| 摘要 |
PROBLEM TO BE SOLVED: To provide homogeneous spindle-shaped metallic magnetic particles essentially consisting of iron, having high dispersibility and also high squareness ratio and high orientation properties in a coating film, having an excellent grain size distribution and particularly useful as the one for high recording density, high sensibility and high output. SOLUTION: Specified spindle-shaped hematite particles are formed into a fixed layer with a layer thickness of 3 to 15 cm, the temperature thereof is raised to 400 to 700 deg.C at a temperature rising rate of 10 to 80 deg.C/min in the atmosphere of reducing gas at an empty tower velocity of 40 to 150 cm/s, and reduction is performed.
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