| 摘要 |
PROBLEM TO BE SOLVED: To repress that dispersion of magnetic properties by making the size and direction of the magnetic field within a vessel containing a powder containing magnetic material and balls, constant. SOLUTION: A ring-shaped magnet 14 having a plurality of number of magnetic poles 14 is arranged along the outer circumference of the casing of a ball mill and the direction of magnetic field created by each magnetic pole is set in mutually different directions along the circumference, and an even magnetic field is given within the space 12 by the magnet 14, thereby the dispersion of magnetic properties of the magnet is repressed, and when magnetic powder and balls are put in, and the ball mill is rotated, powder of a magnetic material showing magnetic characteristics of a high retained magnetic flux dencity or high dielectric constant is produced as the magnetic material powder obtainable by rotation.
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