| 摘要 |
A method of manufacturing magnetic powder is disclosed. This method can provide magnetic powder from which a bonded magnet having excellent magnetic properties and reliability can be manufactured. A melt spinning apparatus 1 is provided with a tube 2 having a nozzle 3 at the bottom thereof, a coil 4 for heating the tube and a cooling roll 5. The cooling roll 5 is constructed from a roll base 51 and a circumferential surface 53 in which gas flow passages 54 for expelling gas are formed. A melt spun ribbon 8 is formed by injecting the molten alloy 6 from the nozzle 3 so as to be collided with the circumferential surface 53 of the cooling roll 5, so that the molten alloy 6 is cooled and then solidified. In this process, gas is likely to enter between a puddle 7 of the molten alloy 6 and the circumferential surface 53, but such gas is expelled by means of the gas flow passages 54. The magnetic powder is obtained by milling thus formed melt spun ribbon 8. In this method, when the average pitch of these gas flow passages 54 is defined as P mu m and the average particle size of the magnetic powder is defined as D mu m, the relationship represented by the formula P < D is satisfied. <IMAGE> |
