| 简介 |
PROBLEM TO BE SOLVED : To inexpensively provide a rare-earth magnet having large residual magnetization and a practically sufficient coercive force by using a simple device, by continuously performing sintering under a low pressure after vacuum sintering. SOLUTION : A molded body is sintered at 1, 000-1, 150 deg.C in a vacuum or an inert gas atmosphere maintained at the atmospheric pressure or lower. Consequently, the open bores in the molded body are vanished by increasing the density of the sintered body to 90-98% of the true density. Continuously, sintering treatment is performed at 900-1, 150 deg.C in an inert gas atmosphere maintained at 1-20 atm, preferably, at 1-10 atm. The sintering time is adjusted to 0.1-5 hours, but 0.5-4 hours are particularly appropriate to minutely control the sintering reaction in the inert gas atmosphere. Finally, a rare-earth magnet is manufactured by subjecting the sintered body to aging treatment, working, and surface treatment. It is preferable to perform the aging treatment one or more times at a temperature lower than the sintering temperature. |
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