摘要 |
In the manufacture of a rare earth sintered magnet of the Nd2Fe14B system, closed voids are formed in the magnet in a predetermined fraction to minimize shrinkage. Unlike open voids or pores in conventional semi-sintered magnets, the closed voids do not incur magnet corrosion since they do not communicate to the magnet exterior. By minimizing shrinkage during sintering in this way, a ring or plate-shaped thin wall anisotropic magnet can be prepared without machining for shape correction, achieving a cost reduction and a productivity improvement. Since a high density compact has a high deflective strength, it is easy to handle, minimizing cracking and chipping between the compacting and sintering steps.
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