发明名称 |
Functionally graded rare earth permanent magnet |
摘要 |
A functionally graded rare earth permanent magnet having a reduced eddy current loss in the form of a sintered magnet body having a composition R a E b T c A d F e O f M g is obtained by causing E and fluorine atoms to be absorbed in a R-Fe-B sintered magnet body from its surface. E is at least one element selected from alkaline earth metal elements and rare earth elements. F is distributed such that its concentration increases on the average from the center toward the surface of the magnet body, the concentration of E/(R+E) contained in grain boundaries surrounding primary phase grains of (R,E) 2 T 14 A tetragonal system is on the average higher than the concentration of E/(R+E) contained in the primary phase grains, the oxyfluoride of (R,E) is present at grain boundaries in a grain boundary region that extends from the magnet body surface to a depth of at least 20 µm, particles of the oxyfluoride having an equivalent circle diameter of at least 1 µm are distributed in the grain boundary region at a population of at least 2,000 particles/mm 2 , the oxyfluoride is present in an area fraction of at least 1%. The magnet body includes a surface layer having a higher electric resistance than in the interior. In the permanent magnet, the generation of eddy current within a magnetic circuit is restrained.
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申请公布号 |
EP1705670(B1) |
申请公布日期 |
2012.03.28 |
申请号 |
EP20060250544 |
申请日期 |
2006.02.01 |
申请人 |
SHIN-ETSU CHEMICAL CO., LTD. |
发明人 |
NAKAMURA, HAJIME;HIROTA, KOICHI;SHIMAO, MASANOBU;MINOWA, TAKEHISA |
分类号 |
H01F1/057;H01F1/058;H01F1/059;H01F41/02 |
主分类号 |
H01F1/057 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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