| 简介 |
FIELD : electricity.
SUBSTANCE : proposed functionally improved rare-earth permanent magnet with low eddy-current losses, in form of a sintered magnet body with composition RaEbTcAdFeOfMg, is obtained through absorption of E and fluorine atoms in a sintered magnet body based on R-Fe-B from its surface. F is distributed such that, its concentration in the middle increases from the centre to the surface of the body of the magnet. Concentration E/(R+E), on the grain boundaries of surrounding grains of the primary phase (R, E)2T14A of the tetragonal system, is on average greater than concentration E/(R+E), in the grains of the primary phase. Oxyfluoride (R, E) is present on the grain boundaries in the inter-grain region, which stretches from the surface of the body of the magnet at a depth of at least 20 mcm. Particles of oxyfluoride, with diametre of equivalent round of at least 1 mcm, are distributed in the inter-grain region with quantity of at least 2000 particles/mm2. Oxyfluoride particles occupy at least 1% surface area. The body of the magnet has a surface layer, with higher electrical resistance than the inner part.
EFFECT : limited generation of eddy currents in magnetic circuit.
4 cl, 4 dwg, 2 tbl, 5 ex |
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