R-T-B system permanent magnet

Details R-T-B system permanent magnet R-T-B system permanent magnet

2004-06-24

2008-12-09

Sheehan, John P. (Department: 1793)

Stock material or miscellaneous articles

All metal or with adjacent metals

Having magnetic properties, or preformed fiber orientation...

C148S302000

Reexamination Certificate

active

07462403

ABSTRACT:
An R-T-B system permanent magnet1comprises a magnet body2comprising a sintered body comprising at least a main phase comprising R2T14B grains (wherein R represents one or more rare earth elements, and T represents one or more transition metal elements including Fe or Fe and Co essentially) and a grain boundary phase containing R in a larger amount than the main phase, the magnet body2having a 300 μm or less thick (not inclusive of zero thick) hydrogen-rich layer21having a hydrogen concentration of 300 ppm or more formed in the surface layer portion, and an overcoat3covering the surface of the magnet body2can improve the corrosion resistance of the R-T-B system permanent magnet1with an overcoat3formed thereon without degrading the magnetic properties thereof. The present invention can be applied to formation of the overcoat3by electrolytic plating, can fully ensure the corrosion resistance as a primary target of the overcoat3formation without substantially degrading the production efficiency, and can provide the R-T-B system permanent magnet1with a high dimensional precision by suppressing the partial collapse (detachment of grains) of the surface thereof.

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English translation of Chinese language office action issued in corresponding Chinese application No. 200480015078.5.

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