Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Patent
1992-11-25
1994-05-24
Walsh, Donald P.
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
428555, 428554, 428553, 428548, B22F 700
Patent
active
053147561
ABSTRACT:
Disclosed is to improve corrosion resistance of rare-earth-element (RE)/transition-metal system permanent magnets by means of surface treatment, the magnets containing one or more of RE comprising yttrium, transition metals mainly comprising Fe. A conductive underlayer is formed on the surface of the magnet, on which an electroplated (hereinafter referred to as e-) Cu layer with the average crystal grain size not larger than 0.9 .mu.m is further formed. The underlayer may be any of an e-Ni layer, an electroless-plated Cu layer, an e-Cu layer by a cyanic Cu bath and another e-Cu layer by a bath of an alkaline organic acid salt of Cu containing phosphoric ester as a primary ingredient. A protective layer may be formed on the e-Cu layer, which is any of an e-Ni layer, an electroless-plated Ni-P layer, an e-Ni-alloy layer. The e-Cu layer is formed with a Cu pyrophosphate bath.
REFERENCES:
patent: 3674660 (1972-07-01), Lyde
patent: 3877478 (1975-04-01), Longworth
patent: 4082620 (1978-04-01), Skurkiss
patent: 4959273 (1990-09-01), Hammamura et al.
patent: 4984226 (1991-01-01), Kobori
Greaves John N.
Hitachi Metals Ltd.
Walsh Donald P.
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