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AssigneeSumitomo Special Metals Co., Ltd.
InventorsFumiaki Kikui, Masako Ikegami, Koshi Yoshimura
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An R—Fe—B permanent magnet body is cleaned by ion sputtering, after which a Ti coating film is formed on the surface of the magnet body by a thin film forming method such as ion plating, after which an Al coating film is formed as an intermediate layer, after which an AlN coating film, TiN coating film, or Ti1−xAlxN coating film is formed by a thin film forming method such as ion reactive plating in N2 gas. By having the Al coating film layer present as an intermediate layer, it acts as a sacrificial coating film for the permanent magnet body and the foundation layer Ti coating film, whereupon adhesion with the Ti coating film is sharply improved, and the time until corrosion develops is lengthened, even in such severe corrosion resistance tests as salt water spray tests. Thus R—Fe—B permanent magnets are obtained which exhibit outstanding salt water spray resistance and wear resistance and which have stable magnetic characteristics.
A permanent magnet made of an R—Fe—B system alloy resistant to salt water corrosion with a layer consisting of Ti as an undercoat coated on a surface layer of said magnet, either a TiN layer, an AlN layer or a Ti1−xAlxN layer (where x:0.03-0.70) as an external layer, and an Al layer inserted as an intermediate layer between the Ti undercoat layer and the external layer.
A production process for a permanent magnet resistant to salt water corrosion, comprising the sequential steps of:
Dependencies are inferred from the claim text.