| 摘要 |
PURPOSE:To obtain an R-Fe-B-based permanent magnet whose corrosion- resistant property is excellent by a method wherein a protective layer is constituted of Ni or an Ni alloy which contains one or more kinds of Co and Fe at a specific wt.%. CONSTITUTION:A protective layer on the surface of a permanent magnet which contains R (where R is one or more kinds of rareearth elements including Y), Fe and B and whose main phase is substantially a tetragonal system is constituted of Ni or an Ni alloy which contains one or more kinds (whose total content is within a below-mentioned range even when they are added in a composite manner) of Co and Fe at 0.4 to 3wt.%. Two or more protective layers are formed. When the content of Co and Fe in the protective layers is less than 0.4wt.%, a pinhole is easy to produce, coarse crystal particles in an Ni-plated film are easy to produce and a corrosion-resistant property is not sufficient. It is undesirable when the content exceeds 3wt.% because a stress in the Ni- plated film becomes large and the film is easy to exfoliate. |
