RARE-EARTH ELEMENT IRON PERMANENT MAGNET SUPERB IN CORROSION RESISTANCE

PURPOSE:To protect the surface of a sintered or casted magnet with a corrosion- resistant film which is superb in adhesion strength and corrosion resistance by providing a nickel/phosphorus-plating film on a permanent magnet surface through a ground film of nickel plating. CONSTITUTION:Ni plating is performed on the surface of a rare-earth element iron permanent magnet and then Ni-P plating is performed. Furthermore, to reinforce resistance against chemicals, it is also effective that chromate treatment is performed onto the above Ni-P plating and chromium oxide film is used for coating. Also, it is recommended to add Ni-P-W plating to increase friction strength especially. In this case, it is also effective to perform chromate treatment to the upper surface and then coat the surface with chromium oxide film. Thus, a rare-earth element iron permanent magnet which easily becomes rusty is superb in corrosion-resistance effect and does not produce rust after long periods of use under a severe environment.