RARE-EARTH MAGNET COVERED WITH PROTECTIVE FILM COMBINING INSULATION AND GAS IMPERMEABILITY

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PROBLEM TO BE SOLVED : To achieve a rare-earth magnet the surface of which is entirely covered with a protective film that satisfies seven requirements as follows, firstly it is insulative, secondly it blocks gas, thirdly it is an extremely thin membrane, fourthly it bonds firmly to a magnet, fifthly it holds a physical defect layer on the magnet surface, sixthly it can be formed by the same manufacturing method regardless of the shape or size the magnet, and seventhly it can be formed at a low cost by using an inexpensive raw material. SOLUTION : A lump of fine particles of a metal oxide (maghemite fine particles 2) combining hard magnetism and insulation is magnetically adsorbed, as a multilayer structure of the fine particles, to the entire surface of a rare-earth magnet (neodymium magnet 1). The entire surface of the rare-earth magnet is covered with a protective film where the multilayer structure of the metal oxide fine particles is covered with a coat of an organic compound (butyl oleic acid 3) comprising a liquid combining insulation and water repellency. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2017, JPO&INPIT