PERMANENT MAGNET HAVING HIGH CORROSION RESISTANCE AND MANUFACTURING METHOD THEREOF

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PROBLEM TO BE SOLVED : To provide a permanent magnet having high corrosion resistance which is realized by reducing the content of an alkali component contained in a glassy protection layer, and also to provide a manufacturing method thereof.SOLUTION : The manufacturing method of a permanent magnet having high corrosion resistance comprises the steps of dipping an R-Fe-B system permanent magnet (R is at least one kind of rare earth elements including Y) into treatment liquid comprising an alkalisilicate solution, or coating the treatment liquid on the surface of the magnet; after then heat hardening it at temperatures of 120-450°C to form a glassy protection layer having thicknesses of 100 nm to 10 μm on the surface of the magnet; and washing the glassy protection layer for 1-60 minutes with hot-water having temperatures of 10-90°C, thereby removing an alkali component.COPYRIGHT : (C)2006, JPO&NCIPI