Patent ID: 6878217

Claim:
A method for producing a permanent magnet comprising a rare earth metal-based permanent magnet having provided directly on the surface thereof a chemical conversion film containing, at least as the constituent components thereof, (a) at least one metal selected from the group consisting of molybdenum, zirconium, vanadium, and tungsten; (b) a rare earth metal from the rare earth metal-based permanent magnet; (c) oxygen; and (d) phosphorous, said method comprising: directly treating the surface of a rare earth metal-based permanent magnet with a treatment solution containing at least one selected from the group consisting of a molybdic acid or a salt thereof, a molybdenum oxide, a molybdophosphoric acid or a salt thereof, a zirconic acid or a salt thereof, a zirconium oxide, a vanadic acid or a salt thereof, a vanadium oxide, a tungstic acid or a salt thereof, a tungsten oxide, wherein said treatment solution further contains a phosphoric acid or a salt thereof and/or a phosphorous acid or a salt thereof, wherein the treating causes a reaction between metallic ions in the treatment solution and the rare earth metals that elute from the magnet.