PERMANENT MAGNET WITH EXCELLENT CORROSION RESISTANCE

PROBLEM TO BE SOLVED: To improve corrosion resistance by a method wherein an electrodeposition coating film having a uniform thickness is formed on the surface of a permanent magnet body in which the atomic % of R, B and Fe as main components is specified and whose main phase is composed of a tetragonal system. SOLUTION: An alloy for a permanent magnet body whose main components are composed of 8 to 30 atomic % of R (where R represents one kind out of rare-earth elements containing Y), 2 to 28 atomic % of B and 42 to 90 atomic % of Fe contains a nonmagnetic phase of 1 to 50% in terms of the volume ratio. In the case of a sintered magnet, a compound having the crystal structure of a tetragonal system whose crystal particle size is in a range of 1 to 100μm is used as a main phase. The permanent magnet body is immersed in an aqueous paint, the permanent magnet body is used as a north pole or a south pole, a DC current is supplied across the permanent magnet body and a counter electrode, the permanent magnet body is electrically painted as a whole, and a corrosion-resistant resin layer having a uniform thickness is formed on the surface. Thereby, it is possible to obtain the permanent magnet body which has an extremely high energy product of 25 MG Oe or higher, whose remanent magnetic flux density is high, whose coercive force is high and whose corrosion resistance is high.