| 摘要 |
PURPOSE:To obtain a magnet being excellent in corrosion resistance, by specifying the composition of an Fe-B-rare-earth permanent magnet material and by coating the surface thereof with a corrosion-resistant resin layer by electrodeposition. CONSTITUTION:A sintered substance having a tetragonal crystal structure as a main phase is made of Nd 11-15 atom % and Dy 0.2-3 atom %, the total quantity of which is 12-17 atom %, and further B 5-8 atom %, CoO 0.5-13 atom %, Al 0.5-4 atom %, C 1000 ppm or less and Fe and inevitable impurities as the rest. Humidity resistance is improved by adding Ti or Nb of 0.1-1 atom % in addition. This magnet substance is dipped in water-based coating, and with the substance made to act as an anode or a cathode, a DC current is let to flow between it and an opposite electrode, so as to coat the whole with corrosion-resistant resin electrically. For anionic electrodeposition coating, polyester or the like is used, and it is neutralized by a base such as KOH, dessolved in a water solution and charged to be negative. For cationic electrodeposition coating, epoxy resin or the like is used, and it is neutralized by an organic acid, dissolved in a water solution and charged to be positive. By this constitution, a magnet being excellent in corrosion resistance can be obtained. |
