METHOD OF PROTECTING FE-ND-B SERIES MAGNETISM POWDER AND HIGH DENSE PERMANENT MAGNET FROM OXIDATION AND ATMOSPHERIC CORROSION

摘要

PURPOSE: To remarkably improve resistance to corrosion due to wet air, by introducing N2 +F2 gas mixture containing a specified amount of fluorine, in a pulverizing process. CONSTITUTION: Magnetic powder composed of chemical composition of NdPrDyBNAlCuFe which is obtained by heat-treating mechanically ground ingot in H2 is pulverized by using N2 +F2 gas mixture, in a jet mill having a chamber. The gas mixture contains fluorine of 1-100 ppm in volume. The obtained fine powder contains fluorine of 600-2000 ppm. Thereby powder of little reactivity and a high density magnet excellent in atmospheric corrosion resistance can be obtained.