Abstract
The Nd-Fe-B alloy powder was kneaded at 283K with the binder of methylcellulose dissolved in water. The mixture was injected at temperature 293K in a die of 353K, which is slightly above the sol-gel transformation temperature of methylcellulose. The magnetic field of 1.35 (MA/m) was applied to produce the alignment of easy magnetization direction of alloy powder in a molded body. The molded body was dehydrated by the vacuum-drying method to suppress the oxidation of alloy powder. By heating it in H2 at 573K for 0.5H, about 80% of carbon in binder was removed, although the oxygen in binder remained unremoved. With the molded body added 2wt% methylcellulose, these treatments can allow to suppress the residual contents of oxygen and carbon in the resulted sintered Nd-Fe-B alloy within less than 9000ppm and 800ppm, respectively. The highest coercive force (iHc) and maximum energy product (BH) m ?? x for a sintered anisotropic magnet prepared by the above mentioned process are 1.10(MA/m) and 287.2(kJ/m3), respectively.
