スプレー造粒粉を用いたNd-Fe-B焼結磁石の磁気特性(II) Magnetic Properties of Nd-Fe-B Magnets Sintered Using Granulated Powders by Spray Drying Method (II)
Nd-Fe-B alloy powder was granulated by spray drying method using methylcellulose (MC) binder in the range from 0.1 to 0.5wt%, in order to improve the powder flowability during feeding and compacting. After adding MC binder, glycerin and pure water to alloy powder, the slurry was stirred at 278K in N<SUB>2</SUB> atmosphere to suppress the oxidation of alloy powder. The granulated powders with MC binder exhibited higher flowability than granulated powders with polyvinylalcohol(PVA) binder. By heating in H<SUB>2</SUB> at 673K after compacting in a magnet field, 96% of carbon in binder was removed, although the oxygen in binder remained unremoved. With the compacted body added 0.20wt% MC, these treatments can allow to suppress the residual contents of oxygen and carbon in the resulted sintered magnets within less than 8500ppm and 600ppm, respectively. The coercive force(iHc) and maximum energy product (BH) <SUB>max</SUB> for a sintered anisotropic magnet prepared by the above mentioned process are 0.96(MA/m) and 241.1 (kJ/m<SUP>3</SUP>), respectively, in which (BH)<SUB>max</SUB> is lower by 15% than that obtained by using PVA binder.
粉体および粉末冶金 43(5), 675-681, 1996-05-15
Japan Society of Powder and Powder Metallurgy