スプレー造粒粉を用いたNd-Fe-B焼結磁石の磁気特性(III) Magnetic Properties of Nd-Fe-B Magnets Sintered Using Granulated Powders by Spray Drying Method(III)
Nd-Fe-B alloy powder was granulated by spray drying method using organic binder consisted of polyvinylalcohol (PVA) or carboxymethylcellulose (CMC) with different tensile strength, in order to improve the powder flowability during feeding and compacting. The relationships between binder composition, polymer/plasticizer ratio and content of binder, and granulated powder characteristics or magnetic characteristics were investigated. By using a polymer with high tensile strength, the bonding strength between alloy powders increased, so that the powder flowability of granulated powders was improved. After compacting these powders in a magnetic field, compacted bodies were heated at 673K in H2. About 96% of carbon in binder was removed, although the oxygen in binder remained. In the case of high tensile strength polymer, remanences (Br) of sintered magnets decreased by about 20%, as compared with those of low tensile strength one. However, by increasing the plasticizer content in organic binder both of Br and maximum energy product (BH)max were improved remarkably.
粉体および粉末冶金 44(8), 775-780, 1997-08-15
Japan Society of Powder and Powder Metallurgy