2004 Volume 51 Issue 3 Pages 160-164
Some nickel coated Nd-Fe-B sintered magnet scraps were recycled as the starting materials for isotropic bonded magnets by using the melt-spinning method. Good magnetic properties (Br=-0.74T, Hcj=-0.94MA/m, and (BH)max=-86.5 kJ/m3) were obtained when the amorphous-like samples prepared at the roll surface velocity of 25 m/s were annealed at 973 K for 3 min in Ar. The magnetic properties were still improved by adding iron metal to the starting material scraps due to the further increase in the intrinsic magnetization of recycled samples. The magnetic properties of bonded magnets prepared from the above powders at 1 GPa were Br=-0.69T, Hcj=-0.81 MA/m, and (BH)max=-73.8 kJ/m3, which were nearly similar to those of the bonded magnet prepared from the commercially available powder with the magnetic properties of Br=-0.73T, Hcj=-0.79 MA/m, and (BH)max=-85.9 kJ/m3. Moreover, the nano-composite powders were prepared by hydrogenation disproportionation and subsequent oxidation of the slugs, which were generated during the recycling process by the melt-spinning. The resultant composite materials showed good absorption properties for the electromagnetic waves in 5-5 GHz range.
