Nd-Fe-B異方性スプレー造粒粉の磁界配向 Magnetic Field Alignment of the Anisotropic Spray Dried Nd-Fe-B Powder
A process to obtain the anisotropic spray dried Nd-Fe-B powder has been studied in order to improve the poor alignment of sintered magnets synthesized by the usual isotropic spray dried powder. A magnetic field of 0.12 MA/m was applied transversely to the flow of droplet where it dried up to be granulated powder which has a good flowability. The measurement of the initial magnetization curve and the X-ray diffraction patterns revealed that the easy axis of powders aligns to the direction of the external field more easily compared with the isotropic powder<BR>spray dried in the same condition without a magnetic field. It suggests that our spray dried powder is anisoptropic; Nd-Fe-B fine powder included in each granular is uniaxially aligned. The alignment of the anisotropic spray dried powder in a low field is dominated by the rotation of granulated powder. When the strength of the magnetic field at compacting is 0.23 MA/m, (BH)max of the sintered magnet obtained from the anisotropic spray dried powder exceeds by 19.2 % than the value for the isotropic one.
粉体および粉末冶金 45(2), 163-168, 1998-02-15
Japan Society of Powder and Powder Metallurgy