Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

• Published in: Physics of metals and metallography 2013-04, Vol.114 (4), p.285-294
• Main Authors: Popov, A. G., Gerasimov, E. G., Terent’ev, P. B., Gaviko, V. S., Shunyaev, K. Yu, Mikhailova, T. L., Vas’kovskii, V. O., Kulesh, N. A.
• Format: Article
• Language: English
• Subjects: Analysis; Chemistry and Materials Science; Densification; Density; Electrical and Magnetic Properties; Ferrous alloys; Lubrication and lubricants; Magnetic fields; Magnetic materials; Magnets; Materials Science; Metal products; Metallic Materials; Powders; Sintering; Specific gravity; Texture; Zinc stearate
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X13040066

Zinc stearate additions have been used to increase the remanence of sintered Nd-Fe-B magnets produced by the powder metallurgy without powder pressing. Zinc stearate acts as an internal lubricant, i.e., it decreases the friction forces between the particles and favors an increase in the degree of texture of the powders, which is induced by the magnetic field. It is shown that the density and the magnetic hysteresis characteristics of sintered magnets produced using additions of 0.15 wt % zinc stearate exceeds the corresponding values obtained for magnets produced without this addition at a filling density of powders in containers of more than 2.9 and 3.0 g/cm 3 in dry and wet states, respectively. Using additions of zinc stearate in the amount of 0.15% with respect to the weight of the powder, magnets with a density of 7.55 g/cm 3 , B r = 14.02 kG, H c = 7.91 kOe, and ( BH ) max = 46.1 MG Oe have been produced.