Modeling of magnetic properties of polymer bonded Nd-Fe-B magnets with surface modifications

Xiao, J.; Otaigbe, J. U.; Jiles, D. C.

Department of Materials Science and Engineering

Iowa State University of Science and Technology

Ames, IA, USA

Abstract

The effects of surface modification on the magnetic properties of polymer-bonded Nd-Fe-B magnets were studied. Two sets of Nd-Fe-B powders, coated and uncoated, were blended and compression molded with polyphenylene sulfide in isotropic form. Their magnetic properties were measured using a Helmholtz coil and a SQUID. The effect of the coating significantly improved the irreversible loss in flux and energy product of the polymer-bonded magnets. The results were interpreted using an isotropic model of hysteresis that takes into account energy losses. The modeling showed that the presence of soft magnetic materials in the Nd-Fe-B powders caused by oxidn. reduces the interaction among magnetic particles, however, the coating treatment alters the magnetic properties by increasing the remanence of polymer-bonded magnets via increasing the interparticle coupling coeff.