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

The effects of surface modification on the magnetic properties of polymer-b onded Nd-Fe-B magnets have been studied. Two sets of Nd-Fe-B powders, coate d and uncoated, were blended and compression molded with polyphenylene sulf ide in isotropic form. Their magnetic properties were measured using a Helm holtz coir and a SQUID. The results showed that the effect of the coating s ignificantly improved the irreversible loss in flux and energy product of t he polymer-bonded magnets. The results have been interpreted using an isotr opic model of hysteresis that takes into account energy losses. The modelin g showed that the presence of soft magnetic materials in the Nd-Fe-B powder s caused by oxidation reduces the interaction among magnetic particles, how ever, the coating treatment alters the magnetic properties by increasing th e remanence of polymer-bonded magnets via increasing the interparticle coup ling coefficient. (C) 2000 Elsevier Science B.V. All rights reserved.