Polymer-bonded magnets, III. Effect of surface modification and particle size on the improved oxidation and corrosion resistance of magnetic rare earth fillers

Xiao, Jun; Otaigbe, Joshua

Department of Materials Science and Engineering

Iowa State University of Science and Technology

Ames, IA USA

Abstract

We studied the effect of surface modification and particle size on the oxidn. and corrosion behavior of neodymium-iron-boron (Nd-Fe-B) magnetic alloy powders by using thermal anal. to accelerate efforts to develop useful poly(phenylene sulfide) bonded Nd-Fe-B magnets. The results indicate that coating the Nd-Fe-B powders with a coupling agent provides the required oxidn. and corrosion resistance for the targeted processing conditions. The coated rare earth powders are thermally and environmentally stable at elevated temps. and in a 100% humid environment, where com. rare earth alloy magnets are not usable. The coating treatment more significantly affects the small particle powders. A mechanism accounting for the improved thermal and environmental stability is presented and discussed. Magnetic measurements were performed to verify the thermal anal. results.