Investigation of the thermo-oxidative degradation of plastic Bonded Rare-Earth-Magnets during the injection molding process

Polymer Bonded Magnets can be cost effectively produced by injection molding of polymers with magnetic fillers. Rare-Earth-fillers (RE) like NdFeB or SmCo in comparison with other permanent magnetic fillers have remarkably higher magnetic properties. Nevertheless they are very reactive and oxygen susceptible which leads to polymer degradation and filler oxidation during the processing. This paper deals with two different methods of resolution to improve the thermal and thermo-oxidative stability of rare earth filled polymers during processing: powder coating and processing under inert atmosphere.