Nanoparticle Synthesis and Coating for Exchange Coupled Permanent Magnets

The formation of exchange coupled permanent magnets consisting of nanometer sized hard magnetic grains enveloped in a soft magnetic matrix has been demonstrated experimentally to increase the energy product of advanced magnetic materials. Additional gains are still predicted, but improved control of the nanostructure must be achieved through a route that is both performance and cost effective. nGimat Co. proposes to utilize their proprietary NanoSpraySM and CCVC processing techniques to produce nanopowders suitable for sintering into dense, nanostructured exchange coupled magnets. Initially, both hard magnetic and soft magnetic nanopowders will be demonstrated individually. The two powders will then be blended as a liquid dispersion or in dry powder form via ball milling for subsequent pressing and sintering into consolidated pellets. Following successful production of the individual powders, core-shell nanopowders will be developed consisting of a hard magnetic core coated with a soft magnetic phase using a dynamic heterogeneous nucleation deposition technique. Core-shell nanocrystals are expected to improve dispersion and contact between the two phases following sintering. Successful completion of Phase I objectives will lead to a Phase II effort to complete the development and commercialization of the proposed nanomaterials for annealing/sintering into high energy density exchange coupled permanent magnets.