SBIR Phase II: Fe-nanoparticle coating of anisotropic magnet powder for nanocomposite permanent magnets with enhanced (BH)max

This Small Business Innovation Research Phase II project proposes the development of an innovative and facile method to synthesize composite magnet powders coated with Fe and/or Fe-Co nanoparticles and to consolidate them into high performance anisotropic nanocomposite magnets. It was theoretically predicted in the 1990s that two phase exchange-coupled nanocomposite magnets consisting of a hard magnetic phase with high magnetocrystalline anisotropy and a soft magnetic phase with high saturation magnetization may exhibit a maximum energy product (BH)max twice the value of the current magnets. In this research effort, Fe and Fe-Co nanoparticles will be deposited onto hard magnetic powders by combined chemical and physical methods. Unlike previously employed techniques, the proposed approach allows the control of the size of soft magnetic phase to the nanoscale. Moreover, the approach is compatible with mass production. Subsequent consolidation of these composite powders by pressure and temperature assisted methods will lead to a new generation of high performance anisotropic nanocomposite permanent magnets with a (BH)max much higher than that of the current commercial magnets. The multiple choices for the core powder will result in new improved magnets for close-to-room-temperature applications (Nd2Fe14B-based), high temperature applications (SmCo5- and Sm2Fe17Nx-based) and ultra-high temperature applications (Sm2Co17-based). The success in the development of the new (nano)composite magnets will directly result in the improvement of the functionality of electromagnetic devices and eventually lead to new applications not possible with the current permanent magnets. The higher performance magnets will result in even lighter weight, smaller footprint and lower the total system cost for electromagnetic devices in both commercial and military applications. The most well known applications are in: hybrid cars (permanent magnet motors and generators, sensors and actuators), spacecraft (momentum wheels, reaction wheels, stepper motors, ion propulsion), microwave sources (traveling wave tube amplifiers, klystrons, magnetrons), microwave components (isolators, circulators), inertial guidance (accelerometers, gyros), and other commercial systems (computer disk drives, computer printers, audio systems, satellite communication, medical imaging, stepper motors, etc). The proposal is a multidisciplinary enterprise involving physics, chemistry, and metallurgy. The bottom-up approach to the synthesis of nanocomposite magnets with uniform and controllable thickness of the soft magnetic shell formed from the precursor nanoparticle coating, will allow for an in-detail experimental characterization of magnetic interactions. This will provide valuable information to understand and substantially diminish the gap between the theoretical predictions and engineering capabilities.