SBIR Phase II: Fe-nanoparticle Coating of Anisotropic Magnet Powder for Nanocomposite Permanent Magnets with Enhanced (BH)max

这一小型企业创新研究第二阶段项目建议开发一种创新和简便的方法来合成包覆有Fe和/或Fe-Co纳米颗粒的复合磁粉，并将其固结为高性能的各向异性纳米复合磁体。20世纪90年代从理论上预测，由具有高磁晶各向异性的硬磁相和具有高饱和磁化强度的软磁相组成的两相交换耦合纳米复合磁体的最大能量积(BH)最大值可能是当前磁体的两倍。本研究采用化学和物理相结合的方法，将Fe和Fe-Co纳米粒子沉积到硬磁粉上。与以前使用的技术不同，所提出的方法允许将软磁相的尺寸控制到纳米级。此外，这种方法与大规模生产兼容。通过压力和温度辅助的方法对这些复合粉末进行后续固结，将得到新一代高性能各向异性纳米复合永磁体，其(BH)max远高于目前商用磁体的(BH)max。磁芯粉末的多种选择将导致新的改进磁体，用于近室温应用(基于Nd2Fe14B)、高温应用(基于SmCo5和Sm2Fe17Nx)和超高温应用(基于Sm2Co17)。新型(纳米)复合磁体的成功开发将直接导致电磁设备功能的改进，并最终导致现有永磁体无法实现的新应用。更高性能的磁体将为商业和军事应用中的电磁设备带来更轻的重量、更小的占地面积和更低的系统总成本。最著名的应用是：混合动力汽车(永磁电机和发电机、传感器和执行器)、航天器(动量轮、反应轮、步进电机、离子推进)、微波源(行波管放大器、速调管、磁控管)、微波组件(隔离器、循环器)、惯性制导(加速计、陀螺仪)和其他商业系统(计算机磁盘驱动器、计算机打印机、音频系统、卫星通信、医学成像、步进电机等)。该提案是一家涉及物理、化学和冶金的多学科企业。采用自下而上的方法合成具有由前驱体纳米颗粒涂层形成的软磁壳厚度均匀且可控的纳米复合磁体，将允许对磁相互作用进行详细的实验表征。这将为理解和大大缩小理论预测和工程能力之间的差距提供有价值的信息。

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.