Posters will be on display in the exhibit hall and authors will be available to chat during networking breaks.
Acid-Free Leaching of Rare Earth Elements from E-Wastes and End-of-Life Magnets
Critical rare earth elements (REEs) are widely used in modern high-tech applications. They are essential for national energy, technological and manufacturing competitiveness, and security. Recycling offers an opportunity to apply circular economy to REEs by recovering them as secondary raw materials from permanent magnets. Proposed hydrometallurgical recycling methods typically dissolve magnets in large volumes of mineral acids and generate significant amounts of acid contaminated wastes. Our process dissolves magnets in water-based solutions, applies to both Nd-Fe-B and Sm-Co magnets and recovers high purity REEs and Co. It is also energy efficient and demonstrated to be economically profitable.
Denis Prodius, Critical Materials Institute
Ikenna C. Nlebedim, Ames Laboratory, US Department of Energy
Exchange-Coupled Inverse Core Shell Nanoparticles
The high cost and supply challenges of heavy rare earth (RE) elements has led to a range of proposals to create a new permanent magnet that offers a competitive energy product while reducing or eliminating the need for RE. One promising idea is the exchange spring magnet (ESM), where a coercive hard phase is coupled to a high-remanence soft phase through the nanoscale exchange interaction. Such a composite system will retain the best properties of both phases, enabling increased energy product and improved high temperature performance. We have developed a model system to study the feasibility of such engineering, composed of soft 12nm Ni nanoparticles coated with a 1nm layer of CoFe2O4. Element-specific magnetometry demonstrates that the hard shell layer acts to suppress the superparamagnetism of the Ni core, creating a hybrid particle where the Ni moments are aligned with the CoFe2O4, gaining an increased coercivity. These results demonstrate the feasibility of the core-shell architecture for exchange coupled nanoparticles, an approach which can be readily extended to include materials such as SmCo5/Fe, matching a much harder shell to a higher remanence core, leading to a magnet with an enhanced energy product and reduced critical materials intensity. This research was sponsored by the Critical Materials Institute, an Energy Innovation Hub funded by the US Department of Energy. Prepared by LLNL under Contract DE-AC52-07NA27344.
Scott K. McCall, Magnet Thrust Lead, Critical Materials Institute, Lawrence Livermore National Laboratory
Tough Sm-Co Sintered Magnets with Novel Heterogeneous Microstructure and Improved Flexural Strength
SmCo5 and Sm2Co17 type sintered magnets have excellent magnetic properties. However, they are quite brittle and easily prone to chipping, cracking or fracture in the courses of magnet manufacture, machining, assembly, shipping, and operation. This could lead to the production loss up to 30 percent. Improving the flexural strength or fracture toughness of Sm-Co magnets is of a great scientific, technical and practical significance. The improvement in the mechanical toughness of Sm-Co magnets while maintaining their high magnetic performance would not only improve their manufacturing efficiency and machinability, reduce part failure rate and effectively use of expensive critical materials, but it would also greatly expand the market share for this class of permanent magnets, by offering opportunities for new applications, new shapes, and lower costs. In this work, flexural strength values of Sm2(CoFeCuZr)17 sintered magnets were enhanced by up to 73 percent (up to 202 MPa) by the formation of novel heterogeneous bi-modal microstructures. Excellent magnetic properties were maintained with the maximum energy product (BH)max (~ 24-26 MGOe) decreased by less than 8 percent, and no decrease of remanence Br values. The tough Sm-Co bulk magnets have a novel 3D gradient harmonic microstructure with a bi-modal grain size microstructure.
Baozhi Cu, Critical Materials Institute, Ames Laboratory, US Department of Energy
Jun Cui, Department of Materials Science and Engineering, Iowa State University
New Potential High Performance Magnet Materials
High performance magnets, such as the Nd2Fe14B and SmCo5 magnets used in numerous applications,
contain three intrinsic properties – high saturation magnetization (usually 10 kG or higher), a high
magnetocrystalline anisotropy, and a Curie point of 500 K or above. However, these properties are not
found only in rare-earth containing magnets. In this poster presentation we will show recent research on
three magnetic systems studied within the U.S. Department of Energy Critical Materials Institute:
• The alloy LaCeCo16Ti, which shows magnetizations approaching 10 kG and anisotropy
fields as large as 6 Tesla.
• Fe5SiB2 and Fe5PB2, which show promise  as Alnico-beating “gap magnets”; and
• Cerium-alloyed Nd2Fe14B, which maintains  most of the favorable magnetic properties
of Nd2Fe14B while reducing the materials cost.
We will also describe the outlook for these and related magnetic systems.
David Parker, Oak Ridge National Laboratory
Alternative Supply Streams of Permanent Magnets from Postconsumer Products and Machining Scraps
Long-term concern about supply and cost of critical rare earth elements used in high strength permanent magnets necessitates the investigation of alternative supply streams for these materials. Two avenues were investigated: direct reuse of magnets extracted from end-of-life hard disk drive magnets and bonded magnet filaments that utilize Sm-Co magnet powder recovered from industrial magnet swarfs (waste generated from machined magnets). Permanent magnet machine designs that incorporate hard-disk drive magnets are described. Greater than 80 percent of the original magnet volume is used. Extrusion of filaments with up to 50 vol.% loading of recycled Sm-Co powder in polylactic acid (PLA) is demonstrated for additive manufacturing purposes.
Helena Khazdozian, Critical Materials Institute, Ames Laboratory, US Department of Energy
A New Contactless Magneto-LC Resonance Technology for Real-Time Respiratory Motion Monitoring
Monitoring the rate of respiration and its pattern is crucial to assessing an individual’s health or progression of an illness, creating a pressing need for fast, reliable and cost-effective monitors. We present here a novel respiratory monitoring technology based on a magnetic microwire coil (MMC) magneto-LC resonance sensor. The 3 mm diameter coil is wound from a melt-extracted amorphous Co69.25Fe4.25Si13B12.5Nb1 microwire. Unlike typical solenoids, the MMC is sensitive to small magnetic fields due to a significant change in impedance attributed to the high-frequency giant magneto-impedance (GMI) effect. We propose an application of the MMC sensor to detect a position-varying source of a small magnetic field (~0.01 – 10 Oe) for real-time respiratory monitoring of a human patient. We simulate this application by mounting a small permanent magnet to a mechanical vibrator and vibrating the magnet at different frequencies, amplitudes, and waveforms ~3 – 15 cm above the MMC. Actual tests performed on a voluntary person demonstrate the excellent performance of the MMC sensor whose sensitivity is much higher compared to conventional magnetic sensors. This newly developed MMC magneto-LC resonance technology is highly promising for active respiratory motion monitoring and other biomedical field sensing applications.
Tatiana Eggers, Ph.D. Candidate, University of South Florida
Enabling End-Uses of Magnetic Materials with Systems Level Modeling
High energy density magnets used in a wide range of permanent magnet machines contain critical rare earth elements, such as neodymium and dysprosium, which raise concern regarding long-term cost and availability. By employing finite element analysis, end-use applications for magnetic materials that conserve critical materials can be identified. Through industrial collaborations, new materials and technologies can be tailored to fit application needs and minimize design changes to aid in adoption. In this poster, we present two paths towards achieving this goal: (1) potential of exchange-spring magnets in direct-drive wind turbines and (2) direct reuse of hard-disk drive magnets in a dryer motor. The performance of an exchange-spring magnet with varied composition was investigated in a permanent magnet generator. Recycled hard-disk drive magnets were substituted in an interior permanent magnet motor.
Helena Khazdozia, Critical Materials Institute