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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Advances in Processing, Manufacturing, and Applications of Magnetic Materials

Magnetic materials are increasingly important for many green energy technologies. Probably, the best known of these are permanent magnets. They are used to supply a magnetic field and are widely used in actuators, motors, generators, data storage, and sensors. These are “hard magnets,” meaning that they retain a large permanent magnetization (difficult to be demagnetized), which is what makes them so useful in motors where an opposing magnetic field can be used to push against them. A coercivity (resistance to demagnetization) of ~400 Oe (32,000 A/m) or more is typically the threshold value for a hard magnet and is typical of isotropic sintered ferrite (SrFe 12 O 19 ) such as found in many “refrigerator magnets.” Comparably important soft magnets are useful for directing magnetic fields and can be very easily (de)magnetized. As such, they typically have a coercivity < 12.5 Oe (1000 A/m), and specialized very soft magnets can have coercivities < 0.00125 Oe (1 A/m). Some common applications include coil cores, transformer cores, and magnetic shielding. Additionally, they are important for many AC electrical applications such as inductors, filters, and resonators, particularly at high frequencies up to and including microwaves.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Near net shape bulk laminated silicon iron electric steel for improved electrical resistance and low high frequency loss

The invention involves producing discontinuous, flake-shaped particles of a soft magnetic material, coating the flake-shaped particles with an electrically insulating coating, and consolidating the coated flaked-shaped particles to form a soft magnetic bulk shape. The consolidated bulk shape can comprise a layer or a simple or complex 3D magnet part shape, which has a consolidated layered microstructure that includes laminated soft magnetic regions that are substantially encapsulated by an electrical insulating layer to increase the resistivity of soft magnetic material, especially when used in silicon iron magnet parts.

Cui, Jun↗
DOE OSTI2020

The Effects of Annealing after Equal Channel Angular Extrusion (ECAE) on Mechanical and Magnetic Properties of 49Fe-49Co-2V Alloy

Equal channel angular extrusion (ECAE) of 49Fe-49Co-2V, also known as Hiperco® 50A or Permendur-2V, greatly improves the strength and ductility of this alloy, while sacrificing soft magnetic performance. In this work, ECAE Hiperco specimens were subjected to post-ECAE annealing in order to improve soft magnetic properties. The microstructure, mechanical properties, and magnetic performance are summarized in this study. Annealing begins above 650°C and a steep decline in yield strength is observed for heat treatments between 700 and 840°C due to grain growth and the Hall-Petch effect, although some strength benefit is still observed in fully annealed ECAE material compared to conventionally processed bar. Soft magnetic properties were assessed through B-H hysteresis curves from which coercivity (Hc) values were extracted. Hc decreases rapidly with annealing above 650°C as well, i.e. improved soft magnetic behavior. The observed trend is attributed to annealing and grain growth in this temperature regime, which facilitates magnetic domain wall movement. The coercivity vs. grain size results generally follow the trend predicted in the literature. The magnetic behavior of annealed ECAE material compares favorably to conventional bar, possibly due to mild crystallographic texturing which enhances properties in the post-ECAE annealed material. Overall, this study highlights a definitive tradeoff between mechanical and magnetic properties brought about by post-ECAE annealing and grain growth.

annealing↗
DOE OSTI2025

Solution‐Phase Metathesis of Li 3 N and FeCl 3 to Synthesize Fe 2 N/Fe 3 N Nanoparticles

Soft magnetic materials play key roles in the flow of energy in electrically driven machines and power conversion electronics, and there is a great need for improvements in their magnetic properties to provide the right combination of high saturation magnetization, low coercivity, and high permeability. Most phases of iron nitride (Fe x N) are soft magnetic materials with these characteristics, but they exist as numerous phases which are not all stoichiometric compounds. While the production and magnetic properties of the different phases of bulk iron nitride are well known, accessing phase‐pure nanoscale iron nitride consistently remains a challenge. Most methods for the synthesis of iron nitride nanoparticles require complicated apparatus to achieve high‐temperature nitriding of nanoparticle precursors with gaseous nitrogen sources such as ammonia. The first solution‐phase metathesis reaction between FeCl 3 and Li 3 N in oleylamine is developed to directly synthesize Fe 2 N/Fe 3 N nanoparticles, requiring only a fume hood, glove box, standard chemistry laboratory glassware, and equipment. Finally, the ≈10–15 nm spheres display nearly soft magnetic behavior with a saturation magnetization ≈50–60 A m 2 kg −1 , coercivities between 40–50 kA m −1 , and susceptibility values from 0.0001–0.0006 m 3 kg −1 , well within the ranges reported with other published Fe x N nanoparticle synthesis methods.

iron nitride↗
DOE OSTI2023

Amorphous Metal Ribbon (AMR) and Metal Amorphous Nanocomposite (MANC) Materials Enabled High Power Density Vehicle Motor Applications (Final Technical Report)

A collaborative team from Carnegie Mellon Univ. (CMU), North Carolina State Univ. (NCSU) and Metglas, South Carolina have studied new high speed motors (HSMs) with high-power density for traction motor applications. These are enabled by hybrid designs, including Flux Switching with Permanent Magnets (FSWPM) motors, exploiting permanent magnets without heavy rare earths (RE-lean) and high induction/high resistivity soft magnetic materials that allow for high switching frequencies needed to increase power densities. Team members include Michael E. McHenry, Prof. Materials Science & Eng., CMU, with > 30 years experience in magnetic materials development; Subashish Bhattacharya, Prof. Electrical Eng. and Freedom Center Director at NCSU with > 30 years experience in development of power electronic components and systems and Eric Theisen, Director of Research at Metglas, the only US located supplier of AMR and MANC materials. The team offers novel axial motor architectures exploiting soft magnetic materials (SMMs) that switch with low loss at high frequencies and heavy rare earth free permanent magnets that address materials criticality issues, supply chain risks, and high costs for traction motors. Axial-flux permanent magnet motors (APFM), offer efficiency improvements reducing rotor losses and also significantly higher power density. Axial-flux construction requires less core material, high torque-to-weight ratio. Since AFPM machines have thin magnets, they are smaller than radial flux motors making them attractive in space-limited applications. Noise and vibration are less and planar air gaps are easily adjusted. Flexibility in air-gap direction allows many topologies.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Amorphous and Nanocomposite Magnets for High Efficiency, High Speed Motor Designs

This project developed metal amorphous nanocomposite (MANC) soft magnetic materials (SMMs) for a rare earth (RE)-free 2.5 kW motor with 4% increased efficiency. The Project modeled RE-free motor topologies. The project outcomes addressed: (a) metal to alloy processing & magnet core production; (b) soft magnetic laminate & core post-processing; and (c) producing a 2.5 kW motor extending to TRL-5.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Canted standing spin-wave modes of permalloy thin films observed by ferromagnetic resonance

Non-collinear spin structures in materials that combine perpendicular and in-plane magnetic anisotropies are of great technological interest for microwave and spin wave-assisted magnetization switching. [Co/Pt] multilayers are well-known perpendicular anisotropy materials that have the potential to pin the magnetization of a soft magnetic layer, such as permalloy (Py), that has in-plane anisotropy, thereby forming a magnetic exchange spring. Here we report on multilayered [Co/Pt]/Pt/Py films, where an additional ultrathin Pt spacer has been included to control the coupling between the sub-units with in-plane and perpendicular magnetic anisotropy. Vector network analyser (VNA)-ferromagnetic resonance (FMR) measurements were made to obtain a complete picture of the resonant conditions, while the dynamical response of the sub-units was probed by synchrotron-based element- and phase selective x-ray detected FMR (XFMR). For all samples, only slight pinning of the dynamic magnetization of the Py by the [Co/Pt] was noted, and the FMR results were dominated by the 50 nm thick Py layer. Out-of-plane VNA-FMR maps reveal the presence of additional modes, e.g. a perpendicular standing spin-wave (PSSW) state. However, as the magnetic field is reduced below the saturation field, the PSSW state morphs continuously through a series of canted standing spin-wave (CSSW) states into a horizontal standing spin-wave (HSSW) state. The PSSW, CSSW and HSSW states are well described using a multilayer model of the Py film. The observation of CSSW modes is of particular relevance to microwave assisted magnetic recording, where microwave excitation stimulates precession of a soft layer canted out of plane by a pulsed magnetic field.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Ribbon Wrinkling Origin and Its Effect on Tape-Wound Core Shape

Improved understanding of advanced manufacturing techniques is needed to fabricate next- generation soft magnetic tape-wound cores. These utilize metal amorphous nano-composites (MANCs) in the form of long thin ribbons. MANCs exhibit attractive soft magnetic properties for use in high frequency and high power density magnetic components. Of particular interest here, the permeability and hysteresis of MANC ribbons can be tuned in a strain annealing process. An unexpected consequence is that wider ribbons develop longitudinal wrinkle patterns. This can substantially reduce the tape-wound core stacking factor. However, when winding a wrinkled ribbon into a toroidal core, the wrinkles can completely flatten, or crinkle. By this phenomenon, the stacking factor can be recovered. To understand the crinkling effect we have developed analytical and finite element analysis (FEA) models. Experiments with known boundary conditions demonstrate the transition from wrinkled to crinkled versus winding curvature. The models utilize an elastic modulus measured via ribbon tensile testing and a ribbon thickness value measurement made by profilometry. The analytical model provides insight into the crinkling effect but cannot explain the length of the transition region from wrinkling to crinkling. With FEA, we successfully predict the transition region and depending on wrinkling amplitude can determine when a ribbon will wind into a useable core. Such mechanics-based insight provides critical feedback for allowable processing parameters in the strain annealing process.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2023

Structural and magnetic properties of magnetostrictive Fe-Ga-Zr nanocrystalline alloy

(Fe 1–x Ga x ) 92 Zr 8 amorphous and nanocrystalline alloys with x = 0.15 to x = 0.36 were investigated to improve the magnetic softness of Galfenol-type alloys and to evaluate their magnetostrictive properties. The samples were prepared by melt spinning of arc melted ingots. The rapidly solidified ribbons were annealed at 823 K for 1 h to produce a nanocrystalline structure. X-ray Diffraction data showed that after annealing, body-centered cubic (BCC) Fe-Ga phase crystallized for x = 0.15 to x = 0.26. When x exceeded 0.26, the ribbons crystallized into BCC and a ternary intermetallic phase (i.e., ZrFe 6 Ga 6 ) which has deteriorating effect on saturation magnetization, magnetic softness and magnetostriction coefficient. The annealed ribbons’ saturation magnetization value decreases from 126 Am 2 /kg to 54 Am 2 /kg as the Ga content increased from x = 0.15 to x = 0.36. The alloy with x = 0.26 annealed at 823 K for 1 h shows a peak magnetostriction of 10 ppm with saturation magnetization of 110 Am 2 /kg and coercivity of 260 A/m.

36 MATERIALS SCIENCE↗