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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

A Flexible Field Mapping System for Accelerator Magnets

Magnetic field mapping is a fundamental magnetic measurement method that typically uses Hall and NMR sensors. In magnet measurement facilities, such systems are likely used in various configurations suitable for a specific task at hand. To address this diversity, the authors developed a flexible field mapping system capable of being configured and tailored to each particular measurement case. The system needs to address the variability introduced by differences in sensors and their readout systems, probe positioning systems, power supply systems and in required mapping geometry (mapping space and grid, measurement steps and sequences). Although the discussed field mapping systems range from a self-propelled, multi-sensor mapper of a large detector magnet to a single 3D Hall sensor system to scan a small permanent magnet, they were all built with the same core mapping system. The variability present in field mapping systems and the measurement system architecture addressing this variability, as well as examples of several field mapping systems built in this architecture are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

High-gradient magnetic filtration of UO 2 colloids from aqueous suspensions

Environmental samples often contain innocuous components that make trace actinide analysis difficult and expensive. Therefore, it is expedient to separate these materials from actinide particles. One characteristic of many actinides is that they are paramagnetic. High-gradient magnetic filtration (HGMF) is a non-destructive technique that selectively captures magnetic constituents from a matrix containing non-magnetic species. Here, in this work, a novel HGMF device made of a permanent magnet array was used to effectively separate UO 2 particles from undesirable soil species. Up to 88% of the UO 2 particles present in suspensions were effectively captured by HGMF, resulting in their enrichment and a substantial reduction in the concentrations of other constituents.

Actinide separations↗
DOE OSTI2023

Internal defect detection and characterization of samarium-cobalt sintered magnets by ultrasonic testing technique

Excessive quantities of samarium-cobalt (Sm-Co) magnet material are being scrapped needlessly due to a lack of understanding of inhomogeneity distribution and unacceptable internal defects. If there is a way to identify, locate, characterize and when needed separate the defective portions of magnet material, utilization can be increased and product quality improved. Further, the magnets’ magnetic and mechanical performance can be improved by reducing the occurrence of internal defects. This paper reports on a cost-effective and efficient nondestructive evaluation method based on an ultrasonic testing (UT) technique applied for detecting and characterizing internal defects in Sm-Co sintered magnets. Applying the UT technique will allow users to comprehensively analyze internal defects, such as inclusions, porosity, microcracks, and other structural irregularities, check for homogeneity and anomalous regions and give the locations of these internal anomalies and defects within the Sm-Co sintered magnets. The UT technique can also be applied to other rare-earth permanent magnets, such as sintered or die-upset neodymium-iron-boron (Nd-Fe-B) magnets. The UT technique can effectively guide quality control and acceptable product selection, in addition to optimizing the magnet alloy design and production processes. Therefore, it can facilitate the improvement of magnet manufacturing efficiency and machinability, reduce scrap, prolong service life, increase the use of what would be post-production waste, and enhance product reuse and recycling at end-of-life disposition.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Controlling magnetic configuration in soft–hard bilayers probed by polarized neutron reflectometry

Hard/soft magnetic bilayer thin films have been widely used in data storage technologies and permanent magnet applications. The magnetic configuration and response to temperatures and magnetic fields in these heterostructures are considered to be highly dependent on the interfacial coupling. However, the intrinsic properties of each of the layers, such as the saturation magnetization and layer thickness, also strongly influence the magnetic configuration. Changing these parameters provides an effective method to tailor magnetic properties in composite magnets. Here, we use polarized neutron reflectometry (PNR) to experimentally probe the interfacial magnetic configurations in the hard/soft bilayer thin films: L1 0 -FePt/A1-FePt, [Co/Pd]/CoPd, [Co/Pt]/FeNi, and L1 0 -FePt/Fe, all of which have a perpendicular magnetic anisotropy in the hard layer. These films were designed with different soft and hard layer thicknesses (t soft and t hard ) and saturation magnetization (M$_s^{soft}$ and M$_s^{hard}$). The influences of an in-plane magnetic field (H ip ) and temperature (T) are also studied using a L1 0 -FePt/A1-FePt bilayer sample. Comparing the PNR results to the micromagnetic simulations reveals that the interfacial magnetic configuration is highly dependent on t soft , M$_s^{soft}, and the external factors (H ip and T) and has a relatively weak dependence on t hard and M$_s^{hard}$. Key among these results, for thin t soft , the hard and soft layers are rigidly coupled in the out-of-plane direction and then undergo a transition to relax in-plane. This transition can be delayed to larger t soft by decreasing M$_s^{soft}$. Understanding the influence of these parameters on the magnetic configuration is critical to designing functional composite magnets for applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A compact and portable gamma-ray spectrometer (GRASP) for inertial confinement fusion and basic science experiments

A compact and portable gamma-ray spectrometer has been designed to diagnose different components of the inertial confinement fusion-relevant γ-ray spectrum with energies between ∼3.7–17.9 MeV. The system is designed to be as compact as possible for convenient transportation and fielding in diagnostic ports on the OMEGA laser, the National Ignition Facility, and other photon-source facilities. The system consists of a conversion foil for Compton scattering in front of four magnetic spectrometer “arms,” each covering a different energy range and constructed out of cylindrical permanent magnet Halbach arrays. Monte Carlo simulations have been used to optimize and assess the performance of the conversion foil, and COSY INFINITY ion-optical simulations have been used to optimize the spectrometer magnets. The performance of the design is assessed for a simulated direct-drive γ-ray spectrum. Spanning its total γ-ray energy bandwidth and using a 1.7 mm thick boron conversion foil, the system’s total energy resolution and efficiency are ∼15.8%–4.5% and 5.4 × 10−7–3.7 × 10−7e−/γ, respectively, with room for improvement. Spectral γ-ray measurements will provide guidance to the inertial confinement fusion program toward achieving high-energy gain relevant to inertial fusion energy and enable new measurement capabilities for basic discovery science.

Instruments & Instrumentation↗
DOE OSTI2022

Accelerating the discovery of novel magnetic materials using machine learning–guided adaptive feedback

Magnetic materials are essential for energy generation and information devices, and they play an important role in advanced technologies and green energy economies. Currently, the most widely used magnets contain rare earth (RE) elements. An outstanding challenge of notable scientific interest is the discovery and synthesis of novel magnetic materials without RE elements that meet the performance and cost goals for advanced electromagnetic devices. Here, we report our discovery and synthesis of an RE-free magnetic compound, Fe 3 CoB 2 , through an efficient feedback framework by integrating machine learning (ML), an adaptive genetic algorithm, first-principles calculations, and experimental synthesis. Magnetic measurements show that Fe 3 CoB 2 exhibits a high magnetic anisotropy ( K 1 = 1.2 MJ/m 3 ) and saturation magnetic polarization ( J s = 1.39 T), which is suitable for RE-free permanent-magnet applications. Our ML-guided approach presents a promising paradigm for efficient materials design and discovery and can also be applied to the search for other functional materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effect of Mg Content in Melt-Spun Mn–Bi–Mg–Sb–In Alloys on the Structure and Properties of Field-Annealed Magnets

Mn-Bi alloys modified with Mg and other elements were recently developed into promising rare-earth-free permanent magnets through successive melt-spinning, warm compaction, and short magnetic-field annealing. This letter reports herein on the crystal structures, texture, and magnetic properties observed in Mn 50 Bi 49-x Mg x Sb 0.5 In 0.5 alloys (x = 0, 1.5, 3.0, 4.5) throughout these processing steps. The Mg substitution favors MnBi-based intermetallic phases over the Bi- and Mn-based solid solutions and the stable α intermetallic phase over the metastable β' intermetallic phase. Magnesium increases the c/a ratio of the α phase lattice parameters for all studied x values and it increases the degree of the field-annealing-induced texture for x ≤ 3. The effect of Mg on coercivity is explained as combination of a positive one via the α phase magnetocrystalline anisotropy and a negative one via the development of texture. The effect of the substitution on the maximum energy product additionally involves the decreasing density of the alloys; the optimum x is found to be ≈3. Additionally reported are the thermal properties of selected alloys. The mechanism of field-annealing effect on the coercivity is briefly discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electric Drive Technologies Research: Bottom-Up Soft Magnetic Composites (FY2022 Annual Progress Report)

In order to meet 2025 goals for enhanced peak power (100 kW), specific power (50 kW/L), and reduced cost (3.3 $\$$/kW) in a motor that can operate at ≥ 20,000 rpm, improved soft magnetic materials must be developed. Better performing soft magnetic materials will also enable rare earth free electric motors. In fact, replacement of permanent magnets with soft magnetic materials was highlighted in the Electrical and Electronics Technical Team (EETT) Roadmap as a R&D pathway for meeting 2025 targets. Eddy current losses in conventional soft magnetic materials, such as silicon steel, begin to significantly impact motor efficiency as rotational speed increases. Soft magnetic composites (SMCs), which combine magnetic particles with an insulating matrix to boost electrical resistivity (ρ) and decrease eddy current losses, even at higher operating frequencies (or rotational speeds), are an attractive solution. Today, SMCs are being fabricated with values of ρ ranging between 10 -3 to 10 -1 μohm∙m, which is significantly higher than 3% silicon steel (~0.05 μohm∙m). The isotropic nature of SMCs is ideally suited for motors with 3D flux paths, such as axial flux motors. Additionally, the manufacturing cost of SMCs is low and they are highly amenable to advanced manufacturing and net-shaping into complex geometries, which further reduces manufacturing costs. There is still significant room for advancement in SMCs, and therefore additional improvements in electrical machine performance. For example, despite the inclusion of a non-magnetic insulating material, the electrical resistivities of SMCs are still far below that of soft ferrites (10 – 10 8 μohm∙m).

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Phase stability and coercivity in La 2 Fe 14 B magnet

Critical rare-earth free La 2 Fe 14 B (2:14:1) has the potential to be a gap permanent magnet. However, La 2 Fe 14 B decomposes into La, α-Fe, and La 4 Fe 4 phases below 1067 K. The phase stability and coercivity have been studied in La 2 Fe 14 B magnet using first principles DFT (density functional theory) calculation and micromagnetic simulation. For a perfect La 2 Fe 14 B cube (edge length of 256 nm) without any structural defects and soft magnetic secondary phases, the coercivity (8.5 kOe) is reduced to ~40% of its magnetocrystalline anisotropy field ( H A = 20 kOe). Further, the coercivity sharply reduces to 3.2 kOe upon forming a thin layer (2 nm) of α-Fe on the surface of the La 2 Fe 14 B cube particle. The DFT calculations indicate that a partial replacement of La by other rare-earth (RE) elements can enhance the structural stability of 2:14:1. The gains in cohesive energy are 0.75, 0.10, and 0.33 eV per formula unit in (La 0.5 RE 0.5 ) 2 Fe 14 B with RE = Ce, Pr, and Nd, respectively. Stabilizing the 2:14:1 structure and mitigating the formation of soft magnetic structural defects or impurity phases such as α-Fe is necessary to develop La 2 Fe 14 B based magnet, which can be moderately achieved via partial substitution of La by other rare earth elements such as Ce, Pr, and Nd.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Bottom-Up Soft Magnetic Composites

In order to meet 2025 goals for enhanced peak power (100 kW), specific power (50 kW/L), and reduced cost (3.3 $/kW) in a motor that can operate at ≥ 20,000 rpm, improved soft magnetic materials must be developed. Better performing soft magnetic materials will also enable electric motors without rare earth elements. In fact, replacement of permanent magnets with soft magnetic materials was highlighted in the Electrical and Electronics Technical Team (EETT) Roadmap as a R&D pathway for meeting 2025 targets. Eddy current losses in conventional soft magnetic materials, such as silicon steel, begin to significantly impact motor efficiency as rotational speed is increased. Soft magnetic composites (SMCs), which combine magnetic particles with an insulating matrix to boost electrical resistivity (ρ) and decrease eddy current losses, even at higher operating frequencies (or rotational speeds), are an attractive solution. Today, SMCs are being fabricated with values of ρ ranging between 10 -3 to 10 -1 μohm∙m, which is significantly higher than 3% silicon steel (~0.5 μohm∙m). The isotropic nature of SMCs is ideally suited for motors with 3D flux paths, such as axial flux motors. Additionally, the manufacturing cost of SMCs is low and they are highly amenable to advanced manufacturing and net-shaping into complex geometries, which further reduces manufacturing costs. There is still significant room for advancement in SMCs, and therefore additional improvements in electrical machine performance. For example, despite the inclusion of a non-magnetic insulating material, the electrical resistivities of SMCs are still far below that of soft ferrites (10 – 10 8 μohm∙m).

36 MATERIALS SCIENCE↗
DOE OSTI2021

Microstructure and Hard Magnetic Properties of Sm 1-x Zr x (Fe,Co) 11.3-y Ti 0.7 By Ingots and Thick Melt-Spun Ribbons

Permanent magnets made from Sm(Fe,Co) 12 -based compounds are being actively pursued through nanostructuring and powder metallurgy. This study was aimed at the development of hard magnetic properties in bulk as-cast alloys and in melt-spun alloys for very low wheel speeds. Slower solidification rates and alloying with Zr promote the tetragonal ThMn 12 -type crystal structure, whereas higher solidification rates and alloying with B replace the ThMn 12 structure type with the TbCu 7 structure type. When introduced simultaneously, Zr and B dramatically reduce the alloy solidification rates required for both the refinement of the 1:12 crystallites and their replacement with the 1:7 phase. In bulk arc-melted alloys, this allowed for a microstructure of separated 1:12 crystallites 1–3 μm in size, although, because of the ferromagnetic nature of a minority phase, the coercivity of these fine-grained alloys reached only 0.73 kOe. A moderately accelerated solidification further refined the 1:12 crystallites and increased the coercivity; a Sm 0.7 Zr 0.4 (Fe,Co) 10.8 Ti 0.7 B 0.5 alloy exhibited a coercivity of 1.5 kOe and a maximum energy product of 3.4 MGOe when it was melt-spun into a 0.26-mm-thick ribbon. A more rapid solidification suppressed the 1:12 phase and after annealing at 800–850 °C, the alloys modified with Zr and B developed reasonably high coercivity and maximum energy product even when melt-spun at a wheel speed of 6 m/s. For the above-mentioned alloy, these values were 4.1 kOe and 7.8 MGOe, respectively. Further, a similarly processed very-Sm-lean Sm 0.5 Zr 0.6 (Fe,Co) 10.6 Ti 0.7 B 0.7 alloy exhibited a remanence of 8.8 kG and an energy product of 7.4 MGOe.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A Medium Frequency RF Sensor for Detection of Magnetized Quark Nuggets

It is hypothesized that dark matter is composed of particles called quark nuggets, and further that these particles have a permanent magnetic dipole moment. If this hypothesis is true, calculations predict that a magnetized quark nugget (MQN) will oscillate when encountering the Earth's magnetosphere, and emit RF radiation between 30kHz and 30MHz. To support testing this hypothesis, a loop antenna sensor was designed and developed, which is described in this report. This sensor operates between 300kHz and 3MHz and achieves about -11dBfT/vHz sensitivity at 1.5MHz.

42 ENGINEERING↗
DOE OSTI2020

Dual Phase Soft Magnetic Laminates for Low-cost, Non/Reduced-Rare-Earth Containing Electrical Machines

To accelerate the mass market adoption of electric drive vehicles, the key technology barriers in electric motors are (1) magnet cost and rare-earth element price volatility; (2) non-rare-earth electric motor performance; and (3) materials property optimization. The goal of this project was to address these barriers by advancing a unique and innovative dual phase soft magnetic material technology and demonstrating the material in a 30-kW synchronous reluctance motor without using any permanent magnet for electric vehicles. Dual phase magnetic materials offer the electric motor designer the ability to locally control the magnetic saturation level in a motor laminate, while at the same time enhancing the mechanical strength of the laminate material, resulting in an enhancement in motor performance and efficiency. Scalable dual phase soft magnetic laminates manufacturing technologies were developed in collaboration with multiple US manufacturers. 1000 lbs of alloy sheet with a thickness of 0.25mm and width of 280 mm was manufactured within the specifications. Batch sizes of up to 240 laminates per run were produced from the alloy sheet. Two prototype motors with dual phase soft magnetic laminates were designed, built, and tested. The major goal of building the subscale prototype as a pathway to develop scalable manufacturing technologies for the dual phase soft magnetic laminates was met. The additional goal of building and testing the subscale prototype in order to validate the calculated performance with the tested motor performance was also met. For the full-scale 30kW continuous power synchronous reluctance motor prototype, the tested performance met the targets in terms of continuous power at the operating speeds up to 8000 rpm. Post-test studies were conducted and the root causes for the discrepancy between the predicted and tested peak power, continuous power at high speed range, and efficiency were identified. Further modeling study showed that the dual phase rotor machine has a 27% higher torque to active weight ratio than an equivalent performance silicon steel rotor machine. Application space and multiple discussions with traction motor and electric vehicle manufacturers for commercialization of the dual phase soft magnetic material technology were identified and conducted. An initial cost model was established based on the developed manufacturing technologies with the US manufacturers. Future paths for further cost reduction were identified, including increasing the market volume by broadening the applications of the dual phase soft magnetic laminate technology for electric machines in other energy sections such as oil & gas, heating, ventilation, and air conditioning (HVAC), and power generation.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

MADE3D: Enabling the next generation of high-torque density wind generators by additive design and 3D printing

Direct-drive wind turbine generators are increasing in popularity, thanks to recent project developments—especially offshore, where reliability and efficiency are major cost drivers. Yet, high capital costs are forcing many original equipment manufacturers to consider lightweight, high-torque density generators for next-generation multi-megawatt turbines that may be difficult to realize by traditional design or manufacturing methods. In this study, we present a new design framework enabled by advanced machine learning and multimaterial additive manufacturing to perform a magnetic topology optimization that maximizes the torque per rotor active mass for a 15-megawatt direct-drive permanent magnet wind generator. A comparison of the proposed approach against conventional topology optimization demonstrated a significant increase in computational efficiency and accuracy in performance predictions. Results using single and multimaterial compositions for rotor core and magnets identify a wider choice of 3D printable designs for a given specification. A hybrid combination of sintered and dysprosium-free polymer-bonded magnets shows good potential for torque performance by saving material costs up to 8.75%. More than 30% improvement in rotor torque densities is identified which can marginally improve the overall generator torque density. With the rapid evolution of multipowder deposition technolgies, this study can greatly inspire a new paradigm for design-driven manufacturing with novel material compositions and lightweight, low-cost, high-strength multimaterial geometries that were previously unexplored for direct-drive generators.

17 WIND ENERGY↗
DOE OSTI2021

MADE3D: Enabling the Next-Generation High-Torque- Density Wind Generators by Additive Design and 3D Printing

Direct-drive wind turbine generators are increasing in popularity, thanks to recent project developments - especially offshore, where reliability and efficiency are major cost drivers. Yet, high capital costs are forcing many original equipment manufacturers to consider lightweight, high-torque density generators for next-generation multi-megawatt turbines that may be difficult to realize by traditional design or manufacturing methods. In this study, we present a new design framework enabled by advanced machine learning and multimaterial additive manufacturing to perform a magnetic topology optimization that maximizes the torque per rotor active mass for a 15-megawatt direct-drive permanent magnet wind generator. A comparison of the proposed approach against conventional topology optimization demonstrated a significant increase in computational efficiency and accuracy in performance predictions. Results using single and multimaterial compositions for rotor core and magnets identify a wider choice of 3D printable designs for a given specification. A hybrid combination of sintered and dysprosium-free polymer-bonded magnets shows good potential for torque performance by saving material costs up to 8.75%. More than 30% improvement in rotor torque densities is identified which can marginally improve the overall generator torque density. With the rapid evolution of multipowder deposition technologies, this study can greatly inspire a new paradigm for design-driven manufacturing with novel material compositions and lightweight, low-cost, high-strength multimaterial geometries that were previously unexplored for direct-drive generators.

3D printing↗
DOE OSTI2020

Transformation enabled nitride magnets absent rare earths and a process of making the same

A process for producing an ordered martensitic iron nitride powder that is suitable for use as a permanent magnetic material is provided. The process includes fabricating an iron alloy powder having a desired composition and uniformity; nitriding the iron alloy powder by contacting the material with a nitrogen source in a fluidized bed reactor to produce a nitride iron powder; transforming the nitride iron powder to a disordered martensitic phase; annealing the disordered martensitic phase to an ordered martensitic phase; and separating the ordered martensitic phase from the iron nitride powder to yield an ordered martensitic iron nitride powder.

Matthiesen, David↗
DOE OSTI2023

Structural Characteristics and Phase Evolution of Calcium-Reduced (Sm,Zr)(Fe,Co,Ti) 12 Particles

Magnetic materials are essential for applications in electronics, energy conversion and many other industrial and technological sectors. Among the permanent magnets, rare-earth magnets exhibit the strongest properties and dominate the market shares in related applications. However, due to the increasing cost and unstable supply, the research on reducing the rare-earth elements in magnets attracts significant increasing interest. Rare-earth-lean samarium transition metal (TM) compounds (SmTM 12 or 1:12 for short) have made breakthroughs in 2020 and the (Sm,Zr)(Fe,Co,Ti) 12 monocrystalline particles synthesized by a Ca reduction of elemental oxides at high temperature demonstrated an order of magnitude improvement in coercivity at room temperature. In this study, we made structural analysis of (Sm,Zr)(Fe,Co,Ti) 12 particles to elucidate the impact of synthesis conditions, microstructure and phase transformation on the evolution of magnetic properties.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Advanced Processing of Functional Magnetic Materials

Functional materials, specifically those which respond to external stimuli such as magnetic and electrical field, are increasingly important for many green energy technologies. Functional magnetic materials are increasingly been investigated from basic and applied sciences perspectives. Probably, the best-known of these are permanent magnets, they are used to supply a magnetic field and are widely applied in motors, generators, data storage, sensors, and actuators. Other examples of functional materials include soft magnets, magnetocalorics, and thermoelectrics.

36 MATERIALS SCIENCE↗