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Journal articles on the topic 'Neodymium-iron-boron magnets'

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

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1

Croat, J. J., and J. F. Herbst. "Rapidly Solidified Neodymium-Iron-Boron Magnets." MRS Bulletin 13, no. 6 (1988): 37–40. http://dx.doi.org/10.1557/s0883769400065489.

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Permanent magnets have long occupied an important position in technology. Among the multitude of products using permanent magnets are televisions, telephones, computers, videocassette recorders, audio systems, household appliances, and perhaps surprisingly to many consumers, automobiles. Figure 1 illustrates the numerous magnet applications in a modern passenger vehicle. These applications include an array of dc electric motors such as the starter, heater and air conditioner blower, windshield wiper, window lift, door lock, and fuel pump motors. A fully equipped car can have more than 30 dc electric motors. Other uses include actuators, gauges, and sensors. In all these examples higher performance magnetic materials may afford the advantages of increased operating efficiency and reduction in size and weight.One performance index or figure of merit for a permanent magnet is the energy product (BH)max, the maximum product of magnetic induction B and applied field H in the second quadrant of the B-H hysteresis curve. The so-called theoretical (BH)max, the highest energy product realizable in principle, is simply given by (4πMs)2/4, where Ms is the saturation magnetization. Progress in the development of technologically significant hard magnets has been monitored generally by improvements in (BH)max. For many years three types of materials were of commercial importance, namely, alnico, ferrite, and samarium-cobalt alloys based on either the SmCo5 or Sm2Co17 intermetallic compounds. Of these the Sm-Co magnets offer the largest energy products, on the order of 20 MGOe.

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2

Bondemark, Lars, Jüri Kurol, and Alf Wennberg. "Orthodontic Rare Earth Magnets—In Vitro Assessment of Cytotoxicity." British Journal of Orthodontics 21, no. 4 (1994): 335–41. http://dx.doi.org/10.1179/bjo.21.4.335.

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The aim of this study was to assess and compare in vitro the cytotoxic effects of uncoated and parylene-coated rare earth magnets, used in orthodontics. Cytotoxicity of samarium-cobalt magnets (SmCo5 and Sm2Co17) and neodymium-iron-boron magnets (Nd2Fe14B) was assessed by two in vitro methods, the millipore filter method and an extraction method. Orthodontic stainless steel brackets served as controls. Uncoated SmCo5-magnets showed high cytotoxicity while uncoated Sm2Co17-magnets demonstrated moderate cytotoxicity. Uncoated neodymium-iron-boron magnets, as well as parylene coated Sm2Co17-magnets and parylene-coated neodymium-iron-boron magnets, showed negligible cytotoxicity. Short-term exposure to a static magnetic field did not cause any cytotoxic effect on the cells.

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3

Herbst, J. F., and J. J. Croat. "Neodymium-iron-boron permanent magnets." Journal of Magnetism and Magnetic Materials 100, no. 1-3 (1991): 57–78. http://dx.doi.org/10.1016/0304-8853(91)90812-o.

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4

Lee, R. W. "Hot‐pressed neodymium‐iron‐boron magnets." Applied Physics Letters 46, no. 8 (1985): 790–91. http://dx.doi.org/10.1063/1.95884.

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5

Stewart, Seán M. "Some simple demonstration experiments involving homopolar motors." Revista Brasileira de Ensino de Física 29, no. 2 (2007): 275–81. http://dx.doi.org/10.1590/s0102-47442007000200012.

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The ready availability of very strong permanent magnets in the form of rare-earth magnetic alloys such as neodymium-iron-boron has lead to renewed interest in one of the oldest types of electric motors - the homopolar motor. The ease with which a demonstration homopolar motor can now be built and operated when neodymium magnets are used is quite remarkable. In this paper some simple homopolar motors employing neodymium magnets suitable for demonstrational purposes are described and discussed.

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6

Palomo, Roberto Eduardo Quintal, and Maciej Gwozdziewicz. "Effect of Demagnetization on a Consequent Pole IPM Synchronous Generator." Energies 13, no. 23 (2020): 6371. http://dx.doi.org/10.3390/en13236371.

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The design and analysis of a permanent magnet synchronous generator (PMSG) are presented. The interior permanent magnet (IPM) rotor was designed asymmetric and with the consequent pole approach. The basis for the design was a series-produced three-phase induction motor (IM) and neodymium iron boron (Nd-Fe-B) cuboid magnets were used for the design. For the partial demagnetization analysis, some of the magnets were extracted and the results are compared with the finite element analysis (FEA).

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7

HERBST, J. F., and J. J. CROAT. "ChemInform Abstract: Neodymium-Iron-Boron Permanent Magnets." ChemInform 23, no. 22 (2010): no. http://dx.doi.org/10.1002/chin.199222315.

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8

Sandler, P. J., and S. D. Springate. "Unerupted Premolars—An Alternative Approach." British Journal of Orthodontics 18, no. 4 (1991): 315–21. http://dx.doi.org/10.1179/bjo.18.4.315.

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9

Hadjipanayis, G. C., K. R. Lawless, and R. C. Dickerson. "Magnetic hardening in iron‐neodymium‐boron permanent magnets." Journal of Applied Physics 57, no. 8 (1985): 4097–99. http://dx.doi.org/10.1063/1.334630.

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10

Imashuku, Susumu, Kazuaki Wagatsuma, and Jun Kawai. "Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets." Microscopy and Microanalysis 22, no. 1 (2016): 82–86. http://dx.doi.org/10.1017/s1431927615015676.

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AbstractScanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium–iron–boron (NdFeB) and samarium–cobalt (Sm–Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm–Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

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11

Beniakar, Minos E., Themistoklis D. Kefalas, and Antonios G. Kladas. "Investigation of the Impact of the Operational Temperature on the Performance of a Surface Permanent Magnet Motor." Materials Science Forum 670 (December 2010): 259–64. http://dx.doi.org/10.4028/www.scientific.net/msf.670.259.

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This paper investigates the impact of different operational temperatures on the performance of a surface permanent magnet (SPM) machine with neodymium-iron-boron (NdFeB) magnets for electric drive applications. The field distribution of the machine for various temperatures is depicted and a comparison of the field distribution in the air gap and the machine output characteristics is performed. On a second step the effect of rotor skew is investigated.

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12

Radwan-Pragłowska, Natalia, and Tomasz Węgiel. "Permanent Magnet Selections for AFPM Disc Generators." Energies 15, no. 20 (2022): 7601. http://dx.doi.org/10.3390/en15207601.

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In this article, the field (FEM) and analytical analyses were used for the optimal selection of magnets material for the Axial Flux Permanent Magnet Generator (AFPMG), without building the prototype before. The tested generator is an axial flux machine which consists of a single stator and two rotor discs with Permanent Magnets (PM). Three-dimensional (3D) ANSYS Maxwell package was used for magnetostatic and transient field (FEM) simulations. Two types of PM were selected for the analysis: Ceramic (also known as “Ferrite”) magnets made from Strontium Ferrite powder and Neodymium Iron Boron magnets (NdFeB). The authors compared obtained electromotive forces (EMF) and generator powers for selected magnets materials, performed FFT analyses of voltages and currents and indicated the optimal solutions. In addition to the operational properties of the AFPMG, the magnet and manufacturing costs were compared.

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13

Anantha Krishna, G. L., and K. M. Sathish Kumar. "Evaluation of brake parameters in copper discs of various thicknesses and speeds using Neodymium – Iron – Boron Magnets." MATEC Web of Conferences 144 (2018): 01003. http://dx.doi.org/10.1051/matecconf/201814401003.

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Neodymium – Iron – Boron (NdFeB) permanent magnets of 12.5 mm thickness and 50 mm diameter are chosen for analyses because of their higher remanence and coercivity. Experimental analyses were carried out with Copper discs of thickness 4 mm, 6 mm and 8 mm at 2000 rpm, 3000 rpm, 4000 rpm and 5000 rpm. Experiments were conducted with three different positions of magnets such as 2 coaxial magnets, single magnet and single magnet with sudden application conditions. The brake parameters recorded are % speed reduction, deceleration and time taken. In 2 coaxial magnets condition, brake parameters are better in 6 mm thick disc. In single magnet condition, the brake parameters in 6 mm thick disc are found to be more consistent than 4 mm and 8 mm thick discs. In single magnet with sudden application condition, in 4 mm thick disc, the brake parameters are found better. During analysis, very high repulsion was experienced by magnet with 8 mm thick Copper disc at all the above mentioned speeds in single magnet with sudden application condition. For high speed train applications, single magnet condition with 6mm thick disc may be suitable. For high speed automotive applications, single magnet with sudden application condition with 4 mm thick disc may be suitable.

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14

Krasil’nikov, A. Ya, and A. A. Krasil’nikov. "TRANSMISSION TORQUE OF A STANDART MAGNETIC COUPLING DEPENDING ON THE PERMANENT MAGNET BRAND AND ITS SHAPE WITH GAP BETWEEN THE MAGNETS OF 5 MM." Spravochnik. Inzhenernyi zhurnal, no. 289 (April 2021): 3–8. http://dx.doi.org/10.14489/10.14489/hb.2021.04.pp.003-008.

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The article considers the possibility of changing the transmitting torque of a cylindrical magnetic coupling depending on the brand of a highly coercive permanent magnet: neodymium–iron–boron, samarium–cobalt and barium hexaferrite types Using the example of a standard magnetic coupling with a magnets diameter of 120 mm and an air gap of 5 mm between the magnetic coupling halves, the change in the transmitting torque of the magnetic coupling is shown to attain without changing its overall dimensions. Variation in the transmission torque of the magnetic coupling is possible by changing the shape, size and brand of permanent magnets, while leaving the same number of magnets in each of the half-coupling.

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15

Lian, F. Z., and W. E. Wallace. "Investigation of high performance neodymium-iron-boron permanent magnets." Metal Powder Report 52, no. 7-8 (1997): 40. http://dx.doi.org/10.1016/s0026-0657(97)80194-4.

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16

Lian, F. "Investigation of high performance neodymium-iron-boron permanent magnets." Metal Powder Report 53, no. 7-8 (1997): 40. http://dx.doi.org/10.1016/s0026-0657(97)84700-5.

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17

MITCHELL, P. "ChemInform Abstract: Corrosion Protection of Neodymium-Iron-Boron Magnets." ChemInform 22, no. 46 (2010): no. http://dx.doi.org/10.1002/chin.199146333.

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18

Donohue, V. E., Fraser McDonald, and R. Evans. "In vitro cytotoxicity testing of neodymium-iron-boron magnets." Journal of Applied Biomaterials 6, no. 1 (1995): 69–74. http://dx.doi.org/10.1002/jab.770060110.

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19

Croat, J. J. "Neodymium—iron—boron permanent magnets prepared by rapid solidification." Journal of Materials Engineering 10, no. 1 (1988): 7–13. http://dx.doi.org/10.1007/bf02834109.

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20

Wooten, Gary D., and Daniel W. Stahura. "Application of neodymium-iron-boron (Nd-Fe-B) magnets." Journal of Materials Engineering 12, no. 3 (1990): 203–9. http://dx.doi.org/10.1007/bf02834496.

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21

Kim, ByeongJun, Yongkeun Lee, and YoungSung Kim. "A study on demagnetization heat treatment of waste neodymium iron boron (NdFeB) magnets by using computer simulation." PeerJ Materials Science 5 (May 2, 2023): e28. http://dx.doi.org/10.7717/peerj-matsci.28.

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In this study, demagnetization heat treatment at 100 ∼400 °C is studied by using computer simulation to secure the optimal demagnetization heat treatment conditions for waste neodymium iron boron (NdFeB) permanent magnets. From the computer simulation, the temperature of the magnet during heat treatment is higher than the set temperature by up to 6 °C. Delay time occurs when the furnace internal temperature and magnet temperature reached the set temperature. A delay time of 15 minutes in an air atmosphere and 10 minutes in a nitrogen atmosphere occurs. The Nd magnet was completely demagnetized at 300 °C as the magnetic flux decreased when the heat treatment temperature increased up to 250 °C. The fully demagnetized magnet could be magnetized to the level of a new magnet. It was confirmed that NdFeB magnets heat treated up to 350 °C in a nitrogen atmosphere can be reusable due to stable demagnetization being possible without surface change.

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22

Szymański, Mateusz, Bartosz Michalski, Marcin Leonowicz, and Zbigniew Miazga. "Recycling of Nd-Fe-B Magnets from Scrap Hard Disc Drives." Key Engineering Materials 682 (February 2016): 308–13. http://dx.doi.org/10.4028/www.scientific.net/kem.682.308.

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A hydrogen-based treatment, including Hydrogen Decrepitation (HD) and Hydrogen Disproportionation-Desorption-Recombination (HDDR), was used as part of a recycling procedure for scrap neodymium-iron-boron magnets. Chemical methods of removing nickel coating out of magnets were tested, however ineffectively. Powders were obtained from magnets after the HD and were further processed by the HDDR. Finally, material with maximum energy product (BH)max of 74 kJ/m3 was produced. Chemical composition of magnets (MS, EDS), magnetic properties (VSM) and microstructure observations (SEM) were carried out.

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23

Krasilʼnikov, A. Ya, and A. A. Krasilʼnikov. "A DETERMINATION OF THE SHEAR FORCE OF THIN HIGH-COERCIVITY PERMANENT MAGNETS MADE FROM THE ALLOY WITH RARE-EARTH ELEMENTS." Spravochnik. Inzhenernyi zhurnal, no. 290 (May 2021): 24–30. http://dx.doi.org/10.14489/hb.2021.05.pp.024-030.

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The article considers the possibility of using a standard method for calculating the shear force of thin, high-coercivity neodymium–iron–boron type permanent magnets in magnetic clutches (couplings). The research results allowed to introduce a correction coefficients in the method of calculating the transmitting torque in magnetic clutches (couplings) with thin magnets. The possibility of 08H22N6T brand steel using for magnetic flux conductors manufacturing in a magnetic couplings.

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24

Kumar, Ram, Antonino La Rocca, Gaurang Vakil, David Gerada, Chris Gerada, and Baylon G. Fernandes. "Significance of Anisotropic Thermal Expansion in High Speed Electric Machines Employing NdFeB Permanent Magnets." Energies 14, no. 22 (2021): 7558. http://dx.doi.org/10.3390/en14227558.

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Many high speed applications employ a surface permanent magnet (PM) machine topology with a retaining sleeve due to its robustness and ability to achieve high overall peripheral speeds as well as efficiencies. One often overlooked feature in the mechanical design of such machines, which has not achieved sufficient attention to date is the anisotropic thermal expansion of rare earth magnets, the degree of which varies for different magnet technologies. This paper investigates the effects of the aforementioned on the mechanical design of a high speed PM spindle machine with NdFeB magnets. The maximum allowable interference is found to be limited by the working temperature of the magnets while the minimum required interference is increased due to their anisotropic thermal expansion. Based on this, appropriate conditions are formulated to integrate a Neodymium Iron Boron (NdFeB) PM in high speed rotors. These modifications considering the shaft together with the magnet anisotropic thermal expansion are included in a proposed rotor design and validated using simulations in ANSYS mechanical environment.

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25

Noar, J. "The durability of parylene coatings on neodymium-iron-boron magnets." European Journal of Orthodontics 21, no. 6 (1999): 685–93. http://dx.doi.org/10.1093/ejo/21.6.685.

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26

Rahman, M., and G. Slemon. "Promising applications of neodymium boron Iron magnets in electrical machines." IEEE Transactions on Magnetics 21, no. 5 (1985): 1712–16. http://dx.doi.org/10.1109/tmag.1985.1064113.

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27

Stadelmaier, H. H., N. A. ElMasry, and S. R. Stallard. "Alternative method of preparing high‐coercivity neodymium‐iron‐boron magnets." Journal of Applied Physics 57, no. 8 (1985): 4149–51. http://dx.doi.org/10.1063/1.335459.

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28

Edwards, C., and S. B. Palmer. "Wideband electromagnetic acoustic transducers utilising neodymium iron boron permanent magnets." IEEE Transactions on Magnetics 26, no. 5 (1990): 2080–84. http://dx.doi.org/10.1109/20.104626.

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29

TENAUD, P., H. LEMAIRE, and F. VIAL. "ChemInform Abstract: Recent Improvements in Neodymium-Iron-Boron Sintered Magnets." ChemInform 23, no. 17 (2010): no. http://dx.doi.org/10.1002/chin.199217346.

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30

Klemettinen, Anna, Andrzej Żak, Ida Chojnacka, et al. "Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids." Minerals 11, no. 12 (2021): 1374. http://dx.doi.org/10.3390/min11121374.

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A simplified approach for rare earth elements leaching from NdFeB (neodymium-iron-boron) magnets was investigated. The possibility of simplifying the magnet recycling process by excluding grinding, milling and oxidative roasting unit operations was studied. Attempts to skip the demagnetization step were also conducted by using whole, non-demagnetized magnets in the leaching process. The presented experiments were conducted to optimize the operating conditions with respect to the leaching agent and its concentration, leaching time, leaching temperature and the form of the feed material. The use of hydrochloric and sulfuric acids as the leaching agents allowed selective leaching of NdFeB magnets to be achieved while leaving nickel, which is covering the magnets, in a solid state. The application of higher leaching temperatures (40 and 60 °C for sulfuric acid and 40 °C for hydrochloric acid) allowed us to shorten the leaching times. When using broken demagnetized magnets as the feed material, the resulting rare earth ion concentrations in the obtained solutions were significantly higher compared to using whole, non-demagnetized magnets.

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31

Chandramouli, M., and G. Thomas. "Microstructure and microanalysis of neodymium iron boron magnets sintered with aluminum." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 486–87. http://dx.doi.org/10.1017/s0424820100138804.

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The magnetic properties of NdFeB magnets sintered with 15 vol.% Al at 850 °C and 1000 °C for 1 hour are dependent on microstructure. Complementary use of SEM and TEM techniques are crucial to elucidate the microstructural differences responsible for the properties. The hysterisis loops shown in Fig. 1 indicate that the higher sintering temperature sample has a larger dip near zero applied field and lower coercivity. This behavior is consistent with a larger volume fraction of soft magnetic phases.Microstructural analysis performed using a JEOL 35 CF SEM does not show significant differences between the samples. As revealed in Fig. 2, a representative backscattered image of the 850 °C sample, the microstructure consists of dark pockets with a gray matrix region with small, bright contrast pockets. Quantitative microanalysis confirmed that the gray matrix phase had a composition consistent with Nd2Fe14B, the ferromagnetic phase in conventionally prepared Nd-Fe-B permanent magnets. The small bright pockets were found to have a high Nd content while the large dark pockets were rich in Al.

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32

Vella, Dominic, Emmanuel du Pontavice, Cameron L. Hall, and Alain Goriely. "The magneto-elastica : from self-buckling to self-assembly." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2162 (2014): 20130609. http://dx.doi.org/10.1098/rspa.2013.0609.

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Spherical neodymium–iron–boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

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33

Mancini, G. "The physical characteristics of neodymium iron boron magnets for tooth extrusion." European Journal of Orthodontics 21, no. 5 (1999): 541–50. http://dx.doi.org/10.1093/ejo/21.5.541.

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34

Jahn, L., R. Schumann, and W. Rodewald. "Magnetic viscosity of modified neodymium iron boron magnets with high coercivities." Journal of Magnetism and Magnetic Materials 153, no. 3 (1996): 302–10. http://dx.doi.org/10.1016/0304-8853(95)00550-1.

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35

PANCHANATHAN, V. "ChemInform Abstract: Developments in Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets." ChemInform 22, no. 48 (2010): no. http://dx.doi.org/10.1002/chin.199148319.

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36

Piotrowicz, A., S. Pietrzyk, P. Noga, and Ł. Mycka. "The use of thermal hydrogen decrepitation to recycle Nd-Fe-B magnets from electronic waste." Journal of Mining and Metallurgy, Section B: Metallurgy, no. 00 (2020): 32. http://dx.doi.org/10.2298/jmmb200207032p.

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Rare earth magnets based upon neodymium-iron-boron (NdFeB) are employed in many high tech applications, including hard disk drives (HDDs). The key elements in manufacturing NdFeB magnets are rare earth elements (REEs) such as neodymium. This element has been subject to significant supply shortfalls in the recent past. Recycling of NdFeB magnets contained within waste of electrical and electronic equipment (WEEE) could provide a secure and alternative supply of these materials. Various recycling approaches for the recovery of sintered NdFeB magnets have been widely explored. Hydrogen decrepitation (HD) can be used as a direct reuse approach and effective method of recycling process to turn solid sintered magnets into a demagnetised powder for further processing. In this work, sintered Nd-Fe-B magnets were processed without prior removal of the metallic protective layer using the thermal HD process as an alternative recycling method. The gas sorption analyzer have been used to determine the quantity of the hydrogen absorbed by a samples of magnets, under controlled pressure (1, 2, 3 and 4 bar) and temperature (room, 100, 300 and 400?C) conditions, using Sieverts? volumetric method. The composition and morphology of the starting and the extracted/disintegrated materials were examined by ICP, XRD and SEM-EDS analysis.

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37

Hono, Kazuhiro. "Toward the Development of Dysprosium-free Neodymium-Iron-Boron High Coercivity Magnets." Materia Japan 54, no. 7 (2015): 351–55. http://dx.doi.org/10.2320/materia.54.351.

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38

Lee, R., E. Brewer, and N. Schaffel. "Processing of Neodymium-Iron-Boron melt-spun ribbons to fully dense magnets." IEEE Transactions on Magnetics 21, no. 5 (1985): 1958–63. http://dx.doi.org/10.1109/tmag.1985.1064031.

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39

Kim, Yong Su, Hong Jun Chae, Seok-Jun Seo, Kyoung-Tae Park, Bum Sung Kim, and Taek-Soo Kim. "Prediction of Diffusion Behaviors Between Liquid Magnesium and Neodymium-Iron-Boron Magnets." Science of Advanced Materials 8, no. 1 (2016): 134–37. http://dx.doi.org/10.1166/sam.2016.2616.

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40

CROAT, J. J. "ChemInform Abstract: Current Status of Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets." ChemInform 24, no. 5 (2010): no. http://dx.doi.org/10.1002/chin.199305330.

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41

DING, XIAOFENG, and CHRIS MI. "MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES." Journal of Circuits, Systems and Computers 20, no. 07 (2011): 1287–301. http://dx.doi.org/10.1142/s021812661100789x.

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The eddy current loss in the magnets of permanent magnet (PM) motors in a hybrid electric vehicle (HEV) and plug-in HEV is usually not taken into consideration in traditional motor design and analysis. However, due to the high conductivity of the rare-earth magnet, neodymium-iron-boron (NdFeB), and slot/tooth harmonics, there is eddy current loss generated inside the magnets. This loss may not attribute very much to the efficiency of the motor, but the temperature-rise inside the magnets caused by this loss can lead to the unpredictable deterioration of the magnets, such as the degradation of performance and potential demagnetization. In addition, the output voltage of pulse-width-modulated (PWM) inverter contains abundant high frequency harmonics, which induce excessive loss in the magnets. The excessive heat in PM motor induced by the eddy current loss combined with other losses can degrade the performance of the machine. This paper presents the modeling and analysis of eddy current loss in surface-mounted-magnets PM synchronous motors (SPMSM) and interior-magnets PM synchronous motors (IPMSM), operated by PWM inverter supply. Analytical methods are implemented, in conjunction with time-stepped finite-element analysis (FEA) for the calculation of eddy current loss in the magnet. Based on the calculated losses in the machines, simplified analytical models are developed as thermal circuits with network of interconnected nodes, thermal resistances and heat sources representing the heat processes within the SPMSM and IPMSM, to predict the temperature of the magnets. The predicted machine temperatures are found to be consistent with the experimental measurement.

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42

Cheedket, Sampart, and Chitnarong Sirisathitkul. "Comparison of closed-form solutions to experimental magnetic force between two cylindrical magnets." EUREKA: Physics and Engineering, no. 4 (July 23, 2021): 141–46. http://dx.doi.org/10.21303/2461-4262.2021.001955.

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The force between permanent magnets implemented in many engineering devices remains an intriguing problem in basic physics. The variation of magnetic force with the distance x between a pair of magnets cannot usually be approximated as x-4 because of the dipole nature and geometry of magnets. In this work, the force between two identical cylindrical magnets is accurately described by a closed-form solution. The analytical model assumes that the magnets are uniformly magnetized along their length. The calculation, based on the magnetic field exerted by one magnet on the other along the direction of their orientation, shows a reduction in the magnetic force with the distance x and a dependence on the size parameters of magnets. To verify the equation, the experiment was set up by placing two cylindrical neodymium iron boron type magnets in a vertical tube. The repulsive force between the identical upper and lower magnets of 2.5 cm in diameter and 7.5 cm in length was measured from the weight on the top of the upper magnet. The resulting separation between the magnets was recorded as x. The forces measured at x=0.004-0.037 m differ from the values calculated using the analytic solution by -0.55 % to -13.60 %. The calculation also gives rise to a practical remnant magnetic field of 1.206 T. When x is much large than the equation of force is approximated as a simple form proportional to 1/x-4. The finding can be directly used in magnetic levitation as well as applied in calculating magnetic fields and forces in other systems incorporating permanent magnets.

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Phelan, Angie, Peter Petocz, William Walsh, and M. Ali Darendeliler. "The force-distance properties of attracting magnetic attachments for tooth movement in combination with clear sequential aligners." Australasian Orthodontic Journal 28, no. 2 (2012): 159–69. http://dx.doi.org/10.2478/aoj-2012-0013.

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Abstract Background: The demand for clear sequential aligner therapy has increased dramatically in recent years. An improved system utilising small neodymium-iron-boron (NdFeB) magnetic attachments has been proposed to enhance appliance capabilities. Aim: The aim of the investigation was to analyse the force system diagrams produced by small attracting NdFeB magnets to determine, 1) whether the force levels were sufficient to induce tooth movement, 2) the effect of magnet morphology on force characteristics and, 3) the most appropriate magnet dimensions that could be utilised for this application. Methods: Twenty-nine NdFeB rectangular magnets of varying dimensions were tested. A Mach-1 universal testing machine (Biosyntech Inc, Quebec, Canada) was used to measure the attractive force of pairs of magnets. Measurements commenced with a magnetic pair in contact and subsequently vertically separated a distance of 10 mm at a speed of 12 mm/minute. For all magnetic configurations four repeat measurements were performed on five magnetic pairs of the same size. Results: The force-distance diagrams for all magnet configurations demonstrated a dramatic decrease in force with increasing magnet separation. Rather than a suggested inverse square law, the experimental data followed an inverse fourth law when an offset determined by a regression analysis was applied to the distance. For the majority of magnets, insignificant forces were attained beyond 2 mm of separation. Magnets with large pole face areas and longer magnetic axes provided the greatest force. Conclusions: A select range of magnet configurations exhibited suitable and reliable attractive forces and therefore could be advocated for prescribed clinical application.

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München, Daniel Dotto, Ronei Tiago Stein, and Hugo Marcelo Veit. "Rare Earth Elements Recycling Potential Estimate Based on End-of-Life NdFeB Permanent Magnets from Mobile Phones and Hard Disk Drives in Brazil." Minerals 11, no. 11 (2021): 1190. http://dx.doi.org/10.3390/min11111190.

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Besides neodymium, the chemical composition of Neodymium–Iron–Boron (NdFeB) permanent magnets possibly contains other rare earth elements (REEs) such as praseodymium, dysprosium, and terbium. Among its applications, NdFeB magnets are essential for Hard Disk Drives (HDDs) in computers for data storage, in Mobile Phones (MPs), and in acoustic transducers. Because REEs were classified as critical raw materials by the European Union and the USA, the recycling of them has become an important strategy to diminish supply risk. Therefore, in this publication, the authors have uncovered the recycling potential estimate (RPE) of these four REEs from both end-of-life (EoL) secondary sources. The results were based on the time-step method, using in-use stock and sales data from Brazil over the last decade (2010–2019). Moreover, the NdFeB magnets were characterized by content and weight to a more accurate RPE. The EoL generation over the decade studied showed different scenarios for MPs and HDDs, mainly due to lifespan, social behavior regarding storage and usage, and resources. Under those circumstances, the RPE revealed 211.30 t of REEs that could return as raw materials in the last decade, of which approximately 80% is neodymium. Unfortunately, recycling rates are still too low, even more so in Brazil, which is problematic for the future REE supply chain and electronic waste figures.

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Łebkowski, A. "A way of neodymium-iron-boron magnets regeneration in surface-mounted PMSM used in electric vehicles." Bulletin of the Polish Academy of Sciences Technical Sciences 65, no. 5 (2017): 751–58. http://dx.doi.org/10.1515/bpasts-2017-0081.

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Abstract The paper describes an efficient method of magnetization of permanent magnets, mounted on synchronous and BLDC motor rotors, which employs an air coil. A developed mathematical model of an electromagnetic circuit is presented, which was simulated in an ANSYS-MAXWELL environment. The performed simulations and experimental tests allowed optimization of the physical process of magnetization of permanent magnets mounted on an electrical machine rotor. The adopted method allowed achieving more favourable conditions of magnetization – less financial expenditure allowed to achieve the same results.

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Constantinides, Steve. "The Elements of Magnetics." MRS Proceedings 1492 (2013): 35–46. http://dx.doi.org/10.1557/opl.2013.174.

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ABSTRACTThe 20th century saw rapid and dramatic improvements in permanent magnet materials. It has been 31 years since the discovery of neodymium-iron-boron and numerous companies and laboratories are seeking to produce a new and superior material. Topics discussed herein are material options, economics of selected materials and market drivers in material selection. Market issues include manufacturability by shape, size, and material yield; raw material supply including cost and dependability of the supply chain; raw material and magnet product price stability; development of applications based on commercial needs, government legislation and consumer demand. “Need is the mother of invention” and no discussion would be complete without covering why a new material would be beneficial from an applications point of view especially in energy production and consumption. Therefore, an introduction will be provided for select, major applications using permanent magnets and the growth forecasts for these.

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Yohanes Setyawan, Eko, Yusuf Ismail Nakhoda, Awan Uji Krismanto, Lalu Mustiadi, Erkata Yandri, and Juris Burlakovs. "Design and Construction of Single Phase Radial Flux Permanent Magnet Generators for Pico hydro Scale Power Plants Using Propeller Turbines in Water Pipes." E3S Web of Conferences 188 (2020): 00006. http://dx.doi.org/10.1051/e3sconf/202018800006.

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Pico hydro or a small scale hydroelectric power plant is used as the rotating energy of the generator. Pico hydro is a hydroelectric power plant that has a power of less than 5 kW. Technically, Pico hydro has three main components namely water, turbine and generator. Turbine type propeller reaction has a special profile that causes a decrease in water pressure during the blades. This pressure difference exerts force on the blade so that the runner (rotating part of the turbine) can rotate. Permanent magnets are used to produce magnetic flux. Permanent magnets used are rare-eatrhrod magnet material, neodymium-iron-boron NdFeB with N35 type. The planned generator released is 36.85 V, 500 rpm, 50 hz. This designed water turbine has four blades which cannot change its angle. As for the measurement results produce a voltage of 35.1 V with a manufacturing efficiency of 95 %. Charging the battery voltage must be more than 12 V, therefore the generator must be turned at least 200 rpm with a voltage of 14 V to be used for charging batteries.

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Stein, Ronei Tiago, Angela Cristina Kasper, and Hugo Marcelo Veit. "Recovery of Rare Earth Elements Present in Mobile Phone Magnets with the Use of Organic Acids." Minerals 12, no. 6 (2022): 668. http://dx.doi.org/10.3390/min12060668.

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Currently, the recovery of materials from secondary sources is increasingly necessary because of the scarcity of materials. Significant amounts of rare earth elements (REE) are found in permanent neodymium-iron-boron (NdFeB) magnets, used in various electrical and electronic equipments, such as mobile phones. However, the estimated recycling rate for REEs is only 1%. Hydrometallurgical routes are the most commonly used for REE recovery from secondary sources. This route usually uses inorganic acids, which are expensive and toxic. Thus, in this work the leaching efficiency of organic acids (acetic and citric) in leaching the REE (neodymium and praseodymium) present in magnets of obsolete or defective mobile phones was evaluated. Different concentrations of acids, solid/liquid relations, times and leaching techniques (microwave, ultrasound and conventional) are also evaluated. The results indicate that acetic and citric acids have the potential to leach Nd and Pr. Microwave leaching was the most effective method, compared to ultrasound and conventional methods. In microwaves, citric acid at 0.5 M (ratio s/l 1/100) leached 57% of Nd and 58% of Pr. Acetic acid at 0.5 M (s/l ratio—1/100) leached 48% of Nd and 65% of Pr, in 15 min. Furthermore, both citric acid and acetic acid also leached high percentages of iron (51% and 72%, respectively).

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Al Zubaidy, Riyadh Zuhair, Jinan Namaa Hamza, and Amna Sahib Hindal. "Effects of Magnetized Water on the Accumulated Depth of Infiltration." Journal of Engineering 23, no. 3 (2017): 94–106. http://dx.doi.org/10.31026/j.eng.2017.03.07.

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This study was carried out to investigate the effects of magnetized water on accumulated infiltration depth. A test rig was designed and constructed for this purpose was installed at the water tests laboratory of the Department of Water Resources Engineering at the University of aghdad. The investigation was carried out by using two types of soil, different flow velocities throughout magnetizing device and different configuration of magnets over and under the water passage of the magnetizing device. The soils that were used in the experiments are clayey and sandy soils. Six different flow velocities throughout magnetizing device ranged between 0.29 to 1.19 cm/s and ten configurations of arranging the magnets over and under the water passage of the magnetizing device were used. The magnates are sintered neodymium-iron-boron type. Tests results obtained with magnetized water were compared with those of untreated water. Results showed that magnetizing water increases the accumulated infiltration depth for the two types of soil. The highest increase in the accumulated infiltration depth is achieved under low flow velocity throughout the magnetizing device and with ten magnets. This highest increase for the clayey and sandy soils was 98.2% and 34.2%, respectively.

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Mendrofa, Mareanus, Perdinan Sinuhaji, and Muljadi Muljadi. "Study on the Production of Bonded Magnet NdFeB and Polyvinyl Butyral." Journal of Technomaterials Physics 2, no. 1 (2020): 25–33. http://dx.doi.org/10.32734/jotp.v2i1.5263.

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bonded magnet is composite magnet material made by mixing magnetic powder with non-magnetic binder. The process in manufacturing bonded magnet NdFeB made by mixing powder of neodymium iron boron (NdFeB) commercial type MQP-B with a polyvinyl butyral powder using a glass beaker. The comparisons of variation in composing NdFeB magnets powders with a binder of PVB (% weight) are 98:2, 96:4, 94:6 and 93:7 of 8 grams from total mass of the sample. After mixing the powder, it is molded by using a compression molding method with 8 tons pressure for 20 minutes at curing temperature 1600C. The molded samples are conducted by characterizing the physical properties which include measurement of density, microstructure analysis using SEM-EDX and magnetic properties which include measurement of the magnetic field strength using a Gaussmeter and hysteresis curve using VSM. The result of the study shows that the addition of and binder PVB in bonded magnet NdFeB causes a decrease in the density and magnetic field strength. The best result of density and magnetic field in the manufacture of bonded magnets is obtained by the addition of 2 % binder of 5.66 g/cm3 and strong magnetic field of 1862.4 G. the score of Mr = 72.86 emu/g, Ms = 103 emu/gram, Hc = 8.490 KOe and BHmax = 5.1 MGOe was obtained on the addition of PVB 2 %.

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