Bonded permanent magnets: Current status and future opportunities (invited)

Ormerod, John G.; Constantinides, S.

doi:10.1063/1.365471

Cited by 132 publications

(69 citation statements)

References 5 publications

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“…However, the coercivity temperature coefficient of NdFeB bonded magnets is about -0.4 %ÁK -1 , which restricts the use of NdFeB bonded magnets at elevated temperatures [12], such as in electric motors. Hence, hybrid bonded magnets mixed with different magnetic powders appear to fill the magnetic property gap of single-component magnets [13]. In the common hybrid magnets, ferrite with positive temperature coefficient of coercivity is used to compensate the undesirable thermal stability of NdFeB [14].…”

Section: Introductionmentioning

confidence: 99%

High-temperature magnetic properties of anisotropic MnBi/NdFeB hybrid bonded magnets

et al. 2015

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Anisotropic MnBi/NdFeB (MnBi contents of 0 wt%, 20 wt%, 40 wt%, 60 wt%, 80 wt%, and 100 wt%) hybrid bonded magnets were prepared by molding compression using MnBi powders and commercial hydrogenation disproportionation desorption and recombination (HDDR) NdFeB powders. Magnetic measurements at room temperature show that with MnBi content increasing, the magnetic properties of the MnBi/NdFeB hybrid bonded magnets all decrease gradually, while the density of the hybrid magnets improves almost linearly. In a temperature range of 293-398 K, the coercivity temperature coefficient of the hybrid magnets improves gradually from -0.59 %ÁK -1 for the pure NdFeB bonded magnet to -0.32 %ÁK -1 for the hybrid bonded magnet with 80 wt% MnBi, and the pure MnBi bonded magnet exhibits a positive coercivity temperature coefficient of 0.61 %ÁK -1 .

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Section: Introductionmentioning

confidence: 99%

High-temperature magnetic properties of anisotropic MnBi/NdFeB hybrid bonded magnets

et al. 2015

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“…9,27 Such microparticles present exceptional magnetic properties 27,28 and can be permanently magnetized. Alternatively, the magnetic response of the polymeric magnetic films can be sufficiently improved arranging the particles in a preferential direction throughout the volume of the polymeric matrix.…”

Section: Introductionmentioning

confidence: 99%

Highly Magneto-Responsive Elastomeric Films Created by a Two-Step Fabrication Process

Marchi

Casu

Bertora

et al. 2015

ACS Appl. Mater. Interfaces

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An innovative method for the preparation of elastomeric magnetic films with increased magneto-responsivity is presented. Polymeric films containing aligned magnetic microchains throughout their thickness are formed upon the magnetophoretic transport and assembly of microparticles during the polymer curing. The obtained films are subsequently magnetized at a high magnetic field of 3 T directed parallel to the microchains orientation. We prove that the combination of both, alignment of the particles along a favorable direction during 2 curing, and subsequent magnetization of the solid films induces an impressive increase of the films' deflection. Specifically, the displacements reach few millimeters, up to 85 times higher compared to the non-treated films with the same particles concentration. Such process can improve the performance of the magnetic films without increasing the amount of magnetic fillers, thus without compromising the mechanical properties of the resulting composites. The proposed method can be used for the fabrication of magnetic films suitable as components in systems where high displacements at relatively low magnetic fields are required, such as sensors, drug delivery or microfluidic systems, especially where remote control of valves is requested to achieve appropriate flow and mixing of liquids.

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“…We have focused on Dy-free Nd bond magnets (BMs) as one type of permanent magnet, which are not only cost efficient but also provide advantages in the molding small and multiplex body magnets. 1) However, the BMs still have a problem in that the flux density (B) is much smaller than that of the Nd-Fe-B-Dy sintered magnets. Therefore, we have focused on a Halbach array of BMs to improve B.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Multipole Magnets with Enhanced Flux Density Using Anisotropic Bond Magnets for Miniature Optical Pickup Devices

et al. 2015

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A prototype magnetizing fixture was designed based on magnetic flux patterns simulated using the three-dimensional finite-element method of the JMAG software package. Rectangular shaped anisotropic bond magnets with dimensions of 6×12×24 mm were magnetized to multipoles using the prototype and a pulse power source. The result was significant enhancement perpendicular to the surface component of magnetic flux density (Bz) in the hard-axis compared with Bz for conventional simple magnets, of which the front and back surfaces are magnetized to opposite polarities. Moreover, Bz reached the close value for the Halbach arrayed magnet, 0.24 T, with the same body size fabricated for the attainment target. The enhanced Bz was attributed to the cusp field formed by the flux from both side coils. Demonstrations indicated that the cusp field out of the easy-axis could be efficiently enhanced due to focusing of the flux.

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Bonded permanent magnets: Current status and future opportunities (invited)

Cited by 132 publications

References 5 publications

High-temperature magnetic properties of anisotropic MnBi/NdFeB hybrid bonded magnets

High-temperature magnetic properties of anisotropic MnBi/NdFeB hybrid bonded magnets

Highly Magneto-Responsive Elastomeric Films Created by a Two-Step Fabrication Process

Fabrication of Multipole Magnets with Enhanced Flux Density Using Anisotropic Bond Magnets for Miniature Optical Pickup Devices

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