Formation of a high-coercive state in sintered Nd-Fe-B-Ga magnets by thermocycling

Попов, А. Г.; Puzanova, T. Z.; Гавико, В. С.; Vasilenko, D. Yu.; Vyatkin, V. P.

doi:10.1134/s0031918x06060044

Cited by 9 publications

(4 citation statements)

References 19 publications

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“…At C SZn ≥ 0.5 wt %, the lattice parameter а of the oxide NdO x with an fcc lattice becomes more than 5.11 Å. However, this oxide, as was noted previously [7], is not capable of forming coher ently bound defect free interlayers at the grain bound aries of the Nd 2 Fe 14 B alloy; thus, the coercive force Н с decreases sharply. Thus, it has been established that, for this scheme of the experiment, the critical concentration of the introduced zinc stearate is 0.2 wt %.…”

Section: Effect Of Zinc Stearate Concentration On Properties Of Sintementioning

confidence: 84%

Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

Попов

Gerasimov

Терентьев

et al. 2013

Phys. Metals Metallogr.

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Abstract-Zinc stearate additions have been used to increase the remanence of sintered Nd-Fe-B magnets produced by the powder metallurgy without powder pressing. Zinc stearate acts as an internal lubricant, i.e., it decreases the friction forces between the particles and favors an increase in the degree of texture of the pow ders, which is induced by the magnetic field. It is shown that the density and the magnetic hysteresis charac teristics of sintered magnets produced using additions of 0.15 wt % zinc stearate exceeds the corresponding values obtained for magnets produced without this addition at a filling density of powders in containers of more than 2.9 and 3.0 g/cm 3 in dry and wet states, respectively. Using additions of zinc stearate in the amount of 0.15% with respect to the weight of the powder, magnets with a density of 7.55 g/cm 3 , B r = 14.02 kG, H c = 7.91 kOe, and (BH) max = 46.1 MG Oe have been produced.

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Section: Effect Of Zinc Stearate Concentration On Properties Of Sintementioning

confidence: 84%

Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

Попов

Gerasimov

Терентьев

et al. 2013

Phys. Metals Metallogr.

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“…Secondly, as for saving Dy, an optimized SC method was investigated for an alloy containing trace amount of Ga. It has been already reported that small amount of Ga in the R-T-B sintered magnets forms a low melting point eutectic Nd compound at grain boundary, and its compound prevents the reverse magnetic domain occurs at grain boundary by effect of better wettability [13,14,15,16], and R2Fe17GaX compound precipitated when sintering improves the coercive force [17,18].…”

Section: Current Issues and New Concept Of Cost Reduction Approachmentioning

confidence: 99%

Development of Highly Efficient Saving Processes of Rare Earth in R-T-B Permanent Magnet

et al. 2014

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In this study, cost reduction of manufacturing R (Nd, Pr, and Dy) -T (Fe, Co)-B permanent magnets was investigated. An efficient direct melting recycle of R-T-B magnet scraps and multiple methods for saving Dy were focused. In the former, Decarburization and deoxidation of R-T-B magnet scraps were developed as a pre-treatment technique for conventional induction melting. The decarburized scraps 0.001mass% carbon or less was subsequently deoxidized by calciothermic reduction. The recycled scraps can be used as low cost alloying elements by remelting. In the latter, the casting conditions for R-T-B alloy with small admixture of Ga and the improved pulverization process of R-T-B magnet alloy were developed. Microstructure of R-T-B magnet alloy with small admixture Ga was optimized by controlling cooling rate during solidification, and its average crystalline size was to be 5 m. In order to obtain finer R-T-B magnet alloy powder preferable to the coercive force, conditions of hydrogen decrepitation (HD) prior to pulverization were optimized. Specific surface area of the HD magnet alloy was increased with decreasing temperature and hydrogen pressure, and its grindability was verified by Jet milling.

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“…The current standard approach for solving this problem is sufficiently enhancing the room-temperature coercivity of the magnet, so it still can have required coercivity at the elevated operating temperature. This is commonly achieved using techniques such as (1) alloying method by substituting some Nd in the magnet with heavy rare earth (HRE: Tb, Dy) [1][2][3][4][5], (2) grain boundary diffusion of HRE [6][7][8][9][10][11][12], (3) grain boundary modification [13][14][15][16][17] and (4) grain refinement [18]. Indeed, the HRE-substituted or grain boundary diffusion-treated Nd-Fe-B-type magnets have been put into full practice for rotor magnet, but the use of HRE still remains particularly worrisome because of its highly limited supply and outrageously expensive price.…”

Section: Introductionmentioning

confidence: 99%

Prospect of developing Nd–Fe–B-type magnet with high electrical resistivity

Kwon

Kang

2019

Rare Met.

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Nd-Fe-B-type magnet is exclusively used as a rotor magnet in the traction motor of hybrid electric vehicle (HEV) and electric vehicle (EV), but its overly high operating temperature is a lingering problem attached to the magnet. The major cause of the high operating temperature is eddy current, which is readily generated in the highly conductive metallic magnet under alternating magnetic field from stator ripple. In this article, temperature rise in the Nd-Fe-B-type magnet with varying electrical resistivity under alternating magnetic field is discussed with the intention of highlighting the importance of enhancing the electrical resistivity for reducing the operating temperature of the Nd-Fe-B-type rotor magnet. Temperature rise in the Nd-Fe-B-type magnet (dielectric salt-added die-upset magnet) with high electrical resistivity is noticeably lower compared to the magnet (commercial sintered rotor magnet) with lower electrical resistivity, substantiating the theory that enhancing the electrical resistivity in the rotor magnet is fairly effective for suppressing the over-rise of its operating temperature during operation. Die-upset process is revealed to be particularly pertinent for the fabrication of highly dense salt-added magnet with high electrical resistivity.

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Formation of a high-coercive state in sintered Nd-Fe-B-Ga magnets by thermocycling

Cited by 9 publications

References 19 publications

Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

Development of Highly Efficient Saving Processes of Rare Earth in R-T-B Permanent Magnet

Prospect of developing Nd–Fe–B-type magnet with high electrical resistivity

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