Oxidation of NdFeB-type magnets modified with additions of Co, Dy, Zr and V

Škulj, Irena; Evans, Hugh E.; Harris, I.R.

doi:10.1007/s10853-007-2229-y

Cited by 33 publications

(20 citation statements)

References 8 publications

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“…The growth of the IOZ was then deduced to be due simply to oxygen diffusion within its Ferich matrix. Similar observations have recently been reported [6] in modified NdFeB alloy variants containing Co, Dy, Zr and V.…”

Section: Introductionsupporting

confidence: 91%

The oxidation kinetics of SmCo alloys

Pragnell

Evans

Williams

2009

Journal of Alloys and Compounds

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Section: Introductionsupporting

confidence: 91%

The oxidation kinetics of SmCo alloys

Pragnell

Evans

Williams

2009

Journal of Alloys and Compounds

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“…As for Dy, it can vary from close to 0 wt% (hard disk drives, HDDs) to as high as 8.5 wt% (electric car motors) [2]. Other REMs (Pr, Tb, Gd, Eu) or other elements such as Al, Co, Ga, Nb, Ni, Si, Zn, etc., can also be used as minor admixtures or coating material for improving the thermal and oxidation-corrosion resistances of the magnets [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Recycling of NdFeB Magnets Using Sulfation, Selective Roasting, and Water Leaching

Önal

Gerven

Guo

et al. 2015

J. Sustain. Metall.

114

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NdFeB magnets currently dominate the magnet market. Supply risks of certain rare earth metals (REMs), e.g., Nd and Dy, demand efficient recycling options that are applicable to different types and compositions with minimum use of chemicals and waste generation. In this study, a hydrometallurgical method is presented, which is adjustable to all NdFeB magnets, regardless of their composition. After completely transforming powdered samples into a sulfate mixture, a suitable selective roasting and water leaching treatment resulted in 95-100 % extraction efficiencies for Nd, Dy, Pr, Gd, Tb, and Eu, while Fe remained in the resultant residue forming a marketable hematitedominated by-product. Impurities other than Fe were also greatly separated from the leachate thereby enabling the production of a liquid with at least 98 % REM purity. Such a solution then can be directly treated with subsequent shortened downstream processes without pretreatments for impurity removal. Due to decomposition reactions of impurities, including Fe, during the selective roasting stage, the majority of consumed acid is recyclable resulting in an environment-friendly flow sheet.

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“…Obviously, this radical coercivity deterioration is attributed to oxidation. Oxidation of Nd 2 Fe 14 B compound has been known to occur through a dissociation of the phase into a mixture of dissociated phases [3,4,6]. The radical coercivity deterioration may be related closely with the phase constitution in the oxidation product.…”

Section: Experimental Workmentioning

confidence: 99%

“…Due to these superior magnetic properties, Nd 2 Fe 14 B-type fine particles have increasingly found new applications, such as in high performance micro-magnets. Since the Nd 2 Fe 14 B compound contains a high content of the rare earth metal Nd, which has a high affinity with oxygen, it is particularly prone to oxidation [3][4][5][6]. What's worse is that the fine Nd 2 Fe 14 B-type particles have an extremely large specific surface area.…”

Section: Introductionmentioning

confidence: 99%

Coercivity of Near Single Domain Size Nd₂Fe₁₄B-type Particles

Kwon¹,

Yu²

2012

Journal of Magnetics

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The coercivity of near single domain size Nd 2 Fe 14 B-type particles prepared by ball milling of HDDR-treated Nd 12.5 Fe 80.6 B 6.4 Ga 0.3 Nb 0.2 alloy was investigated. The feasibility of a surface nitrogenation for improving the coercivity stability of the fine Nd 2 Fe 14 B-type particles was also studied. The near single domain size Nd 2 Fe 14 Btype particles had a high coercivity of over 9 kOe. However, the coercivity radically deteriorated as the temperature increased in air (< 2 kOe at 200 o C). This coercivity reduction was attributed to the soft magnetic phases, α-Fe and Fe 3 B, which formed on the surface of the fine particle due to oxidation. Surface nitrogenation of the fine particles significantly improved the stability of their coercivity. The improvement in coercivity stability was attributed to the formation of a thin nitrogenated layer on the surface of the fine Nd 2 Fe 14 B-type particles, which enhanced the anisotropy field and gave improved resistance to oxidation (dissociation).

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Oxidation of NdFeB-type magnets modified with additions of Co, Dy, Zr and V

Cited by 33 publications

References 8 publications

The oxidation kinetics of SmCo alloys

The oxidation kinetics of SmCo alloys

Recycling of NdFeB Magnets Using Sulfation, Selective Roasting, and Water Leaching

Coercivity of Near Single Domain Size Nd₂Fe₁₄B-type Particles

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Oxidation of NdFeB-type magnets modified with additions of Co, Dy, Zr and V

Cited by 33 publications

References 8 publications

The oxidation kinetics of SmCo alloys

The oxidation kinetics of SmCo alloys

Recycling of NdFeB Magnets Using Sulfation, Selective Roasting, and Water Leaching

Coercivity of Near Single Domain Size Nd2Fe14B-type Particles

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Product

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Coercivity of Near Single Domain Size Nd₂Fe₁₄B-type Particles