Characterisation of oxidation products of modified Nd–Fe–B type magnets

Škulj, Irena; Douvalis, Alexios P.; Harris, I.R.

doi:10.1016/j.jallcom.2005.06.033

Cited by 10 publications

(4 citation statements)

References 23 publications

(28 reference statements)

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“…Exposure of Nd-Fe-B to hydrogen pressure leads to penetration of hydrogen into the grain boundaries, reaction of hydrogen with the grain boudary phase, expansion of grain boundaries, and embrittlement of the material. Decrepitation in the hydrogen atmosphere limits oxidation of Nd-Fe-B and can form phases like Nd 2 Fe 14 BH x and Nd 1+ E Fe 4 B 4 . − The surface morphology and EDS mapping of the decrepitated (Nd,Pr)-Fe-B magnet before leaching are presented in the SEM micrograph in Figure and Figure S9. The particle sizes of hydrogen decrepitated magnet powders range from 2 to 10 μm.…”

Section: Resultsmentioning

confidence: 99%

Sustainable Urban Mining of Critical Elements from Magnet and Electronic Wastes

Prodius

Gandha

Mudring

et al. 2019

ACS Sustainable Chem. Eng.

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A straightforward and environment-friendly process for acid-free leaching of rare-earth elements and cobalt, which are critical materials, from waste magnet materials has been developed. The process also allows for selective leaching of rare-earth elements from magnet-containing electronic wastes, such as end-of-life hard disk drives and electric motors. The use of copper salts eliminates the use of volatile toxic acids in the dissolution and separation processes, which allows for a more eco-friendly approach to recovering critical elements and a safer work environment. Recovered critical materials were shown to be suitable for reinsertion into the materials supply chain.

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Section: Resultsmentioning

confidence: 99%

Sustainable Urban Mining of Critical Elements from Magnet and Electronic Wastes

Prodius

Gandha

Mudring

et al. 2019

ACS Sustainable Chem. Eng.

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“…The REC of Nd 64 Co 36 is lower than the conventional Nd-rich phase, which contains $80 at.% Nd [23,24]. Besides, the standard electrode potential of Co (À0.277 V) is more positive than Fe (À0.440 V) [4,25]. Therefore, it is inferred that the addition of Nd 64 Co 36 will increase the electrode potential of the intergranular phase, thus improving the corrosion potential of magnets.…”

Section: Resultsmentioning

confidence: 97%

Magnetic properties and corrosion resistance of Nd–Fe–B magnets with Nd64Co36 intergranular addition

Zhang¹,

Liang²,

Jin³

et al. 2014

Journal of Alloys and Compounds

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“…However, only non-hydrogenated and as-recycled magnet materials were studied for their thermal oxidation and leaching behaviors up to now. From a different aspect, there are also studies regarding the oxidation-corrosion behavior of end magnet products [5,[22][23][24][25][26][27][28]. Here, the main purpose is primarily to investigate the weakest spot of Nd-Fe-B magnets during their life cycle under oxidative and/or corrosive environments.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Comparative oxidation behavior of Nd-Fe-B magnets for potential recycling methods: Effect of hydrogenation pre-treatment and magnet composition

Önal

Jönsson

Zhou

et al. 2017

Journal of Alloys and Compounds

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Recycling of Nd-Fe-B magnets is one of the few solutions to alleviate the supply risks of certain rare earth elements (REE) such as Nd and Dy. One of the most promising solutions with regards to extraction of end-oflife (EOL) magnets is to apply hydrogen decrepitation and to physically separate the Nd-Fe-B as a demagnetized hydrogenated powder. Such a powder can be directly recycled into new sintered magnets, or indirectly recycled by a conventional oxidation roasting and acid leaching flowsheet. The oxidation stability of powders, the microstructure after oxidation and the role of compositional variations can be of importance for the success of such subsequent direct or indirect recycling routes. In this study, magnets with varying compositions were subjected to different hydrogen treatments (e.g. hydrogenation, partial or full degassing and vacuum or conventional disproportionation) and subsequently studied for their comparative oxidation behavior and microstructural changes. While initial magnet composition was found to have little or no effect on oxidation behavior, the treatment type was found to have a direct impact on both the particle size distribution and the oxidation mechanism. The general oxidation rate was found to be the equally highest for hydrogenated and partially degassed samples followed by fully degassed and then disproportionated samples. After complete oxidation, complex REE-Fe-O compounds were formed more extensively in hydrogenated and fully degassed NdFeB samples than in the disproportionated samples.

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Characterisation of oxidation products of modified Nd–Fe–B type magnets

Cited by 10 publications

References 23 publications

Sustainable Urban Mining of Critical Elements from Magnet and Electronic Wastes

Sustainable Urban Mining of Critical Elements from Magnet and Electronic Wastes

Magnetic properties and corrosion resistance of Nd–Fe–B magnets with Nd64Co36 intergranular addition

Comparative oxidation behavior of Nd-Fe-B magnets for potential recycling methods: Effect of hydrogenation pre-treatment and magnet composition

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