A comparative study on the corrosion behavior of NdFeB magnets in different electrolyte solutions

Song, Yingwei; Zhang, H.; Yang, Hongjun; Song, Z. L.

doi:10.1002/maco.200804175

Cited by 41 publications

(7 citation statements)

References 12 publications

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“…As shown, the distinctive Fe-rich granules covered in Nd-rich particles observed on magnet particles before SCFE (Figure a) are not observed on post-SCFE samples. The lack of apparent surface Nd-rich particles is due to the preferential dissolution of the Nd-rich and B-rich intergranular phases over the Fe-rich granules because the former phases have a poor corrosion resistance because of the high reactivity of Nd. , An increase in the particle size was observed after SCFE, likely because the smaller Fe-rich particles were more readily dissolved, leaving behind the larger particles. The run showing the lowest overall REE extraction (run 18, Figure b) and the one with the highest overall REE extraction (validation run 5, Figure c) show different morphologies.…”

Section: Resultsmentioning

confidence: 99%

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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There is a global need for efficient and environmentally sustainable processes to close the life cycle loop of waste electrical and electronic equipment (WEEE) through recycling. Conventional WEEE recycling processes are based upon pyrometallurgy or hydrometallurgy. The former is energy-intensive and generates greenhouse gas (GHG) emissions, while the latter relies on large volumes of acids and organic solvents, thus generating hazardous wastes. Here, a novel “aeriometallurgical” process was developed to recycle critical rare earth elements, namely, neodymium (Nd), praseodymium (Pr), and dysprosium (Dy), from postconsumer NdFeB magnets utilized in wind turbines. The new process utilizes supercritical CO2 as the solvent, which is safe, inert, and abundant, along with the tributyl-phosphate–nitric acid (TBP–HNO3) chelating agent and 2 wt % methanol as a cosolvent. Nd (94%), Pr (91%), and Dy (98%) extraction was achieved with only 62% iron (Fe) coextraction and minimal waste generation. Fundamental investigations into the extraction mechanism demonstrated that metal ion charge has an important impact on the extraction efficiency. Fundamental investigations indicate that extraction proceeds by corrosion of the magnet particle’s surface layer. This work demonstrates that supercritical fluid extraction would find widespread applicability as a cleaner, a more sustainable option to recycle value metals from end-of-life products to enable the circular economy.

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Section: Resultsmentioning

confidence: 99%

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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“…Therefore, the results showed that iron corruption is a critical factor that has a great effect on the dissipation rate of fosthiazate in the ZVI system. Song et al (2008) reported that the corrosion behaviors of NdFe-B magnets were different in different types of electrolyte solutions, as well as in different concentrations of the same electrolyte solutions. Due to the formation of passivation films on the surface of magnets, Nd-Fe-B only slightly suffers from corrosion in the NaOH and H 2 C 2 O 4 solutions.…”

Section: Effects Of Common Electrolyte Solutions On the Reaction Ratementioning

confidence: 98%

Effective removal of nemacide fosthiazate from an aqueous solution using zero-valent iron

Shen

Zhang

et al. 2015

Journal of Environmental Management

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“…Sintered NdFeB magnets have been widely used in industry applications, such as electronics, communications and automation, due to their excellent magnetic properties [ 1 , 2 ]. However, magnets present poor corrosion resistance in various environments due to the high reactivity of Nd and the existence of a multiple-phase structure, which strictly limits their further applications [ 3 , 4 , 5 , 6 ]. According to our knowledge, many attempts have been made to improve the corrosion resistance of NdFeB magnets, such as alloy addition and surface treatment [ 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Morphology and Anti-Corrosive Performance of Cr(III) Passivated Zn–Fe Alloy Coating on NdFeB Substrate

Zhou

Chen

et al. 2022

Materials

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In this study, low-iron Zn–Fe alloy coatings and pure Zn coatings, with or without trivalent chromium passivation treatment, were electrodeposited onto a sintered NdFeB magnet from a weak acid chloride bath. The surface morphology and structure of the coatings were then examined using the X-ray diffraction, a scanning electron microscope and 3D white-light interfering surface analysis. Meanwhile, the electrodeposition behavior and anti-corrosive properties of the coatings were investigated using cyclic voltammetry, potentiodynamic polarization, electrochemical impedance spectroscopy, and natural salt spray tests. The results indicate that a passivated Zn–Fe alloy coating with a 0.9 wt.% Fe content provided much better corrosion resistance than a pure Zn coating and could provide both anodic protection and physical barrier function in the NdFeB substrates. The Fe element in Zn–Fe alloy coating was predominantly in solid solution in η-phase and small amounts in elemental form, which was beneficial to acquire a compact coating and passivation film. Finally, the passivated Zn–Fe alloy coating withstood 210 h against a neutral 3.5 wt.% NaCl salt spray without any white rust, which was 3–4 times longer than the pure Zn coating.

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A comparative study on the corrosion behavior of NdFeB magnets in different electrolyte solutions

Cited by 41 publications

References 12 publications

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Effective removal of nemacide fosthiazate from an aqueous solution using zero-valent iron

Morphology and Anti-Corrosive Performance of Cr(III) Passivated Zn–Fe Alloy Coating on NdFeB Substrate

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