As a critical functional material in rapidly advancing scientific and technological fields,neodymium-iron-boron(NdFeB)magnets have witnessed continuous expansion of application domains and sustained year-on-year growth in global de-mand.NdFeB magnets are predominantly employed in permanent magnet motors across diverse industrial and consumer appli-cations.As these motors reach end-of-life,the resulting decommissioned units yield significant quantities of spent magnets-Posing dual challenges of environmental contamination and inefficient utilization of critical rare earth elements.Recycling these urban minerals can mitigate the rare earth resource imbalance,reduce associated environmental burdens,and support the es-tablishment of a circular magnet economy.This review systematically analyzes the technical characteristics of key remanufac-turing processes for high-performance NdFeB magnets derived from end-of-life sources,and critically evaluates current techno-logical limitations and emerging research priorities.
Cerium-based passivation films were deposited on Zn-5％Al coating,followed by stearic acid modification of the films deposited for varying durations to form a superhydrophobic coating.The microstructure of the cerium-based coating was examined using scanning electron microscopy(SEM),and surface roughness was assessed via laser confocal microscopy(LCM).The chemical composition of the coating was analyzed by energy dispersive spectroscopy(EDS)and X-ray photoelec-tron spectroscopy(XPS).Static contact angles were measured using a contact angle goniometer,and corrosion resistance was evaluated through electrochemical impedance spectroscopy(EIS)measurements performed on an electrochemical workstation.The results reveal that with the increasing of deposition time,the Ce content and film thickness on the Zn-5％Al coating in-creases continuously,accompanied by an increase in film thickness and a progressive enhancement of hydrophilicity.The ste-aric acid-modified film surface developed a micro-nanoscale rough structure,and the hydrophobicity increased progressively with prolonged passivation time.The modified film formed after 30 minutes of deposition achieved a water contact angle of 164°.The superhydrophobic surface is mainly composed of stearic acid,CeO2/Ce(OH)4,Ce2O3/Ce(OH)3,forming an air barrier that impedes liquid penetration into corrosive media.As the deposition time increases from 5 to 30 minutes,the corro-sion resistance shows a progressive enhancement.
The production of carbon monoxide(CO)through the electrocatalytic carbon dioxide reduction reaction(CO2RR)is of great significance for realizing the resource utilization of CO2,demonstrating favorable industrial potential.However,the development of electrocatalysts with high activity and selectivity remains a challenge.Rare earth metals have garnered extensive attention in the field of electrocatalysis due to their unique electronic structures and multivalent properties.In this study,a composite material(Pr6O11/g-C3N4)was synthesized through a multi-step process,featuring Pr6O11 nanopar-ticles supported on two-dimensional graphitic carbon nitride.The construction of the supported structure led to a decrease in the crystallinity of the Pr6O11 nanoparticles,resulting in a distorted lattice structure and altered electronic states of Pr.This re-sults in the Pr6O11/g-C3N4 catalyst exhibiting excellent CO selectivity during the electrocatalytic CO2RR.At a potential of-1.55 V(versus the reversible hydrogen electrode,RHE),the catalyst achieves a current density of 3.3 mA·cm-2 and a Faraday efficiency for CO of 80％,significantly outperforming the comparison samples.Additionally,the Pr6O11/g-C3N4 cata-lyst demonstrated a larger electrochemical active surface area and lower charge transfer resistance.This work provides new in-sights into the design and synthesis of efficient rare-earth-based electrocatalysts for the electroreduction of CO2.
To elucidate the influence of yttrium(Y)on the grain boundary diffusion behavior of dysprosium(Dy)in Nd-Fe-B and Nd-Ce-Fe-B sintered magnets,single-source(DyHx)and co-diffusion(DyHx+YHx)treatments were implemented via grain boundary diffusion processing.The study systematically evaluated how Y incorporation modulates the penetration depth,distribution uniformity,and magnetic isolation efficiency of Dy at grain boundaries across the two magnet systems.For the Nd-Ce-Fe-B magnet with 50％Ce(Mass fraction)substitution,the coercivity attains 13.58 kOe following synchronous grain boundary diffusion of YHx and DyHx,representing an enhancement of 1.55 kOe relative to magnets treated solely with DyHx.Microstructural and compositional analyses demonstrate that synchronous grain boundary diffusion markedly enhances the diffusivity of dysprosium(Dy)—A heavy rare earth element in Nd-Ce-Fe-B sintered magnets.This treatment promotes the formation of a continuous,chemically well-defined Dy-rich shell at intragranular depths beyond the primary grain boundaries,thereby substantially improving coercivity.However,the coercivity of Nd-Fe-B sintered magnets subjected to YHx/DyHx co-diffusion is lower than that achieved with DyHx-only diffusion treatment.
A solid-phase extraction(SPE)method utilizing an iminodiacetic acid-based chelating resin as the stationary phase was developed for the determination of 14 rare earth elements in seawater by inductively coupled plasma mass spectrome-try(ICP-MS).Adjust the pH value of water sample to the range of 8.5～9.0,followed by adsorption and enrichment of the target elements through solid-phase extraction.The detection limit of rare earth elements was 0.017 μg/L～0.024 μg/L,the relative standard deviation(RSD)of the method was 2.7％～4.8％,the recovery rates of spiking was 81.4％～105.0％.The proposed methodology is characterized by operational simplicity,high sensitivity,and efficiency,yielding highly satisfactory experimental results.
