RSC Advances
·
2024
·Vol. 14
·期 13
·8641-8651
·
IF 3.9
Li Xiaoya,Ma Yongcun,Peng Shusen,Tian lixi
The traditional aqueous electroplating of zinc film causes significant corrosion of NdFeB during the electroplating process, which is accompanied by hydrogen evolution reactions. In this study, electroplating zinc film is carried out from a chloride-free nonaqueous bath using zinc acetate (Zn(OAc)2) as the main salt, sodium acetate (NaOAc) as the conducting salt, and ethylene glycol (EG) as the solvent. The electrochemical properties of the EG bath with Zn(OAc)2 and NaOAc are characterized by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) together with a Hull cell test on brass. The results of the experiment show that the Zn(OAc)2 concentration, current density, and temperature significantly impact the deposition behavior of zinc. Moreover, the open circuit potential (OCP) test and scanning electron microscopy (SEM) results demonstrated that the corrosion of NdFeB in the EG bath containing 0.7 M Zn(OAc)2 and NaOAc is effectively inhibited compared to when using the traditional aqueous zinc plating bath. A dense zinc film with a metallic appearance is successfully deposited on the NdFeB surface from the EG bath containing 0.7 M Zn(OAc)2 and NaOAc at 6 mA cm−2 and 60 °C. Comparative experiments demonstrate that the as-deposited Zn film exhibits superior protective performance and exerts less damage to NdFeB compared to the aqueous electroplating film.
研究领域:
材料科学
·
电化学
·
表面工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2019
·
IF 5.107
Yusheng Yang,Chaoqun Lan,Yingcai Wang,Zengwu Zhao,Baowei Li
In this work, a simple and sustainable approach is proposed to recover rare earths and iron from an ultrafine NdFeB waste. Rare earths are directly recovered by one-step precipitation in hydrofluoric acid and the dissolved iron by electrodeposition. The rate constant and activation energy of the reaction of rare earth hydroxide with hydrofluoric acid are investigated to understand the kinetics of iron leaching and rare earth precipitation. The rare earth precipitation is much faster than the iron leaching, enabling the rare earths separation from iron after a complete iron dissolution. The cathodic deposits of iron were characterized by X-ray photoelectron spectrometer (XPS) and scanning electron microscope (SEM). The nano-scale FeF 2 (s) and Fe(s) were deposited on Pt electrode in hydrofluoric acid solution with pH 2.3 and pH 2.89, respectively. The reduction of Fe(III) to Fe(0) was investigated by cyclic voltammetry, chronopotentiometry and open circuit chronopotentiometry. This reduction was a quasi-reversible process which was controlled by diffusion. The temperature dependence of the diffusion coefficient was established as lnD = −9.84 − 1805.43/ T and the activation energy value of the diffusion process was calculated to be −15.01 kJ mol −1 . The relationship between the Gibbs energy of intermetallic Fe-Pt formation and the temperature was established to be Δ G = −487.53 + 0.936 T . The hydrofluoric acid after the electrodeposition could be recycled for the leaching of the ultrafine NdFeB waste again.
研究领域:
材料科学
·
环境工程
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Hongxing Chen,Renquan Wang,Jun Li,Chang Liu,Xiaojiao Yang,Ying Liu
The combination of high coercivity and resistivity is a strong requirement for permanent magnets to resist thermal demagnetization under complex operating conditions. However, this still remains a challenge for conventional strategies, which always sacrifice the maximum energy product as the coercivity or resistivity increases. In this work, we report a unique strategy of introducing only 0.1 wt% of insulating nano-diamonds (NDs) into the hot-deformed Nd-Fe-B magnets to significantly and simultaneously improve both magnetic properties ( H ci , B r , (BH) max and H k / H cj ) and resistivity. In particular, the coercivity increased by 60% from 746 to 1193 kA/m. Further microstructure observations indicate that this exceptional effect stems from NDs can effectively inhibit the formation of coarse grains and optimize the distribution of Nd-rich phases, ensuring a strong pinning effect to enhance hard magnetic performance. Meanwhile, the presence of additional grain boundaries and NDs can also lead to higher resistivity by preventing the movement of free electrons. Our work provides a distinctive strategy for interface modification with excellent comprehensive performance in permanent magnets.
研究领域:
材料科学
·
磁学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Chang Du,Shuai Ma,Meiying Xie,Fan Yang,Zhigang Zhao,Yun Chen,Ying Ma
This paper proposes a new integrated method for recycling permanent magnet waste by betaine hydrochloride ([Hbet]Cl) solution extraction. The orthogonal experiment method was used to analyze four factors in the leaching process to explore the primary and secondary factors influencing the leaching results. The following optimum leaching conditions were obtained: leaching temperature of 200 ℃, leaching time of 8 h, lixiviant [Hbet]Cl concentration of 0.2 mol/L, and solid–liquid ratio of 1:150 g/ml. These conditions yielded the optimum leaching results of 99.81 % Pr, 97.05 % Nd, 95.51 % Gd, 56.24 % Ce and 0.20 % Fe, and almost all iron oxide remained in the residue. Compared with the results for common lixiviants, the proposed method showed a better leaching rate and selectivity, and the leaching sequence was in line with established chemical properties. The method is characterized by a high recovery rate, strong selectivity, environmental friendliness and low cost. The leaching mechanism was analyzed, and the crystal lattice energy U values of ionic crystal decomposition were calculated to explain the dissolution sequence and solubility difference of metal oxides, laying a foundation for the recovery process.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2021
·
IF 3.712
He Sun,Tuoyao Wang,Chengxiang Li,Yusheng Yang
Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing. Fluorine-containing wastewater is a common type of industrial wastewater, such as stainless steel pickling wastewater. In this work, rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride. The reaction process was investigated through UV-Vis-NIR, thermogravimetry/differential thermogravimetry (TG/DTG), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH) 2 F, and Nd(OH) 2 F was then transformed into neodymium oxyfluoride after decomposition. The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm. The reaction kinetics of forming Nd(OH) 2 F was investigated. The reaction kinetic equation was established and the reaction activation energy was calculated. The effect of fluorine ion concentration on the reaction rate and products was evaluated. The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01 – 1.5 mol/L, but it has little effect. In addition, the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride. The recycling process not only realizes the sustainable utilization of rare earths, but also reduces the concentration of fluorine ions in the fluorine-containing wastewater, achieving two goals with one stone.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
Small
·
2025
·
IF 12.1
Zhen Shi,Chenxi Fang,Jiaqian Li,Sateesh Bandaru,Muwen Liu,Lizhong Zhao,Xuefeng Zhang
In spite of superior magnetic properties, neodymium–iron–boron (Nd-Fe-B) applications in harsh environments have been greatly hindered by their susceptibility to corrosion, humidity, mechanical, and temperature attacks. Herein, a construction strategy of robust slippery liquid-infused porous surfaces (SLIPS) coatings is proposed via the multi-dimensional design of surface, bulk coating, and interface. The manipulation of colloidal states of silica particles by chemical hydrophobization allows for building a dense polymer network, enhancing interfacial adhesion and locking lubricant film effectively. The resulting coating is demonstrated to be extremely stable, endowing the magnet with excellent liquid repellency, anti-corrosion, and anti-icing properties. Strikingly, no trace of corrosion is detected after 136-day immersion in 3.5 wt.% NaCl solution and the impedance modulus at 0.1 Hz can be maintained as the initial of 3.31 × 10 8 Ω·cm 2 even after 132-day immersion, which is far superior to that of commercial Ni-Cu-Ni, Zn, and EP coatings. Additionally, anti-icing performance at low temperatures is evidenced by the delayed icing time and decreased ice adhesion strength. Importantly, the self-healing property offers the surface intensified durability even after mechanical damage. This work demonstrates a construction strategy of robust SLIPS coatings with a multi-dimensional design, enabling the practical applications of Nd-Fe-B magnets in extreme environments like offshore wind turbines.
研究领域:
材料科学
·
表面工程
·
腐蚀防护
✓ 已验证
产品关联
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2020
·
IF 3.99
Xunwen Su,Liqun Zhu,Weiping Li,Haining Chen,Rui Cao,Huicong Liu
Alumina sol was prepared with ascorbic acid (also known as Vitamin C, Vc) as peptizer instead of the traditional used HCl. The prepared sol was then used for the anti-corrosion protection of NdFeB magnets. After substitution, the protective ability of the alumina sol film on NdFeB magnets improved significantly. Systematic comparison of the two alumina sol film were taken. Result showed that the Vc peptized alumina sol (AS-Vc) film showed a more uniform and complete surface which can help repair the defects on NdFeB surface without causing other damages. The electrochemical test showed the corrosion current density of NdFeB with AS-Vc film further reduced to 7.682 × 10 −8 A cm -2 , which is almost one-third of that in AS-Cl film. Along with the salt-water immersion test result, the data showed the corrosion is obviously suppressed after substitution. What’s more, the differences of the film formation mechanism between the two alumina films were investigated. By comparison, NdFeB in AS-Vc showed an about 200 mV more positive open circuit potential than it in HCl peptized alumina sol (AS-Cl), which means less redox reaction during the film formation process. Above all, the Vc peptized alumina sol provides higher corrosion resistance ability for NdFeB, which is wery suitable for the simple protection of NdFeB materials.
研究领域:
材料科学
·
腐蚀与防护
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2020
·
IF 3.104
Zhengyu Liu,Jiaming Wu,Xinyu Liu,Wen Wang,Ziwei Li,Ruijing Xu,Yue Ding,Junlian Wang
Rare earths (REs) and Co are critical strategic resources. Their recovery is crucial for ensuring that their supplies are adequate and for reducing environmental pollution. End-of-life NdFeB magnets are important secondary RE sources. The separation of Dy, Nd, and Co from NdFeB leachate using a relatively new extractant (2,3-dimethylbutyl) (2,4,4′-trimethylpentyl)phosphinic acid (INET-3), was investigated in this study. The separation parameters, such as equilibrium pH, phase ratio, INET-3 concentration, and number of counter-current extraction stages, were optimised. The results show that INET-3 can separate Dy, Nd, and Co efficiently. For the preferential extraction of Dy from synthetic iron-free NdFeB leachate, the optimum equilibrium pH is 2.60. Under this condition, separation of Dy from the leachate requires four counter-current extraction stages at A/O (volume ratio of aqueous to organic) = 1:2. This is demonstrated by a simulated four-stage counter-current extraction process. At equilibrium pH = 2.52 and A/O = 1:2, 98% of Dy is recovered with 95% purity. As to the subsequent separation of Nd from the leachate, nearly 100% is recovered with 99% purity through a simulated three-stage counter-current extraction process at equilibrium pH = 5.33 and A/O = 1:1. Approximately 95% of Co remains in the raffinate with 99.98% purity.
研究领域:
资源回收
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Yusheng Yang,Ying Qin,Tuoyao Wang,Yazhu Zhang,Tianyi Shi,Jiayi Li,Haoran Xu,Zhengxiang Xia,He Sun,Zengwu Zhao
Neodymium-iron-boron (NdFeB) magnets are the rare earth products with the largest output, and their recycling is of significance for the sustainable development of rare earth resources. Currently, the recycling technology of NdFeB wastes is more concerned with the recovery of rare-earth elements, while iron is regarded as a low-value by-product. In this work, chemical dealloying method in molten chlorides was proposed to separate neodymium from FeNd alloy and simultaneously to prepare porous iron alloy. The effects of the molar ratio of reactants, dealloying temperature and time on the separation efficiency of neodymium were investigated. The maximum separation efficiency of neodymium from FeNd alloy can reach 96 %. The separation process of neodymium and the formation process of porous iron alloy were estimated based on the ICP, XRD, XPS, SEM-EDS analyses of recycled products. Neodymium was separated from FeNd alloy by the reaction with Nd(III) ions to form Nd(II) ions in molten chlorides, while the porous iron alloy was formed. The formed Nd(II) ions can be transformed into Nd(III) ions and metallic neodymium particles by the disproportionation reaction. In the process, Nd(III) ions can act as a complement to react with FeNd alloy. And neodymium was recovered in the form of metallic neodymium and NdOCl from the chloride melt and the rinsing solution of porous iron alloy, respectively. The formed porous iron alloy had the surface area of unit volume in the range of (2 ∼ 20) × 10 4 cm 2 cm −3 , the pore width around 10 nm and good hardness. The porous iron alloy is a high value-added product.
研究领域:
材料科学
·
资源回收
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yang Li,Jieliang Chen,Long Meng,Shirong Chen,Boren Tan,Tao Qi,Yong Wang
The pulse disc and doughnut columns (PDDC) require high energy input when dealing with systems where the dispersed phase is difficult to break, which limits its application. To address this, a novel extraction column, pulsed sieve − disc and doughnut column (PSDDC) was designed. The hydrodynamics and extraction performance in the PSDDC were investigated systematically using neodymium-iron-boron (NdFeB) magnet scraps acid leachate–PC-88A extractant system. The results indicated that inducing sieve plates effectively reduced droplet size at a mild pulse intensity. Furthermore, compared with the required pulse intensity of 1.5 cm/s to shift operation zone from mixer-settler zone to emulsion zone in PDDC, PSDDC only required 1.0 cm/s. In the mixer-settler zone, the dispersed phase holdup ( x d ) values were comparable in both columns, while in the emulsion zone the x d values in PSDDC were higher than those in PDDC. At a medium pulse intensity of 1.5 cm/s, the extraction performance of rare earth elements (REEs) in the PSDDC was enhanced, with an extraction efficiency of 65.19 %, representing a 6-fold increase over the PDDC. Additionally, new correlations were established for the Sauter mean droplet size ( d 32 ), x d and mass transfer coefficients of dispersed phase ( K od ) in PSDDC, yielding average relative residual errors ( AARE s) of 9.43 %, 10.96 %, and 10.04 %, respectively. Briefly, compared with PDDC, PSDDC exhibited excellent extraction performance for REEs in the NdFeB acid leachate–PC-88A system.
研究领域:
化学工程
·
湿法冶金
·
资源回收
·
分离科学
·
环境工程
·
材料循环利用
✓ 已验证
产品关联
DOI
高影响因子
Surfaces and Interfaces
·
2025
·
IF 6.3
Wei Cai,Xinqi Zhang,Jianwei Zheng,Jingwu Zheng,Rongyao Li,Haibo Chen,Liang Qiao,Yao Ying,Wangchang Li,Jing Yu,Juan Li,Shenglei Che
To address the operational safety hazards associated with using high-concentration inorganic phosphoric acid as a surface treatments to enhance the high-temperature oxidation resistance of Nd-Fe-B magnetic powders, this study innovatively proposes an environmentally friendly organic phosphonic acid (methylene diphosphonic acid, MDPA) as an alternative solution. By comparing the effects of inorganic phosphoric acid and MDPA surface treatments on the magnetic properties and thermal stability of magnetic powders, it was found that phosphating-treated samples exhibited slight decrease in coercivity H cj and maximum magnetic energy product (BH) max at room temperature compared to untreated samples. However, at 340 °C, the (BH)max and Hcj of untreated samples dropped sharply by 98.55 % (from 4.97 to 0.07 MGOe) and 92.72 % (from 9.62 to 0.70 kOe), respectively. In contrast, the inorganic phosphate-treated samples showed only a slight decline of 13.55 % (from 4.53 to 3.92 MGOe) and 1.22 % (from 9.39 to 9.28 kOe). The MDPA-treated samples exhibited the best thermal stability, with minimal losses in both (BH)max and Hcj, decreasing by only 6.88 % (from 4.66 to 4.34 MGOe) and 0.69 % (from 9.43 to 9.36 kOe), respectively. Microstructural analysis revealed that the dense metal phosphate conversion layer formed during phosphating was the key to maintaining high-temperature magnetic performance. Specifically, inorganic phosphoric acid treatment preferentially corroded Nd-rich intergranular phases, resulting in a higher Nd content in the conversion layer. In contrast, the iron phosphate salt formed by MDPA treatment dominates the transformation layer, effectively reduces the damage to the microstructure of the magnetic powder. Our research provides a surface treatment solution that combines safety and efficiency for the performance protection of rare-earth magnetic powders in high-temperature injection molding processes.
研究领域:
材料科学
·
表面工程
·
磁学
·
环境化学
·
稀土材料
✓ 已验证
产品关联
DOI
高影响因子
Advanced Intelligent Systems
·
2024
·
IF 6.8
Xingcheng Ou,Yu Sheng,Jiaqi Huang,Dantong Huang,Xiaohong Li,Ran Bi,Guoliang Chen,Weijie Hu,Shuang-Zhuang Guo
Inspired by the efficient swimming capabilities of swordfish, a novel wireless soft swordfish-like robot with programmable magnetization has been developed, integrating direct-ink-writing (DIW) 3D printing and assembly technology. This 20 mm long robot features a streamlined form and magnetically programmable movements, enabling biomimetic locomotion patterns such as straight-line swimming and turning swimming. The robot includes a silicone-based torso (body, abdomen, and pectoral fin) and a crescent-shaped tail fin made from a magnetically programmable polymer embedded with neodymium-iron-boron (NdFeB) particles. The tail fin, fabricated by multi-material alternating printing to achieve a gradient magnetism distribution, is controlled by an external magnetic field to mimic the rapid oscillation of a swordfish's tail, achieving a swimming speed of 0.51 BL/ s. The tail fin's asymmetric oscillation amplitudes, adjusted by magnetic field control, allow the robot to transition seamlessly from high-speed straight swimming to agile turning. The robot can perform tracking swimming along specific planned paths, such as “C” and “Z” shaped trajectories. Potential applications include environmental monitoring and targeted drug release. The multi-material 3D printing technology enhances the robot's efficiency and sensitivity in simulating natural biological movements, extending to the design and development of various flexible devices and soft robots.
研究领域:
机器人技术
·
生物医学工程
·
材料科学
·
仿生学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）