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861.
《中国稀土学报(英文版)》2023,41(4):621-631
This study proposes an advanced leaching method using organic acids to recover rare earth elements (REEs) from NdFeB permanent magnets from end-of-life computers hard disk drives (HDDs). The end-of-life HDDs were first dismantled in order to recover NdFeB magnets, which were then thermally demagnetized at 350 °C during 30 min before crushing in a ball mill under inert atmosphere. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) analyses performed on the NdFeB magnets show the heterogeneous structure containing the major matric phase Nd2Fe14B and the REEs-rich phase containing Nd and Pr oxides. Additionally, X-ray diffraction (XRD) and Mössbauer spectroscopy (MS) analyses on the ground NdFeB magnet show that grinding NdFeB magnets under inert atmosphere helps to minimize its oxidation. Chemical analysis shows that the composition of the ground sample is Nd: 22.8 wt%, Pr: 3.3 wt%, Dy: 1.2 wt%, Fe: 62.6 wt%, Co: 1.5 wt%, B: 0.9 wt%, Ni: 0.6 wt%. Diagrams of speciation and equilibrium phases (Eh vs. pH) were calculated to determine the predominance of the formed species in the REEs–organic acids systems. The influence of the organic acid type (acetic acid, formic acid, citric acid and tartaric acid), the acid concentration (10 vol%, up to saturation), and the solid/liquid (S/L) ratio (0.5%–10%) on NdFeB magnets leaching was investigated employing an optimal experimental design conceived by the statistical software JMP. Acetic acid (CH₃COOH) shows the highest leaching performance of REEs, allowing leaching yields over 90% for Nd, Dy and Pr in the acid concentration range of 1.6–10 mol/L and the S/L ratio range of 0.5%–5% at a temperature of 60 °C. The results presented in this investigation suggest that REEs can be recovered from magnets of end-of-life HDDs using an eco-friendly method assisted by organic acids. 相似文献
862.
NdFeB合金表面激光非晶化的改性技术 总被引:1,自引:0,他引:1
对NdFeB永磁合金表面非晶镀(涂)覆层的设计原则、成分设计、沉积方法及非晶镀(涂)覆层的形成条件和可行性研究了理论分析及探讨,提出了NdFeB永磁合金表面激光非晶化改性的技术方法。 相似文献
863.
高温耐磨损Cr3C2-25%NiCr涂层制备及其性能研究 总被引:3,自引:0,他引:3
采用超音速火焰喷涂球形烧结态Cr3C2-25%NiCr复合粉末制备高温耐磨损涂层,用扫描电子显微镜(SEM)分析粉末和涂层显微组织,用图像处理软件分析涂层孔隙率。通过结合强度、表面硬度和摩擦磨损等实验检测涂层机械性能。结果表明:粉末烧结状态、Cr3C2硬质相及粉末粒度因素影响涂层机械性能,KF-70涂层具有最高结合强度和表面硬度。 相似文献
864.
Shuwei Zhong Munan Yang Sajjad Ur Rehman Sangen Luo Longgui Li Chao Li Jiajie Li Shuhua Xiong Ihor Bulyk Bin Yang 《中国稀土学报(英文版)》2023,41(7):1068-1072
In view of the uneven distribution of the core-shell structure of sintered Nd-Fe-B magnets after grain boundary diffusion,this study proposes to use high-melting-point and reactive element titanium(Ti) as an additive to increase the diffusion channels and to enhance the diffusion of heavy rare earth elements along the grain boundary phase.By adding Ti element,the diffusion depth and hence the intrinsic coercivity of magnets are increased significantly.The addition of Ti increases the coercivity ... 相似文献
865.
866.
867.
Qisong Luo Yang Luo Zilong Wang Haijun Peng Wenlong Yan Wenjian Yan Tianhao Li Shengjie Zhu Dunbo Yu 《中国稀土学报(英文版)》2023,41(9):1353-1359
Anisotropic NdFeB/SmFeN hybrid bonded magnets were prepared by warm compaction process under an orientation magnetic field of 22 kOe,mixing with anisotropic SmFeN powders in different addition and HDDR-NdFeB powders in different coercivity.With the addition of 20 wt% SmFeN,the density and remanence of hybrid magnets increase from 5.58 g/cm3,8.4 kGs to 6.02 g/cm3,9.0 kGs,respectively.And as the addition amount of SmFeN powders varies from 20 wt% to 40 wt%,the maximum energy ... 相似文献
868.
Yaping Wu Minggang Zhu Qisong Sun Lele Zhang Peng Shen Yikun Fang Wei Li 《中国稀土学报(英文版)》2023,41(1):122-129
The electrochemical corrosion behavior of both(Ce15Nd85)30FebalB1 M sintered magnets prepared with dual-main-phase method and N45-type magnets was studied in 3.5 wt% NaCl,1.1 wt% NaH2 PO4,and2.5 wt% NaOH solutions,respectively.The(Ce15Nd85)30FebalB1 M sintered magnets perform superior corrosion resistance than N45-type magnets in the tested solutions.In general,two ... 相似文献
869.
《Journal of the European Ceramic Society》2023,43(8):3351-3359
Owing to their multiple applications, lithium ferrites are relevant materials for several emerging technologies. For instance, LiFeO2 has been spotted as an alternative cathode material in Li-ion batteries, while LiFe5O8 is the lowest damping ferrite, holding promise in the field of spintronics. The Li-content in lithium ferrites has been shown to greatly affect the physical properties, and in turn, the performance of functional devices based on these materials. Despite this, lithium content is rarely accurately quantified, as a result of the low number of electrons in Li hindering its identification by means of routine materials characterization methods. In the present work, magnetic lithium ferrite powders with Li:Fe ratios of 1:1, 1:3 and 1:5 have been synthesized, successfully obtaining phase-pure materials (LiFeO2 and LiFe5O8), as well as a controlled mixture of both phases. The powders have been compacted and subsequently sintered by thermal treatment (Tmax = 1100 °C) to fabricate dense pellets which preserve the original Li:Fe ratios. Li-content on both powders and pellets has been determined by two independent methods: (i) Rutherford backscattering spectroscopy combined with nuclear reaction analysis and (ii) Rietveld analysis of powder X-ray diffraction data. With good agreement between both techniques, it has been confirmed that the Li:Fe ratios employed in the synthesis are maintained in the sintered ceramics. The same conclusion is drawn from spatially-resolved confocal Raman microscopy experiments on regions of a few microns. Field emission scanning electron microscopy has evidenced the substantial grain growth taking place during the sintering process – mean particle sizes rise from ≈ 600 nm in the powders up to 3.8(6) µm for dense LiFeO2 and 10(2) µm for LiFe5O8 ceramics. Additionally, microstructural analysis has revealed trapped pores inside the grains of the sintered ceramics, suggesting that grain boundary mobility is governed by surface diffusion. Vibrating sample magnetometry on the ceramic samples has confirmed the expected soft ferrimagnetic behavior of LiFe5O8 (with Ms = 61.5(1) Am2/kg) and the paramagnetic character of LiFeO2 at room temperature. A density of 92.7(6)% is measured for the ceramics, ensuring the mechanical integrity required for both their direct utilization in bulk shape and their use as targets for thin-film deposition. 相似文献
870.
Kinjal Gandha Mariappan Parans Paranthaman Haobo Wang Xubo Liu Ikenna C. Nlebedim 《Journal of the American Ceramic Society》2023,106(1):166-171
In this research, anisotropic NdFeB + SmFeN hybrid and NdFeB bonded magnets are additively printed in a polyphenylene sulfide (PPS) polymer binder. Printed NdFeB + SmFeN PPS bonded magnets displayed excellent magnetic properties (Br [remanence] = 6.9 kG [0.69 T], Hcj [coercivity] = 8.3 kOe [660 kA/m], and BHmax [energy product] = 9.9 MGOe [79 kJ/m3]) with superior corrosion resistance and thermal stability. The anisotropic NdFeB bonded magnet shows a high coercivity of 14.6 kOe (1162 kA/m) with a BHmax of 8.7 MGOe (69 kJ/m3). The coercivity and remanence temperature coefficients for NdFeB + SmFeN hybrid bonded magnets are −0.10%/K and −0.46%/K, and for NdFeB bonded magnets are −0.14%/K and −0.53%/K in the range of 300–400 K, indicating that the hybrid bonded magnets are thermally stable. The average flux aging loss for hybrid magnets was also determined to be very stable over 2000 h at 448 K (175°C) in air with 2.04% compared to that of NdFeB magnets with 3.62%. 相似文献