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学者姓名：刘卫强
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Abstract ：
关于钕铁硼磁体回收的研究越来越受到重视,但在起步阶段回收制备技术是否能够真正带来环境效益是不确定的。采用ReCiPe评价方法,选取制备1 kg黏结钕铁硼磁体为功能单位,分别对黏结钕铁硼磁体直接制备和回收制备流程的环境影响进行评价并对比。结果表明直接制备流程中对环境影响最大的关键阶段为熔炼阶段,环境影响主要由钕和电力产生。回收制备流程对环境影响最大的关键阶段为去除有机物阶段和热压固化阶段,环境影响主要由次氯酸钠和电力产生。生产1 kg黏结钕铁硼磁体,直接制备工艺对人体健康损害、生态健康损害和资源耗竭的环境损害分别是回收制备工艺的158.40%、180.63%、63.37%。
Keyword ：
黏结钕铁硼 黏结钕铁硼 回收再利用 回收再利用 固体废弃物 固体废弃物 生命周期评价 生命周期评价 绿色制造 绿色制造 环境影响 环境影响
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| GB/T 7714 | 刘敏 , 高可 , 朱佩鸿 et al. 黏结钕铁硼磁体生产和回收生命周期评价 [J]. | 北京工业大学学报 , 2024 , (03) : 290-298 . |
| MLA | 刘敏 et al. "黏结钕铁硼磁体生产和回收生命周期评价" . | 北京工业大学学报 03 (2024) : 290-298 . |
| APA | 刘敏 , 高可 , 朱佩鸿 , 杨雅轩 , 刘卫强 , 路清梅 et al. 黏结钕铁硼磁体生产和回收生命周期评价 . | 北京工业大学学报 , 2024 , (03) , 290-298 . |
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Abstract ：
采用密度泛函理论方法系统研究分析了四方结构MnGa合金体在a轴1GPa应力下的结构、形成、电子性质和磁性质.结果表明，应力下MnGa合金a, b轴晶格参数增大，c轴晶格参数减小，三轴夹角有偏离90°的趋势，晶胞体积增大. Mn-Ga不成键，Mn-Mn之间的强键作用进一步增强，Ga-Ga之间的强键作用消失. Mn-Mn结合键长和Ga-Ga结合键长均减小，而Mn-Ga间距增大，排斥作用减弱.应力下MnGa合金形成焓由-4.85 eV减小到-5.4 eV,其更容易生成.应力下其能带整体向下移动，导带和浅能级价带分布较宽，有效质量较小；深能级价带分布较窄，有效质量较大.自旋向下的电子能带没有带隙，自旋...
Keyword ：
电子性质 电子性质 MnGa合金 MnGa合金 磁性质 磁性质 应力 应力
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| GB/T 7714 | 路清梅 , 张飞鹏 , 房慧 et al. 应力下MnGa合金体电子性质及磁性质的研究 [J]. | 原子与分子物理学报 , 2023 , 40 (01) : 134-142 . |
| MLA | 路清梅 et al. "应力下MnGa合金体电子性质及磁性质的研究" . | 原子与分子物理学报 40 . 01 (2023) : 134-142 . |
| APA | 路清梅 , 张飞鹏 , 房慧 , 李虹霏 , 刘卫强 , 张东涛 et al. 应力下MnGa合金体电子性质及磁性质的研究 . | 原子与分子物理学报 , 2023 , 40 (01) , 134-142 . |
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Abstract ：
电动汽车和风力涡轮机等绿色能源技术的日益发展为化石燃料的使用和环境污染提供了极具前景的解决方案,其中RE-Fe-B (RE=La, Ce, Pr, Nd)烧结磁体作为重要组成部分发挥了关键作用。开发具有高丰度稀土(La/Ce)元素的RE-Fe-B烧结磁体是平衡稀土资源利用的重要途径,也有利于降低磁体的原材料成本,降低对关键稀土元素Pr/Nd的依赖。然而,Ce基烧结磁体的内禀磁性能下降和固有结构缺陷(REFe_2相和Ce~(4+)离子)严重限制了其磁性能~([1,2])。在这项工作中,我们提出了一种新的策略,即使用适当的La取代Ce,以实现矫顽力、剩磁、最大磁能积和温度稳定性的同时提高,从而克服LaCe基RE-Fe-B烧结磁体中剩磁和矫顽力的固有矛盾。通过适量的La取代Ce,我们首次实现了RE-Fe-B烧结磁体中REFe_2相、Ce价态和晶界结构的协同调控。详细的微观结构研究表明,La取代Ce可以抑制REFe_2相的形成,并导致烧结磁体中晶界相的形态、结构和组成发生颠覆性变化。同时,La元素倾向于分布在三角晶界中,并促进RE/Cu/Ga元素的分布产生偏析,有助于形成高Ce/Nd/Cu/Ga元素浓度的连续薄层晶界相。因此,烧结磁体的矫顽力在克服了La元素导致HA降低带来的负面影响外实现了提高。此外,La元素进入RE_2Fe_(14)B相有利于提高磁体的剩磁和温度稳定性,同时导致的晶格膨胀促进了Ce~(3+)离子比例的显著提升,这为提高磁体的剩磁提供了额外帮助。这项研究揭示了La取代Ce对烧结磁体磁性能的影响机制,以及实现剩磁和矫顽力同时提升的根本原因,对促进La/Ce元素的综合利用并为开发低成本高性能的RE-Fe-B烧结磁体提供了一种有效可行的方法。
Keyword ：
晶界结构 晶界结构 Ce价态 Ce价态 高丰度La/Ce 高丰度La/Ce 磁性能 磁性能 REFe_2相 REFe_2相
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| GB/T 7714 | 陈昊 , 刘卫强 , 李玉卿 et al. La替代Ce对RE-Fe-B烧结磁体磁性能和微观结构的影响 [C] //中国稀土学会第四届青年学术会议摘要集 . 2023 . |
| MLA | 陈昊 et al. "La替代Ce对RE-Fe-B烧结磁体磁性能和微观结构的影响" 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
| APA | 陈昊 , 刘卫强 , 李玉卿 , 张红国 , 岳明 . La替代Ce对RE-Fe-B烧结磁体磁性能和微观结构的影响 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
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Abstract ：
高性能Nd-Fe-B磁粉是制备粘结磁体和增材制造磁体等的重要原料,直接影响着最终磁体的性能。但Nd-Fe-B磁粉由于含有稀土,表面活性较高,在使用过程中极容易受到氧气和化学介质的侵蚀。因此,在磁粉加工的过程中,防氧化工艺尤为重要。常用的方法是对磁粉进行表面包覆处理,在磁粉表面形成有机化合物或金属涂层,使粉末与外界的氧气和化学介质隔离。有机物涂层抗氧化效果显著,但耐湿热性差、抗老化性弱,且在包覆有机物涂层时容易引入杂质原子。金属涂层具有良好的热稳定性和抗氧化性,但包覆金属镀层的方法较为复杂,且难以控制金属镀层的沉积率。旋转包覆工艺是包覆介质在旋转的容器内高温下与物体短暂摩擦而沉积在物体表面的过程。该工艺包覆效果均匀、适应性强、包覆介质可重复使用、且成本低廉,容易实现量产。我们基于此开发了一种新型滚镀金属涂层包覆Nd-Fe-B磁粉的工艺。以锌包覆层为例,只需要将磁粉与锌粒混合均匀后放入可旋转的管式炉内进行加热处理,并通过调整加热温度、加热时间和炉内真空度等来获得所需厚度的均匀镀层,有效提高了磁粉的抗高温氧化能力。未经处理的磁粉质量在30～450℃的氧化增重实验中增加了2.82%,而镀锌磁粉的质量仅增加了0.40%,且后者的磁性能与未处理的磁粉相比变化不大。利用该工艺还可以包覆锌以外的其它低熔点金属或者合金,为研究开发高性能抗氧化腐蚀的Nd-Fe-B磁粉创造了有利条件。
Keyword ：
稀土永磁 稀土永磁 Nd-Fe-B Nd-Fe-B 抗氧化腐蚀 抗氧化腐蚀 旋转包覆 旋转包覆
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| GB/T 7714 | 张红国 , 刘卫强 , 高京园 et al. Nd-Fe-B磁粉的抗氧化改性研究 [C] //中国稀土学会第四届青年学术会议摘要集 . 2023 . |
| MLA | 张红国 et al. "Nd-Fe-B磁粉的抗氧化改性研究" 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
| APA | 张红国 , 刘卫强 , 高京园 , 许福有 , 奚望 , 岳明 . Nd-Fe-B磁粉的抗氧化改性研究 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
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Abstract ：
粘结钕铁硼二次资源短流程回收的难点在于在保护磁粉的同时有效的去除固化聚合物基体。本研究采用氢氧化钠乙醇溶液对粘结钕铁硼二次资源中的聚合物基体进行分解,并研究了回收工艺对磁性粉末的影响。在最佳反应条件下聚合物基体基本被去除,而磁性相未被破坏。与废旧磁粉相比,回收磁粉的碳、氧含量分别下降了92.96%和89.30%。饱和磁化强度M_S、剩磁M_r和内禀矫顽力H_(cj)分别达到了原始磁粉的99.8%、98.5%和95.9%。为了解粘结钕铁硼二次资源中聚合物基体在反应前后的变化,对聚合物基体的固化和分解过程进行了分析。在固化过程中,双氰胺和双酚A环氧树脂分别充当桥梁和骨架,最终形成热固性三维网络结构。在碱性醇溶液中,桥梁和骨架被乙醇中的游离羟基和游离氢自由基破坏并生成小分子产物溶解于溶液中。
Keyword ：
固化机理 固化机理 粘结钕铁硼二次资源 粘结钕铁硼二次资源 热固性聚合物 热固性聚合物 分解机理 分解机理 短流程回收 短流程回收 磁性能 磁性能
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| GB/T 7714 | 朱佩鸿 , 刘敏 , 杨亚轩 et al. 利用化学反应回收粘结钕铁硼二次资源及其机理 [C] //中国稀土学会第四届青年学术会议摘要集 . 2023 . |
| MLA | 朱佩鸿 et al. "利用化学反应回收粘结钕铁硼二次资源及其机理" 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
| APA | 朱佩鸿 , 刘敏 , 杨亚轩 , 刘卫强 , 路清梅 , 岳明 . 利用化学反应回收粘结钕铁硼二次资源及其机理 中国稀土学会第四届青年学术会议摘要集 . (2023) . |
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Abstract ：
Nitrogenation is an indispensable process for the formation of Sm2Fe17N3 and has a major influence on its magnetic properties. In this work, the effect of nitrogenation on the magnetic properties of Sm2Fe17N3 was investigated by micromagnetic simulation. The normal coercivity, remanence, and the maximum energy product of incompletely nitrided Sm2Fe17N3 with a nonnitrided Sm2Fe17 core size less than 16 nm approach nearly 99% of their values in fully nitrided Sm2Fe17N3. Thus, a small nonnitrided Sm2Fe17 core does not affect the effective utilization of Sm2Fe17N3 permanent magnets. The magnetization reversal mode of incompletely nitrided Sm2Fe17N3 with different sizes of nonnitrided Sm2Fe17 cores was evaluated, providing an in-depth fundamental understanding of the demagnetization processes in Sm2Fe17N3 particles. This work could be useful for optimizing nitrogenation conditions to improve the magnetic properties of Sm2Fe17N3 permanent magnets.
Keyword ：
Hard magnetic materials Hard magnetic materials Magnetic cores Magnetic cores Nitrogen Nitrogen micromagnetic models micromagnetic models Magnetic anisotropy Magnetic anisotropy Coercive force Coercive force Perpendicular magnetic anisotropy Perpendicular magnetic anisotropy magnetic alloys magnetic alloys Iron Iron Saturation magnetization Saturation magnetization
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| GB/T 7714 | Yang, Zhi , Chen, Yuanyuan , Li, Yuqing et al. Micromagnetic Simulation of Nitrogenation Effect on the Magnetic Properties of Sm2Fe17N3 Alloy [J]. | IEEE MAGNETICS LETTERS , 2022 , 13 . |
| MLA | Yang, Zhi et al. "Micromagnetic Simulation of Nitrogenation Effect on the Magnetic Properties of Sm2Fe17N3 Alloy" . | IEEE MAGNETICS LETTERS 13 (2022) . |
| APA | Yang, Zhi , Chen, Yuanyuan , Li, Yuqing , Zhang, Dongtao , Liu, Weiqiang , Lu, Qingmei et al. Micromagnetic Simulation of Nitrogenation Effect on the Magnetic Properties of Sm2Fe17N3 Alloy . | IEEE MAGNETICS LETTERS , 2022 , 13 . |
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Abstract ：
Retaining the chemical heterogeneity of 2:14:1 main phase grains and forming continuous grain boundary (GB) layers are considered two significant contributions to high coercivity in multi-main-phase (MMP) Nd-La-Ce-Fe-B sintered magnets. In this work, the trade-off between chemical heterogeneity and the GB layers in MMP Nd-La-Ce-Fe-B sintered magnets was tackled by designing the composition of LaCe-free alloys. The coercivity of the MMP LaCe-40 (LaCe/TRE = 40 wt.%, TRE: total rare earth) magnets prepared by replacing conventional Nd30.5FebalM1.8B0.96 (Nd-normal) with Nd42.1FebalB0.79 (Nd-rich) as a LaCefree alloy increased by 52.7%, reaching an ultra-high coercivity of 11.10 kOe. Analysis of the microstructure showed that chemical heterogeneity was retained in the MMP LaCe-40 sintered magnets prepared with Nd42.1FebalB0.79. In addition, thick Nd-rich hard magnetic shells and continuous GB layers were constructed. On the one hand, magnetization reversal of the LaCe-rich grains was hindered by the adjacent strongly magnetic LaCe-free grains. On the other hand, this enhanced the anisotropic field of the LaCerich grains and weakened the ferromagnetic coupling effect. These provided a guarantee for preventing the nucleation and propagation of reversed domains, thereby achieving high coercivity. This study offers a new solution for the contradiction between the retention of chemical heterogeneity and the regulation of the GB structure in the MMP Nd-La-Ce-Fe-B sintered magnets, creating the conditions for further improving the coercivity of magnets. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keyword ：
Grain boundary Grain boundary Multi-main-phase Multi-main-phase Nd-La-Ce-Fe-B Nd-La-Ce-Fe-B Magnetic properties Magnetic properties Chemical heterogeneity Chemical heterogeneity
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| GB/T 7714 | Chen, Hao , Liu, Weiqiang , Guo, Zizhen et al. Coercivity enhancement of Nd-La-Ce-Fe-B sintered magnets: Synergistic effects of grain boundary regulation and chemical heterogeneity [J]. | ACTA MATERIALIA , 2022 , 235 . |
| MLA | Chen, Hao et al. "Coercivity enhancement of Nd-La-Ce-Fe-B sintered magnets: Synergistic effects of grain boundary regulation and chemical heterogeneity" . | ACTA MATERIALIA 235 (2022) . |
| APA | Chen, Hao , Liu, Weiqiang , Guo, Zizhen , Yang, Tianyuan , Wu, Haihui , Qin, Yuan et al. Coercivity enhancement of Nd-La-Ce-Fe-B sintered magnets: Synergistic effects of grain boundary regulation and chemical heterogeneity . | ACTA MATERIALIA , 2022 , 235 . |
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Abstract ：
We achieved ultra-high coercivity of 5.65 kOe in L1(0)-Mn1.33Ga alloy via the hot deformation (HD) method and revealed the hardening mechanism. Hot deformation led to recrystallization and grain refinement, where the average grain size was reduced to about 1.5 mu m for HD-88% magnet. The coercivity mechanism indicated a weak pinning model by magnetic mini-loop analysis. It was found that small grains were formed, accompanied by a certain number of {111} < 11-2 > twins for HD magnets. The magnetic domain observation showed that both the sub-micro grain boundary and the twin boundary were acted as the pinning center of the domain wall, but the latter had weaker pinning effect. The ultra-high coercivity of the HD-88% Mn1.33Ga magnet originated mainly from the pinning of the grain boundary enhanced by grain refinement. Further grain refinement and twin structure inhibition will be promising approaches in order to obtain higher magnetic properties for L1(0)-MnxGa bulk magnets. Published under an exclusive license by AIP Publishing.
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| GB/T 7714 | Lu, Q. M. , Gao, S. , Li, Y. Q. et al. Grain refinement leading to the ultra-high coercivity in L1(0)-Mn1.33Ga bulk magnet via hot deformation [J]. | APPLIED PHYSICS LETTERS , 2022 , 120 (15) . |
| MLA | Lu, Q. M. et al. "Grain refinement leading to the ultra-high coercivity in L1(0)-Mn1.33Ga bulk magnet via hot deformation" . | APPLIED PHYSICS LETTERS 120 . 15 (2022) . |
| APA | Lu, Q. M. , Gao, S. , Li, Y. Q. , Zhang, H. G. , Liu, W. Q. , Yue, M. . Grain refinement leading to the ultra-high coercivity in L1(0)-Mn1.33Ga bulk magnet via hot deformation . | APPLIED PHYSICS LETTERS , 2022 , 120 (15) . |
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Abstract ：
基于密度泛函理论方法系统研究了四方结构MnGa合金体的结构、形成、电子结构和磁性质。结果表明,四方MnGa合金晶胞的生成焓为-4.85 eV,高于一些不含d电子的体系。其呈现导体的能带结构,其中d电子主要形成深能级价带,定域性最强。四方MnGa合金存在着明显的自旋极化,靠近费米能级两侧的s电子和靠近费米能级下方的p电子具有较弱的自旋极化。形成浅能级价带和导带的d电子产生高强度的自旋极化,对磁性质贡献较大。Mn的s电子和Mn的p电子自旋极化作用较弱,Mn的d电子形成浅能级价带和导带,自旋极化作用最强。形成深能级价带的Ga的d电子自旋极化作用较弱,不同位置的Ga原子的自旋极化不同。四方MnGa合金...
Keyword ：
MnGa合金 MnGa合金 磁性质 磁性质 磁性材料 磁性材料 密度泛函理论 密度泛函理论 电子结构 电子结构
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| GB/T 7714 | 张飞鹏 , 路清梅 , 李虹霏 et al. MnGa合金体的电子结构与磁性质的研究 [J]. | 人工晶体学报 , 2022 , 51 (01) : 65-71 . |
| MLA | 张飞鹏 et al. "MnGa合金体的电子结构与磁性质的研究" . | 人工晶体学报 51 . 01 (2022) : 65-71 . |
| APA | 张飞鹏 , 路清梅 , 李虹霏 , 房慧 , 刘卫强 , 张东涛 et al. MnGa合金体的电子结构与磁性质的研究 . | 人工晶体学报 , 2022 , 51 (01) , 65-71 . |
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Abstract ：
The oil-based Nd-Fe-B sludge waste was directly recycled to single-phase Nd2Fe14B powders via the combination of purification and modified Ca-reduction reaction method. The impurities and organics in the purified Nd-Fe-B sludge waste were greatly reduced, reducing calcium consumption in the subsequent reduction and diffusion (RD) process, thereby reducing the cost. By further optimizing the Ca-reduction diffusion parameters, especially the mass ratio of CaCl2 and KCl, where the liquid CaCl2, along with the gaseous KCl provide conditions for sufficient and uniform Ca-reduction reaction, high-property Nd-Fe-B magnetic powders with good dispersion, uniform particle sizes, and excellent orientation, were successfully obtained. Using the mixed diffusion medium of CaCl2 and KCl with a mass ratio of 1:1, the room-temperature magnetization of the recycled Nd-Fe-B powders was increased to 157 emu/g at 3 T-magnetic field, which was about 28 % higher than that of the original sludge. The contents of carbon, hydrogen, and oxygen in the recycled magnetic powders were significantly reduced from 6.8, 1.8, and 5.9 wt% to 0.1, 0.19, and 0.56 wt%, respectively. In addition, the uniform grain size with X-50 = 3.6 mu m and good distribution greatly improved the orientation, which can be beneficial to the preparation of the bonded or sintered Nd-Fe-B based magnets. The reasons that CaCl2-KCl mixed diffusion medium can lead to well-dispersed, uniform recycled powder with high magnetization arise from a combination of factors for improving the liquid phase reaction environment and the gaseous KCl to prevent agglomeration and inhibit particles merging or growth.
Keyword ：
Recycling Recycling Purification Purification Nd-Fe-B sludge waste Nd-Fe-B sludge waste Ca-reduction reaction Ca-reduction reaction
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| GB/T 7714 | Xu, Haibo , Wang, Feng , Lu, Qingmei et al. Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process [J]. | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2022 , 543 . |
| MLA | Xu, Haibo et al. "Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process" . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 543 (2022) . |
| APA | Xu, Haibo , Wang, Feng , Lu, Qingmei , Qiu, Yubing , Liu, Weiqiang , Chen, Jingwu et al. Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2022 , 543 . |
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