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Sample records for ndfeb permanent magnet

  1. Investigation Procedure of Magnetic Performances of NdFeB Permanent Magnets

    DEFF Research Database (Denmark)

    Calin, Marius-Daniel; Helerea, Elena; Ritchie, Ewen

    2011-01-01

    The permanent magnet applications based on carbon steel magnets, hard ferrites and AlNiCo magnets classes are renewed with new classes of advanced magnetic materials based on rare earth elements, the Sm-Co and NdFeB types. Performance increase of the hard magnetic materials and their use...... in specific applications impose also great advances in the field of magnetic measurement. New researches need to be validated in order to investigate the NdFeB permanent magnets performances, including their stability under different thermal operational regimes. In this paper a specific investigation...... procedure of magnetic performances of NdFeB permanent magnets in correlation with the range of operating temperature is proposed based on modern hysteresisgraph method and impulse magnetization technique....

  2. Some Character of Application of Nd-Fe-B Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The character of application of Nd-Fe-B permanent magnet is characterized in an irreversible loss of magnetic flux in the various environment conditions. According to the size of permanent magnet in the various environment conditions the irreversible loss of the permanent magnets is very different. Therefore, the irreversible loss and the application method according to the size of permanent magnets and the intervals in the magnetic system are discussed.

  3. Effective anisotropy and coercivity in nanocrystalline single-phase NdFeB permanent magnetic material

    Institute of Scientific and Technical Information of China (English)

    韩广兵; 高汝伟; 冯维存; 刘汉强; 王标; 张鹏; 陈伟; 李卫; 郭永权

    2003-01-01

    The effect of exchange-coupling interaction on the effective anisotropy and its varying tendency in nanocrystalline single-phase NdFeB permanent magnetic material have been investigated. The results show that the exchange-coupling interaction between grains makes the effective anisotropy of material, Keff, decrease with the reduction of grain size. The variation of Keff is basically the same as that of coercivity. The decrease in effective anisotropy is the main reason of the reduction of coercivity for nanocrystalline single-phase NdFeB permanent magnetic material. In order to get high anisotropy and coercivity in nanocrystalline single-phase NdFeB permanent material, the grain size should be larger than 35 nm.

  4. Net Shape 3D Printed NdFeB Permanent Magnet

    CERN Document Server

    Jacimovic, J; Herrmann, L G; Greuter, F; Genta, J; Calvo, M; Tomse, T; Simon, R A

    2016-01-01

    For two decades, NdFeB based magnets have been a critical component in a range of electrical devices engaged in energy production and conversion. The magnet shape and the internal microstructure of the selected NdFeB grade govern their efficiency and size. However, stricter requirements on device efficiency call for better performing magnets preferably with novel functionality not achievable today. Here we use 3D metal printing by Selective Laser Melting to fabricate dense net shape permanent magnets based on NdFeB that exhibit high magnetic performance. Evidence is provided that the internal microstructure, not achievable by traditional manufacturing means, is the origin of the solid magnetic properties. The freedom in magnet body shape and size that ranges from the millimeter to tens of centimeter scale opens up a design freedom that could be a catalyzer for the next generation of electrical devices.

  5. Magnetic force microscope study on anisotropic NdFeB permanent magnets

    Institute of Scientific and Technical Information of China (English)

    刘薇; 蒋建华; 吴建生; 李刚

    2003-01-01

    NdFeB permanent magnets prepared by powder metallurgy were investigated using magnetic force microscopy(MFM).The excellent MFM images of sample along the surfaces parallel and perpendicular to the alignment axis were collected respectively.The results show the necessity of annealing procedure in the preparation of the samples to remove the polishing surface stress and to illustrate the real magnetic domain structure,so that the much information about both the magnetic structure and the topographic microstructure is obtained.The hard MFM tip is verified to be effective for this material especially for the sample with the examined surface parallel to alignment axis.By analyzing these well-captured magnetic force images,magnetic domains and alignment degree as well as thetopographic information such as grain size and the nonmagnetic phases at the grain boundaries were demonstrated.

  6. The Effect of Nano-TiC Addition on Sintered Nd-Fe-B Permanent Magnets

    DEFF Research Database (Denmark)

    Mural, Zorjana; Kollo, Lauri; Xia, Manlong

    2017-01-01

    This paper addresses the effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets. TiC nanoparticles were added to sintered Nd-Fe-B magnets with a specific aim to improve the Curie temperature and thermal stability. A standard powder metallurgy route was adopted to prepare the magnets. I...... for such magnets showed an improved shape and VSM analysis a coercivity value of 1188 kA/m, a remanence value of 0.96 T and a maximum energy product of 132 kJ/m3. The maximum working point and the Curie temperature of the developed magnets were 373 K and 623 K respectively....

  7. Preparation Technology and Performances of Zn-Cr Coating on Sintered NdFeB Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    Yu Shengxue; Chen Ling

    2006-01-01

    Zn-Cr coating was prepared on the surface of sintered NdFeB permanent magnet samples and preparation parameters were established.The anticorrosive property of Zn-Cr coating on NdFeB was studied by whole-immersion test in NaCl solution and compared with that of zinc plating and nickel plating on NdFeB.Open-circuit potential and self-corrosion current of NdFeB samples with and without Zn-Cr coating were measured.The micro-morphology and composition of Zn-Cr coating were analyzed through SEM, XPS, EDS and XRD.The effect of Zn-Cr coating on magnetic property of NdFeB magnet was also investigated.It is exposed that Zn-Cr coating is anodic type coating for NdFeB magnet, and provided substrate electrochemical protection, barrier protection and passivation protection.The anticorrosion property of NdFeB magnet is obviously enhanced by Zn-Cr coating while the magnet property of NdFeB magnet changed little.

  8. Study of Technology of Stripping Nickel Coating on NdFeB Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    Rao Houzeng; Li Guohua; Jiang Longfa; Lin Guanjie

    2004-01-01

    The influences of category and density of reagents, temperature and the value of pH in the solution of stripping the nickel coating on NdFeB permanent magnet on the stripping result were studied systematically.The practical formular contains mainly the oxidant m-O2NC6H4SO3Na, the complex reagent ( NaOOCCH2 ) 2N( CH2 ) 2N( CH2COOH)2,the reagent of retarding corrosion KF and the calatyze RL-3 was obtained.

  9. The Studies of Composite Electroless Plating Process on Sintering Ndfeb Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    HU Jian-wen; MA Jing; YAN Dong-qing; GAO Qing; MENG Yong-qiang

    2004-01-01

    A reasonable pre-treatment and an ultrasonic pre-plating Cu film were applied for sintering NdFeB permanent magnet. The samples were then plated in neutral bath (PH=7) for 40min and in acidic bath (PH=4.8~5.1) for 2h. A composite electroless plating with different phosphor content was obtained. The results show that the composite plating coatings are dense and have a strong bond with the substrate, which contribute to the excellent corrosion resistance of the plating coating.

  10. The Studies of Composite Electroless Plating Process on Sintering Ndfeb Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    HUJian-wen; MAJing; YANDong-qing; GAOQing; MENGYong-qiang

    2004-01-01

    A reasonable pre-treatment and an ultrasonic pre-plating Cu film were applied for sintering NdFeB permanent magnet. The samples were then plated in neutral bath (PH=7) for 40rnin and in acidic bath (PH=4.8-5.1) for 2h. A composite electroless plating with different phosphor content was obtained. The results show that the composite plating coatings are dense and have a strong bond with the substrate, which contribute to the excellent corrosion resistance of the plating coating.

  11. Effect of microstructure on the coercivity of HDDR Nd-Fe-B permanent magnetic alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations of the structure defect factors based on the nucleation and pinning mechanism with 2r0/lex (where r0 and lex are the defect thickness and the length of exchange coupling, respec-tively) were calculated. The results show that the coercivity mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary. For a fixed lex, when 2r0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r0/lex = 1.67. The calcula-tion result is consistent well with the experimental result given by Morimoto et al.

  12. Influence of dynamic crystallization on exchange-coupled NdFeB nanocrystalline permanent magnets

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ran; LIU Ying; MA Yilong; ZHANG Longfeng; XU Jianchuan; GAO Shengji

    2006-01-01

    Dynamic crystallization was introduced to improve the magnetic properties of NdFeB nanocrystalline permanent magnets by optimizing microstructure. The microstructure was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It has been determined that, compared with the conventional heat treatment, dynamic crystallization can shorten the crystallization time. Moreover, dynamic crystallization can refine grains, enhance the exchange-coupled interaction among grains, and promote the magnetic properties. As a result, the optimal magnetic properties of Nd10.5(FeCoZr)83.4B6.1(Br=0.685T, Hci =732 kA·m -1 , Hcb =429 kA·m-1 ,( BH )m=75 kJ·m -3 ) are obtained after dynamic crystallization heat treatment at 700 ℃ for 10 min.

  13. Cathode electrophoretic technology for bonded NdFeB permanent magnet

    Institute of Scientific and Technical Information of China (English)

    CHEN Gang; YANG Xiao-lin; GAO Dan-ying; NI Jian-sen; XU Hui; ZHOU Bang-xin

    2006-01-01

    The bonded NdFeB permanent magnet was painted by cathode electrophoretic technology. The effect of technological parameters on the thickness of the layer was researched. The optimum voltage, time, electrophoresis temperature, area-ratio and spacing between cathode and anode are 220-250 V, 2-3 min, 25-32 ℃, 7-10 cm and (2-4)∶1, respectively. After treated under optimum conditions, the excellent corrosion resistance of the bonded magnet is achieved, with temperature and humidity resistant time of 468 h, brine-fast resistant time of 48 h. The cathode electrophoretic technology and treating process were successfully applied to produce bonded magnets with mass capacity of tens of million pieces per year.

  14. Increased Efficiency of a Permanent Magnet Synchronous Generator through Optimization of NdFeB Magnet Arrays

    Science.gov (United States)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    2014-03-01

    The United States is currently dependent on fossil fuels for the majority of its energy needs, which has many negative consequences such as climate change. Wind turbines present a viable alternative, with the highest energy return on investment among even fossil fuel generation. Traditional commercial wind turbines use an induction generator for energy conversion. However, induction generators require a gearbox to increase the rotational speed of the drive shaft. These gearboxes increase the overall cost of the wind turbine and account for about 35 percent of reported wind turbine failures. Direct drive permanent magnet synchronous generators (PMSGs) offer an alternative to induction generators which eliminate the need for a gearbox. Yet, PMSGs can be more expensive than induction generators at large power output due to their size and weight. To increase the efficiency of PMSGs, the geometry and configuration of NdFeB permanent magnets were investigated using finite element techniques. The optimized design of the PMSG increases flux density and minimizes cogging torque with NdFeB permanent magnets of a reduced volume. These factors serve to increase the efficiency and reduce the overall cost of the PMSG. This work is supported by a National Science Foundation IGERT fellowship and the Barbara and James Palmer Endowment at the Department of Electrical and Computer Engineering of Iowa State University.

  15. First-Principles Study of the Role of Cu in Improving the Coercivity of Nd-Fe-B Permanent Magnets

    Science.gov (United States)

    Tatetsu, Y.; Tsuneyuki, S.; Gohda, Y.

    2016-12-01

    We study the magnetic and electronic properties of Cu-doped Nd2 Fe14 B /NdOx systems with first-principles calculations in order to understand the roles of Cu in improving the coercivity of Nd-Fe-B permanent magnets. By analyzing the formation energies of several model systems, we find that Cu prefers to be at the interface. We conclude that the Cu addition to Nd-Fe-B magnets is a practical way of not only increasing the anisotropy of Nd atoms at the interface but also of lessening the magnetic coupling between the Nd and Fe atoms. Particularly, substituting Fe at the interface of the main phase with Cu works effectively in terms of improving the magnetic anisotropy in Nd atoms. This may explain the coercivity improvements reported recently.

  16. EXPERIMENTAL STUDIES FOR DEVELOPMENT HIGH-POWER AUDIO SPEAKER DEVICES PERFORMANCE USING PERMANENT NdFeB MAGNETS SPECIAL TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Constantin D. STĂNESCU

    2013-05-01

    Full Text Available In this paper the authors shows the research made for improving high-power audio speaker devices performance using permanent NdFeB magnets special technology. Magnetic losses inside these audio devices are due to mechanical system frictions and to thermal effect of Joules eddy currents. In this regard, by special technology, were made conical surfaces at top plate and center pin. Analysing results obtained by modelling the magnetic circuit finite element method using electronic software package,was measured increase efficiency by over 10 %, from 1,136T to13T.

  17. Structure and magnetic properties of bulk nanocrystalline Nd-Fe-B permanent magnets prepared by hot pressing and hot deformation

    Institute of Scientific and Technical Information of China (English)

    SONG Jie; YUE Ming; ZUO Jianhua; ZHANG Zirui; LIU Weiqiang; ZHANG Dongtao; ZHANG Jiuxing

    2013-01-01

    Structure and magnetic properties were studied for bulk nanocrystalline Nd-Fe-B permanent magnets that were prepared at 650 ℃ for 3 min under 300 MPa using the SPS-3.20-MK-V sintering machine and the hot pressed magnets were then submitted to hot deformation with height reduction of 50%,60%,70%,80%,and 85%.Effects of height reduction (HR) and deformation temperature on the structure and magnetic properties of the magnets were investigated.The crystal structure was evaluated by means of X-ray diffraction (XRD) and the microstructure was observed by transmission electron microscopy (TEM).The magnetic properties of the magnets were investigated by vibrating sample magnetometer (VSM).As the height reduction increased,the remanence (Br) of the magnets increased first,peaks at 1.3 T with HR=60%,then decreased again,and the coercivity (Hci) of the magnets decreased monotonically.On the other hand,as the deformation temperature increased,the Br of the magnets increased first,peaks at 1.36 T with HR=60%,then decreased again,and the Hci of the magnets decreased monotonically.Under optimal conditions,the hot deformed magnet possessed excellent magnetic properties as Br=l.36 T,Hci=1143 kA/m,and (BH)max=370 kJ/m3,suggesting the good potential of the magnets in practical applications.

  18. Corrosion Resistance of Sintered NdFeB Permanent Magnet With Ni-P/TiO2 Composite Film

    Institute of Scientific and Technical Information of China (English)

    SONG Lai-zhou; YANG Zhi-yong

    2009-01-01

    The Ni-P/TiO2 composite film on sintered NdFeB permanent magnet was investigated by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectrometer (EDX).The corrosion resistance of Ni-P/TiO2 film coated on NdFeB magnet, in 0. 5 mol/L NaCl solution, was studied by potentiodynamic polarization, salt spray test and electrochemical impedance spectroscopy (EIS) techniques. The selfcorrosion current density (icorr) and the polarization resistance (Rp) of Ni-P/TiO2 film are 0. 22 μA/cm2 (about 14% of that of Ni-P coating), and 120 kΩ·cm2 (about 2 times of that of Ni-P coating), respectively. The anti-salt spray time of Ni-P/TiO2 film is about 2.5 times of that of the Ni-P coating. The results indicate that Ni-P/TiO2 film has a better corrosion resistance than Ni-P coating, and the composite film increases the corrosion resistance of NdFeB magnet markedly.

  19. Effect of optimal aging treatment on magnetic performance and mechanical properties of sintered Nd-Fe-B permanent magnets

    Institute of Scientific and Technical Information of China (English)

    DING Xia; DING Kai-hong; CUI Sheng-li; SUN Yong-cong; LI Mu-sen

    2016-01-01

    The magnetic performance and mechanical properties including hardness, brittleness, fracture toughness and strength characteristics of the as-sintered and the optimal aged Nd-Fe-B magnets were examined in this work. A new method of Vickers hardness indentation combined with acoustic emission was used to test the brittleness of the magnets.The results show that the magnetic properties of the magnets could be improved through aging treatment, especially the intrinsic coercive force. But it is accompanied by a decrease of strength and fracture toughness. Theoretical calculation confirms that acoustic emission energy accumulated count value could be used to characterize the material brittleness. The bending fracture morphologies of the as-sintered and the optimal aged NdFeB magnets were investigated with the emphasis on the relationship between mechanical properties and microstructure using a field emission scanning electron microscopy (FE-SEM). The research results indicate that the intergranular fracture is the primary fracture mechanism for both as-sintered and optimal aged NdFeB magnets. Aging treatment changes the morphology and distribution of the Nd-rich phases, reducing the sliding resistance between Nd2Fe14B main crystal grains and lowers the grain boundary strength, which is the main reason for the strength and fracture toughness decrease of the aged Nd-Fe-B magnets.

  20. Grain boundary engineering in sintered Nd-Fe-B permanent magnets for efficient utilization of heavy rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, Konrad

    2016-10-18

    The first part of the thesis investigates the diffusion of rare-earth (RE) elements in commercial sintered Nd-Fe-B based permanent magnets. A strong temperature dependence of the diffusion distance and resulting change in magnetic properties were found. A maximum increase in coercivity of ∼+350 kA/m using a Dy diffusion source occurred at the optimum annealing temperature of 900 C. After annealing for 6 h at this temperature, a Dy diffusion distance of about 4 mm has been observed with a scanning Hall probe. Consequently, the maximum thickness of grain boundary diffusion processed magnets with homogeneous properties is also only a few mm. The microstructural changes in the magnets after diffusion were investigated by electron microscopy coupled with electron probe microanalysis. It was found that the diffusion of Dy into sintered Nd-Fe-B permanent magnets occurs along the grain boundary phases, which is in accordance with previous studies. A partial melting of the Nd-Fe-B grains during the annealing process lead to the formation of so - called (Nd,Dy)-Fe-B shells at the outer part of the grains. These shells are μm thick at the immediate surface of the magnet and become thinner with increasing diffusion distance towards the center of the bulk. With scanning transmission electron microscopy coupled with electron probe analysis a Dy content of about 1 at.% was found in a shell located about 1.5 mm away from the surface of the magnet. The evaluation of diffusion speeds of Dy and other RE (Tb, Ce, Gd) in Nd-Fe-B magnets showed that Tb diffuses significantly faster than Dy, and Ce slightly slower than Dy, which is attributed to differences in the respective phase diagrams. The addition of Gd to the grain boundaries has an adverse effect on coercivity. Exemplary of the heavy rare earth element Tb, the nano - scale elemental distribution around the grain boundaries after the diffusion process was visualized with high resolution scanning transmission electron microscopy

  1. Cerium: an unlikely replacement of dysprosium in high performance Nd-Fe-B permanent magnets.

    Science.gov (United States)

    Pathak, Arjun K; Khan, Mahmud; Gschneidner, Karl A; McCallum, Ralph W; Zhou, Lin; Sun, Kewei; Dennis, Kevin W; Zhou, Chen; Pinkerton, Frederick E; Kramer, Matthew J; Pecharsky, Vitalij K

    2015-04-24

    Replacement of Dy and substitution of Nd in NdFeB-based permanent magnets by Ce, the most abundant and lowest cost rare earth element, is important because Dy and Nd are costly and critical rare earth elements. The Ce, Co co-doped alloys have excellent high-temperature magnetic properties with an intrinsic coercivity being the highest known for T ≥ 453 K.

  2. CRADA/NFE-15-05761 Report: Additive Manufacturing of Isotropic NdFeB Bonded Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans [ORNL

    2016-07-18

    The technical objective of this technical collaboration phase I proposal is to fabricate net shape isotropic NdFeB bonded magnets utilizing additive manufacturing technologies at the ORNL MDF. The goal is to form complex shapes of thermoplastic and/or thermoset bonded magnets without expensive tooling and with minimal wasted material. Two additive manufacturing methods; the binder jet process; and big area additive manufacturing (BAAM) were used. Binder jetting produced magnets with the measured density of the magnet of 3.47 g/cm3, close to 46% relative to the NdFeB single crystal density of 7.6 g/cm3 were demonstrated. Magnetic measurements indicate that there is no degradation in the magnetic properties. In addition, BAAM was used to fabricate isotropic near-net-shape NdFeB bonded magnets with magnetic and mechanical properties comparable or better than those of traditional injection molded magnets. The starting polymer magnet composite pellets consist of 65 vol% isotropic NdFeB powder and 35 vol% polyamide (Nylon-12). The density of the final BAAM magnet product reached 4.8 g/cm3, and the room temperature magnetic properties are: Intrinsic coercivity Hci = 8.65 kOe, Remanence Br = 5.07 kG, and energy product (BH)max = 5.47 MGOe (43.50 kJ/m3). This study provides a new pathway for preparing near-net shape bonded magnets for various magnetic applications.

  3. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn; Huang, Z.X.; Luo, J.M.; Zhong, Z.C., E-mail: zzhong.2006@yahoo.com.cn

    2014-04-15

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H{sub 2}SO{sub 4} solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H{sub 2}SO{sub 4} solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates.

  4. Effect of Stabilization Heat Treatment on Time-Dependent Polarization Losses in Sintered Nd-Fe-B Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tuominen S.

    2013-01-01

    Full Text Available Some companies in the motor and generator industry utilizing sintered NdFeB magnets have adopted pre-ageing heat treatment in order to improve the stability of the magnets. The parameters of this stabilization heat treatment are based mainly on assumptions rather than on any published research results. In this work, the effects of pre-ageing treatment on the time-dependent polarization losses of two different types of commercial sintered NdFeB magnets were studied. The material showing the squarer J(H curve did not benefit from the pre-ageing treatment, since it seems to be stable under a certain critical temperature. In contrast, a stabilizing effect was observed in the material showing rounder J(H curve. After the stabilization heat treatment, the polarization of the magnets was found to be at lower level, but unchanged over a certain period of time. The length of this period depends on the temperature and the duration of the pre-ageing treatment. In addition, our analysis reveals that the stabilization heat treatment performed in an open circuit condition does not stabilize the magnet uniformly.

  5. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    Science.gov (United States)

    Xu, J. L.; Huang, Z. X.; Luo, J. M.; Zhong, Z. C.

    2014-04-01

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H2SO4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H2SO4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings.

  6. Magnetic microstructure and coercivity mechanism of high performance Nd-Fe-B magnets

    Institute of Scientific and Technical Information of China (English)

    ZHU Minggang; LIU Xingmin; FANG Yikun; LI Zhengbang; LI Wei

    2006-01-01

    Magnetic microstructure of high performance Nd-Fe-B magnets was investigated by using magnetic force microscopy. The correlation between magnetic microstructure and coercivity for high performance Nd-Fe-B magnets was studied. It is found that the magnets with different coercivity mechanism take on different microstructures and magnetism. Moreover, the magnetic microstructures of high performance permanent magnets can be explained by the starting field theory model.

  7. Corrosion of rapidly solidified neodymium-iron-boron (Nd-Fe-B) permanent magnets and protection via sacrificial zinc coatings

    Energy Technology Data Exchange (ETDEWEB)

    Attanasio, S.A. [Massachusetts Inst. of Tech., Cambridge (United States). Dept. of Materials Science and Engineering; Latanision, R.M. [Massachusetts Inst. of Tech., Cambridge (United States). Dept. of Materials Science and Engineering

    1995-07-15

    Rapidly solidified Nd-Fe-B alloys were found to corrode actively at open circuit in aerated Na{sub 2}SO{sub 4} and NaCl at 30 C and 80 C. Estimated penetration rates (greater than 27 mil year{sup -1}) indicate the need for corrosion control methods.The use of sacrificial zinc coatings in controlling the corrosion of Nd-Fe-B alloys may have previously been overlooked because of two potential limitations: incomplete protection and hydrogen damage. The electrochemical activity of Nd may prevent zinc from providing complete sacrificial protection to Nd-Fe-B at breaks in the coating, and cracking could occur when hydrogen production is galvanically stimulated on Nd-Fe-B at breaks in the coating.This study focuses on the evaluation of the protection conferred to Nd-Fe-B when a Zn/Nd-Fe-B galvanic couple is formed due to coating penetration. Quantitative solution analysis was used to demonstrate that the dissolution of Nd, Fe and B is essentially prevented by the galvanic coupling of Nd-Fe-B to zinc in NaCl at 25 C. Galvanic coupling to zinc also reduces the rate of environmentally assisted cracking of Nd-Fe-B. Sacrificial zinc coatings appear to be a viable, cost-effective corrosion control method for Nd-Fe-B, and the limitations described above should not preclude their use in this application. (orig.)

  8. ASPECTS REGARDING MECHANICAL PROCESSING OF STEELS FOR MAGNETS, NDFEB BASED

    Directory of Open Access Journals (Sweden)

    MELANIA TĂMAŞ

    2015-05-01

    Full Text Available This paper presents experimental research concerning the behavior on cutting by turning of steels for magnets NdFeB based. In this context, cutting by rough turning of steels magnet neodymium and boron ferrite based were performed. Turning processing with the values of the cutting parameters recommended by European Union and Sandvik Coromant company rules, taking into account the chemical composition of the processed material and cutting tool were performed. The tables have been drawn up with different values of the cutting parameters. By comparing these data it can be concluded that steels for permanent magnets, NdFeB based have acceptable behavior, the process by rough turning. A full assessment of the optimization of the cutting by turning process of steels for permanent magnet, NdFeB base will result from subsequent experimental research that will take into account the wear of cutting tools and quality (roughness of processed surface.

  9. Impulse Magnetization of Nd-Fe-B Sintered Magnets for Sensors.

    Science.gov (United States)

    Przybylski, Marek; Kapelski, Dariusz; Ślusarek, Barbara; Wiak, Sławomir

    2016-04-21

    Magnetization of large Nd-Fe-B sintered permanent magnets is still challenging. This type of permanent magnet is electrically conductive, so impulse magnetization causes a flow of eddy currents which prevent magnetization of the whole volume of the magnet. The paper deals with the impulse magnetization of sintered Nd-Fe-B permanent magnets and shows a method for the determination of suitable parameters for the supply system. The necessary magnetic field strength for magnetization of the magnet to saturation was determined. The optimal magnetizing fixture supply voltage for magnetization to saturation was determined from simulations in PSpice software, finite element analyses in Maxwell 15 and measurements. Measurements of magnetic induction on the surface of the Nd-Fe-B magnet are also presented to ensure that a magnet with 70 mm diameter and 20 mm in height is fully saturated.

  10. Impulse Magnetization of Nd-Fe-B Sintered Magnets for Sensors

    Directory of Open Access Journals (Sweden)

    Marek Przybylski

    2016-04-01

    Full Text Available Magnetization of large Nd-Fe-B sintered permanent magnets is still challenging. This type of permanent magnet is electrically conductive, so impulse magnetization causes a flow of eddy currents which prevent magnetization of the whole volume of the magnet. The paper deals with the impulse magnetization of sintered Nd-Fe-B permanent magnets and shows a method for the determination of suitable parameters for the supply system. The necessary magnetic field strength for magnetization of the magnet to saturation was determined. The optimal magnetizing fixture supply voltage for magnetization to saturation was determined from simulations in PSpice software, finite element analyses in Maxwell 15 and measurements. Measurements of magnetic induction on the surface of the Nd-Fe-B magnet are also presented to ensure that a magnet with 70 mm diameter and 20 mm in height is fully saturated.

  11. International comparison of the properties of NdFeB permanent magnets measured using an electromagnet and a pulsed field magnetometer

    Science.gov (United States)

    Hall, Michael

    2013-08-01

    An IEC TC 68 comparison on the measurement of the magnetic properties of permanent magnets was completed in 2011. Measurements were performed on 6 NdFeB magnets with intrinsic coercivities ranging from 1000 to 2600 kA/m by 8 institutes based in China, Japan, Italy, Belgium, Germany and the UK. Many versions of a Pulsed Field Magnetometer (PFM) that can determine the full BH curve in as little as 100 ms have been developed during the last 2 decades. By comparing measurements made using an internationally accepted electromagnet method and pulsed methods, the influence of the dynamic effects of the latter could be investigated and established. For the quantities remanence, B r , magnetic flux density coercivity, H cB and energy product, BH max the measurements agree within the combined uncertainties. For the intrinsic coercivity, H cJ , the dependence of the measurement of this quantity on the speed at which the magnetic field is reversed was found to be significant with the largest changes in value occurring as a DC measurement condition is approached.

  12. Application of positron lifetime spectroscopy to the study of material processing of Nd-Fe-B permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Nishiuchi, T., E-mail: Takeshi_Nishiuchi@hitachi-metals.co.j [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., 2-15-17 Egawa, Shimamoto, Osaka 618-0013 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sakashita, S.; Hirosawa, S. [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., 2-15-17 Egawa, Shimamoto, Osaka 618-0013 (Japan); Nakamura, M.; Kakimoto, M.; Kawabayashi, T.; Mizuno, M.; Araki, H. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Shirai, Y. [Graduate School of Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

    2010-05-15

    A positron lifetime spectroscopy was applied to a series of samples of Nd-Fe-B based alloys prepared by hydrogenation-disproportionation-desorption-recombination (HDDR) process with various desorption-recombination (DR) times and the results were compared to the results of cross-sectional observation with scanning electron microscopy (SEM). From these studies, it is strongly suggested that microstructural changes, which causes the sudden onset of coercivity during DR stage progress abruptly in a relatively short period of time. Positron lifetime spectroscopy can detect the microstructural changes during DR treatment and furthermore, it is suggested that positron annihilation site is directly related to the region which determines the coercivity of the HDDR-processed Nd-Fe-B alloys.

  13. Improving sintered NdFeB permanent magnets by powder compaction in a 9 T superconducting solenoid

    Science.gov (United States)

    Mulcahy, T. M.; Hull, J. R.; Rozendaal, E.; Wise, J. H.; Turner, L. R.

    2003-05-01

    Commercial-grade magnet powder (Magnequench UG) was axial die pressed in the 76.2 mm warm bore of a 9 T superconducting solenoid. Otherwise, processing was performed as part of normal factory operations. This pressing was done to improve the alignment of the anisotropic single-crystal particles of the compact and, thus, the remanent magnetization of the sintered cylindrical permanent magnets (12.7 mm diameter). Although the press was operated in batch mode for this proof-of-concept study, its design enables automated production. Improvements of up to 8% in magnetization and 16% in energy products were obtained, as the alignment field H was increased above the 2 T maximum field of electromagnets used in industry. The greatest improvements were obtained for magnets with the smallest length-to-diameter ratios, L/D<0.5. The production of quality magnets in this near-final-shape size range is currently being pursued by industry to eliminate expensive machining steps. To understand the potential for 2-8 T alignment fields to overcome the distortions created in the otherwise uniform field by the self-field of short compacts, electromagnetic code (Opera) calculations were made. A simple material model was used to predict the distortions. The trends in the predicted field-line inclinations, with L/D and H, compare to trends in the improvement of the magnetic properties.

  14. Permanent magnet design methodology

    Science.gov (United States)

    Leupold, Herbert A.

    1991-01-01

    Design techniques developed for the exploitation of high energy magnetically rigid materials such as Sm-Co and Nd-Fe-B have resulted in a revolution in kind rather than in degree in the design of a variety of electron guidance structures for ballistic and aerospace applications. Salient examples are listed. Several prototype models were developed. These structures are discussed in some detail: permanent magnet solenoids, transverse field sources, periodic structures, and very high field structures.

  15. Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

    Science.gov (United States)

    Xu, J. L.; Xiao, Q. F.; Mei, D. D.; Zhong, Z. C.; Tong, Y. X.; Zheng, Y. F.; Li, L.

    2017-03-01

    Amorphous SiO2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the "coral reef" like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 μm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO2 and a few amorphous Fe2O3 and Nd2O3. The amorphous SiO2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees.

  16. Changes in domain structures of NdFeB permanent magnet after magnetization and temperature treatment%NdFeB磁体磁化及温度处理后磁畴结构的变化

    Institute of Scientific and Technical Information of China (English)

    陈杰; 张明; 徐光亮; 向海蓉; 王敬东

    2012-01-01

    We studied the phase components and magnetic domain structure of sintered NdFeB permanent magnet after magnetization and high-temperature treatment using magnetic force microscopy (MFM) and X-ray diffraction (XRD) as well as high-coercivity Co-Cr magnetic probe, made an analysis of the effect of magnetization and heat treatment on the phase components and magnetic domain structures. It is found that magnetization and high-temperature treatment result in no changes in the phase components, but obvious changes occurs in the magnetic domain structure ; open-circuit magnetic flux loss may attribute to the change of magnetic domain structures.%采用磁力显微镜(Magnetic force microscopy,MFM)和X射线衍射(XRD)研究了烧结NdFeB磁体磁化及125℃高温处理后的磁畴结构,分析了磁化及温度处理对磁体物相成分及磁畴结构的影响.结果发现,磁化及高温处理后磁体的相结构没有发生变化,而磁畴结构却发生明显变化;开路磁通的变化是磁畴结构变化引起的.

  17. Multilayer ceramic coating for impeding corrosion of sintered NdFeB magnets

    Institute of Scientific and Technical Information of China (English)

    A.Ali; A.Ahmad; K.M.Deen

    2009-01-01

    Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments.The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic coating applied through cathodic arc physical vapour deposition(CAPVD) for protection of sintered NdFeB permanent magnets.The performance of ceramic coating was compared to the electrodeposited nickel coating having a copper interlayer.Electrochemical impedance spectroscopy(EIS) and cyclic polar...

  18. Pembuatan Bonded Anisotropi Magnet NdFeB dan Karakterisasinya

    OpenAIRE

    Nuraini, Siti

    2015-01-01

    Research on fabrications of bonded magnets NdFeB type MQA-37-16 with polivynil chloride binder has been done. The purpose of this study the effect of field strength and orientation on the physical and magnetic properties in the manufacture of bonded magnets NdFeB. Preparation process by dry mixing powder magnets NdFeB and polivynil chloride binder bi using Shaker Mill. For each sample takes 4 grams total mass of bonded magnet NdFeB. Printing is done isotropic and anisotropy using a magnetic f...

  19. Designing a Virtual laboratory for Simulating to Production of Nanocomposite NdFeB Magnets

    Directory of Open Access Journals (Sweden)

    Musa Faruk Çakir

    2014-02-01

    Full Text Available The talent figure for a permanent magnet is the multiplication of the maximum energy (BHmax. Less volume magnet is required for the production of magnet flux density if the BHmax value is higher. Mathematical functions are obtained from the data related to resiudal flux density, magnetic coercitivy, permanent magnet flux product capability, Curie temperature and density which were obtained as a result of the studies on different NdFeB alloys in the laboratory. Besides this, mathematical functions of NdFeB hard magnet’s resiudal flux density are obtained by adding elements. In this study, a virtual laboratory for producing nanocompositedNdFeB magnet has been designed. The virtual laboratory software has been used to simulate NdFeB hard magnets for industrial utilities.

  20. Assessment of corrosion resistance of Nd-Fe-B magnets by silanization for orthodontic applications

    Science.gov (United States)

    Fabiano, F.; Celegato, F.; Giordano, A.; Borsellino, C.; Bonaccorsi, L.; Calabrese, L.; Tiberto, P.; Cordasco, G.; Matarese, G.; Fabiano, V.; Azzerboni, B.

    2014-02-01

    Nd-Fe-B permanent magnets are characterised by excellent magnetic properties. However, being extremely vulnerable to the attack of both climate and corrosive environments, their applications are limited. This paper describes how, at different thicknesses of N-propyl-trimetoxy-silane, the coating affects the magnetic force of nickel plated magnets. We also investigate if the corrosion resistance of silanized Nd-Fe-B magnets increases in mildly corrosive environments by immersing them in a synthetic saliva solution. It was found that the silanization treatment does not affect the strength of the magnetic force and provide an enhancement of the corrosion resistance of the substrate.

  1. Reduction in Flux Loss of an Nd-Fe-B Bonded Ring Magnet for an SPM Motor

    OpenAIRE

    Yanai, Takeshi; Horita, Satoshi; Nakano, Masaki; Tsutsumi, Shinichi; Fukunaga, Hirotoshi

    2014-01-01

    We have previously proposed a simulation method of an initial flux loss in permanent magnets using finite element method, and confirmed that predicted flux loss of an Nd-Fe-B boned ring magnet showed good agreement with measured flux loss. In this paper, we applied our proposed method to an Nd-Fe-B boned ring magnet in an SPM motor. We modeled a rotor composed of an Nd-Fe-B bonded ring magnet and a soft magnetic core made from silicon steels, and carried out the simulations for magnetizing pr...

  2. 汽车用42V钕铁硼永磁发电机稳压分析%An Analysis.on the Voltage Stability of 42V Automotive Generator with Nd-Fe-B Permanent-magnet Rotor

    Institute of Scientific and Technical Information of China (English)

    张学义; 史立伟

    2011-01-01

    Nd-Fe-B permanent-magnet rotor is used in a 42V automotive generator. The theory of voltage stability for the permanent-magnet rotor generator is expounded with the relation of armature-reaction reactance, winding leakage reactance and load terminal voltage versus generator speed analyzed. A voltage stabilizer with five-phase semi-control bridge rectification is developed, which integrates the functions of voltage stabilization and current rectification and is composed of reference circuit, comparator circuit, trigger circuit and rectifier circuit. With the voltage stabilizer, the problem of output voltage instability in 42 V permanent-magnet generator at wide ranges of speed and load of vehicle is solved.%在汽车42V发电机中采用钕铁硼永磁转子.阐述了该永磁发电机的稳压原理,分析了其电枢反应电抗、绕组漏抗和负载端压与发电机转速的关系.研制出了集稳压、整流于一体和由基准电路、比较电路、触发电路和整流电路集成的五相半控桥式整流稳压器,解决了汽车用42V永磁发电机在宽转速、宽负载范围内输出电压不稳定的问题.

  3. Overview on the permanent magnets technology of rare earth based on Nd-Fe-B; Panorama general sobre tecnologia de imanes permanentes de tierras raras a base de Nd-Fe-B

    Energy Technology Data Exchange (ETDEWEB)

    Rosales Vazquez, Maria Ines [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    In this paper the technological development in the area of permanent magnetic materials, is shown, from the 1930`s when the first aluminum-nickel-cobalt (Al-Ni-Co) magnets appeared. As a result of the continuous worldwide research in this field, it was made known, during the 1980`s decade of a new type of magnets based on Neodymium (Nd). In accordance with the outstanding magnetic properties of these magnets, at the Instituto de Investigaciones Electricas (IIE), their development was initiated, focussed on the stages and parameters definition of their manufacturing process. Up to now, the research has been oriented to the preparation of magnets of the isotropic agglutinated type and the manufacturing process encompasses the following stages: a) Alloy preparation; b) Microcrystals obtainment; c) Magnet preparation. The preliminary results that have been obtained in the magnetic characterization show that the quality of the prepared magnets is comparable to the quality of the imported magnets and/or to the ones other research groups report. [Espanol] En este trabajo se muestra el desarrollo tecnologico del area de materiales magneticos permanentes a partir de los anos treinta en que surgieron los primeros imanes de aluminio-niquel-cobalto (Al-Ni-Co). Como resultado de la constante investigacion a nivel mundial en ese campo, durante el decenio de los ochenta se informo en torno a un nuevo tipo de imanes a base de neodimio (Nd). Atendiendo a las propiedades magneticas sobresalientes de estos imanes, en el Instituto de Investigaciones Electricas (IIE), se inicio el desarrollo de los mismos, enfocandolo a la definicion de las etapas y parametros del proceso de fabricacion. Hasta ahora, la investigacion se ha orientado a la preparacion de imanes de tipo isotropico aglutinado y el proceso de fabricacion comprende las etapas: a) preparacion de la aleacion; b) obtencion de microcristales, y c) preparacion de los imanes. Los resultados preliminares que se han obtenido en la

  4. Magnetic properties of sintered high energy sm-co and nd-fe-b magnets

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2006-01-01

    Full Text Available Magnetic properties of permanent magnetic materials based on intermetallic compounds of Sm-Co and Nd-Fe-B are in direct dependence on the microstructure. In the first part of this paper, having in mind the importance of the regime of sintering and heat treatment to obtain the optimal magnetic structure, yet another approach in defining the most adequate technological parameters of the sintering process for applied heat treatment conditions was made. The goal of these investigations was to use the correlation that exists between sintering conditions (temperature and time and intensity of the diffraction peak of the (111 plane of the SmCo5 phase to optimize. In the second part a brief overview of high energy magnetic materials based on Nd-Fe-B is presented with special emphasis to the current research and development of high remanent nanocomposite magnetic materials based on Nd-Fe-B alloys with a reduced Nd content. Part of experimental results gained during research of the sintering process of SmCo5 magnetic materials were realized and published earlier. The scientific meeting devoted to the 60th anniversary of Frankel’s theory of sintering was an opportunity to show once more the importance and role of sintering in optimization of the magnetic microstructure of sintered Sm Co5 magnetic materials.

  5. Application of bonded NdFeB magnet for C-Band circulator component

    Science.gov (United States)

    Kristiantoro, T.; Idayanti, N.; Sudrajat, N.; Septiani, A.; Dedi

    2016-11-01

    In this paper bonded NdFeB permanent magnets of the crashed-ribbon type were made as an alternative for circulator magnet to improve their magnetic performance. The fabrication process is also easier than the sintered NdFeB because there had no shrinkage of product (such as sintered barium ferrite magnet), with the others advantages as follows; large freeness of product shapes, high precision of dimension and good corrosion resistance. The dimension of the samples was measured to calculate its bulk densities and the magnetic properties were characterized by Permagraph to obtain values such as; Remanence induction (Br) in kG, Coercivity value (Hcj) in kOe, the Maximum energy product (BH max) in MGOe. Whereas the surface magnetic field strength (B) was observed by the Gauss-meter. The bonded NdFeB permanent magnets revealed 6.39 kG of Br, 6.974 kOe of Hcj and 7.13 MGOe of BHmax. The circulator performance was measured using Vector Network Analyzer (VNA). The optimum values of the circulator measurement at a frequency of 5 GHz show a VSWR value of 1.062 and insertion loss of -0.463 dB. The bonded magnet could be used as component of permanent magnets on the circulator that working on C-Band at a frequency range of 4 GHz - 8 GHz.

  6. Physical and magnetic properties, microstructure of bonded magnet NdFeB prepared by using synthesis rubber

    Science.gov (United States)

    Suprapedi; Sardjono, P.; Muljadi

    2016-11-01

    The magnet permanent has been made by using NdFeB (NQP-B) powder with purity 99.90% and polymer rubber with purity 90%. This research was done to determine the effect of the polymer (rubber) composition as binder in the manufacture of bonded magnet NdFeB on physical properties, microstructure and magnetic properties. Bonded magnets are magnet material made from a mixture of magnetic powder as a filler and the polymer as a matrix material or as binder to bind the magnetic particles. The NdFeB (NQP-B) powder fractions of bonded magnets NdFeB investigated were as follows: a) 97 wt.% of NdFeB (NQP-B) and 3 wt.% of rubber,b) 95wt.% of NdFeB (NQP-B) and 5 wt.% of rubber, c) 93 wt.% of NdFeB (NQP-B) and 7 wt.% of rubber, d) 91 wt.% of NdFeB (NQP-B) and 9 wt.% of rubber. Both raw materials were mixed by using mixer until homogen with total weight about 16 g for each sample, then added 0.3 ml of catalyst and mixed again and put in dies mould and compacted at pressure 30 MPa, then dried for 2 hours at room temperature. The dried samples was characterized such as: bulk density measurement and magnetic properties by using BH-curve permeagraph. The bulk density values of the sample bonded NdFeB magnets using the binder 3% wt. and 5% wt. rubber are respectively 4,70 g/cm3 and 4.88 g/cm3. The result from BH- curve shows that the highest value of remanence (Br = 5.12 kGauss) is at sample with 3% wt. of rubber, but sample with 5% wt. of rubber has lowest value of remanance (Br = 4.40 kGauss). Based on the observation of the SEM photograph shown that the rubber material has been successfully covered the whole surface of the grain and fill some of the voids that are in the grain boundary.

  7. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2 ·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirements from AMS, and satisfies the strict safety standards of NASA.

  8. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    陈和生

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirem

  9. Design and construction of permanent magnetic gears

    OpenAIRE

    Jørgensen, Frank Thorleif

    2010-01-01

    This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical mechanical gears. The new magnetic gear will have a high torque density1 relationship –high efficiency and are maintenance free. In this project was manufactured two test gears which is tested and verifie...

  10. Effect of Annealing on the Magnetism of the Sintered NdFeB Magnet

    Institute of Scientific and Technical Information of China (English)

    ZHENG Hua-jun; HUANG Jian-guo; MA Chun-an

    2004-01-01

    This paper deals with the effect of annealing on the magnetism of the sintered NdFeB magnet with a composition of Nd30B5.1Dy1.2A10.6Nb0.7Fe62.4. Microstructural investigations of the grain size and grain boundaries with SEM were carried out. Microstructural investigations showed the presence of some Nd-rich phase in grain boundaries and main phase.The results of magnetic properties analysis shows that this non-magnetic Nd-rich phase, produced in annealing process,can increase or decrease the magnetism of the sintered NdFeB-type permanent magnet. Appropriate amount of Nd-rich phase will strengthen the pinning field and elevated the coercive force of magnet, but too many these non-magnetism phases in Nd2Fe14B main phase will decrease it. When the sintered NdFeB magnet was annealed at 3Pa and 492℃ for an hour the coercive force would raise from 915.6kA/m to 1164.8kA/m, and the (BH)max from 277.7kJ/m to 349.5kJ/m. However, annealing at a non-optimized temperature at 542℃, microstructure changes in some main phase will leading the decrease of properties.

  11. History of Sintered NdFeB Magnets(Continued)

    Institute of Scientific and Technical Information of China (English)

    LUO Yang

    2007-01-01

    @@ 2. Output of sintered NdFeB magnets increased rapidly at the beginning of 21st century Annual output growth rate of magnets in China kept 25.2% from 1995-2000, and in Japan, USA and Europe was 26.2%,10% and 10.3% respectively.

  12. Magnetizing of permanent magnets using HTS bulk magnets

    Science.gov (United States)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2012-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

  13. NdFeB磁性材料表面化学镀Ni-W-P合金研究%Electroless Ni-W-P plating alloy on the surface of the NdFeB permanent magnets

    Institute of Scientific and Technical Information of China (English)

    刘炜; 王憨鹰

    2011-01-01

    通过不同的化学镀工艺配方,在NdFeB永磁体表面获得4种不同W含量的化学镀Ni-W-P三元合金镀层.利用SEM对镀层的微观组织观察与分析表明:镀层表面形貌呈致密胞状结构,Ni、W、P元素分布均匀.进一步的衍射分析和硬度测试表明:随镀层中W和P元素含量的不同,镀层结构分别由纳米晶态、混晶态和非晶态组成,镀层的硬度随镀层结构从非晶态-混晶态-晶态的转变而增加.%Four ternary Ni-W-P alloy coatings on the surface of the Nd-Fe-B permanent magnet with different W contents were obtained by four different electroless Ni-W-P plating bath. The SEM observation and analysis of the coatings indicate that the morphology appeares closely nodules structure, and Ni, Cu, P elements distribute homogeneously in the coatings. The X-ray diffraction analysis and the hardness measurement suggest that with the changing of W and P content, the coating structures are crystalline, mixed crystalline and amorphous respectively. And the hardness of coatings also increases with its structure changing from amorphous into mixed crystalline and crystalline.

  14. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders

    Science.gov (United States)

    Nlebedim, I. C.; Ucar, Huseyin; Hatter, Christine B.; McCallum, R. W.; McCall, Scott K.; Kramer, M. J.; Paranthaman, M. Parans

    2017-01-01

    Considerations for achieving high degree of alignment in polymer bonded permanent magnets are presented via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. The thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.

  15. Heat treatment process of new NdFeB magnet prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    李涛; 岳明; 张久兴; 王公平; 肖耀福; 王润

    2003-01-01

    In recent years, spark plasma sintering technique(SPS) has been a focus in the field of material preparation due to its advantages. SPS technique is first introduced for preparation of high quality NdFeB magnets. The effects of heat treatment process on the magnetic properties of SPS NdFeB magnet were investigated. Meanwhile, the effects of heat treatment process on the microstructure, tropism and dimensional precision of the SPS NdFeB magnets were also studied. The high quality NdFeB magnets with fine grains were prepared under proper heat treatment process. The results show that the magnetic properties of SPS NdFeB can be further improved through proper heat treatment process. Meanwhile, the experiment also demonstrates that it is feasible to prepare near-net-shape NdFeB magnets with fine grains and high magnetic property by spark plasma sintering.

  16. Influence of bath PH value on microstructure and corrosion resistance of phosphate chemical conversion coating on sintered Nd-Fe-B permanent magnets

    Science.gov (United States)

    Ding, Xia; Xue, Long-fei; Wang, Xiu-chun; Ding, Kai-hong; Cui, Sheng-li; Sun, Yong-cong; Li, Mu-sen

    2016-10-01

    The effect of bath PH value on formation, microstructure and corrosion resistance of the phosphate chemical conversion (PCC) coatings as well as the effect on the magnetic property of the magnets is investigated in this paper. The results show that the coating mass and thickness increase with the decrease of the bath PH value. Scanning electron microscopy observation demonstrates that the PCC coatings are in a blocky structure with different grain size. Transmission electron microscope and X-ray diffractometer tests reveal the coatings are polycomponent and are mainly composed of neodymium phosphate hydrate and praseodymium phosphate hydrate. The electrochemical analysis and static immersion corrosion test show the corrosion resistance of the PCC coatings prepared at bath PH value of 0.52 is worst. Afterwards the corrosion resistance increases first and then decreases with the increasing of the bath PH values. The magnetic properties of all the samples with PCC treatment are decreased. The biggest loss is occurred when the bath PH value is 0.52. Taken together, the optimum PH range of 1.00-1.50 for the phosphate solution has been determined.

  17. Life cycle inventory of the production of rare earths and the subsequent production of NdFeB rare earth permanent magnets.

    Science.gov (United States)

    Sprecher, Benjamin; Xiao, Yanping; Walton, Allan; Speight, John; Harris, Rex; Kleijn, Rene; Visser, Geert; Kramer, Gert Jan

    2014-04-01

    Neodymium is one of the more critical rare earth elements with respect to current availability and is most often used in high performance magnets. In this paper, we compare the virgin production route of these magnets with two hypothetical recycling processes in terms of environmental impact. The first recycling process looks at manual dismantling of computer hard disk drives (HDDs) combined with a novel hydrogen based recycling process. The second process assumes HDDs are shredded. Our life cycle assessment is based both on up to date literature and on our own experimental data. Because the production process of neodymium oxide is generic to all rare earths, we also report the life cycle inventory data for the production of rare earth oxides separately. We conclude that recycling of neodymium, especially via manual dismantling, is preferable to primary production, with some environmental indicators showing an order of magnitude improvement. The choice of recycling technology is also important with respect to resource recovery. While manual disassembly allows in principle for all magnetic material to be recovered, shredding leads to very low recovery rates (<10%).

  18. New permanent magnets; manganese compounds.

    Science.gov (United States)

    Coey, J M D

    2014-02-12

    The exponential growth of maximum energy product that prevailed in the 20th century has stalled, leaving a market dominated by two permanent magnet materials, Nd2Fe14B and Ba(Sr)Fe12O19, for which the maximum theoretical energy products differ by an order of magnitude (515 kJ m(-3) and 45 kJ m(-3), respectively). Rather than seeking to improve on optimized Nd-Fe-B, it is suggested that some research efforts should be devoted to developing appropriately priced alternatives with energy products in the range 100-300 kJ m(-3). The prospects for Mn-based hard magnetic materials are discussed, based on known Mn-based compounds with the tetragonal L10 or D022 structure or the hexagonal B81 structure.

  19. Electron holography on remanent magnetization distribution of melt-spun Nd-Fe-B magnets.

    Science.gov (United States)

    Park, Young-Gil; Shindo, Daisuke

    2004-01-01

    Microstructures and magnetic domain structures of melt-spun Nd-Fe-B permanent magnets were investigated in detail by analytical electron microscopy and electron holography. While the crystal orientation of matrix Nd2Fe14B grains was analyzed by nanobeam electron diffraction, precipitates of a few tens of nanometers at grain boundaries were identified to be alpha-Fe by energy-dispersive X-ray spectroscopy. The detailed magnetization distribution in Nd2Fe14B grains and at their boundaries was visualized by electron holography. Ex situ experimentation with an electromagnet revealed that the domain walls in the demagnetized state and remanent states were pinned at grain boundaries, and Fe precipitates at the grain boundary were situated at the center of the closure domain.

  20. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco

    2011-01-01

    Permanent magnet arrays are often employed in a broad range of applications: actuators, sensors, drug targeting and delivery systems, fabrication of self-assembled particles, just to name a few. An estimate of the magnetic forces in play between arrays is required to control devices and fabrication...... procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  1. Metal Injection Molding (MIM of NdFeB Magnets

    Directory of Open Access Journals (Sweden)

    Hartwig T.

    2014-07-01

    Full Text Available Due to the increased and unstable prices for Rare Earth elements there are activities to develop alternative hard magnetic materials. Reducing the amount of material necessary to produce complex sintered NdFeB magnets can also help to reduce some of the supply problem. Metal Injection Molding (MIM is able to produce near net shape parts and can reduce the amount of finishing to achieve final geometry. Although MIM of NdFeB has been patented and published fairly soon after the development of the NdFeB magnets there has never been an industrial production. This could be due to the fact that MIM was very young at that time and hardly developed. Thus, the feasibility of the process needs to be revaluated. This paper presents results of our work on determining the process parameters influencing the magnetic properties of the sintered magnets as well as the shrinkage during processing. The role of binder and powder loading on the alignment of the particles as well as on the carbon and oxygen contamination was examined.

  2. Design and construction of permanent magnetic gears

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif

    This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical...... calculation models for determination of gear output torque from different magnetic gear types are analysed. These analytical calculations models are used together with optimisation tools in order to improve the performance of investigated magnetic gear types. Experimental test gears are designed to validate...... is searched and only a single reference [74] is found and that is why the combination of a cycloidal gear and a magnetic gear are considered as an innovative supplement to magnetic gear technology. A magnetic cycloidal gear is designed with a gearing of 1:21 and a calculated active torque density of 142 [Nm...

  3. Grain Growth Behavior in Sintered Nd-Fe-B Magnets

    Institute of Scientific and Technical Information of China (English)

    Liu Xianglian; Zhou Shouzeng

    2007-01-01

    The Nd2Fe14B grain growth behavior in sintered Nd-Fe-B magnets was quantitatively described. The effects of sintering temperature and time, and alloy powder size and its distribution on grain growth process were analyzed. Hence, possible grain growth mechanisms in these magnets were qualitatively discussed. The Nd2Fe14B grain growth proceeded at quite a high rate in the initial 0~1 h of sintering and from then onwards the grain growth rate decreased. A large average particle size or a wide particle size distribution of initial alloy powders was found to remarkably accelerate the grain growth process and even result in the occurrence of abnormal grain growth. On the basis of experimental results, two grain growth mechanisms were considered to operate during sintering of Nd-Fe-B magnets, that is, dissolution and re-precipitation of Nd2Fe14B particles, and Nd2Fe14B particle growth by coalescence. It was believed that Nd2Fe14B particle growth by coalescence not only produced a large average grain size and a wide grain size distribution, but also was the fundamental reason for the formation of abnormally large grains in the microstructure of sintered Nd-Fe-B magnets.

  4. Use of paired, bonded NdFeB magnets in redox magnetohydrodynamics.

    Science.gov (United States)

    Arumugam, Prabhu U; Clark, Emily A; Fritsch, Ingrid

    2005-02-15

    Bonded neodymium-iron-boron (NdFeB) permanent magnets in a paired configuration were successfully used to control mass transport in redox-based, magnetohydrodynamics (MHD). Control of fluid flow based on magnetic fields has potential for use in portable lab-on-a-chip (LOAC) and analytical devices. Bonded magnets, composed of magnetic powder and organic binder materials, are less expensive and easier to fabricate and pattern than electromagnets and sintered permanent magnets, which have been previously used in MHD studies on electrochemical systems. The ability to pattern bonded magnets near and around the electrodes is expected to allow for better control over the magnetic field distribution and solution flow. Current was generated at an 800-microm-radius platinum disk electrode in a solution of 0.06 M nitrobenzene and 0.5 M tetra-n-butylammonium hexafluorophosphate in acetonitrile. Increases in limiting current in the presence of the magnetic field, which indicate enhancement in mass transport, for sintered (210+/-14%, N = 4, where B(r) = 1.23 T and magnetic field strength is 0.55 T) and bonded (94+/-8%, N = 4, where B(r) = 0.41 T and magnetic field strength is 0.20 T) magnets, were similar to those obtained using an electromagnet with the same magnetic flux densities. The magnetic field strength and not the magnet type is important in controlling fluid flow, which is encouraging for integration of bonded permanent magnets into LOAC devices.

  5. Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets

    Science.gov (United States)

    Li, Ling; Tirado, Angelica; Nlebedim, I. C.; Rios, Orlando; Post, Brian; Kunc, Vlastimil; Lowden, R. R.; Lara-Curzio, Edgar; Fredette, Robert; Ormerod, John; Lograsso, Thomas A.; Paranthaman, M. Parans

    2016-10-01

    Additive manufacturing allows for the production of complex parts with minimum material waste, offering an effective technique for fabricating permanent magnets which frequently involve critical rare earth elements. In this report, we demonstrate a novel method - Big Area Additive Manufacturing (BAAM) - to fabricate isotropic near-net-shape NdFeB bonded magnets with magnetic and mechanical properties comparable or better than those of traditional injection molded magnets. The starting polymer magnet composite pellets consist of 65 vol% isotropic NdFeB powder and 35 vol% polyamide (Nylon-12). The density of the final BAAM magnet product reached 4.8 g/cm3, and the room temperature magnetic properties are: intrinsic coercivity Hci = 688.4 kA/m, remanence Br = 0.51 T, and energy product (BH)max = 43.49 kJ/m3 (5.47 MGOe). In addition, tensile tests performed on four dog-bone shaped specimens yielded an average ultimate tensile strength of 6.60 MPa and an average failure strain of 4.18%. Scanning electron microscopy images of the fracture surfaces indicate that the failure is primarily related to the debonding of the magnetic particles from the polymer binder. The present method significantly simplifies manufacturing of near-net-shape bonded magnets, enables efficient use of rare earth elements thus contributing towards enriching the supply of critical materials.

  6. Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets.

    Science.gov (United States)

    Li, Ling; Tirado, Angelica; Nlebedim, I C; Rios, Orlando; Post, Brian; Kunc, Vlastimil; Lowden, R R; Lara-Curzio, Edgar; Fredette, Robert; Ormerod, John; Lograsso, Thomas A; Paranthaman, M Parans

    2016-10-31

    Additive manufacturing allows for the production of complex parts with minimum material waste, offering an effective technique for fabricating permanent magnets which frequently involve critical rare earth elements. In this report, we demonstrate a novel method - Big Area Additive Manufacturing (BAAM) - to fabricate isotropic near-net-shape NdFeB bonded magnets with magnetic and mechanical properties comparable or better than those of traditional injection molded magnets. The starting polymer magnet composite pellets consist of 65 vol% isotropic NdFeB powder and 35 vol% polyamide (Nylon-12). The density of the final BAAM magnet product reached 4.8 g/cm(3), and the room temperature magnetic properties are: intrinsic coercivity Hci = 688.4 kA/m, remanence Br = 0.51 T, and energy product (BH)max = 43.49 kJ/m(3) (5.47 MGOe). In addition, tensile tests performed on four dog-bone shaped specimens yielded an average ultimate tensile strength of 6.60 MPa and an average failure strain of 4.18%. Scanning electron microscopy images of the fracture surfaces indicate that the failure is primarily related to the debonding of the magnetic particles from the polymer binder. The present method significantly simplifies manufacturing of near-net-shape bonded magnets, enables efficient use of rare earth elements thus contributing towards enriching the supply of critical materials.

  7. Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets

    Science.gov (United States)

    Li, Ling; Tirado, Angelica; Nlebedim, I. C.; Rios, Orlando; Post, Brian; Kunc, Vlastimil; Lowden, R. R.; Lara-Curzio, Edgar; Fredette, Robert; Ormerod, John; Lograsso, Thomas A.; Paranthaman, M. Parans

    2016-01-01

    Additive manufacturing allows for the production of complex parts with minimum material waste, offering an effective technique for fabricating permanent magnets which frequently involve critical rare earth elements. In this report, we demonstrate a novel method - Big Area Additive Manufacturing (BAAM) - to fabricate isotropic near-net-shape NdFeB bonded magnets with magnetic and mechanical properties comparable or better than those of traditional injection molded magnets. The starting polymer magnet composite pellets consist of 65 vol% isotropic NdFeB powder and 35 vol% polyamide (Nylon-12). The density of the final BAAM magnet product reached 4.8 g/cm3, and the room temperature magnetic properties are: intrinsic coercivity Hci = 688.4 kA/m, remanence Br = 0.51 T, and energy product (BH)max = 43.49 kJ/m3 (5.47 MGOe). In addition, tensile tests performed on four dog-bone shaped specimens yielded an average ultimate tensile strength of 6.60 MPa and an average failure strain of 4.18%. Scanning electron microscopy images of the fracture surfaces indicate that the failure is primarily related to the debonding of the magnetic particles from the polymer binder. The present method significantly simplifies manufacturing of near-net-shape bonded magnets, enables efficient use of rare earth elements thus contributing towards enriching the supply of critical materials. PMID:27796339

  8. Recycling of waste Nd-Fe-B sintered magnets by doping with dysprosium hydride nanoparticles

    Institute of Scientific and Technical Information of China (English)

    刘卫强; 李超; ZAKOTNIK Miha; 岳明; 张东涛; 黄秀莲

    2015-01-01

    Recycling of waste sintered Nd-Fe-B permanent magnets by doping DyH3 nanoparticles was investigated. The effect of the DyH3 nanoparticles on the microstructure and magnetic properties of the recycled magnets was studied. As the DyH3 nanoparticles additive increased, the coercivity of recycled magnet increased gradually. The recycled magnets with DyH3 nanoparticle content be-tween 0.0 wt.% and 1.0 wt.% maintained the remanence (Br), but, with higher additions, theBr began to decrease rapidly. The best recycled magnet produced contained 1.0 wt.% of DyH3 nanoparticles when compared to the properties of the starting waste sintering magnet. TheHcj,Br and (BH)max values of 101.7%, 95.4%, and 88.58%, respectively, were recovered.

  9. Main Problems Faced by Chinese RE Permanent Magnetic Industry

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Under over 50 years' development, Chinese rare earth magnetic industry developed into the global AINiCo, ferrite permanent magnets and NdFeB magnets manufacturing center, and average consumption of magnets per person in China increased to 1.026 tons in 2003 from 0.217 ton in 1990. Although China has been the large producing country of rare earth permanent magnetic materials, to be the strongest one, there are many problems to solve. Main Problems Faced By Chinese Permanent Magnet Industry

  10. Magnetostatic interactions and forces between cylindrical permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Vokoun, David [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)], E-mail: vokoun@fzu.cz; Beleggia, Marco [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Heller, Ludek; Sittner, Petr [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)

    2009-11-15

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  11. Magnetostatic interactions and forces between cylindrical permanent magnets

    Science.gov (United States)

    Vokoun, David; Beleggia, Marco; Heller, Luděk; Šittner, Petr

    2009-11-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  12. A route for recycling Nd from Nd-Fe-B magnets using Cu melts

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Martina; Gebert, Annett, E-mail: a.gebert@ifw-dresden.de; Stoica, Mihai; Uhlemann, Margitta; Löser, Wolfgang

    2015-10-25

    Phase evolutions in Nd-Fe-B magnet/Cu systems have been explored with regard to Nd recycling. It was demonstrated that large scale phase separation into a ferromagnetic Fe(B)-rich ingot core with α-Fe main phase and a non-magnetic (Cu,Nd)-rich ingot rim takes place upon arc melting with Cu fractions ≥ 21.5 wt.-%. The re-solidification of the Nd{sub 2}Fe{sub 14}B magnet main phase is suppressed. The rim consists of the Cu{sub 2}Nd main phase and CuNd/Cu{sub 4}Nd minority phases in which Al traces from the magnetic material are gathered. Induction melting of such Nd-Fe-B/Cu mixtures can support the separation of these phase regions with very sharp boundaries. Main features of liquid phase separation and microstructure evolution have been interpreted on the basis of Nd-Fe-Cu phase diagram data. The key advantage with respect to Nd recycling from Nd-Fe-B permanent magnet scrap is the substantial accumulation of Nd in the (Cu,Nd)-rich region of the phase separated solidified specimen, which can be easily detached from the Fe-rich part by mechanical-magnetic treatments. Such portions contained up to ∼44 wt.-% Nd (25 at.-%) in first lab-scale experiments. Nd recovery from the (Cu,Nd)-rich fractions is possible by exploiting the large chemical property differences between the reactive rare earths elements and Cu. - Highlights: • phase evolution analysis in Nd-Fe-B magnet/Cu systems with regard to Nd recycling. • Cu ≥ 21 wt.-%, large scale phase separation- Fe(B)-rich ingot core, (Cu,Nd)-rich rim. • high Nd content (∼44 wt.-%) of (Cu,Nd)-rich region, mechanical-magnetic treatments.

  13. Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process

    Science.gov (United States)

    Ohtori, Hiroyuki; Iwano, Kaoru; Mitsumata, Chiharu; Yano, Masao; Kato, Akira; Shoji, Tetsuya; Manabe, Akira; Ono, Kanta

    2014-05-01

    We analyzed the dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process through visualizing magnetic dipolar interaction. We obtained magnetization distribution images experimentally by using scanning transmission X-ray microscopy (STXM). The magnetic dipolar interaction was calculated by the interaction between the magnetization at each point and those at the other points on the STXM image. We showed the dipolar energy in the nanocrystalline Nd-Fe-B magnets and compared it with the exchange energy at various applied fields. Our results indicated the significance of the dipolar energy in magnetization reversal process.

  14. Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet.

    Science.gov (United States)

    Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P; Keiderling, Uwe; Ono, Kanta

    2016-06-20

    We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.

  15. Method for forming permanent magnets with different polarities for use in microelectromechanical devices

    Science.gov (United States)

    Roesler, Alexander W.; Christenson, Todd R.

    2007-04-24

    Methods are provided for forming a plurality of permanent magnets with two different north-south magnetic pole alignments for use in microelectromechanical (MEM) devices. These methods are based on initially magnetizing the permanent magnets all in the same direction, and then utilizing a combination of heating and a magnetic field to switch the polarity of a portion of the permanent magnets while not switching the remaining permanent magnets. The permanent magnets, in some instances, can all have the same rare-earth composition (e.g. NdFeB) or can be formed of two different rare-earth materials (e.g. NdFeB and SmCo). The methods can be used to form a plurality of permanent magnets side-by-side on or within a substrate with an alternating polarity, or to form a two-dimensional array of permanent magnets in which the polarity of every other row of the array is alternated.

  16. Corrosion and protection of NdFeB type magnets

    Science.gov (United States)

    Cavalloti, P.; Bozzini, B.; Cecchini, R.; Bava, G. F.; Davies, H. A.; Hoggarth, C.

    1992-02-01

    A general mechanism for the corrosion behaviour of NdFeB magnets is presented, related to the magnet heterogeneity with the presence of different phases. Cathodic control is outlined. An electrochemical method to assess the corrosion resistance of magnets, with and without coatings, is proposed; it is based on the study of the transient voltage at the magnet surface after a second cathodic current pulse in a suitable aggressive solution and its dependence on the amount of cathodic current circulating. Suitable pretreatments have been tried and interesting results obtained with passivation pretreatments, giving phosphorous Nd at grain boundaries. Coatings if sintered and plastic magnets have been tried using several methods. Good results are obtained with Zn-Co layers on sintered magnets and a sol-gel glass on powders for plastic magnets. Improved ACS (Autocatalytic Chemical Deposition) Ni=P coatings have been realized, with an alkaline brass flash plating to start ACD deposition.

  17. Corrosion behaviors of NdFeB magnets prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    Tao Li; Ming Yue; Aizhi Sun; Baoqin Qiu; Yaofu Xiao; Jiuxing Zhang

    2004-01-01

    The spark plasma sintering (SPS) technique was introduced into the field of NdFeB preparation due to its own advantages.High property NdFeB magnets with fine grains were prepared by SPS method. The corrosion behaviors of SPS NdFeB were studied by electrochemical measurements and 92% RH hyther tests at 353 K. The results were compared with those of the traditional sintered NdFeB magnets. It shows that both the SPS NdFeB and the traditional sintered NdFeB have good corrosion resistance in alkaline environment due to surface passivation; while, the fine grain microstructure of SPS NdFeB results in a more homogeneous phase composition distribution and thus reduces the electrochemical inhomogenity between the ferromagnetic phase and the Nd-rich intergranular phase in the magnet. Therefore, the SPS NdFeB exhibits better corrosion resistance than the traditional sintered NdFeB in neutral and weak acidic environment.

  18. Oscillating Permanent Magnets.

    Science.gov (United States)

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  19. Dysprosium-free melt-spun permanent magnets.

    Science.gov (United States)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-02-12

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

  20. Development of Sintered NdFeB Magnet Industry in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Rare earth performance materials grow rapidly in recent years with technical progress in electronic information, autos and manufacturing industries. As the fastest developing functional materials, NdFeB magnets have become the main force that pushes the development of whole rare earth industry.Applications of NdFeB magnets have been extended to many high tech fields with the continuous technique innovation in production process and improvement of product performances. Relying on abundant RE resources and lower labor cost, China has become the largest producer and also the biggest consumer of NdFeB magnets.

  1. Thermal aging of melt-spun NdFeB magnetic powder in hydrogen

    Science.gov (United States)

    Pinkerton, Frederick E.; Balogh, Michael P.; Ellison, Nicole; Foto, Aldo; Sechan, Martin; Tessema, Misle M.; Thompson, Margarita P.

    2016-11-01

    High energy product neodymium-iron-boron (NdFeB) magnets are the premier candidate for demanding electrified vehicle traction motor applications. Injection molded (IM) or compression molded (CM) magnets made using NdFeB powders are promising routes to improve motor efficiency, cost, and manufacturability. However, IM and CM NdFeB magnets are susceptible to substantial thermal aging losses at motor operating temperatures when exposed to the automatic transmission fluid (ATF) used as a lubricant and cooling medium. The intrinsic coercivity Hci of NdFeB IM and CM magnets degrades by as much as 18% when aged for 1000 h in ATF at 150 °C, compared to a 3% loss when aged in air. Here we report aging studies of rapidly quenched NdFeB powder in air, ATF, and H2 gas. Expansion of the NdFeB crystal lattice in both ATF and H2 identified hydrogen dissociated from the ATF during aging and diffused into the primary NdFeB phase as the probable cause of the coercivity loss of IM and CM magnets.

  2. Electrochemical Corrosion Behavior of Nd-Fe-B Sintered Magnets in Different Acid Solutions

    Institute of Scientific and Technical Information of China (English)

    Zheng Jingwu; Jiang Liqiang; Chen Qiaoling

    2006-01-01

    Electrochemical corrosion behavior of Nd-Fe-B sintered magnets in nitric acid, hydrochloric acid, sulfuric acid, phosphate acid and in oxalic acid was studied.Potentiodynamic polarization curves and immersion time dependence of corrosion rates of Nd-Fe-B sintered magnets in different acid solutions were tested.Microstructures of corroded Nd-Fe-B sintered magnets were investigated by means of SEM and AFM.The results indicate that in strong acid solutions of similar hydrogen ion concentration, the corrosion current increases in the order of HCl>H2SO4>HNO3 solution and Nd-Fe-B sintered magnets are passivated in phosphate acid and oxalic acid.Within 25 min, the corrosion rates of Nd-Fe-B sintered magnets in H2SO4 and H3PO4 solutions show a declining trend with immersion time, while in HNO3 and HCl solutions the corrosion rates are rising.And in H2C2O4 solution, weight of the magnets increases.The brim of Nd-Fe-B sintered magnets is corroded rather seriously and the size of the magnets changed greatly in nitric acid.The surfaces of the corroded magnets in the above mentioned acid solutions are all coarse.

  3. Protection of NdFeB magnets by corrosion resistance phytic acid conversion film

    Science.gov (United States)

    Nan, Haiyang; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2015-11-01

    Phytic acid conversion film was prepared on NdFeB magnets by dipping the NdFeB into phytic acid solution. The morphology, composition, structure and corrosion resistance of the film were systematically investigated. The results showed that the phytic acid film was effective in improving the corrosion resistance of NdFeB magnets. XRD, TEM and FT-IR analyses revealed that the film was amorphous and had a strong peak of phosphate radical (PO43-). The formation mechanism of the film was also explored by XPS and the potential of zero charge (Epzc) measurement at the solution-metal interface.

  4. Performance Prediction of Bonded NdFeB Permanent Magnet Based on Least Square Support Vector Machine%基于LS-SVM的粘结NdFeB永磁体磁性能预测

    Institute of Scientific and Technical Information of China (English)

    周胜海; 查五生; 王向中

    2012-01-01

    基于粘结NdFeB永磁体制备工艺优化实验,建立了一个最小二乘支持向量机(LS- SVM)算法模型用于工艺参数的优化.以粘结剂含量、固化温度、固化时间以及单位压制力大小四个工艺参数为影响因数,以剩余磁感应强度Br、矫顽力Hcj;和最大磁能积(BH)m为影响对象,通过最小二乘支持向量机算法模型建立起影响因素与影响对象之间的复杂的非线形关系.针对多影响对象,提出了一种γ和σ选择算法;以均匀设计试验结果为样本进行训练,用训练好的模型进行预测.结果表明,LS - SVM模型的实验结果与预测结果吻合良好,二者相对误差很小,对比ANN模型预测结果,LS - SVM模型具有更高的精度和运算速度,具有很好的实用性.%Based on the optimized preparation process of bonded NdFeB magnets, a least squares support vector machine model was built to optimize process parameters. With Binder content, thermosetting temperature, thermosetting time and pressure as influence factors, Br, Hcj and (BH) m as influence object, a new algorithm was proposed for selecting and , and Uniform Design experiment was taken to get data samples. Experimental results show that the relative error of magnetic properties between their measured value and predicted value are very small, and compared with ANN model, the prediction accuracy and prediction speed are much higher.

  5. Thermal aging of melt-spun NdFeB magnetic powder in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Pinkerton, Frederick E., E-mail: frederick.e.pinkerton@gm.com [Chemical and Materials Systems Laboratory, General Motors Research and Development Center, Warren, MI 48092 (United States); Balogh, Michael P.; Ellison, Nicole [Chemical and Materials Systems Laboratory, General Motors Research and Development Center, Warren, MI 48092 (United States); Foto, Aldo [Element Materials Technology Wixom, Inc (United States); Sechan, Martin; Tessema, Misle M.; Thompson, Margarita P. [Powertrain Materials/Fluids/AMPPD Engineering and Labs, GFL VE/PT Materials Engineering, General Motors LLC, Pontiac, MI 48340 (United States)

    2016-11-01

    High energy product neodymium-iron-boron (NdFeB) magnets are the premier candidate for demanding electrified vehicle traction motor applications. Injection molded (IM) or compression molded (CM) magnets made using NdFeB powders are promising routes to improve motor efficiency, cost, and manufacturability. However, IM and CM NdFeB magnets are susceptible to substantial thermal aging losses at motor operating temperatures when exposed to the automatic transmission fluid (ATF) used as a lubricant and cooling medium. The intrinsic coercivity H{sub ci} of NdFeB IM and CM magnets degrades by as much as 18% when aged for 1000 h in ATF at 150 °C, compared to a 3% loss when aged in air. Here we report aging studies of rapidly quenched NdFeB powder in air, ATF, and H{sub 2} gas. Expansion of the NdFeB crystal lattice in both ATF and H{sub 2} identified hydrogen dissociated from the ATF during aging and diffused into the primary NdFeB phase as the probable cause of the coercivity loss of IM and CM magnets. - Highlights: • Injection molded NdFeB magnets age rapidly in automatic transmission fluid (ATF). • Coercivity loss is not due to direct chemical reaction between ATF and the powder. • Chemical reaction with the binder does not play a major role in aging. • Hydrogen dissociates from ATF and diffuses into Nd{sub 2}Fe{sub 14}B, reducing coercivity.

  6. NdFeB磁性材料表面化学镀Ni-Cu-P实验研究%Electroless plating of Ni-Cu-P alloy on the surface of NdFeB permanent magnets

    Institute of Scientific and Technical Information of China (English)

    王憨鹰; 李增生; 李成荣; 陈焕铭

    2011-01-01

    In order to improve corrosion resistance of electroless plating Ni-Cu-P coating, plating bath and plating parameters of eletroless deposition of Ni-Cu-P alloy on the surface of NdFeB magnets was optimized by an orthogonal experiment. The optimal formula of electroless Ni-Cu-P plating bath was obtained as follows: 25 g/L of nickel sulfate, 0.4 g/L of copper sulfate, 35 g/L of sodium hypophosphite, 48 g/L of complexant, 50 g/L of buffering agent and pH value of 9. The effect of pH and CuSO4 ? 5H2O content in solution on plating rate and deposit composition was investigated. It is found that the plating rate and the copper and nickel contents of the deposit increase with increasing pH, while phosphorus content decreases; with increasing CuSO4?5H2O content in solution, the copper content of the deposit increases, while the phosphorus contents first increase and then decrease with a simultaneous decrease in the nickel content.%为提高Ni-Cu-P合金镀层的耐腐蚀性,采用正交试验法对NdFeB磁体表面化学镀Ni-Cu-P合金的镀液配方和施镀工艺进行优化,获得NdFeB磁体表面化学镀Ni-Cu-P合金的最佳成分配方为:硫酸镍25g/L,硫酸铜0.4 g/L,次亚磷酸钠35 g/L,络合剂48 g/L,缓冲剂50 g/L,pH值9.分析镀液pH值和镀液中CuS04·5H20浓度对沉积速度和镀层成分的影响.结果表明:随镀液pH值增加,沉积速度提高,镀层中Cu和Ni含量略升高,P含量逐渐降低;随镀液中CuS04·5H20浓度的增加,镀层中Cu含量升高,P含量先升高后降低,Ni含量降低.

  7. Influence of Segmentation of Ring-Shaped NdFeB Magnets with Parallel Magnetization on Cylindrical Actuators

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Eckert

    2014-07-01

    Full Text Available This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and to present a general overview of the influence of parallel magnetization by varying the number of segments and comparing the results with ideal radially magnetized rings. The analysis is first performed by modelling mathematically the radial and circumferential components of magnetization for both radial and parallel magnetizations, followed by an analysis carried out by means of the 3D finite element method. Results obtained from the models are validated by measuring radial and tangential components of magnetic flux distribution in the air gap on a prototype which employs magnet rings with eight segments each with parallel magnetization. The axial force produced by the actuator was also measured and compared with the results obtained from numerical models. Although this analysis focused on a specific topology of cylindrical actuator, the observed effects on the topology could be extended to others in which surface-mounted permanent magnets are employed, including rotating electrical machines.

  8. Influence of segmentation of ring-shaped NdFeB magnets with parallel magnetization on cylindrical actuators.

    Science.gov (United States)

    Eckert, Paulo Roberto; Goltz, Evandro Claiton; Flores Filho, Aly Ferreira

    2014-07-21

    This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and to present a general overview of the influence of parallel magnetization by varying the number of segments and comparing the results with ideal radially magnetized rings. The analysis is first performed by modelling mathematically the radial and circumferential components of magnetization for both radial and parallel magnetizations, followed by an analysis carried out by means of the 3D finite element method. Results obtained from the models are validated by measuring radial and tangential components of magnetic flux distribution in the air gap on a prototype which employs magnet rings with eight segments each with parallel magnetization. The axial force produced by the actuator was also measured and compared with the results obtained from numerical models. Although this analysis focused on a specific topology of cylindrical actuator, the observed effects on the topology could be extended to others in which surface-mounted permanent magnets are employed, including rotating electrical machines.

  9. Influence of Segmentation of Ring-Shaped NdFeB Magnets with Parallel Magnetization on Cylindrical Actuators

    Science.gov (United States)

    Eckert, Paulo Roberto; Goltz, Evandro Claiton; Filho, Aly Ferreira Flores

    2014-01-01

    This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and to present a general overview of the influence of parallel magnetization by varying the number of segments and comparing the results with ideal radially magnetized rings. The analysis is first performed by modelling mathematically the radial and circumferential components of magnetization for both radial and parallel magnetizations, followed by an analysis carried out by means of the 3D finite element method. Results obtained from the models are validated by measuring radial and tangential components of magnetic flux distribution in the air gap on a prototype which employs magnet rings with eight segments each with parallel magnetization. The axial force produced by the actuator was also measured and compared with the results obtained from numerical models. Although this analysis focused on a specific topology of cylindrical actuator, the observed effects on the topology could be extended to others in which surface-mounted permanent magnets are employed, including rotating electrical machines. PMID:25051032

  10. Statistical model of magnetization reversal in Nd-Fe-B sintered magnets

    Institute of Scientific and Technical Information of China (English)

    WANG Huijie; ZHU Minggang; LI Wei; ZHANG Xin

    2006-01-01

    Statistical model of magnetization reversal was used to simulate the magnetization reversal behavior in the sintered Nd-Fe-B magnets with double grain-size distributions due to the abnormal grain growth (AGG). The magnetic properties and mechanical properties due to the formation of AGG grains in Nd-Fe-B sintered magnets were tested. The results show that the magnetic properties, especially the rectangularity were severely deteriorated after the formation of the AGG grains and a step was shown on the demagnetization curve, and the occurrence of AGG mayaccount for the poor rectangularity and existence of the step on demagnetization curve according to the statistical model of magnetization reversal. The fracture toughness and bending strength are lowered because of the stress concentration in the AGG grains. The SEM images show that the formation of AGG grains is caused by the solid sintering due to the absence of RE-rich phase. Statistical model of magnetization reversal can qualitative by explain the dependence of the magnetization reversal behavior on the grain size in the Nd-Fe-B sintered magnets.

  11. Improved Electrical Insulation of Rare Earth Permanent Magnetic Materials With High Magnetic Properties

    Institute of Scientific and Technical Information of China (English)

    CHANG Ying; WANG Da-peng; LI Wei; PAN Wei; YU Xiao-jun; QI Min

    2009-01-01

    Rare earth permanent magnetic materials are typical electrical conductor, and their magnetic properties will decrease because of the eddy current effect, so it is difficult to keep them stable for a long enough time under a high frequency AC field. In the present study, as far as rare earth permanent magnets are concerned, for the first time, rare earth permanent magnets with strong electrical insulation and high magnetic performance have been obtained through experiments, and their properties are as follows:(1) Sm2TM17: Br=0.62 T, jHc=803.7 kA/m, (BH)m= The magnetic properties of Sm2TM17 and NdFeB are obviously higher than those of ferrite permanent magnet, and the electric insulating characteristics of Sm2TM17 and NdFeB applied have in fact been approximately the same as those of ferrite. Therefore, Sm2TM17 and NdFeB will possess the ability to take the place of ferrite under a certain high frequency AC electric field.

  12. Permanent magnet microstructures using dry-pressed magnetic powders

    Science.gov (United States)

    Oniku, Ololade D.; Bowers, Benjamin J.; Shetye, Sheetal B.; Wang, Naigang; Arnold, David P.

    2013-07-01

    This paper presents microfabrication methods and performance analysis of bonded powder permanent magnets targeting dimensions ranging from 10 µm to greater than 1 mm. For the structural definition and pattern transfer, a doctor blade technique is used to dry press magnetic powders into pre-etched cavities in a silicon substrate. The powders are secured in the cavities by one of the three methods: capping with a polyimide layer, thermal reflow of intermixed wax-binder particles, or conformal coating with a vapor-deposited parylene-C film. A systematic study of micromagnets fabricated using these methods is conducted using three different types of magnetic powders: 50 µm Nd-Fe-B, 5 µm Nd-Fe-B and 1 µm barium ferrite powder. The isotropic magnets are shown to exhibit intrinsic coercivities (Hci) as high as 720 kA m-1, remanences (Br) up to 0.5 T and maximum energy products (BHmax) up to 30 kJ m-3, depending on the magnetic powder used. Process compatibility experiments demonstrate the potential for the magnets to withstand typical microfabrication chemical exposure and thermal cycles, thereby facilitating their integration into more complex process flows. The remanences are also characterized at elevated temperatures to determine thermal sensitivities and maximum operating temperature ranges.

  13. Temperature stability and microstructure of ultra-high intrinsic coercivity Nd-Fe-B magnets

    Institute of Scientific and Technical Information of China (English)

    HU Zhihua; CHENG Xinghua; ZHU Minggang; LI Wei; LIAN Fazeng

    2008-01-01

    The variations of intrinsic coercivity and remanence of sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity were investigated.The results showed that the intrinsic coercivity and remanence declined simultaneously with increasing temperature,but the squareness of the magnets has hardly been changed.The temperature coefficients of remanence (α) and coercivity (β) for the magnets were calculated by two different methods,and the variations of the temperature coefficients and the microstructure of sintered Nd-Fe-B magnets were analyzed.The temperature coefficients of remanence (α) and coercivity (β) for the sintered magnets are very small,and the existence of free microstructure is necessary to obtain sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity.

  14. The attenuation of the levitation force of HTS bulk exposed to AC magnetic field on the above NdFeB guideway

    Science.gov (United States)

    Liu, Minxian; Wang, Yan

    2012-01-01

    In the present High Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets make the magnetic fields above the NdFeB guideway non-uniform. So it is required to study the characteristics of levitation force of the HTS bulk affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we have studied the characteristics of the levitation force relaxation by an experiment in which AC magnetic field generated by an electromagnet is used to simulate the time-varying magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it is found that the levitation force is attenuated with the application of the AC field, and the attenuation is increased with the amplitude of the AC field, but the attenuation is almost independent of the frequency the AC magnetic field.

  15. Bonded permanent magnets: Current status and future opportunities (invited)

    Science.gov (United States)

    Ormerod, John; Constantinides, Steve

    1997-04-01

    Permanent magnets play a vital role in modern society as a component in a wide range of devices utilized by many industries and consumers. In 1995, the world production of permanent magnets was estimated to be valued at 3.6 billion and growing at an annual rate of 12%. Bonded permanent magnets are the fastest growing segment of this market. Bonded magnet technology enables a wide variety of magnetic powders to be combined with several polymer and binder systems to produce magnetic components utilizing several processing options. In this article, we review the development of bonded magnet technology. The major classes of magnetic powders, binder systems, and processing technologies are described. Recent developments in magnetic material grades, e.g., anisotropic NdFeB, rare earth lean NdFeB, SmFe(N,C) are outlined. The current status of processing and binder options aimed at increasing the upper application temperature limit of these materials is highlighted. Finally, the improvements and future opportunities for bonded magnets are discussed.

  16. Enduring Attraction: America’s Dependence On and Need to Secure Its Supply of Permanent Magnets

    Science.gov (United States)

    2012-10-01

    high technology businesses, especially the defense industry. They combine with other elements (specifically iron, boron, and cobalt ) to make...exceptional permanent magnets. Samarium- cobalt (SmCo) magnets have the highest known resistance to demagnetization.13 This capability, meaning the magnet...an equal mass of traditional ferrite magnet, an NdFeB magnet has over 10 times the magnetic energy product.14 Accordingly, a much smaller amount of

  17. The Behavior Of Asymmetric Frontal Couplings With Permanent Magnets In Magnetic Powder And High Temperature Environments

    Directory of Open Access Journals (Sweden)

    Ion DOBROTA

    2002-12-01

    Full Text Available The main purpose of this paper is the comparative analysis of the behavior of frontal couplings with Nd-Fe-B permanent magnets in difficult environments, specific to metallurgy – such as environments with magnetic powders and high temperature – in two constructive variants: symmetric couplings and asymmetric couplings (with divided poles. The results show the superior performance of asymmetric couplings under the given conditions

  18. Hydrogen Embrittlement Processes and Al/Al2O3 Hydrogen Resistance Coatings of NdFeB Magnets

    Institute of Scientific and Technical Information of China (English)

    张万里; 彭斌; 蒋洪川; 张文旭; 杨仕清

    2004-01-01

    After analyzing the phenomena and processes of hydrogen embrittlement of NdFeB permanent magnets,RF magnetron sputtering was used to fabricate Al thin films and then oxidized to form the Al/Al2O3 composite films on the magnets as the hydrogen resistance coatings.SEM and EDS were used to examine the morphology and composition respectively.Hydrogen resistance performance was tested by exposing the magnets in 10 MPa hydrogen gas at room temperature.The results show that the magnets with 8 μm Al/Al2O3 coatings can withstand hydrogen of 10 MPa for 65 min without being embrittled into powder.The samples with and without hydrogen resistance coatings have almost the same magnetic properties.

  19. Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process

    Directory of Open Access Journals (Sweden)

    Wenfeng Liu

    2017-01-01

    Full Text Available Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100 substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and perpendicular coercivities firstly drastically increase and then slowly decrease with NdFeB layer thickness increasing. The highest in-plane and perpendicular coercivities can be obtained at NdFeB layer thickness of 750 nm, which are 21.2 kOe and 19.5 kOe, respectively. In addition, the high remanence ratio (remanent magnetization/saturation magnetization of 0.87 can also be achieved in Ta/Nd/NdFeB (750 nm/Nd/Ta film.

  20. Additive Manufacturing of Near-net Shaped Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans [ORNL

    2016-07-26

    The technical objective of this technical collaboration phase I proposal is to fabricate near net-shaped permanent magnets using alloy powders utilizing direct metal deposition technologies at the ORNL MDF. Direct Manufacturing using the POM laser system was used to consolidate Nd2Fe14B (NdFeB) magnet powders into near net-shape parts efficiently and with virtually no wasted material as part of the feasibility study. We fabricated builds based on spherical NdFeB magnet particles. The results show that despite the ability to fabricate highly reactive materials in the laser deposition process, the magnetic coercivity and remanence of the NdFeB hard magnets is significantly reduced. X-ray powder diffraction in conjunction with electron microscopy showed that the material experienced a primary Nd2Fe17Bx solidification due to the undercooling effect (>60K). Consequently the presence of alpha iron phase resulted in deterioration of the build properties. Further optimization of the processing parameters is needed to maintain the Nd2Fe14B phase during fabrication.

  1. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  2. Magnetic properties and thermal stability of anisotropic bonded Nd-Fe-B magnets by warm compaction

    Institute of Scientific and Technical Information of China (English)

    TAO Siwu; LU Xin; TIAN Jianjun; QU Xuanhui; Y. Honkura; H. Mitaraib; K. Noguchi

    2009-01-01

    Anisotropic bonded magnets were prepared by warm compaction using anisotropic Nd-Fe-B powder. The forming process, magnetic properties, and temperature stability were studied. The results indicate that the optimal temperature of the process, which was decided by the viscosity of the binders, was 110℃. With increasing pressure, the density of the magnets increased. When the pressure was above 700 MPa, the powder particles were destroyed and the magnetic properties decreased. The magnetic properties of the anisotropic bonded magnets were as follows: remanence Br = 0.98 T, intrinsic coercivity iHc=1361 kA/m, and maximum energy product BHmax = 166 kJ/m3. The magnets had excellent thermal stability because of the high coercivity and good squareness of demagnetization curves. The flux density of the magnets was 35% higher than that of isotropic bonded Nd-Fe-B magnets at 120℃ for 1000 h. The flux density of the bonded magnets showed little change with regard to temperature.

  3. Microstructure of explosively compacted Nd-Fe-B magnet by TEM

    Institute of Scientific and Technical Information of China (English)

    AO Qi; LIU Wei; CAO Li-jun; WU Jian-sheng

    2005-01-01

    The microstructure of an explosively compacted Nd-Fe-B permanent magnet(Nd-Fe-B) was investigated by means of TEM and XRD. It is shown that there are three kinds of phases: Nd2 Fe14 B matrix phase, O-rich phases and Nd-rich phase with different structures and compositions in the magnet. The hard magnetic phase Nd2 Fe14 B is tetragonal, which lattice parameters are determined to be a=0. 88 nm and c= 1.22 nm. The O-rich phase locates at the grain boundaries and the triple junctions has fcc structure whose lattice parameter is a=0. 559 nm. A dislocation is observed in this phase. It is also found that a large number of the block-shaped Nd-rich phases with hcp structure are embedded in the Nd2 Fe14B matrix or at grain boundary. Their lattice parameters are determined to be a=0. 395 nm and c=0.628 nm.

  4. Magnetic Microstructure of Sintered Nd-Fe-B Magnets Made from Casting Strips

    Institute of Scientific and Technical Information of China (English)

    FANG Yi-Kun; ZHU Ming-Gang; GUO Yong-Quan; LI Wei; HAN Bao-Shan

    2004-01-01

    @@ The magnetic microstructures of two Dy-Al substituted sintered Nd-FeB magnets with the different nominal compositions of Nd12.2Dy0.6Fes0.4Al0. 7B6 (at. %) (composition-A, C-A) and Nd13.7Dy0.6Fe78.8Al0.7B6.2 (at. %)(composition-B, C-B) prepared by strip casting technique have been revealed by using a magnetic force microscope.

  5. Enhanced magnetic properties in Nd-Fe-B magnets prepared by spark plasma sintering via die-upsetting process

    Institute of Scientific and Technical Information of China (English)

    HU Zhihua; CHU Linhua; LI Jun; LIU Ying

    2011-01-01

    The magnetic properties and microstructure of Nd-Fe-B magnets prepared by spark plasma sintering with different die-upsetting processes were investigated.The results showed that the optimum magnetic properties of die-upset Nd-Fe-B magnets were obtained at 680 ℃ when the die-upset level was 60%,and the degree of magnetic alignment was 0.84.The microstructures showed that the coarse grains occurred predominantly within certain areas,and abnormal grain growth was not observed within the major areas of well-aligned grains.There existed many small spherical grains,which stacked together and were not aligned during die upsetting when the deformation temperature was 650 ℃.These small spherical grains grew up,and were aligned when the deformation temperature increased from 650 to 680 ℃,which could improve the crystallographic alignment of die-upset Nd-Fe-B magnets.

  6. Material Flow Analysis of NdFeB magnets for Denmark: A comprehensive waste flow sampling and analysis approach

    DEFF Research Database (Denmark)

    Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter

    2014-01-01

    Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key Rare Earth Elements (REEs) i.e. neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets allowing for consider......Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key Rare Earth Elements (REEs) i.e. neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets allowing...... of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global level by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products...

  7. Factors Affecting the Squareness of Hysteresis Loops of Sintered NdFeB Magnets

    Institute of Scientific and Technical Information of China (English)

    Wang Zhanyong; Wang Xianying; Jin Minglin

    2007-01-01

    Investigation into the magnets with different squareness of hysteresis loop (SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deteriorates the SHL seriously. The shape of the grain and the grain boundary affect the intensity of demagnetization field, and consequently on the SHL. The added elements have effects on the phase structures and distributions in the magnets, which influences the uniform of demagnetization field.

  8. Laboratory scale fabrication of Nd-Fe-B sintered magnets; Fabricacao de imas sinterizados de Nd-Fe-B em escala piloto

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Daniel; Beneduce Neto, Flavio; Landgraf, Fernando Jose Gomes; Neiva, Augusto Camara; Romero, Sergio; Missell, Frank Patrick

    1992-12-31

    Results are presented on magnetic properties of Nd-Fe-B sauntered magnets produced from 1 kg of alloy caste in vacuum induction furnace. The fabrication viability of these magnets, with properties similar to the commercial magnets, and the influence of particle size in the energy product, through the effect on the H{sub k} field, is confirmed 12 refs., 7 figs., 1 tab.

  9. Recycle for Sludge Scrap of Nd-Fe-B Sintered Magnet as Isotropic Bonded Magnet

    Institute of Scientific and Technical Information of China (English)

    Masahiro Itoh; Masahiro Masuda; Shunji Suzuki; Ken-ichi Machida

    2004-01-01

    The reduction diffusion method was performed for the sludge scrap of Nd-Fe-B sintered magnets with adding Ca metal to recover the oxidized Nd-Fe-B phase. After washing the resultant powders to remove Ca metal component, the powders obtained were recycled as an isotropic magnetic powder by the melt spinning method. The magnetic properties of powders as recycled were inferior, especially for the coercivity value, due to the deletion of rare earth metals during the washing process. The adjustment of metal composition, i.e., the addition of Nd metal, at the melt spinning process improved the magnetic properties to be Br=~0.75 T, Hcj=~0.93 mA·m-1, and(BH)max=~91 kJ·m-3. The magnetic properties of the bonded magnets prepared from the composition-adjusted powders were Br=~0.66 T, Hcj=~0.92 mA·m-1, and(BH)max=~70 kJ·m-3, which are approximately comparable to the commercially available MQPB boned one(Br=~0.73 T, Hcj=~0.79 mA·m-1, and(BH)max=~86 kJ·m-3).

  10. Improved Nonambipolar Electron Source Operation with Permanent Magnets

    Science.gov (United States)

    Gudmundson, Jesse; Hershkowitz, Noah

    2008-11-01

    The Nonambipolar Electron Source (NES) is a Radio Frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface. All electrons are extracted at an electron sheath through a biased ring and all ions are lost radially to a biased Faraday shield. An electromagnet in the original NES has been replaced by a NdFeB permanent magnet array. A portion of the magnet array consists of a ring of radially aligned magnets followed by a ring of axially aligned magnets that produce a peak field of approximately 800 Gauss. Axial magnetic field strength at the extraction ring was increased using an additional ring of axially aligned magnets. Measurement of the magnetic field was in good agreement with field predicted by the FEMM (Finite Element Method Magnetics) code. Optimization of the single turn antenna and biased ring position in the magnetic field will be discussed. At least 15 A of electron current was extracted using a flow rate of 15 sccm Ar at 600 W of rf power at 13.56 MHz. For comparison, the original NES required 1200 W of power to achieve 15 A of extracted current. Compared to the previous coil design, the NdFeB magnets are lighter weight and require no power.

  11. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...

  12. Magnetostrictions and Magnetic Properties of Nd-Fe-B and SrFe12019

    Institute of Scientific and Technical Information of China (English)

    CHEN Hai-Ying; ZHANG Yan; YANG Yun-Bo; CHEN Xue-Gang; LIU Shun-Quan; WANG Chang-Sheng; YANG Ying-Chang; YANG Jin-Bo

    2011-01-01

    The magnetostrictions of polycrystalline Nd-Fe-B and Sr-ferrite at different temperatures are reinvestigated using a strain gauge rotating-sample method.It is found that the magnetostriction λs of Nd-Fe-B is +52× 10-6,and that of Sr-ferrite is -25×10-6 under a magnetic field of 8 T at room temperature.The maximum energy product (BH)max of the Nd-Fe-B magnet is improved when the powders are magnetically aligned perpendicular to the pressing direction,whereas that of the Sr-ferrite magnet is better when the powders are aligned parallel to the pressing direction.These experimental results suggest that the magnetostriction can generate compressive strain anisotropy resulting from the inverse effect of the magnetostriction.Thus,the magnetization of materials with a negative coefficient of magnetostriction are easier to be aligned normal to the stress direction,while for the materials with a positive coefficient of magnetostriction,the magnetization is easier to be aligned along the stress direction. Therefore,the magnetostriction anisotropy can be used to improve the alignment of the magnetic powders as well as the performance of the magnets.

  13. Binder Jetting: A Novel NdFeB Bonded Magnet Fabrication Process

    Science.gov (United States)

    Paranthaman, M. Parans; Shafer, Christopher S.; Elliott, Amy M.; Siddel, Derek H.; McGuire, Michael A.; Springfield, Robert M.; Martin, Josh; Fredette, Robert; Ormerod, John

    2016-07-01

    The goal of this research is to fabricate near-net-shape isotropic (Nd)2Fe14B-based (NdFeB) bonded magnets using a three dimensional printing process to compete with conventional injection molding techniques used for bonded magnets. Additive manufacturing minimizes the waste of critical materials and allows for the creation of complex shapes and sizes. The binder jetting process works similarly to an inkjet printer. A print-head passes over a bed of NdFeB powder and deposits a polymer binding agent to bind the layer of particles together. The bound powder is then coated with another layer of powder, building the desired shape in successive layers of bonded powder. Upon completion, the green part and surrounding powders are placed in an oven at temperatures between 100°C and 150°C for 4-6 h to cure the binder. After curing, the excess powder can be brushed away to reveal the completed "green" part. Green magnet parts were then infiltrated with a clear urethane resin to achieve the measured density of the magnet of 3.47 g/cm3 close to 46% relative to the NdFeB single crystal density of 7.6 g/cm3. Magnetic measurements indicate that there is no degradation in the magnetic properties. This study provides a new pathway for preparing near-net-shape bonded magnets for various magnetic applications.

  14. Investigation of Optimal Megnetic Properties in NdFeB Magnets by Artificial Neural Network

    Institute of Scientific and Technical Information of China (English)

    Lian Lixian; Liu Ying; Hu Wang; Hou Tinghong; Gao Shengji; Tu Mingjing

    2004-01-01

    In order to study the effect of alloy component on magnetic properties of NdFeB magnets, the experiment schemes are carried out by the uniform design theory, and the relationship between the component and the magnetic properties is established by artificial neural network(ANN) predicting model.The element contents of alloys are optimized by the ANN model.Meanwhile, the influences of mono-factor or multi-factor interaction on alloy magnetic properties are respectively discussed according to the curves ploted by ANN model.Simulation result shows that the predicted and measured results are in good agreement.The relative error is every low, the error is not more than 1.68% for remanence Br, 1.56% for maximal energy product (BH)m, and 7.73% for coercivity Hcj.Hcj can be obviously improved and Br can be reduced by increasing Nd or Zr content.Co and B have advantageous effects on increasing Br and disadvantageous effects on increasing Hcj.Influence of alloying elements on Hcj and Br are inverse, and the interaction among the alloying elements play an important role in the magnetic properties of NdFeB magnets.The ANN prediction model presents a new approach to investigate the nonlinear relationship between the component and the magnetic properties of NdFeB alloys.

  15. Magnetic Properties of Nd-Fe-B Sintered Magnet Powders Recovered by Yb Metal Vapor Sorption

    Institute of Scientific and Technical Information of China (English)

    Horikawa T; Itoh M; Suzuki Shunji; Machida K

    2004-01-01

    Fine ground powders of Nd-Fe-B sintered magnet bulks(particle size=46~125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders(remanence Br=~0.95 T, coercivity Hcj =~227 kA·m-1 and maximum energy product(BH)max=~48.8 kJ·m-3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the Br, Hcj and(BH)max values were increased to be 0.98 T, 712 kA·m-1 and 173 kJ·m-3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction(XRD), scanning electron microscopy(SEM), and electron probe X-ray microanalyzer(EPMA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a(Nd,Yb)Fe2 phase.

  16. A Practical Permanent Magnetic Motor Drive for Hybrid Motorcycle

    Institute of Scientific and Technical Information of China (English)

    崔巍; 江建中; 邵定国; 杨斌

    2003-01-01

    A novel embedded-type permanent magnetic motor for hybrid motorcycle, which employs asymmetric design of eccentric air-gap, is proposed in the paper. This special design of air-gap well conforms to the mono-directional operation characteristic of motorcycle and effectively suppresses the distortion of air-gap magnetic field caused by armature reaction. Hence the torque ripple is reduced. A drive system consisting of the newly-designed Nd-Fe-B permanent magnet synchronous motor and parallel-MOSFET threephase inverter for hybrid motorcycle propulsion is established. Wide-range speed operation is realized through a simple and novel control strategy. Computer simulation is described and experimental results given to verify the practicality of the proposed motor design and control strategy.

  17. Development of permanent magnetic refrigerator at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Jiaohong; LIU Jinrong; JIN Peiyu; YAN Hongwei; QIU Jufeng; XU Laizi; ZHANG Jiuxing

    2006-01-01

    A reciprocating magnetic refrigerator was developed based on the active magneticregeneration technology. Rare earth metal Gd and intermetallic compound LaFe11.2Co0.7Si1.1 were used as the magnetic operating materials in the machine. The particles of the magnetic operating materials, with diameter of 0.5- 2 mm and total mass of 950 g, were mounted in the cooling bed. A magnetic field was assembled using NdFeB rare earth permanent magnets. It had the magneticfield space of Φ 34×200 and the magnetic induction of 1.5 T. The water at pH=10 is used as a heat transfer fluid. When the ambient temperature is 296 K, a temperature span of 18 K was achieved after operation of 45 min at a frequency of 0.178 Hz. The temperature span and the output power increase significantly with the increasing velocity of heat transfer.

  18. NdFeB Residue to Be Recycled

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ NdFeB is a permanent magnetic material with excellent performances. It is widely used in electronics and communications. Around 30% of rare earth elements (among which 90% is Nd, others are Tb and Dy) and 2-3% of Co element are contained in the material. NdFeB plays an important role in the development of our society and our economy.

  19. Effects of Fe fine powders doping on hot deformed NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Min, E-mail: linm@nimte.ac.cn [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China); Wang, Huijie [Ningbo Jinji Strong Magnetic Material Company, Ningbo 315041 (China); Zheng, Jingwu [Zhejiang University of Technology, Hangzhou 310014 (China); Yan, Aru [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China)

    2015-04-01

    The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The B{sub r} and the (BH){sub max} get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase. - Highlights: • The doped Fe powders have little influence on the c-axis alignment of magnets. • The elongated Fe powders are more than the spherical Fe powders in the magnets. • The corrosion resistance is improved effectively with the increasing Fe fraction. • The bending strength is enhanced by the elongated α-Fe phase embedded in the matrix.

  20. Electromagnetic acceleration of permanent magnets

    CERN Document Server

    Dolya, S N

    2015-01-01

    We consider the acceleration of the permanent magnets, consisting of neodymium iron boron by means of the running magnetic field gradient. It is shown that the specific magnetic moment per nucleon in neodymium iron boron is determined by the remained magnetization of the substance. The maximum accessable gradient of the magnetic field accelerating the permanent magnets is determined by the coercive force thirty kilogauss. For the neodymium iron boron magnets this gradient is equal to twenty kilogauss divided by one centimeter. The finite velocity of the magnets six kilometers per second, the length of acceleration is six hundred thirty-seven meters.

  1. Production of NdFeB powders by HDDR from sintered magnets; Obtencao de pos de NdFeB por HDDR a partir de imas sinterizados

    Energy Technology Data Exchange (ETDEWEB)

    Janasi, S.R.; Rodrigues, D.; Landgraf, F.J.G. [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil). Lab. de Metalurgia e Materiais Ceramicos; Silva, B.F.A. da; Takiishi, H [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Campos, M.F. de [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2010-07-01

    The production of NdFeB powders by the HDDR process from metallic alloys has been widely investigated. Different HD and DR conditions have been used to induce anisotropy and to improve the intrinsic coercivity of the obtained powders. The purpose of this study is to apply the HDDR process in the reprocessing of NdFeB sintered magnet scraps. There were investigated different processing conditions as temperature and time of desorption and recombination (DR). The results of X ray diffraction show the formation of the magnetic phase Nd{sub 2}Fe{sub 14}B in all the investigated conditions. Magnetic measurements by vibrating sample magnetometer indicate that powders with intrinsic coercivity up to 790 kA/m were obtained. (author)

  2. Lodestone: Nature's own permanent magnet

    Science.gov (United States)

    Wasilewski, P.

    1976-01-01

    Magnetic hysteresis and microstructural details are presented which explain why the class of magnetic iron ores defined as proto-lodestones, can behave as permanent magnets, i.e. lodestones. Certain of these proto-lodestones which are not permanent magnets can be made into permanent magnets by charging in a field greater than 1000 oersted. This fact, other experimental observations, and field evidence from antiquity and the middle ages, which seems to indicate that lodestones are found as localized patches within massive ore bodies, suggests that lightning might be responsible for the charging of lodestones. The large remanent magnetization, high values of coercive force, and good time stability for the remanent magnetization are all characteristics of proto-lodestone iron ores which behave magnetically as fine scale ( 10 micrometer) intergrowths when subjected to magnetic hysteresis analysis. The magnetic results are easily understood by analysis of the complex proto lodestone microstructural patterns observable at the micrometer scale and less.

  3. Quantum Hall effect in epitaxial graphene with permanent magnets

    Science.gov (United States)

    Parmentier, F. D.; Cazimajou, T.; Sekine, Y.; Hibino, H.; Irie, H.; Glattli, D. C.; Kumada, N.; Roulleau, P.

    2016-12-01

    We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.

  4. Temperature stability and fracture toughness of Nd-Fe-B magnets

    Institute of Scientific and Technical Information of China (English)

    LI Ying; QI Yuxuan; LI Xiumei

    2006-01-01

    Temperature stability and toughness of magnets are very important properties especially for application in motor. In this paper, it is found that temperature stability and toughness of magnets are improved when Fe is substituted with Co andheavy rare earth is substituted for Nd in part and suitable rich B grain-boundary phase is added. In addition, heavy rare earth substitution decreases the remanence temperature coefficient greatly, but has a little effect on Curie temperature of the magnets, which is beneficial to Nd-Fe-B magnets for the application in motor.

  5. Material flow analysis of NdFeB magnets for Denmark: a comprehensive waste flow sampling and analysis approach.

    Science.gov (United States)

    Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter; Dall, Ole; Wenzel, Henrik

    2014-10-21

    Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key rare earth elements (REEs), i.e., neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets, allowing for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of a secondary supply of neodymium and dysprosium from recycling of NdFeB magnets. For this purpose, material flow analysis (MFA) has been carried out to perform the detailed mapping of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global levels by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products representing 18 various product types. The results show that the current amount of neodymium and dysprosium in NdFeB magnets present in the Danish waste stream is only 3 and 0.2 Mg, respectively. However, this number is estimated to increase to 175 Mg of neodymium and 11.4 Mg of dysprosium by 2035. Nevertheless, efficient recovery of these elements from a very diverse electronic waste stream remains a logistic and economic challenge.

  6. Effect of FeGa{sub 3} powder addition on the magnetic properties of NdFeB sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, T.S.; Kim, Y.B.; Jeung, W.Y.

    1999-09-01

    NdFeB sintered magnets with the addition of various amounts of FeGa{sub 3} powder were prepared by blending during the ball milling process. The magnetic properties and microstructure of the NdFeB magnets were studied. It was found that the addition of 0.1--0.2 wt.% FeGa{sub 3} powder increases the coercivity of the magnets without reducing the remanence. The improvement in coercivity by the addition of FeGa{sub 3} powder may be related to the formation of a Nd{sub 6}Fe{sub 14{minus}x}Ga{sub x} (x {approx{underscore}equal} 1) intergranular phase in the magnets.

  7. Identification and recovery of rare-earth permanent magnets from waste electrical and electronic equipment.

    Science.gov (United States)

    Lixandru, A; Venkatesan, P; Jönsson, C; Poenaru, I; Hall, B; Yang, Y; Walton, A; Güth, K; Gauß, R; Gutfleisch, O

    2017-10-01

    Nd-Fe-B permanent magnets are a strategic material for a number of emerging technologies. They are a key component in the most energy efficient electric motors and generators, thus, they are vital for energy technologies, industrial applications and automation, and future forms of mobility. Rare earth elements (REEs) such as neodymium, dysprosium and praseodymium are also found in waste electrical and electronic equipment (WEEE) in volumes that grow with the technological evolution, and are marked as critical elements by the European Commission due to their high economic importance combined with significant supply risks. Recycling could be a good approach to compensate for the lack of rare earths (REs) on the market. However, less than 1% of REs are currently being recycled, mainly because of non-existing collection logistics, lack of information about the quantity of RE materials available for recycling and recycling-unfriendly product designs. To improve these lack of information, different waste streams of electrical and electronic equipment from an industrial recycling plant were analyzed in order to localize, identify and collect RE permanent magnets of the Nd-Fe-B type. This particular type of magnets were mainly found in hard disk drives (HDDs) from laptops and desktop computers, as well as in loudspeakers from compact products such as flat screen TVs, PC screens, and laptops. Since HDDs have been investigated thoroughly by many authors, this study focusses on other potential Nd-Fe-B resources in electronic waste. The study includes a systematic survey of the chemical composition of the Nd-Fe-B magnets found in the selected waste streams, which illustrates the evolution of the Nd-Fe-B alloys over the years. The study also provides an overview over the types of magnets integrated in different waste electric and electronic equipment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The attenuation of the levitation force of HTS bulk exposed to AC magnetic field on the above NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Liu Minxian, E-mail: liukey_sjtu@263.net [School of Computer Science and Technology, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Wang Yan [Luoyang Institute of Science and Technology, Luoyang, Henan 471023 (China)

    2012-01-15

    The characteristic of the levitation force relaxation was studied by experiment. The levitation force is attenuated with the application of the AC external magnetic field. The decay increases with the amplitude of the A external magnetic field. The decay is almost independent of the frequency of AC field. In the present High Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets make the magnetic fields above the NdFeB guideway non-uniform. So it is required to study the characteristics of levitation force of the HTS bulk affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we have studied the characteristics of the levitation force relaxation by an experiment in which AC magnetic field generated by an electromagnet is used to simulate the time-varying magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it is found that the levitation force is attenuated with the application of the AC field, and the attenuation is increased with the amplitude of the AC field, but the attenuation is almost independent of the frequency the AC magnetic field.

  9. Modification of the Interface Nanostructure and Magnetic Properties in Nd-Fe-B Thin Films.

    Science.gov (United States)

    Koike, Kunihiro; Kusano, Takanao; Ogawa, Daisuke; Kobayashi, Keisuke; Kato, Hiroaki; Oogane, Mikihiko; Miyazaki, Takamichi; Ando, Yasuo; Itakura, Masaru

    2016-12-01

    The effects of Nd2Fe14B grain size and Nd coating on the coercivity in sputter-deposited Nd-Fe-B/Nd thin films have been investigated in order to gain an insight into the coercivity mechanism of Nd-Fe-B magnets. Highly textured Nd2Fe14B particles were grown successfully on the MgO(100) single-crystal substrate with the Mo underlayer. As the Nd-Fe-B layer thickness t NFB was decreased from 70 to 5 nm, the coercivity H c increased gradually from 6.5 to 16 kOe. By depositing the Nd overlayer onto these films and post-annealing at 500 °C, the H c value further increased from 17.5 kOe (t NFB=70 nm) to 26.2 kOe (t NFB=5 nm). The amount of H c increase by the combination of the Nd coating and post-annealing was about 10 kOe irrespective of the t NFB value. These results therefore suggest an independence of size and interface effects on the coercivity of Nd-Fe-B magnets.

  10. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Directory of Open Access Journals (Sweden)

    Grujić Aleksandar

    2005-01-01

    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

  11. Magnetic Fields: Visible and Permanent.

    Science.gov (United States)

    Winkeljohn, Dorothy R.; Earl, Robert D.

    1983-01-01

    Children will be able to see the concept of a magnetic field translated into a visible reality using the simple method outlined. Standard shelf paper, magnets, iron filings, and paint in a spray can are used to prepare a permanent and well-detailed picture of the magnetic field. (Author/JN)

  12. Magnetic Field Analysis of Interior Composite-Rotor Controllable-Flux Permanent Magnet Synchronous Machine

    Institute of Scientific and Technical Information of China (English)

    CHEN Yiguang; PAN Wei; SHEN Yonghuan; TANG Renyuan

    2006-01-01

    Conventional permanent magnet synchronous machine(PMSM)has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets(PMs)are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current id, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.

  13. Magnetovisual method for monitoring thermal demagnetization of permanent magnets used in magnetostrictive actuators

    Institute of Scientific and Technical Information of China (English)

    J. Kaleta; P. Wiewiórski

    2014-01-01

    The design and measuring potential of the latest generation of the magnetic scanner called Magscanner-Maglab System (MMS) was presented. It enabled the fast acquisition of 3D signals from magnetic sensors and their visualization as digitalized mag-netic images. This system was used for monitoring of a thermal demagnetization process of permanent magnets. The original method and measurement devices were capable for examination of magnetic, mechanical and thermal defects in cylindrical rods made of NdFeB and non-rare earth components. Effectiveness of the method and device was tested for the reference demagnetized magnet dedicated for magnetostrictive actuators.

  14. Regeneration of waste sintered Nd-Fe-B magnets to fabricate anisotropic bonded magnets

    Institute of Scientific and Technical Information of China (English)

    李现涛; 岳明; 刘卫强; 张东涛; 左铁镛

    2015-01-01

    The waste sintered Nd-Fe-B magnets were regenerated as magnetic powders via manually crushing (MC) or hydrogen de-crepitation (HD) to fabricate anisotropic bonded magnets. Effect of size distribution on the magnetic properties of the regenerated magnetic MC and HD powders was investigated. For the MC powders, as the particle size decreased, the remanence (Br) increased first, and then decreased again, while the coercivity (Hci) dropped monotonically. The powders with particle size in the range of 200–450μm possessed the best magnetic properties ofBr of 1.22 T andHci of 875.6 kA/m. The corresponding bonded magnet exhibited magnetic properties ofBr of 0.838 T,Hci of 940.9 kA/m, and (BH)max of 91.4 kJ/m3, respectively. On the other hand, the HD powders with particle size range of 200-450μm bore the best magnetic properties ofBr of 1.24 T andHci of 860.4 kA/m. Compared with magnetic proper-ties of the waste magnet, the powders retained 93.9% ofBr and 70.0% ofHci, respectively. The bonded magnet produced from HD powders possessedBr of 0.9 T,Hci of 841.4 kA/m, and (BH)max of 111.6 kJ/m3, indicating its good potential in practical applications.

  15. Isotropic and anisotropic nanocrystalline NdFeB bulk magnets prepared by binder-free high-velocity compaction technique

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xiangxing [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Zhongwu, E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Hongya [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Xiao, Zhiyu [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang, Guoqing [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China)

    2015-09-15

    NdFeB powders were consolidated into nanocrystalline bulk magnets by a near-net-shape process of high-velocity compaction (HVC) at room temperature with no binder employed. The nanostructure can be maintained after compaction. The compacted magnets with relatively high density can inherit the coercivity of the starting powders. The mechanical strength of the HVCed magnet after heat treatment is comparable to that of the conventional bonded NdFeB magnets. The anisotropic magnet has also been prepared by hot deformation using HVCed magnet as the precursor. The remanence value along the pressing direction increased from 0.64 to 0.95 T and maximum energy product (BH){sub max} increased from 65 to 120 kJ/m{sup 3} after hot deformation. The processing–structure–properties relationships for both isotropic and anisotropic magnets are discussed. - Highlights: • HVC is a feasible binder-free approach for preparing NdFeB magnets. • The compacted magnets can inherit the coercivity of the starting powders. • The magnets post heat treatment have compression strength higher than bonded magnets. • The approach of HVC is a potential pre-process for anisotropic NdFeB bulk magnets.

  16. Enhanced method of magnetic powder alignment for production of PLP Nd-Fe-B magnets

    Science.gov (United States)

    Popov, A. G.; Golovnia, O. A.; Protasov, A. V.

    2017-04-01

    It is demonstrated how the high degree of powder alignment in PLP magnets can be achieved by loading the powder into a container placed in a magnetic field of moderate strength. The strip-cast alloy with a composition of 30.00 Nd, 1.95 Dy, 66.42 Fe, 0.99 B, 0.54 Co, 0.1 Ga (wt%) was subjected to hydrogen decrepitation and then milled in a vibratory mill in toluene to an average particle size of 2.9 μm determined by the FSSS method. The powder was compacted in the magnetic field of 0.2 - 1.2 T to the filling density 2.6 - 3.2×103 kg/m3. It is shown that loading the powder into a container placed in a magnetic field enhances the degree of powder alignment in sintered Nd-Fe-B magnets produced from non-pressed powder. At the filling density less than 3.2×103 kg/m3, the density of magnets is high but insufficient, because of the formation of magnetostatic chains of particles, which impedes the powder compaction. The simulation by the discrete-element method qualitatively proves that the magnetostatic interaction of the chains of particles that are formed in the course of loading in the magnetic field stimulates a decrease in the density of the sintered magnets and its non-uniform distribution over the sample. As a result of the optimization of the parameters of the alignment and compaction of the powder loaded in a magnetic field, PLP magnets with Br ≥1.34 T, Нc ≥950 kA/m, (BH)max ≥340 kJ/m3, and the degree of alignment exceeding 96% were produced.

  17. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, S., E-mail: ohashi@ipcku.kansai-u.ac.j [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan); Kobayashi, S. [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-10-15

    Magnetic levitation using the pinning force of the YBaCuO high-T{sub c} bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  18. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Science.gov (United States)

    Ohashi, S.; Kobayashi, S.

    2009-10-01

    Magnetic levitation using the pinning force of the YBaCuO high- Tc bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  19. Influence of dysprosium substitution on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method

    Institute of Scientific and Technical Information of China (English)

    胡志华; 瞿海锦; 马冬威; 罗成; 王会杰

    2016-01-01

    The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi-tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blend-ing two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sin-tered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the in-crease in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase dur-ing sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.

  20. Manganese-based Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Ian Baker

    2015-08-01

    Full Text Available There is a significant gap between the energy product, BH, where B is the magnetic flux density and H is the magnetic field strength, of both the traditional ferrite and AlNiCo permanent magnets of less than 10 MGOe and that of the rare earth magnets of greater than 30 MGOe. This is a gap that Mn-based magnets could potentially, inexpensively, fill. This Special Issue presents work on the development of both types of manganese permanent magnets. Some of the challenges involved in the development of these magnets include improving the compounds’ energy product, increasing the thermal stability of these metastable compounds, and producing them in quantity as a bulk material.[...

  1. Overview on permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Permanent magnetic actuator (PMA), as a new electronic actuator of vacuum circuit breakers, certainly will be used to replace the traditional mechanical actuator. It has such advantages as simple structure, high reliability, free maintenance, and so on. This paper summarizes the development, structure, magnetic analysis, character analysis, and control strategy of PMA, and also predicts the future trend of PMA development

  2. Topology optimized permanent magnet systems

    CERN Document Server

    Bjørk, R; Insinga, A R

    2016-01-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. First, the Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown, albeit with an increase of 3.8 pp. in field inhomogeneity - a value compared to the inhomogeneity in a 16 segmented Halbach cylinder. Following this a topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111% for the chosen dimensions. Finally, a permanent magnet with alternating high and low field regions is considered. Here a $\\Lambda_\\mathrm{cool}$ figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  3. Technique for recovering rare-earth metals from spent sintered Nd-Fe-B magnets without external heating

    Directory of Open Access Journals (Sweden)

    Ryo Sasai

    2016-06-01

    Full Text Available To selectively recover rare-earth metals with higher purity from spent sintered Nd-Fe-B magnets without external heating, we investigated the mechano-chemical treatment of spent sintered Nd-Fe-B magnet powder with a reaction solution of HCl and (COOH2 at room temperature. The results of various experiments showed that the mechano-chemical treatment with HCl and (COOH2 is very effective for recovering the rare-earth metals contained in spent sintered Nd-Fe-B magnet powder; the recovery rate and purity of the rare-earth metals were 95.3 and 95.0 mass%, respectively, under optimal conditions ([HCl] = 0.2 mol/dm3 and [(COOH2] = 0.25 mol/dm3.

  4. Study of Nd-Fe-B alloys with nonstoichiometric Nd content in optimal magnetic state

    Directory of Open Access Journals (Sweden)

    Ćosović V.

    2009-01-01

    Full Text Available Characterization of two rapid-quenched Nd-Fe-B alloys with nonstoichiometric Nd content in the optimized magnetic state was carried out using the X-ray diffractometry (XRD, 57Fe Mössbauer spectroscopic phase analysis (MS, electron microscopy (TEM, high resolution TEM (HREM and Superconducting Quantum Interference Device (SQUID magnetometer. The experimental results demonstrate the fundamental difference in the structure and magnetic properties of the two investigated alloys in the optimized magnetic state. The Nd-Fe-B alloy with the reduced Nd content (Nd4.5Fe77B18.5 was found to have the nanocomposite structure of Fe3B/Nd2Fe14B and partly α-Fe/Nd2Fe14B, with mean grain size below 30 nm. On the other side, the overstoichiometric Nd14Fe79B7 alloy has almost a monophase structure with the dominant content of the hard magnetic phase Nd2Fe14B (up to 95 wt. % and a mean crystallite size about 60 nm, as determined by XRD and TEM analysis. The results of magnetic measurements on SQUID magnetometer also suggest the nanocomposite structure of the Nd-low alloy and nanocrystalline decoupled structure of the Nd-rich alloy after the optimal heat treatment.

  5. The cycloid Permanent Magnetic Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

    2008-01-01

    This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

  6. Micromagnetic Simulation of Demagnetization Curves for Single-Phase Nanocrystalline Nd-Fe-B Magnet

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The demangetization curves for the nanocrystalline Nd-Fe-B magnets of the stoichiometric com position were calculated by using the finite element technique of micromagnetism, The curve, especially iHc become smaller with increase of N. The most small iHc from a series of the curves along different field directions is closer to that for N=∞. iHc increases with increase of L. and are close or some what smaller than that the experimental values should be.

  7. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    DEFF Research Database (Denmark)

    Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian

    2017-01-01

    and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 104 ppm and 4·104 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting......The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon...

  8. Permanent magnets including undulators and wigglers

    OpenAIRE

    Bahrdt, J.

    2011-01-01

    After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrat...

  9. Development of Sintered NdFeB Magnet Industry in China (Continued)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Ⅳ. Intensive competition in NdFeB industry 2. Competition features of NdFeB industry Competition in NdFeB industry will be fierce in the future affected by tight supply and high price level of raw materials.

  10. Relationship between controllable preparation and microstructure of NdFeB sintered magnets

    Institute of Scientific and Technical Information of China (English)

    李岩峰; 朱明刚; 李安华; 冯海波; 黄书林; 李卫; 杜安; 齐岩

    2014-01-01

    The double hard magnetic phase magnets with nominal compositions of Nd30-xDyxFe69B1 (x=2, and 4) (wt.%) were pre-pared. The magnetic properties of the magnets were measured with a NIM-2000H hysteresigraph. The crystalline structures of the magnets were identified by X-ray diffraction (XRD). The Rietveld refinement was carried out using the FULLPROF software. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were carried out in order to investigate the microstructure of the magnets. It showed that the magnets consisted mainly of Nd2Fe14B phase, and some Nd-rich phase. Two types of matrix-phase grains in dark grey and light grey were found in the magnets with x=2 and 4. The Dy content was obviously dif-ferent in the two types of grains, which proved that the double hard magnetic phases (Dy-rich and Dy-lean phases) coexisted in the magnet. It revealed that the Nd-rich phases in junction regions had fcc structure, with the unit cell parameter of about 0.52-0.56 nm. The weak superlattice spots were found in the SAD patterns of the junction Nd-rich phases with large scale. The double hard mag-netic phase structure seemed to improve the magnetic properties of NdFeB magnets with high coercivity, while decrease the con-sumption of Dy element, compared with the single alloy magnet.

  11. Effects of terbium sulfide addition on magnetic properties, microstructure and thermal stability of sintered Nd-Fe-B magnets

    Science.gov (United States)

    Xiang-Bin, Li; Shuo, Liu; Xue-Jing, Cao; Bei-Bei, Zhou; Ling, Chen; A-Ru, Yan; Gao-Lin, Yan

    2016-07-01

    To increase coercivity and thermal stability of sintered Nd-Fe-B magnets for high-temperature applications, a novel terbium sulfide powder is added into (Pr0.25Nd0.75)30.6Cu0.15FebalB1 (wt.%) basic magnets. The effects of the addition of terbium sulfide on magnetic properties, microstructure, and thermal stability of sintered Nd-Fe-B magnets are investigated. The experimental results show that by adding 3 wt.% Tb2S3, the coercivity of the magnet is remarkably increased by about 54% without a considerable reduction in remanence and maximum energy product. By means of the electron probe microanalyzer (EPMA) technology, it is observed that Tb is mainly present in the outer region of 2:14:1 matrix grains and forms a well-developed Tb-shell phase, resulting in enhancement of H A, which accounts for the coercivity enhancement. Moreover, compared with Tb2S3-free magnets, the reversible temperature coefficients of remanence (α) and coercivity (β) and the irreversible flux loss of magnetic flow (h irr) values of Tb2S3-added magnets are improved, indicating that the thermal stability of the magnets is also effectively improved. Project supported by the Science Funds from the Ministry of Science and Technology, China (Grant Nos. 2014DFB50130 and 2011CB612304) and the National Natural Science Foundation of China (Grant Nos. 51172168 and 51072139).

  12. Research of warm compaction technology on nylon bonded Nd-Fe-B magnets

    Institute of Scientific and Technical Information of China (English)

    Xiuhai ZHANG; Weihao XIONG; Dameng YE; Jun QU; Zhenhua YAO

    2009-01-01

    Warm compaction and room temperature compaction were applied to prepare bonded Nd-Fe-B magnets. The results indicated that the density of magnet was determined by the compaction pressure and warm compaction temperature, whereas, the ther-mosetting temperature could hardly affect the density of magnet. The mechanical properties of magnets were the best when the thermosetting temperature was 200 ℃.The Br, Hcb, and (BH)max of warm compaction magnet were higher than those of room compaction. When the warm compaction temperature and thermosetting tem-perature were invariable, the density of magnet increased with the increase of com-paction pressure, which resulted in the increase of Br, Hob, and (BH)max of magnet and the decrease of Hcj of magnet. When the warm compaction temperature and compaction pressure were invariable, the magnetic properties of magnets decreased with the increase of thermosetting temperature. The magnetic properties of warm compaction molding magnets were better than those of injection molding magnets.

  13. PERMANENT-MAGNET INDUCTION GENERATORS: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    K. S. S. RAMAKRISHNAN

    2011-06-01

    Full Text Available The advantage of using a permanent-magnet induction generator (PMIG instead of a conventional induction generator is its ability to suppress inrush current during system linking when synchronous input is performed. Induction machines excited with permanent-magnet (PM are called permanent-magnet induction generators. This paper presents an exhaustive survey of the literature discussing the classification of permanent-magnet machines, process of permanent-magnet excitation and voltage build-up, modelling, steady-state and performance analysis of the permanent-magnet induction generators.

  14. Investigation of the coercivity mechanism for Nd-Fe-B based magnets prepared by a new technique of strip casting

    Institute of Scientific and Technical Information of China (English)

    LI Bo; HU Jifan; WANG Dongling; GUO Binglin; WANG Xinlin

    2004-01-01

    The coercivity mechanism of Nd-Fe-B based magnets prepared by a new technique of strip casting was investigated. Different from the traditional magnets, α-Fe phases are difficult to be found in Nd-Fe-B magnets prepared by strip casting. Meanwhile, the rich-Nd phases occur not only near the grain boundaries of main phases, but also within the main-phase grains. Investigation on the magnetizing field dependence of the coercivity for the (Nd0.935Dy0.065)14.5Fe79.4B6.1magnet and the temperature dependence of the coercivity for the Nd14.5Fe79.4B6.1magnet have been done. Results show that coercivities for strip casting magnets are controlled by the nucleation mechanism.

  15. 21 CFR 886.4445 - Permanent magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove...

  16. INTER-GRAIN EXCHANGE INTERACTION FOR SINGLE-PHASE NANOCRYSTALLINE Nd-Fe-B MAGNETS

    Institute of Scientific and Technical Information of China (English)

    WANG XUE-FENG; JIN HAN-MIN; ZHAO SU-FEN; YAN YU

    2001-01-01

    The demagnetization curve as a function of intensity of the inter-grain exchange interaction was calculated for single-phase nanocrystalline Nd-Fe-B magnets by use of the finite-element technique of micromagnetics. Also,the strength of the exchange interaction was estimated as a function of the Nd content x for the nanocrystalline NdxFe94-xB6 magnets by comparing the above result with the experimental relation between iHc and x for the magnets. We found that the inter-grain exchange interaction decreases with the increase of x, are≈70% and≈60% of the inter-grain exchange interaction for x=15.5(p0 iHc ≈2.0T) and x=19(p0 iHc ≈2.3T), respectively.

  17. Thermomagnetic treatment effects on microstructure in Nd-Fe-B type sintered magnets

    Science.gov (United States)

    PaigeSmith, Catherine

    Optimizing the microstructure of sintered Nd-Fe-B type magnets has become increasingly important. Sintered magnets are key components to the growing industry of alternative energy, particularly wind turbines and electric car generators. With rising costs and limited supply of rare earth elements, special attention has been dedicated to improving magnetic properties of these magnets through processing rather than compositional modifications. The magnetic property needing the most improvement in Nd-Fe-B type sintered magnets is coercivity. Coercivity dictates the performance of magnets at temperatures still below the demagnetizing threshold temperature. It has been shown that annealing sintered magnets in a magnetic field can enhance coercivity when compared to conventional post-sinter annealing in the absence of a magnetic field. However, little is known about the microstructural changes that occur in sintered magnets as a result of these thermo-magnetic treatments. This work presents themicrostructural characterization of Dy-free and Dy-containing sintered magnets that have undergone annealing in a magnetic field of 9T. Microstructural characterization techniques were used to identify phases, analyze the texture of phases identified, and to study intergranular phases. Microstructural findings were then used to propose a solidification scheme during annealing and connect such findings to magnetic property results, as well as to make suggestions for optimizing the manufacturing process. In addition to the magnetic phase, phases identified in the Dy-free and Dy-containing Nd-Fe-B sintered magnets consisted of Nb-rich precipitates, Nd-rich phases, and phases from the Nd-Fe-Cu ternary system. Nd-Fe-Cu phases included alpha-Nd, NdCu, and the tau (Nd6Fe13Cu). The Nd-rich phases were specifically identified to be NdOx precipitates in an alpha-Nd matrix, and contained an orientation relationship described by (0001)alpha-Nd||(111)NdOx and [112¯0]alpha-Nd||[1¯10]NdO x. This

  18. Trans-permanent magnetic actuation

    Science.gov (United States)

    Farmer, Daniel Jay

    The demands for an actuator to deploy, position and shape large spaced-based structures form a unique set of design criteria. In many applications it is desirable to hold displacements or forces between two points to within specified requirements (the regulation problem) and to periodically to change position (the tracking problem). Furthermore, the interest generally lies in satisfying the dynamic performance requirements while expending minimal power, while meeting tight tolerances and while experiencing little wear and fatigue. The actuator must also be able to withstand a variety of operational conditions such as impacts and thermal changes over an extended period of time. Current trends in large-scale structures have addressed the demands by using conventional actuators and motors, along with elaborate linkages or mechanisms to shape, position, protect and deploy. The developed designs use unique characteristics of permanent magnets to create simple direct-acting actuators and motors very suitable for space based structures. The developed trans-permanent magnetic (T-PM) actuators and motors are systems consisting of one or more permanent magnets, some of whose magnetic strengths can be switched on-board by surrounding pulse-coils. The T-PM actuator and motors expend no power during regulation. The T-PM can periodically change or remove the strength of its own magnets thereby enabling both fine-tune adjustments (microsteps) and large-scale adjustments (rotation). The fine (microstep) adjustments are particularly helpful in thermally varying space environments. The large-scale adjustments (rotation) are particularly helpful in deployment where the structure or antenna must experience large-angle rotations and/or large displacements. T-PM concepts are illustrated in direct acting actuators and built into stepper motor and permanent magnet motor applications. Several examples of design, analysis and testing are developed to verify the technology and supporting

  19. Origin of (105) Reflection of X-Ray Diffraction and Quantitative Evaluation of Alignment Degree for Sintered Nd-Fe-B Magnets

    Institute of Scientific and Technical Information of China (English)

    HE Ye-Qing; ZHOU Shou-Zeng; ZHANG Zhen-Rong; HAN Bao-Shan

    2001-01-01

    A new method for quantitatively evaluating the alignment degree ofsintered Nd-FeB magnets by x-ray diffraction spectra has been proposed. It has been experimentally revealed that the strong (105) reflection existing in almost all x-ray diffraction spectra of sintered Nd-FeB magnets stems from the misalignment grains whose easy axes are at an angle of 15.5° with respect to the orientated direction of the magnet.

  20. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    Science.gov (United States)

    Meakin, J. P.; Speight, J. D.; Sheridan, R. S.; Bradshaw, A.; Harris, I. R.; Williams, A. J.; Walton, A.

    2016-08-01

    Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.- computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd2O3 and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10-13 cm2/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated temperatures in the literature. This indicates that the growth of the room temperature oxidation products are likely defect enhanced processes at the NdFeB triple junctions.

  1. Electrophoretic deposition of graphene oxide as a corrosion inhibitor for sintered NdFeB

    Science.gov (United States)

    He, Wenting; Zhu, Liqun; Chen, Haining; Nan, Haiyang; Li, Weiping; Liu, Huicong; Wang, Yan

    2013-08-01

    Graphene oxide (GO) was deposited uniformly on the surface of permanent magnet material NdFeB by electrophoretic deposition (EPD). Electrophoretic deposited graphene oxide (EPD-GO) coating was reduced partially after EPD process, owing to the removal of oxygen functional groups. And EPD-GO coating showed excellent adhesion to the NdFeB matrix. According to the results of electrochemical tests, the decrease in corrosion current density and the positive shift in corrosion potential have both demonstrated that EPD-GO coating served as a corrosion inhibitor, protecting NdFeB from NaCl aqueous solution.

  2. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    Science.gov (United States)

    Zhang, Longcai; Wang, Suyu; Wang, Jiasu; Zheng, Jun

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  3. High-performance nanocrystalline NdFeB magnets by CAPA process

    Science.gov (United States)

    Kim, H. T.; Kim, Y. B.; Jeon, J. W.; Jang, I. H.; Kapustin, G. A.; Kim, H. S.

    2006-09-01

    The anisotropic NdFeB magnets were prepared from the melt-spun isotropic powders by CAPA process. The precursor isotropic magnet shows the uniform magnetic properties according to the overall position in the magnet. In the case of the anisotropic magnet, the outer position shows higher remanence and energy product compared to the center position. The magnetic properties of the anisotropic magnet obtained from Nd 14Fe 80B 6 powders are B=15 kG, iH=4.1 kOe and BH=36 MG Oe. In the case of addition of Zn to Nd 14Fe 80B 6 powders, the energy product increased because of the improved coercivity. The magnetic properties of the Zn-added magnet are B=14.5 kG, iH=9.7 kOe and BH=52 MG Oe. The Zn addition is effective to depress Nd 2Fe 14B grain growth of the interparticle regions during plastic deformation.

  4. High-performance nanocrystalline NdFeB magnets by CAPA process

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.T. [Tesla Co., Ltd., 340-1 Songsan-Ri, Yanggam-Myeon, Hwasung City, Gyeonggi-Do, 445-396 (Korea, Republic of)]. E-mail: htkim@gotesla.com; Kim, Y.B. [Korea Research Institute Standards and Sciences, 305-600, Daejeon (Korea, Republic of); Jeon, J.W. [Chonbuk National University, 756-356, Jeonju (Korea, Republic of); Jang, I.H. [Tesla Co., Ltd., 340-1 Songsan-Ri, Yanggam-Myeon, Hwasung City, Gyeonggi-Do, 445-396 (Korea, Republic of); Kapustin, G.A. [RRC Kurchatov Institute, Moscow, 123182 (Russian Federation); Kim, H.S. [Chonbuk National University, 756-356, Jeonju (Korea, Republic of)

    2006-09-15

    The anisotropic NdFeB magnets were prepared from the melt-spun isotropic powders by CAPA process. The precursor isotropic magnet shows the uniform magnetic properties according to the overall position in the magnet. In the case of the anisotropic magnet, the outer position shows higher remanence and energy product compared to the center position. The magnetic properties of the anisotropic magnet obtained from Nd{sub 14}Fe{sub 80}B{sub 6} powders are B{sub r}=15kG, {sub i}H{sub c}=4.1kOe and BH{sub max}=36MGOe. In the case of addition of Zn to Nd{sub 14}Fe{sub 80}B{sub 6} powders, the energy product increased because of the improved coercivity. The magnetic properties of the Zn-added magnet are B{sub r}=14.5kG, {sub i}H{sub c}=9.7kOe and BH{sub max}=52MGOe. The Zn addition is effective to depress Nd{sub 2}Fe{sub 14}B grain growth of the interparticle regions during plastic deformation.

  5. THE EFFECT OF Mo ADDITION ON COERCIVITY OF NdFeB SINTERED MAGNET PREPARED BY BLENDING METHOD

    Institute of Scientific and Technical Information of China (English)

    J.Q.Zhou; M.G. Zhang

    2005-01-01

    Alloy modification, accompanying with proper heat treatment, is commonly used to improve the thermal stability of NdFeB magnet. Traditional alloy modification is performed through melting process with alloy elements to form the multi-alloy. In doing so, these alloy elements not only are introduced into the inter-granular boundaries, but partly into the main phase, thus decreasing to some extent the magnetism of the main phase. In this paper, the blending method is used to prepare the Nd22Fe71B/Mo sintered magnet, and its magnetic properties and microstructures are investigated. The results show that by adding 1.5% (mass fraction) Mo, the intrinsic coercivity Hc of the magnet reaches the maximum value of 1719.36KA/m, while continually increasing the amount of Mo has a less effect on iHc Microstructures analysis indicates that Mo-free Nd-Fe-B magnet has not uniform grains in size, while that with Mo element has uniform grains in size and smooth grain boundaries. Experiments show that after the NdFeB magnet is sintered at 1273K and annealed at 873K, the added Mo element could prevent the equilibrium transformation between the main phase and Nd-rich phase, thus resulting in the precipitation of fine second main phase (Nd2Fe14-xMoxB) from the main phase boundaries, preventing the nucleation and expansion of anti-magnetic domain, and enhancing the coercivity.

  6. Cellular uptake of magnetite nanoparticles enhanced by NdFeB magnets in staggered arrangement

    Science.gov (United States)

    Lu, Yi-Ching; Chang, Fan-Yu; Tu, Shu-Ju; Chen, Jyh-Ping; Ma, Yunn-Hwa

    2017-04-01

    Magnetic force may greatly enhance uptake of magnetic nanoparticles (MNPs) by cultured cells; however, the effects of non-uniformity of magnetic field/ magnetic gradient on MNP internalization in culture has not been elucidated. Cellular uptake of polyacrylic acid coated-MNP by LN229 cells was measured with cylindrical NdFeB magnets arranged in a staggered pattern. The magnetic field generated by placing a magnet underneath (H-field) elicited a homogenous distribution of MNPs on the cells in culture; whereas the field without magnet underneath (L-field) resulted in MNP distribution along the edge of the wells. Cell-associated MNP (MNPcell) appeared to be magnetic field- and concentration-dependent. In H-field, MNPcell reached plateau within one hour of exposure to MNP with only one-min application of the magnetic force in the beginning of incubation; continuous presence of the magnet for 2 h did not further increase MNPcell, suggesting that magnetic force-induced uptake may be primarily contributed to enhanced MNP sedimentation. Although MNP distribution was much inhomogeneous in L-field, averaged MNPcell in the L-field may reach as high as 80% of that in H-field during 1-6 h incubation, suggesting high capacity of MNP internalization. In addition, no significant difference was observed in MNPcell analyzed by flow cytometry with the application of H-field of staggered plate vs. filled magnet plate. Therefore, biological variation may dominate MNP internalization even under relatively uniformed magnetic field; whereas non-uniformed magnetic field may serve as a model for tumor targeting with MNPs in vivo.

  7. Micromagnetic simulation of the orientation dependence of grain boundary properties on the coercivity of Nd-Fe-B sintered magnets

    Science.gov (United States)

    Fujisaki, Jun; Furuya, Atsushi; Uehara, Yuji; Shimizu, Koichi; Ataka, Tadashi; Tanaka, Tomohiro; Oshima, Hirotaka; Ohkubo, Tadakatsu; Hirosawa, Satoshi; Hono, Kazuhiro

    2016-05-01

    This paper is focused on the micromagnetic simulation study about the orientation dependence of grain boundary properties on the coercivity of polycrystalline Nd-Fe-B sintered magnets. A multigrain object with a large number of meshes is introduced to analyze such anisotropic grain boundaries and the simulation is performed by combining the finite element method and the parallel computing. When the grain boundary phase parallel to the c-plane is less ferromagnetic the process of the magnetization reversal changes and the coercivity of the multigrain object increases. The simulations with various magnetic properties of the grain boundary phases are executed to search for the way to enhance the coercivity of polycrystalline Nd-Fe-B sintered magnets.

  8. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

    2017-08-01

    Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

  9. Decay Characteristics of Levitation Force of YBCO Bulk Exposed to AC Magnetic Field above NdFeB Guideway

    Science.gov (United States)

    Liu, Minxian; Lu, Yiyun; Wang, Suyu; Ma, Guangtong

    2011-04-01

    The superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the nonuniformity of the magnetic field along the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneity of the material property of the NdFeB magnet. So it is required to study the characteristics of levitation force of the bulks affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we will study the characteristics of the levitation force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet is used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experimental results, it has found that the levitation force is decreasing with the application of the AC external magnetic field, and the decay increasing with the amplitude of the applied magnetic field and is almost independent of the frequency.

  10. Large output-power, low-speed permanent magnet synchronous motor designs for ship propulsion drive

    Energy Technology Data Exchange (ETDEWEB)

    Rosu, M.

    2001-07-01

    Over the last decade, serious development has taken place in electric motor technology, and its impact is being felt in the shipbuilding community. This development has brought about a new generation of compact, high efficiency electrical machines. High performance, lightweight permanent magnet motors and generators have been developed for a wide range of applications including vehicle propulsion, power generation, pump and compressor drives. These machines combine the advances in magnetic materials and electronic design to provide shipbuilders new options for weight, energy and cost reduction. Permanent magnet machines were built in many different configurations and power classes, ranging from a few hundred watts to multi-megawatts for ship propulsion. Permanent magnet motors and generators for marine use were constructed and tested, all of these machines providing the same outstanding torque and power density. The basic electromagnetic, thermal and mechanical design approaches were established and tested in small prototype machines, the development of larger machines constituting the engineering later in the design process. The goal of this research work is to find an optimum solution in terms of design and suitability of a low-speed and high-power permanent magnet motor for ship propulsion drive. In this work, the study-case analyses are limited to the electromagnetic part of the motor. Two types of radial flux permanent magnet synchronous motors are designed and optimised to meet the propulsion requirements. The first motor has the permanent magnets mounted on the surface of the rotor while the second motor has the permanent magnets mounted on the rotor surface and covered by laminated pole shoes. In their construction, high-energy NdFeB permanent magnets were chosen. These magnetic materials provide a sufficient airgap magnetic flux density with a low volume of material. Moreover, the NdFeB permanent magnets are endowed with high coercivity. As an immediate

  11. Design, Prototyping, and Analysis of a Novel Modular Permanent Magnet Transverse Flux Disk Generator

    DEFF Research Database (Denmark)

    Hosseini, Seyedmohsen; Moghani, Javad Shokrollahi; Ershad, Nima Farrokhzad;

    2011-01-01

    This paper presents the design, prototyping, and analysis of a novel modular transverse flux permanent magnet disk generator. The disk-shaped structure simplifies the construction procedure by using laminated steel sheets. To reduce output harmonics, the excitation of the generator is done...... by circular flat shaped Nd-Fe-B permanent magnets. First, a typical low power generator is designed, and then partially optimized. The optimization objective is to find an inner radius which maximizes the power factor, the output power to mass ratio and the efficiency. The generator equivalent circuit...... parameters are computed by three dimensional finite element analyses. The simulation results show that the power factor of the proposed structure is considerably greater than the power factor previously reported for other transverse flux permanent magnet generator structures. To verify the simulation results...

  12. Micromagnetic simulations on the grain shape effect in Nd-Fe-B magnets

    Science.gov (United States)

    Yi, Min; Gutfleisch, Oliver; Xu, Bai-Xiang

    2016-07-01

    Micromagnetic simulations were performed to study the effect of grain shape and defect layer in Nd-Fe-B magnets. It was found that the coercivity can be increased by a factor of ˜2 by changing the grain shape from the triangular prism to the spheroid. Both the anisotropy field contribution and the shape contribution to the coercivity, and thus also the final coercivity, were found to decrease in the order: spheroid > circular prism > hexagonal prism > square prism > triangular prism. Sputtered columnar grains and hot-deformed platelet grains with a constant volume were also considered. Results show that the coercivity initially increases with the aspect ratio and then nearly saturates above the ratio of ˜4. Simulations of multigrain ensembles showed that depending on the grain shape, compared to the case of single grain, a further decrease of ˜10%-45% in the coercivity is induced by magnetostatic coupling.

  13. Effect of additions of zinc stearate on the properties of sintered Nd-Fe-B magnets

    Science.gov (United States)

    Popov, A. G.; Gerasimov, E. G.; Terent'ev, P. B.; Gaviko, V. S.; Shunyaev, K. Yu.; Mikhailova, T. L.; Vas'kovskii, V. O.; Kulesh, N. A.

    2013-04-01

    Zinc stearate additions have been used to increase the remanence of sintered Nd-Fe-B magnets produced by the powder metallurgy without powder pressing. Zinc stearate acts as an internal lubricant, i.e., it decreases the friction forces between the particles and favors an increase in the degree of texture of the powders, which is induced by the magnetic field. It is shown that the density and the magnetic hysteresis characteristics of sintered magnets produced using additions of 0.15 wt % zinc stearate exceeds the corresponding values obtained for magnets produced without this addition at a filling density of powders in containers of more than 2.9 and 3.0 g/cm3 in dry and wet states, respectively. Using additions of zinc stearate in the amount of 0.15% with respect to the weight of the powder, magnets with a density of 7.55 g/cm3, B r = 14.02 kG, H c = 7.91 kOe, and ( BH)max = 46.1 MG Oe have been produced.

  14. Effects of orientation and interaction of grains on coercivity for sintered NdFeB magnets

    Institute of Scientific and Technical Information of China (English)

    高汝伟; 李卫; 张建成; 吴良学; 喻晓军

    1999-01-01

    The coercivity of NdFeB magnets is determined by the coercivity of individual grains and the interaction between the grains composed of the magnets. The coercivity of individual grains and the intergrain interaction depend on the degree of the grain alignment. "tanθ type" Ganssian function is applied to describing the degree of the grain alignment. According to different coercivity mechanisms, there are different formula on the coercivity and the angular dependence of coercivity. The interaction between grains can be classified as the long-range magnetostatic interaction and the exchange-coupling interaction of neighboring grains. For the sintered magnet, the grain size is large and the grain boundaries are mostly separated by the non-magnetic phase. So, the long-range magnetostatic interaction is much stronger than the exchange coupling interaction and it makes the coercivity of the magnet composed of misaligned grains be bigger than that of the magnet composed of ideally aligned grains. The effects o

  15. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    Science.gov (United States)

    Xia, M.; Abrahamsen, A. B.; Bahl, C. R. H.; Veluri, B.; Søegaard, A. I.; Bøjsøe, P.; Millot, S.

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 104 ppm and 4·104 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small.

  16. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Meakin, J.P., E-mail: jxm764@bham.ac.uk; Speight, J.D.; Sheridan, R.S.; Bradshaw, A.; Harris, I.R.; Williams, A.J.; Walton, A.

    2016-08-15

    Highlights: • Room temperature atmospheric oxidation behaviour of sintered NdFeB. • 3D laser confocal microscopy measurement of oxide phase growth. • Significant height increase of oxide phase only observed at triple points. • Raman spectroscopy identified oxide phase to be Nd{sub 2}O{sub 3}. • Diffusion coefficient determined to be 4 × 10{sup −13} cm{sup 2}/s. - Abstract: Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.— computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd{sub 2}O{sub 3} and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10{sup −13} cm{sup 2}/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth

  17. Modeling of magnetic hystereses in soft MREs filled with NdFeB particles

    Science.gov (United States)

    Kalina, K. A.; Brummund, J.; Metsch, P.; Kästner, M.; Borin, D. Yu; Linke, J. M.; Odenbach, S.

    2017-10-01

    Herein, we investigate the structure-property relationships of soft magnetorheological elastomers (MREs) filled with remanently magnetizable particles. The study is motivated from experimental results which indicate a large difference between the magnetization loops of soft MREs filled with NdFeB particles and the loops of such particles embedded in a comparatively stiff matrix, e.g. an epoxy resin. We present a microscale model for MREs based on a general continuum formulation of the magnetomechanical boundary value problem which is valid for finite strains. In particular, we develop an energetically consistent constitutive model for the hysteretic magnetization behavior of the magnetically hard particles. The microstructure is discretized and the problem is solved numerically in terms of a coupled nonlinear finite element approach. Since the local magnetic and mechanical fields are resolved explicitly inside the heterogeneous microstructure of the MRE, our model also accounts for interactions of particles close to each other. In order to connect the microscopic fields to effective macroscopic quantities of the MRE, a suitable computational homogenization scheme is used. Based on this modeling approach, it is demonstrated that the observable macroscopic behavior of the considered MREs results from the rotation of the embedded particles. Furthermore, the performed numerical simulations indicate that the reversion of the sample’s magnetization occurs due to a combination of particle rotations and internal domain conversion processes. All of our simulation results obtained for such materials are in a good qualitative agreement with the experiments.

  18. Novel Switched Flux Permanent Magnet Machine Topologies

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2012-01-01

    This paper overviews various switched flux permanent magnet machines and their design and performance features,with particular emphasis on machine topologies with reduced magnet usage or without using magnet,as well as with variable flux capability.

  19. Finite element modeling of permanent magnet devices

    Science.gov (United States)

    Brauer, J. R.; Larkin, L. A.; Overbye, V. D.

    1984-03-01

    New techniques are presented for finite element modeling of permanent magnets in magnetic devices such as motors and generators. These techniques extend a previous sheet-current permanent magnet model that applies only for straight line B-H loops and rectangular-shaped magnets. Here Maxwell's equations are used to derive the model of a permanent magnet having a general curved B-H loop and any geometric shape. The model enables a nonlinear magnetic finite element program to use Newton-Raphson iteration to solve for saturable magnetic fields in a wide variety of devices containing permanent magnets and steels. The techniques are applied to a brushless dc motor with irregular-shaped permanent magnets. The calculated motor torque agrees well with measured torque.

  20. The epoxy resin variation effect on microstructure and physical properties to improve bonded NdFeB flux magnetic density

    Science.gov (United States)

    Rusnaeni, N.; Sarjono, Priyo; Muljadi; Noer, Nasrudin

    2016-11-01

    NdFeB magnets have been fabricated from a mixture of powder NdFeB (MPQ-B+) and epoxy resins (ER) with a variation of 0% wt, 2% wt, 4% wt and 6% wt. The pellets samples were made by pressing 4 tons of the mixture powder at room temperature before curing at 100°C for 1 hour. The SEM-EDX results showed the microstructure with ER were evenly smeared the NdFeB magnetic particles due to higher percent C and lower transition metals value. Sample with 2% wt epoxy resin was able to achieve the highest density of 5.35 g/cm3 and the highest magnetic flux of 2121 Gauss. The magnetic properties characterization using the permagraph indicates that the sample pellets with 2% wt epoxy resin has a value of remanence (Br) = 4.92 kG, coercivity (Hc) = 7.76 kOe, and energy product (Bhmax) = 4.58 MGOe. Despite low remanence value in the pellet samples, the resistance to demagnetization value was still acceptable.

  1. Superconducting Solenoid and Press for Permanent Magnet Fabrication

    Science.gov (United States)

    Mulcahy, T. M.; Hull, J. R.

    2002-08-01

    For the first time, a superconducting solenoid (SCM) was used to increase the remnant magnetization of sintered NdFeB permanent magnets (PMs). In particular, improved magnetic alignment of commercial-grade PM powder was achieved, as it was axial die pressed into 12.7-mm diameter cylindrical compacts in the 76.2-mm warm bore of a 9-T SCM. The press used to compact the powder is unique and was specifically designed for use with the SCM. Although the press was operated in the batch mode for this proof of concept study, its design is intended to enable automated production. In operation, a simple die and punch set made of nonmagnetic materials was filled with powder and loaded into a nonmagnetic press tube. The cantilevered press tube was inserted horizontally, on a carrier manually advanced along a track, into the SCM. The robustness of the mechanical components and the SCM, in its liquid helium dewar, were specifically designed to allow for insertion and extraction of the magnetic powder and compacts, while operating at 9 T.

  2. Design and fabrication of sintered Nd-Fe-B magnets with a low temperature coefficient of intrinsic coercivity

    Directory of Open Access Journals (Sweden)

    Cui X.G.

    2009-01-01

    Full Text Available To decrease the temperature coefficients of sintered Nd-Fe-B magnets, the influencing factors on temperature coefficients, especially the reversible temperature coefficient β of intrinsic coercivity Hcj, were analyzed. The results showed that the absolute value of β decreased with increasing Hcj and also the ratio of microstructure parameter c to Neff, indicating that the increase of magnetocrystalline anisotropy field HA and c/Neff can effectively decrease the absolute value of β. On the basis of this analysis, a sintered Nd-Fe-B magnet with a low temperature coefficient of Hcj was fabricated through composition design, and the value of β was only -0.385%/ºC in the temperature interval of 20-150ºC.

  3. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    A permanent magnet assembly in which the flux density can be altered by a mechanical operation is often significantly smaller than comparable electromagnets and also requires no electrical power to operate. In this paper five permanent magnet designs in which the magnetic flux density can...

  4. The impact of processing parameters on the properties of Zn-bonded Nd-Fe-B magnets

    Science.gov (United States)

    Kelhar, Luka; Zavašnik, Janez; McGuiness, Paul; Kobe, Spomenka

    2016-12-01

    We report on the effect of loading factor and pressure on the density and the magnetic properties of Zn-bonded Nd-Fe-B magnets produced by pulsed-electric-current sintering (PECS). The idea behind this study is to fabricate bonded magnets with a metallic binder in order for the bonded magnet to operate at temperatures higher than 180 °C: the current upper-limit for polymer-bonded magnets. These composites are made of hard-magnetic powder in the form of melt-spun ribbons bonded with the low-melting-point metal Zn. The binder additions were varied from 10 to 30 wt%, and pressures of 50 and 500 MPa were applied. The high-pressure mode with 20 wt% Zn resulted in a 24% increase of Jr, compared to the low-pressure mode. The magnetic measurements revealed a maximum remanence of 0.64 T for 10 wt% Zn, while the coercivity is largely unaffected by the processing conditions. The density of the composites was up to 7.0 g/cm3, corresponding to 94% of the theoretical density. Compared to commercial polymer-bonded magnets, the Zn-bonded counterparts exhibit a slightly lower Jr, but the coercivity is retained. We show that there is a minor diffusion of Zn into the Nd-Fe-B, forming a 1 μm thin transition layer, but it does not harm the magnetic properties. These metal-bonded Nd-Fe-B magnets are ideal for use in high-temperature automotive applications like under-the-hood sensors and other magnet-based devices that are close to the engine.

  5. Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

    Directory of Open Access Journals (Sweden)

    Minna Haavisto

    2014-01-01

    Full Text Available Stable polarization of permanent magnets over the lifetime of the application is an important aspect in electrical machine design. Specification of the long-term stability of magnet material is difficult, since knowledge of the phenomenon is incomplete. To be able to optimize magnet material selection, the long-term magnetic behavior of the material must also be understood. This study shows that material with a very square JH curve is stable until a certain critical operating temperature is reached. Major losses are detected as the critical temperature is exceeded. Material with a rounder JH curve does not show a well-defined critical temperature, but increasing losses over a large temperature range. The critical temperature of a material is also dependent on the field conditions. Results differ whether the tests are performed in an open or closed magnetic circuit. In open-circuit tests, the opposing field is not homogeneously distributed throughout the volume of the magnet and thus the long-term behavior is different than that in closed-circuit conditions. Open-circuit tests seem to give bigger losses than closed-circuit tests in cases where the permeance coefficient of the open-circuit sample is considered to be the average permeance coefficient, calculated according to the dimensions of the magnet.

  6. Development of NdFeB Magnet Industry in New Century

    Institute of Scientific and Technical Information of China (English)

    LUO Yang

    2006-01-01

    @@ Editor's note: The paper was quoted from the papers collection of the "19th International Workshop on Rare Earth Permanent Magnets (Et) Their Applications", held in Beijing on August 30-September 2 of 2006.

  7. ANISOTROPIC CHARACTERISTICS OF DEMAGNETIZATION CURVE FOR NANOCRYSTALLINE Nd-Fe-B MAGNET CALCULATED BY MICROMAGNETICS

    Institute of Scientific and Technical Information of China (English)

    金汉民; 王学凤; 赵素芬; 闫羽

    2001-01-01

    The demagnetization curves for nanocrystalline Nd-Fe-B magnets of a stoichiometric composition were calculated by making use of the finite element technique of micromagnetics. The curve, especially iHc, varies in a wide range with the direction of applied field if the grain number N is taken to be small. With the increase of N, the range becomes smaller and the average of iHc decreases and approaches a limit iHc(N = ∞). iHc for finite N is larger than, or at least equal to, iHc(N= o∞). Jr/Js is weakly affected by N and the field direction. Jr/Js(N = oo) decreases with the increase of grain size L. These are larger than the experimental values for the Nd-rich Nd2.33Fe14B1.06Si0.21 magnets by ~0.05. iHc(N = ∞) increases with the increase of L, and is close to or somewhat smaller than the experimental values of the Nd-rich magnet, as would be expected. In contrast, the curve calculated for the non-interacting grain system (Stoner-Wohlfarth model) of N 30 depends neither on the field direction nor on N.

  8. Stability considerations of permanent magnet quadrupoles for CESR phase-III upgrade

    Directory of Open Access Journals (Sweden)

    W. Lou

    1998-06-01

    Full Text Available The Cornell electron storage ring (CESR phase-III upgrade plan includes very strong permanent magnet quadrupoles in front of the cryostat for the superconducting quadrupoles and physically as close as possible to the interaction point. Together with the superconducting quadrupoles, they provide tighter vertical focusing at the interaction point. The quadrupoles are built with neodymium iron boron (NdFeB material and operate inside the 15 kG solenoid field. Requirements on the field quality and stability of these quadrupoles are discussed and test results are presented.

  9. Inducing magnetic anisotropy and optimized microstructure in rapidly solidified Nd-Fe-B based magnets by thermal gradient, magnetic field and hot deformation

    Science.gov (United States)

    Zhao, L. Z.; Li, W.; Wu, X. H.; Hussain, M.; Liu, Z. W.; Zhang, G. Q.; Greneche, J. M.

    2016-10-01

    Direct preparation of Nd-Fe-B alloys by rapid solidification of copper mold casting is a very simple and low cost process for mini-magnets, but these magnets are generally magnetically isotropic. In this work, high coercivity Nd24Co20Fe41B11Al4 rods were produced by injection casting. To induce magnetic anisotropy, temperature gradient, assisted magnetic field, and hot deformation (HD) procedures were employed. As-cast samples showed non-uniform microstructure due to the melt convection. The thermal gradient during solidification led to the formation of radially distributed acicular hard magnetic grains, which gives the magnetic anisotropy. The growth of the oriented grains was confirmed by phase field simulation. A magnetic field up to 1 T applied along the casting direction could not induce significant magnetic anisotropy, but it improved the magnetic properties by reducing the non-uniformity and forming a uniform microstructure. The annealed alloys exhibited high intrinsic coercivity but disappeared anisotropy. HD was demonstrated to be a good approach for inducing magnetic anisotropy and enhanced coercivity by deforming and refining the grains. This work provides an alternative approach for preparing fully dense Nd-rich anisotropic bulk Nd-Fe-B magnets.

  10. Evaluation of effect of surface treatment on corrosion resistance of Nd-Fe-B magnets; Avaliacao do efeito de tratamentos superficiais na resistencia a corrosao de magnetos de Nd-Fe-B

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Emerson Alves

    2009-07-01

    Nd-Fe-B magnets produced by powder metallurgy are highly susceptible to corrosion due to their complex microstructure and intrinsic porosity due to their fabrication process. Moreover, these magnets have excellent magnetic properties and find many applications. In the nuclear area, permanent magnets based on rare earth transition-iron-boron (Ne-Fe-B) are used in the manufacture of magnetic media (magnetic levitation) for ultra-centrifuges used for isotopic enrichment of uranium employed in nuclear reactors. In dentistry these types of magnets are used to fix total and partial prostheses on implants; in orthodontics to correct dental malocclusion and make moves; in buco-maxillo-facial surgery for setting facial prostheses of large defects of the face. In electronic equipment, they are used in scales, locks, electric motors and particularly in the manufacturing of hard drives of computers. The objective of this study is to evaluate the corrosion resistance of the magnet tested and surface treatments that could replace chromating that generates toxic residues and present high cost of processing waste with treatments that are environmentally friendly. The evaluation of the corrosion resistance was carried out through the analysis potentiodynamic polarization curves, electrochemical impedance spectroscopy, monitoring of corrosion potential as a function of test time and scanning electron microscopy to try to correlate the magnet microstructure with its corrosion resistance. The results show that these magnets are highly susceptible to corrosion that occurs preferentially in the Nd-rich phase, located in the boundaries of the magnetic matrix phase ({psi}). Treatment with silane, cerium, sam, Cr 6{sup +}, tricationic phosphate followed by bath of chromium trioxide and in NaH{sup 2}PO{sup 4} solution for 24 hours followed by bath of zinc sulphate did not improve the corrosion resistance of the magnet. Among the treatments used, immersion in NaH{sup 2}PO{sup 4} solution for

  11. Micromachined permanent magnets and their MEMS applications

    Science.gov (United States)

    Cho, Hyoung Jin

    2002-01-01

    In this research, new micromachined permanent magnets have been proposed, developed and characterized for MEMS applications. In realizing micromachined permanent magnets, a new electroplating technique using external magnetic field and a bumper filling technique using a photolithographically defined mold with resin bonded magnetic particles have been developed. The newly developed micromachining techniques allow thick film-type permanent magnet components to be integrated to magnetic MEMS devices with dimensional control and alignment. Permanent magnet arrays with the dimensions ranging from 30 mum to 200 mum have been developed with an energy density up to 2.7 kJ/m3 in precisely defined forms in the micro scale. For the applications of the permanent magnets developed in this work, three novel magnetic MEMS devices such as a bi-directional magnetic actuator, a magnetically driven optical scanner, and a magnetic cell separator have been successfully realized. After design and modeling, each device has been fabricated and fully characterized. The bi-directional actuator with the electroplated permanent magnet array has achieved bi-directional motion clearly and shown good agreement with the analytical and simulated models. The optical scanner has shown linear bi-directional response under static actuation and stable bi-directional scanning performance under dynamic actuation. As a potential BioMEMS application of the developed permanent magnet, the prototype magnetic cell separator using the electroplated permanent magnet strip array has been proposed and demonstrated for magnetic bead patterning. In conclusion, new thick film-type, electroplated CoNiMnP and epoxy resin bonded Sr-ferrite permanent magnets have been developed and characterized, and then, three new magnetic MEMS devices using the permanent magnets such as a bi-directional magnetic actuator, an optical scanner and a magnetic cell separator have been realized in this research. The new micromachined

  12. Macroscopic Simulation of Isotropic Permanent Magnets

    CERN Document Server

    Bruckner, Florian; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2015-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material.

  13. Macroscopic simulation of isotropic permanent magnets

    Science.gov (United States)

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2016-03-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material.

  14. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    Permanent Magnet (IPM) or Surface Permanent. Magnet ... desired torque is produced to rotate the motor in the desired ... u axis, and the direct-axis of the rotor is at angle θ from the ..... Based Stator Flux Estimator” International. Journal of ...

  15. COMPARATIVE ANALYSIS OF THE BEHAVIOR OF COAXIAL AND FRONTAL COUPLINGS – WITH PERMANENT MAGNETS – IN HIGH TEMPERATURE ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    Marcel Oanca

    2004-12-01

    Full Text Available This paper presents a comparative analysis of the behavior of coaxial and frontal couplings – with permanent magnets – in high temperature environments specific to iron and steel industry. The comparative analysis is made at the level of the specific forces developed in the most difficult environments. The maximum temperature was limited for reasons of thermal stability of the Nd-Fe-B permanent magnets. In this context it was studied, by the help of the PDE-ase soft that uses the finite element method, the way magnetic induction modifies, the specific forces developed and the distribution of temperature within the coaxial and frontal couplers with permanent magnets, for variations of the distance between the magnets (air gap within the limits 2-20 mm.

  16. Macroscopic Simulation of Isotropic Permanent Magnets

    OpenAIRE

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2015-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the...

  17. Novel design configurations for permanent magnet wind generators

    Science.gov (United States)

    Chen, Yicheng

    2004-12-01

    The aim of this research is to search for optimal designs of permanent magnet (PM) wind generators of different topologies. The dissertation deals with the development of analytical design equations and formulas for PM wind generators of different topologies, including equivalent magnetic circuit model for magnets, calculation of leakage flux, influence of d-q axis armature reaction, flux waveform analysis, as well as performance verification. 3-D and simplified 2-D finite element analysis is used to enhance the design precision, by which analytical formulas are modified. A new and improved formula is proposed for lamination loss calculations, based on a large experimental data set provided by steel manufacturers. The temperature stability of NdFeB magnets is analyzed and some proposals for eliminating irreversible demagnetization are presented. Two existing experimental machines are used to validate the design equations. The genetic algorithms are used to investigate the multi-objective design optimization of PM wind generators for a high efficiency and light-weight design. The reasoning behind the selection of the objective functions, design variables and constraints are given as guidance for the PM wind generator optimum design. The implementation of the genetic algorithm is also given. A comparison of PM wind generators of different topologies is presented. Conclusions are drawn for topology selections of PM wind generators. The group of soft magnetic composites (SMC) has recently been expanded by the introduction of new materials with significantly improved frequency properties. This has made SMC a viable alternative to steel laminations for a range of new applications, especially axial-flux wind generators. The isotropic nature of the SMC combined with the unique shaping possibilities opens up new design solutions for axial-flux wind generators. Through careful design, an axial-flux PM wind generator with SMC core is built and tested, demonstrating the

  18. Direct Iron Coating onto Nd-Fe-B Powder by Thermal Decomposition of Iron Pentacarbonyl

    Energy Technology Data Exchange (ETDEWEB)

    Yamamuro, S; Okano, M; Tanaka, T [Department of Materials Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Sumiyama, K [Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Nozawa, N; Nishiuchi, T; Hirosawa, S [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals, Ltd., Osaka 618-0013 (Japan); Ohkubo, T, E-mail: yamamuro@eng.ehime-u.ac.jp [Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2011-01-01

    Iron-coated Nd-Fe-B composite powder was prepared by thermal decomposition of iron pentacarbonyl in an inert organic solvent in the presence of alkylamine. Though this method is based on a modified solution-phase process to synthesize highly size-controlled iron nanoparticles, it is in turn featured by a suppressed formation of iron nanoparticles to achieve an efficient iron coating solely onto the surfaces of rare-earth magnet powder. The Nd-Fe-B magnetic powder was successfully coated by iron shells whose thicknesses were of the order of submicrometer to micrometer, being tuneable by the amount of initially loaded iron pentacarbonyl in a reaction flask. The amount of the coated iron reached to more than 10 wt.% of the initial Nd-Fe-B magnetic powder, which is practically sufficient to fabricate Nd-Fe-B/{alpha}-Fe nanocomposite permanent magnets.

  19. Effect of bonding process on the properties of isotropic epoxy resin-bonded Nd-Fe-B magnets

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiuhai; XIONG Weihao

    2009-01-01

    Bonded NdFeB magnets were prepared by compression molding. The effect of preparation technology on their magnetic and mechanical properties was studied through the analysis of density, Br Hcj, (BH)max, bending strength, and compressive strength of the bonded magnets. The results showed that the magnetic properties decreased with increasing binder content, whereas the mechanical properties increased. Brand (BH)max increased with rising pressure, whereas Hcj decreased. For a fixed mass fraction of the binder, the optimal pressure was 620 MPa and the best thermosetting temperature was 160℃. These conditions made the bonded magnets have the optimal mechanical properties. Scanning electron microscopy (SEM) analyses of the fracture surfaces indicated that the epoxy resin bonded magnets exhibited brittle behavior.

  20. Permanent Magnetic Bearing for Spacecraft Applications

    Science.gov (United States)

    Morales, Winfredo; Fusaro, Robert; Kascak, Albert

    2008-01-01

    A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  1. Force prediction in permanent magnet flat linear motors (abstract)

    Science.gov (United States)

    Eastham, J. F.; Akmese, R.

    1991-11-01

    The advent of neodymium iron boron rare-earth permanent magnet material has afforded the opportunity to construct linear machines of high force to weight ratio. The paper describes the design and construction of an axial flux machine and rotating drum test rig. The machine occupies an arc of 45° on a drum 1.22 m in diameter. The excitation is provided by blocks of NdFeB material which are skewed in order to minimize the force variations due to slotting. The stator carries a three-phase short-chorded double-layer winding of four poles. The machine is supplied by a PWM inverter the fundamental component of which is phase locked to the rotor position so that a ``dc brushless'' drive system is produced. Electromagnetic forces including ripple forces are measured at supply frequencies up to 100 Hz. They are compared with finite-element analysis which calculates the force variation over the time period. The paper then considers some of the causes of ripple torque. In particular, the force production due solely to the permanent magnet excitation is considered. This has two important components each acting along the line of motion of the machine, one is due to slotting and the other is due to the finite length of the primary. In the practical machine the excitation poles are skewed to minimize the slotting force and the effectiveness of this is confirmed by both results from the experiments and the finite-element analysis. The end effect force is shown to have a space period of twice that of the excitation. The amplitude of this force and its period are again confirmed by practical results.

  2. ANALYTIC EXPRESSION OF MAGNETIC FIELD DISTRIBUTION OF RECTANGULAR PERMANENT MAGNETS

    Institute of Scientific and Technical Information of China (English)

    苟晓凡; 杨勇; 郑晓静

    2004-01-01

    From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk, but also for that of several rectangular permanent magnet bulks. By using this expression,the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets,in order to describe its distribution,two quantities,one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field,were defined. Furthermore, the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.

  3. The influence of low temperature on gamma-ray irradiated permanent magnets.

    Science.gov (United States)

    Han, Young Chul; Cha, Hyun Gil; Kim, Chang Woo; Ji, Eun Sun; Kim, Young Hwan; Kang, Dong In; Kang, Young Soo

    2009-12-01

    The temperature effect on the magnetic property of gamma-ray irradiated Nd-Fe-B and Sr-Ferrite magnets has been investigated. When the permanent magnets are exposed to gamma-ray, it's magnetic and other related properties are declined with degree of dose. The decreased magnetic property by gamma-ray irradiation at low temperature is similar with the result of magnet at high temperature. The temperature effect on the gamma-ray irradiation at exposed moment is also regarded as one of the important parameters for the reduced magnetic properties. The gamma-irradiation at low temperature was carried out at 195 K, and the changed properties of two kinds of magnets before and after gamma-irradiation were comparatively studied. The increased demagnetization of the magnets were studied by Hall probe. And changed Curie temperature and micro-crystal structure of each permanent magnet by gamma-ray irradiation has been also studied. Moreover the strong and broad single line shape of ESR signal in the resonance magnetic field is attributed to unpaired electron of Fe2+ in the sample by the effect of gamma-ray irradiation.

  4. Permanent Magnet Boosted Modular Switched Reluctance Motor

    Directory of Open Access Journals (Sweden)

    SZABÓ Loránd

    2016-10-01

    Full Text Available This paper deals with the analyses of a novel motor structure obtained by boosting with permanent magnets a formerly studied modular switched reluctance motor. Upon dynamic simulation results the improvements of the proposed motor are emphasized.

  5. Nanocompositional Electron Microscopic Analysis and Role of Grain Boundary Phase of Isotropically Oriented Nd-Fe-B Magnets

    Directory of Open Access Journals (Sweden)

    Gregor A. Zickler

    2017-01-01

    Full Text Available Nanoanalytical TEM characterization in combination with finite element micromagnetic modelling clarifies the impact of the grain misalignment and grain boundary nanocomposition on the coercive field and gives guidelines how to improve coercivity in Nd-Fe-B based magnets. The nanoprobe electron energy loss spectroscopy measurements obtained an asymmetric composition profile of the Fe-content across the grain boundary phase in isotropically oriented melt-spun magnets and showed an enrichment of iron up to 60 at% in the Nd-containing grain boundaries close to Nd2Fe14B grain surfaces parallel to the c-axis and a reduced iron content up to 35% close to grain surfaces perpendicular to the c-axis. The numerical micromagnetic simulations on isotropically oriented magnets using realistic model structures from the TEM results reveal a complex magnetization reversal starting at the grain boundary phase and show that the coercive field increases compared to directly coupled grains with no grain boundary phase independently of the grain boundary thickness. This behaviour is contrary to the one in aligned anisotropic magnets, where the coercive field decreases compared to directly coupled grains with an increasing grain boundary thickness, if Js value is > 0.2 T, and the magnetization reversal and expansion of reversed magnetic domains primarily start as Bloch domain wall at grain boundaries at the prismatic planes parallel to the c-axis and secondly as Néel domain wall at the basal planes perpendicular to the c-axis. In summary our study shows an increase of coercive field in isotropically oriented Nd-Fe-B magnets for GB layer thickness > 5 nm and an average Js value of the GB layer < 0.8 T compared to the magnet with perfectly aligned grains.

  6. Design and performance of electromagnetic machines based on Nd-Fe-B magnets

    Science.gov (United States)

    Hanitsch, R.

    1991-10-01

    The application of rare-earth permanent magnets - replacing wound coils - in electrical devices is advantageous concerning performance and cost. The benefits are: increased efficiency, reduced time constant, smaller volume and weight, and cost effective production. These magnets have mainly been installed in high-precision small-size motors such as brushless dc motors, stepping motors and coreless motors. Motors of these types are used in computer peripherals and portable electronic products. Because of improvements in the materials rare-earth magnets are now also used for automotive applications and industrial drives. In addition to sintered materials bonded materials are also used for motor and actuator designs.

  7. Forces Between a Permanent Magnet and a Soft Magnetic Plate

    DEFF Research Database (Denmark)

    Beleggia, Marco; Vokoun, David; De Graef, Marc

    2012-01-01

    Forces between a hard/permanent magnet of arbitrary shape and an ideally soft magnetic plate in close proximity are derived analytically from the image method applied to magnetostatics. We found that the contact force, defined as the force required to detach the hard magnet from the plate......, coincides with that between two identical touching permanent magnets. Furthermore, if the hard and the soft magnets are displaced by some amount, their attraction equals that between two identical permanent magnets displaced by twice that amount. Experimental results are presented that validate...

  8. Development of Sintered NdFeB Magnet Industry in China (Continued)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Ⅲ. Changes in NdFeB industry pattern With the development of China economy, many oversea companies have shifted the resource-intensive,energy-consumption and labor-intensive industries to China due to lack of predominance of resources and production cost in the competition with China.

  9. Dense arrays of cobalt nanorods as rare-earth free permanent magnets.

    Science.gov (United States)

    Anagnostopoulou, E; Grindi, B; Lacroix, L-M; Ott, F; Panagiotopoulos, I; Viau, G

    2016-02-21

    We demonstrate in this paper the feasibility to elaborate rare-earth free permanent magnets based on cobalt nanorods assemblies with energy product (BH)max exceeding 150 kJ m(-3). The cobalt rods were prepared by the polyol process and assembled from wet suspensions under a magnetic field. Magnetization loops of dense assemblies with remanence to a saturation of 0.99 and squareness of 0.96 were measured. The almost perfect M(H) loop squareness together with electron microscopy and small angle neutron scattering demonstrate the excellent alignment of the rods within the assemblies. The magnetic volume fraction was carefully measured by coupling magnetic and thermogravimetric analysis and found in the range from 45 to 55%, depending on the rod diameter and the alignment procedure. This allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m(-3) was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets.

  10. Design of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Tim; Zeitler, Benno; Gruener, Florian [University of Hamburg and Center for Free-Electron Laser Science, Hamburg (Germany); Floettmann, Klaus [DESY, Hamburg (Germany); Manz, Stephanie [MPSD, University of Hamburg (Germany)

    2013-07-01

    The Relativistic Electron Gun for Atomic Exploration REGAE is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. Two future experiments at REGAE, an external injection experiment for Laser Wakefield Acceleration (LWA) and a time resolving Transmission Electron Microscopy (TEM) setup, require strong focusing magnets inside the target chamber. Permanent magnetic solenoids can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. Solenoids are fundamentally non-linear focusing elements whose non-linearity is worst for short, strong magnets as required for REGAE. The induced emittance growth is investigated and minimized for different setups with axially and radially magnetized annular magnets. Since permanent magnetic solenoids cannot be switched off but are not needed in every experiment at REGAE, a mechanical lifting-system and a magnetic shielding has to ensure, that the different experiments do not disturb each other.

  11. Technological and economical analysis of salient pole and permanent magnet synchronous machines designed for wind turbines

    Science.gov (United States)

    Gündoğdu, Tayfun; Kömürgöz, Güven

    2012-08-01

    Chinese export restrictions already reduced the planning reliability for investments in permanent magnet wind turbines. Today the production of permanent magnets consumes the largest proportion of rare earth elements, with 40% of the rare earth-based magnets used for generators and other electrical machines. The cost and availability of NdFeB magnets will likely determine the production rate of permanent magnet generators. The high volatility of rare earth metals makes it very difficult to quote a price. Prices may also vary from supplier to supplier to an extent of up to 50% for the same size, shape and quantity with a minor difference in quality. The paper presents the analysis and the comparison of salient pole with field winding and of peripheral winding synchronous electrical machines, presenting important advantages. A neodymium alloy magnet rotor structure has been considered and compared to the salient rotor case. The Salient Pole Synchronous Machine and the Permanent Magnet Synchronous Machine were designed so that the plate values remain constant. The Eddy current effect on the windings is taken into account during the design, and the efficiency, output power and the air-gap flux density obtained after the simulation were compared. The analysis results clearly indicate that Salient Pole Synchronous Machine designs would be attractive to wind power companies. Furthermore, the importance of the design of electrical machines and the determination of criteria are emphasized. This paper will be a helpful resource in terms of examination and comparison of the basic structure and magnetic features of the Salient Pole Synchronous Machine and Permanent Magnet Synchronous Machine. Furthermore, an economic analysis of the designed machines was conducted.

  12. Permanent magnet flux-biased magnetic actuator with flux feedback

    Science.gov (United States)

    Groom, Nelson J. (Inventor)

    1991-01-01

    The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.

  13. Dovetail spoke internal permanent magnet machine

    Science.gov (United States)

    Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi; Lokhandwalla, Murtuza; Shah, Manoj Ramprasad; VanDam, Jeremy Daniel

    2011-08-23

    An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

  14. A novel method combining additive manufacturing and alloy infiltration for NdFeB bonded magnet fabrication

    Science.gov (United States)

    Li, Ling; Tirado, Angelica; Conner, B. S.; Chi, Miaofang; Elliott, Amy M.; Rios, Orlando; Zhou, Haidong; Paranthaman, M. Parans

    2017-09-01

    In this paper, binder jetting additive manufacturing technique is employed to fabricate NdFeB isotropic bonded magnets, followed by an infiltration process with low-melting point eutectic alloys [i.e., Nd3Cu0.25Co0.75 (NdCuCo) and Pr3Cu0.25Co0.75 (PrCuCo)]. Densification and mechanical strength improvement are achieved for the as-printed porous part. Meanwhile, the intrinsic coercivity Hci is enhanced from 732 to 1345 kA/m and 1233 kA/m after diffusion of NdCuCo and PrCuCo, respectively. This study presents a novel method for fabricating complex-shaped bonded magnets with promising mechanical and magnetic properties.

  15. Effect Of DyMn Alloy-Powder Addition On Microstructure And Magnetic Properties Of NdFeB Sintered Magnets

    Directory of Open Access Journals (Sweden)

    Lee M.-W.

    2015-06-01

    Full Text Available Micostructural change and corresponding effect on coercivity of a NdFeB sintered magnet mixed with small amount of DyMn powder was investigated. In the sintered magnet mixed with the DyMn alloy-powder Dy-rich shell was formed at outer layer of the main grains, while Mn was mostly concentrated at Nd-rich triple junction phase (TJP, lowering melting temperature of the Nd-rich phase that eventually improved the microstructural characteristics of the gain boundary phase. The coercivity of a magnet increased more than 3.5 kOe by the mixing of the DyMn alloy-powder.

  16. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...

  17. Multifaceted Material Substitution: The Case of NdFeB Magnets, 2010-2015

    Science.gov (United States)

    Smith, Braeton J.; Eggert, Roderick G.

    2016-07-01

    Substitution is an important response for material users when faced with disruption to the availability or price of an essential material. In economic terms, substitution refers to the ability of firms to alter their patterns of material use in response to exogenous market shocks. Substitution comes in different forms which vary from situation to situation. This paper uses expert opinion to identify the specific forms of substitution that occurred in permanent magnets, specifically neodymium-iron-boron magnets, following the significant increase in rare earth prices in 2010-2011. The paper provides a framework for understanding the multifaceted nature of substitution and assesses the relative importance of five different types of substitution. Technology-for-element, grade-for-grade, and system-for-system substitution appear to have been more important than element-for-element and magnet-for-magnet substitution. Cost pass-through and absorption were also important responses.

  18. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  19. Optimally segmented permanent magnet structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    We present an optimization approach which can be employed to calculate the globally optimal segmentation of a two-dimensional magnetic system into uniformly magnetized pieces. For each segment the algorithm calculates the optimal shape and the optimal direction of the remanent flux density vector...

  20. Relation between Nd{sub 2}Fe{sub 14}B grain alignment and coercive force decrease ratio in NdFeB sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Yutaka, E-mail: Yutaka_Matsuura@hitachi-metals.co.jp [Hitachi Metals Ltd., NEOMAX Division, 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka 618-0013 (Japan); Hoshijima, Jun; Ishii, Rintaro [Hitachi Metals Ltd., NEOMAX Division, 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka 618-0013 (Japan)

    2013-06-15

    It was found that the coercive force of NdFeB sintered magnets decreases as the Nd{sub 2}Fe{sub 14}B grain alignment improves. Because of this phenomenon, studies looked at the relation between this alignment and the coercive force decrease ratio. In experiments, it was expected that the coercive force of perfectly aligned magnet reached 0.7 of coercive force in istotropically aligned magnet. When it is postulated that the coercive force is determined by the Stoner–Wohlfarth model, coercive force increases as the alignment improves and it becomes difficult to explain our experimental data. On the other hand, when the coercive force is determined by magnetic domain wall motion, the coercive force decreases as the alignment improves and the coercive force of the perfectly aligned magnet reaches 1/√(2) of the isotropically aligned magnet. This tendency and value was very close to our data. It strongly suggests that the coercive force of NdFeB sintered magnets is determined by the domain wall motion. - Highlights: ► Coercive force of NdFeB sintered magnets decreases as grains alignment improves. ► Coercive force decrease ratio reaches −30% at the perfect aligned magnet. ►These experimental results are different from the Stoner–Wohlfarth model. ► The magnetic domain wall motion could explain this coercive force decrease ratio.

  1. Design Study Of Cyclotron Magnet With Permanent Magnet

    Science.gov (United States)

    Kim, Hyun Wook; Chai, Jong Seo

    2011-06-01

    Low energy cyclotrons for Positron emission tomography (PET) have been wanted for the production of radio-isotopes after 2002. In the low energy cyclotron magnet design, increase of magnetic field between the poles is needed to make a smaller size of magnet and decrease power consumption. The Permanent magnet can support this work without additional electric power consumption in the cyclotron. In this paper the study of cyclotron magnet design using permanent magnet is shown and also the comparison between normal magnet and the magnet which is designed with permanent magnet is shown. Maximum energy of proton is 8 MeV and RF frequency is 79.3 MHz. 3D CAD design was done by CATIA P3 V5 R18 [1] and the All field calculations had been performed by OPERA-3D TOSCA [2]. The self-made beam dynamics program OPTICY [3] is used for making isochronous field and other calculations.

  2. Development of Strip Casting Technology in Rare Earth Permanent Magnet Alloys and Hydrogen Storage Alloys in China

    Institute of Scientific and Technical Information of China (English)

    Han Weiping; Guo Binglin; Yu Xiaojun; Zhu Jinghan; Cheng Xinghua

    2007-01-01

    The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in rare earth permanent magnet alloys and hydrogen storage alloys were analyzed integrative, on the basis of summary of SC technique development in this paper. The paper mainly includes development history of SC technology, effect of SC technology on alloy microstructure, application of SC technology in RE storage hydrogen alloy and sintered Nd-Fe-B alloy, development of SC equipment and SC product industry. At the same time, the paper points out the existing problem of SC products.

  3. Evaluation of the effects of aging in synthetic saliva solution of both commercial and silanized Nd-Fe-B magnets for dental application

    Science.gov (United States)

    Fabiano, F.; Puliafito, V.; Calabrese, L.; Borsellino, C.; Bonaccorsi, L. M.; Giordano, A.; Fabiano, V.; Cordasco, G.

    2016-04-01

    Neodymium-iron-boron magnets are able to ensure a magnetic flux with high maximum energy product also at miniaturized size. In the past, due to their marked corrosion in saliva they were unsuccessfully implemented in orthodontic systems. Thereby, we propose a multi-layered organic-inorganic coating able to supply anticorrosion resistance, wear resistance and durability to the whole assembly. We evaluated the influence on the magnetic force of commercial nickel plated and silanized Nd-Fe-B during aging time in synthetic Fusayama saliva. Two magnets based-micromagnetic simulations were performed in order to analyze the magnetic field generated which is linked to the magnetic force. Our key results underline that the proposed hybrid coating does not affect the magnetic force of Nd-Fe-B magnets, moreover, preventing corrosion degradation in aggressive solution. Thus the limiting aspects avoiding the use of Nd-Fe-B magnets for orthodontic and prosthodontic applications can be overcome by using silane agents as surface coating.

  4. Manufacturing of Injection-Molded NdFeB Magnet with (BH)max111 kJ · m-3

    Institute of Scientific and Technical Information of China (English)

    Duan Bohua; Qu Xuanhui; Xu Zhengzhou; Guo Shibo; Qin Mingli

    2004-01-01

    The bonded NdFeB magnets prepared by injection molding meet with the development tendency of the magnet in small volume, light weight and high performance ,and have a good prospect.In this paper, a modified nylonbased binder was developed for powder injection molding of NdFeB bonded magnets.The effects of pretreatment of NdFeB anisotropic magnetic powder produced with HDDR processing on the anti-oxidation behaviors of powder and the final magnetic properties of the molded bonded magnets were studied.The optimal powder loading of 65 vol% was achieved with the modified binder.It was found that the properties of the bonded magnets were mainly affected by the powder surface pretreatment and the intensity of the applied alignment magnetic field during injection molding for a certain powder.Bonded magnets with remanence of 0.820 T, intrinsic coercivity of 1140.3 kA· m-1 and maximum energy product of 111 kJ · m-3 were produced with the optimal processing.

  5. Comparing superconducting and permanent magnets for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Nielsen, Kaspar Kirstein; Bahl, C. R. H.

    2016-01-01

    We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the r......We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio...

  6. DEVELOPMENT OF NEW DESIGN TO IMPROVE THE PERFORMANCE OF PERMANENT MAGNET SYNCHRONOUS RELUCTANCE MOTOR USING FINITE ELEMENT METHOD

    Directory of Open Access Journals (Sweden)

    D. Vimalakeerthy,

    2011-02-01

    Full Text Available Induction Motors(IM are preferred as the most common drive for industrial and civil applications due to their simple construction and robustness. But they are not suitable when the application requires speed regulation. In several cases high torque, high efficiency, and simple controllability are often desired. Permanent Magnet Synchronous Reluctance Motor “PMSRM” has gained interest due to several factors like reduced cost, ability to operate at near zero speed even at full load and flux weakening capability for spindle and traction applications. As the high field strength of neodymium- ron-boron (NdFeB magnets become commercially available with affordable prices, PMSRMs are receiving increasing attention due totheir high speed, high power density and high efficiency. A modified design in the location of permanent magnets in the flux barriers of PMSRM is proposed and its results are validated to improve theperformance. Finite Element Method(FEM is used to analyze the design parameters.

  7. Effects of lanthanum substitution on microstructures and intrinsic magnetic properties of Nd-Fe-B alloy

    Institute of Scientific and Technical Information of China (English)

    李智; 刘卫强; 查善顺; 李玉卿; 王云峤; 张东涛; 岳明; 张久兴

    2015-01-01

    (Nd1–xLax)30Fe69B (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) alloys were prepared by inducting melting, and the effect of substitution of La for Nd on their microstructure and intrinsic magnetic properties were investigated. With the increase of La content, Curie tem-perature (Tc) decreased from 582.4 to 557.4 K, saturation magnetization (Ms) decreased from 1.59 to 1.37 T, and anisotropy field (HA) decreased from 5394 to 3911 kA/m. However, the reductions of the intrinsic magnetic properties were relatively gentle as La content increased, which meant that the intrinsic magnetic properties still had the potential to fabricate permanent magnets. Moreover, further microstructure observations showed that La tended to diffuse into the Nd-rich grain boundary phase instead of main phase during the substitute process. Such aggregation behavior was beneficial to fabricating La containing magnet with high Ms.

  8. Hybrid high gradient permanent magnet quadrupole

    Science.gov (United States)

    N'gotta, P.; Le Bec, G.; Chavanne, J.

    2016-12-01

    This paper presents an innovative compact permanent magnet quadrupole with a strong gradient for potential use in future light source lattices. Its magnetic structure includes simple mechanical parts, rectangular permanent magnet blocks and soft iron poles. It has a wide aperture in the horizontal plane to accommodate an x-ray beam port, a common constraint in storage ring-based light sources. This specificity introduces field quality deterioration because of the resulting truncation of the poles; a suitable field quality can be restored with an optimized pole shape. A 82 T /m prototype with a bore radius of 12 mm and a 10 mm vertical gap between poles has been constructed and magnetically characterized. Gradient inhomogeneities better than 10-3 in the good field region were obtained after the installation of special shims.

  9. Towards high-performance permanent magnets without rare earths.

    Science.gov (United States)

    Kuz'min, M D; Skokov, K P; Jian, H; Radulov, I; Gutfleisch, O

    2014-02-12

    Achieving a very strong magnetic anisotropy in a 3d material is a difficult, but not an impossible task. It is difficult because there is no general recipe (necessary condition) for a strong anisotropy in a band magnet. Several strategies can be pursued in this situation. One of them is to re-examine the less studied 3d compounds, somewhat neglected since the discovery of the Nd-Fe-B magnets 30 years ago. As an example, a single crystal of (Fe0.7Co0.3)2B has been investigated in this work.

  10. Permanent magnet motor technology design and applications

    CERN Document Server

    Gieras, Jacek F

    2009-01-01

    Demonstrates the construction of permanent magnet (PM) motor drives and supplies ready-to-implement solutions to common roadblocks along the way. This book also supplies fundamental equations and calculations for determining and evaluating system performance, efficiency, reliability, and cost. It explores modern computer-aided design of PM motors.

  11. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  12. Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Y.; Kitagawa, J., E-mail: j-kitagawa@fit.ac.jp [Department of Electrical Engineering, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka 811-0295 (Japan); Ono, T.; Tsubota, M. [Physonit Inc., 6-10 Minami-Horikawa, Kaita Aki, Hiroshima 736-0044 (Japan)

    2015-11-15

    The sustainable society requires the recycling of rare metals. Rare earth Nd is one of rare metals, accompanying huge consumption especially in Nd-Fe-B magnets. Although the wet process using acid is in practical use in the in-plant recycle of sludge, higher selectivity between Nd and Fe at room temperature is desired. We have proposed a pretreatment of corrosion before the dissolution into HCl and the oxalic acid precipitation. The corrosion produces γ-FeOOH and a Nd hydroxide, which have high selectivity for HCl solution at room temperature. Nd can be recovered as Mn{sub 2}O{sub 3}-type Nd{sub 2}O{sub 3}. The estimated recovery-ratio of Nd reaches to 97%.

  13. Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

    Directory of Open Access Journals (Sweden)

    Y. Kataoka

    2015-11-01

    Full Text Available The sustainable society requires the recycling of rare metals. Rare earth Nd is one of rare metals, accompanying huge consumption especially in Nd-Fe-B magnets. Although the wet process using acid is in practical use in the in-plant recycle of sludge, higher selectivity between Nd and Fe at room temperature is desired. We have proposed a pretreatment of corrosion before the dissolution into HCl and the oxalic acid precipitation. The corrosion produces γ-FeOOH and a Nd hydroxide, which have high selectivity for HCl solution at room temperature. Nd can be recovered as Mn2O3-type Nd2O3. The estimated recovery-ratio of Nd reaches to 97%.

  14. Permanent magnet design for high-speed superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (5519 S. Bruner, Hinsdale, IL 60521); Uherka, Kenneth L. (830 Ironwood, Frankfort, IL 60423); Abdoud, Robert G. (13 Country Oaks La., Barrington Hills, IL 60010)

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  15. Coercivity enhancement of hot-deformed Nd-Fe-B magnets by the eutectic grain boundary diffusion process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8577 (Japan); Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Yano, M.; Kato, A.; Shoji, T. [Toyota Motor Corporation, Advanced Material Engineering Div., Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8577 (Japan)

    2016-05-05

    Nd-M (M = Al, Cu, Ga, Zn, Mn) alloys with compositions close to eutectic points were investigated as diffusion sources for the grain boundary diffusion process to hot-deformed Nd-Fe-B magnets. Coercivity enhancement was observed for most of the alloys. Among them, the sample processed with Nd{sub 90}Al{sub 10} exhibited the highest coercivity of 2.5 T at room temperature. However, the sample processed with Nd{sub 70}Cu{sub 30} exhibited the highest coercivity of 0.7 T at 200 {sup °}C. Microstructural observations using scanning transmission electron microscope (STEM) showed that nonferromagnetic Nd-rich intergranular phase envelops the Nd{sub 2}Fe{sub 14}B grains after the diffusion process. Abnormal grain growth and the dissolution of Al into the Nd{sub 2}Fe{sub 14}B grains were observed in the sample processed with Nd{sub 90}Al{sub 10}, which explains its inferior thermal stability of coercivity compared to the sample processed with Nd{sub 70}Cu{sub 30}. The coercivity enhancement and poor thermal stability of the coercivity of the Nd{sub 90}Al{sub 10} diffusion-processed sample are discussed based on microstructure studies by transmission electron microscopy. - Highlights: • Coercivity of hot-deformed Nd-Fe-B magnets is enhanced by the infiltration of various R-TM eutectic alloys. • The sample infiltrated with Nd{sub 90}Al{sub 10} shows the highest coercivity of 2.5 T at room temperature. • At 200 °C, Nd{sub 70}Cu{sub 30} diffusion-processed sample possesses the highest coercivity of 0.7 T.

  16. Sensorless Control of Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Matzen, Torben N.

    Permanent magnet machines, with either surface mounted or embedded magnets on the rotor, are becoming more common due to the key advantages of higher energy conversion efficiency and higher torque density compared to the classical induction machine. Besides energy efficiency the permanent magnet...... are dependent on the phase currents and rotor position. Based on the flux linkages the differential inductances are determined and used to establish the inductance saliency in terms of ratio and orientation. The orientation and its dependence on the current and rotor position are used to analyse the behaviour...... and establish the suitability of the machine for sensorless control using inductance saliency tracking methods. The same electromagnetic behaviour is used in the implementation of a dynamical simulation model of the machine useful for evaluation of sensorless control methods at the control design stage. Further...

  17. Tunable high-gradient permanent magnet quadrupoles

    CERN Document Server

    Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

    2014-01-01

    A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

  18. Modifying bone scaffold architecture in vivo with permanent magnets to facilitate fixation of magnetic scaffolds.

    Science.gov (United States)

    Panseri, S; Russo, A; Sartori, M; Giavaresi, G; Sandri, M; Fini, M; Maltarello, M C; Shelyakova, T; Ortolani, A; Visani, A; Dediu, V; Tampieri, A; Marcacci, M

    2013-10-01

    The fundamental elements of tissue regeneration are cells, biochemical signals and the three-dimensional microenvironment. In the described approach, biomineralized-collagen biomaterial functions as a scaffold and provides biochemical stimuli for tissue regeneration. In addition superparamagnetic nanoparticles were used to magnetize the biomaterials with direct nucleation on collagen fibres or impregnation techniques. Minimally invasive surgery was performed on 12 rabbits to implant cylindrical NdFeB magnets in close proximity to magnetic scaffolds within the lateral condyles of the distal femoral epiphyses. Under this static magnetic field we demonstrated, for the first time in vivo, that the ability to modify the scaffold architecture could influence tissue regeneration obtaining a well-ordered tissue. Moreover, the association between NdFeB magnet and magnetic scaffolds represents a potential technique to ensure scaffold fixation avoiding micromotion at the tissue/biomaterial interface.

  19. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  20. Localization for the Non-Invasive Detecting Capsule in GI Tract Utilizing Permanent Magnet and Magnetoresistive Sensors

    Institute of Scientific and Technical Information of China (English)

    HE Wen-hui; YAN Guo-zheng; GUO Xu-dong

    2007-01-01

    The paper reports the localization principle and method for the capsule in the non-invasive detecting system of gastrointestinal (GI) tract utilizing one permanent and three magnetoresistive sensors. When the capsule is localized in practice, the permanent magnet is fixed inside the capsule, and the four magnetoresistive sensors are installed outside body. The permanent magnet's coordinate values can be solved by the magnetic dipole theory and optimum iterated method. The experiment shows the localization distance can reach 300 mm by employing the HMCI023 magnetoresistive sensors and the NdFeB45 φ9 mm × 5 mm permanent magnet, and the errors of single coordinate direction and radius vector are 0 - 58 mm and 0.1-62.9 mm respectively. The localization precision is acceptable basically, and it has some possibilities improving the precision and distance in the future. Moreover, the localization system makes the localization be reality because of decreasing the number of sensors, and it economizes the capsule's volume because of decreasing the permanent magnet's dimension, too.

  1. Study of sintered Nd-Fe-B magnet with high performance of Hcj (kOe + (BHmax (MGOe > 75

    Directory of Open Access Journals (Sweden)

    Bo-Ping Hu

    2013-04-01

    Full Text Available We have developed a Nd-Fe-B sintered magnet of extremely high performance. The intrinsic coercivity Hcj is as high as 35.2 kOe (2803kA/m together with the maximum energy product (BHmax of 40.4 MGOe (321.6kJ/m3. These values result in Hcj (kOe + (BHmax (MGOe > 75. Between 293 K (20ºC and 473 K (200ºC, the temperature coefficients of remanence and intrinsic coercivity are αBr = −0.122 %/°C and αHcj = −0.403%/°C, respectively. A maximum operating temperature of 503 K (230ºC is obtained when permeance coefficient Pc = −B/H = 2. Grain boundary diffusion (GBD technique on magnet surface has been developed to increase Hcj by 3.6 kOe without significantly decrease of Br and (BHmax. The intrinsic coercivity of the GBD treated magnet Hcj(C has a linear relationship with that of the untreated magnet Hcj(B between 200 K and 473 K (in unit of kOe: Hcj(C = 1.03Hcj(B + 2.38. The enhancement of Hcj by GBD treatment has contributions not only from the improvement of microstructure but also from the increase of Ha in the grain surface layer. It is also found that GBD treatment brings no deterioration in corrosion resistance of untreated magnet.

  2. Effects of additive elements (Cu, Zr, Al) on morphological and magnetic properties of NdFeB thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.G. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China); Li, R.S. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China); Yang, Z. [Research Institute of Magnetic Materials, Lanzhou University, Lanzhou 730000 (China)]. E-mail: yangz@lzu.edu.cn; Matsumoto, M. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Morisako, A. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Takei, S. [Department of Information Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2005-03-25

    Cu, Zr, Al were doped into the NdFeB thin films to improve the morphological and magnetic properties of the films. Distinct results have been observed due to the different nature of these additives (such as atomic radius and chemical affinity, etc.). The morphological and magnetic properties of the films could be improved selectively according to the additive element. Grains in the Cu-doped film significantly grew and became strip-like. Both Zr and Al addition effectively reduced the grain size. But Zr addition led to a large grain size distribution while Al addition produced more uniformly sized grains in the film. The perpendicular coercivities of NdFeB films could be enhanced by doping a certain amount of the additive element. Addition of 1.0 at.% Cu or 3.8 at.% Zr increased the perpendicular coercivity H {sub cperpendicular} up to 487 or 565 kA/m from 382 kA/m, respectively. On the other hand, addition of 5.0 at.% Al could effectively moderate H {sub cperpendicular} to 279 kA/m while remained a high perpendicular remanent magnetization ratio S{sub perpendicular} around 0.9. Magnetization reversal mechanisms of the doped samples were also discussed according to the angular dependence of the coercivity H {sub c}({theta}) and M-H loop shapes. It was suggested that magnetization reversal of Cu-doped sample was initiated by domain wall motion and ended by domain wall pinning. Most of the grains in the Zr-doped sample were inversely magnetized by magnetization coherent rotation, but the rest were demagnetized by magnetization incoherent switching. In the Al-doped sample, magnetization reversal was proceeded mainly by magnetization incoherent rotation.

  3. A compact permanent-magnet system for measuring magnetic circular dichroism in resonant inelastic soft X-ray scattering.

    Science.gov (United States)

    Miyawaki, Jun; Suga, Shigemasa; Fujiwara, Hidenori; Niwa, Hideharu; Kiuchi, Hisao; Harada, Yoshihisa

    2017-03-01

    A compact and portable magnet system for measuring magnetic dichroism in resonant inelastic soft X-ray scattering (SX-RIXS) has been developed at the beamline BL07LSU in SPring-8. A magnetic circuit composed of Nd-Fe-B permanent magnets, which realised ∼0.25 T at the center of an 11 mm gap, was rotatable around the axis perpendicular to the X-ray scattering plane. Using the system, a SX-RIXS spectrum was obtained under the application of the magnetic field at an angle parallel, nearly 45° or perpendicular to the incident X-rays. A dedicated sample stage was also designed to be as compact as possible, making it possible to perform SX-RIXS measurements at arbitrary incident angles by rotating the sample stage in the gap between the magnetic poles. This system enables facile studies of magnetic dichroism in SX-RIXS for various experimental geometries of the sample and the magnetic field. A brief demonstration of the application is presented.

  4. Robotized Surface Mounting of Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Erik Hultman

    2014-10-01

    Full Text Available Using permanent magnets on a rotor can both simplify the design and increase the efficiency of electric machines compared to using electromagnets. A drawback, however, is the lack of existing automated assembly methods for large machines. This paper presents and motivates a method for robotized surface mounting of permanent magnets on electric machine rotors. The translator of the Uppsala University Wave Energy Converter generator is used as an example of a rotor. The robot cell layout, equipment design and assembly process are presented and validated through computer simulations and experiments with prototype equipment. A comparison with manual assembly indicates substantial cost savings and an improved work environment. By using the flexibility of industrial robots and a scalable equipment design, it is possible for this assembly method to be adjusted for other rotor geometries and sizes. Finally, there is a discussion on the work that remains to be done on improving and integrating the robot cell into a production line.

  5. A Novel Permanent Magnetic Angular Acceleration Sensor

    OpenAIRE

    Hao Zhao; Hao Feng

    2015-01-01

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it h...

  6. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  7. Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets

    Science.gov (United States)

    Barmada, S.; Rizzo, R.; Sani, L.

    2009-01-01

    In this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented simplistically. This simplistic treatment does not allow the students to develop a complete…

  8. Comparing superconducting and permanent magnets for magnetic refrigeration

    Directory of Open Access Journals (Sweden)

    R. Bjørk

    2016-05-01

    Full Text Available We compare the cost of a high temperature superconducting (SC tape-based solenoid with a permanent magnet (PM Halbach cylinder for magnetic refrigeration. Assuming a five liter active magnetic regenerator volume, the price of each type of magnet is determined as a function of aspect ratio of the regenerator and desired internal magnetic field. It is shown that to produce a 1 T internal field in the regenerator a permanent magnet of hundreds of kilograms is needed or an area of superconducting tape of tens of square meters. The cost of cooling the SC solenoid is shown to be a small fraction of the cost of the SC tape. Assuming a cost of the SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, the superconducting solenoid is shown to be a factor of 0.3-3 times more expensive than the permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspect ratio of the regenerator. This factor decreases for increasing field strength, indicating that the superconducting solenoid could be suitable for high field, large cooling power applications.

  9. Forces between permanent magnets: experiments and model

    Science.gov (United States)

    González, Manuel I.

    2017-03-01

    This work describes a very simple, low-cost experimental setup designed for measuring the force between permanent magnets. The experiment consists of placing one of the magnets on a balance, attaching the other magnet to a vertical height gauge, aligning carefully both magnets and measuring the load on the balance as a function of the gauge reading. A theoretical model is proposed to compute the force, assuming uniform magnetisation and based on laws and techniques accessible to undergraduate students. A comparison between the model and the experimental results is made, and good agreement is found at all distances investigated. In particular, it is also found that the force behaves as r -4 at large distances, as expected.

  10. Dynamics of Permanent-Magnet Biased Active Magnetic Bearings

    Science.gov (United States)

    Fukata, Satoru; Yutani, Kazuyuki

    1996-01-01

    Active magnetic radial bearings are constructed with a combination of permanent magnets to provide bias forces and electromagnets to generate control forces for the reduction of cost and the operating energy consumption. Ring-shaped permanent magnets with axial magnetization are attached to a shaft and share their magnet stators with the electromagnets. The magnet cores are made of solid iron for simplicity. A simplified magnetic circuit of the combined magnet system is analyzed with linear circuit theory by approximating the characteristics of permanent magnets with a linear relation. A linearized dynamical model of the control force is presented with the first-order approximation of the effects of eddy currents. Frequency responses of the rotor motion to disturbance inputs and the motion for impulsive forces are tested in the non-rotating state. The frequency responses are compared with numerical results. The decay of rotor speed due to magnetic braking is examined. The experimental results and the presented linearized model are similar to those of the all-electromagnetic design.

  11. Solidification process in melt spun Nd-Fe-B type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changping [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    A generalized solidification model has been developed based on a systematic investigation on the microstructure of melt spun Nd-Fe-B alloys. Melt spinning was conducted on initial stoichiometric and TiC added Nd2Fe14B (2-14-1) compositions to produce under, optimally and over quenched microstructures. Microstructural characterization was carried out by TEM, SEM, Optical microscopy, XRD, DTA, VSM and DC SQUID techniques. By taking the dendritic breakup during recalescence into consideration, this generalized model has successfully explained the solidification process of the melt spun Nd-Fe-B alloys. Challenging the conventional homogeneous nucleation models, the new model explains the fine and uniform equiaxed 2-14-1 microstructure in optimally quenched ribbons as a result of the breakup of the 2-14-1 dendrites which nucleate heterogeneously from the wheel surface and grow dendritically across the ribbon thickness due to the recalescence. Besides this dendritic breakup feature, the under quenched microstructure is further featured with another growth front starting with the primary solidification of Fe phase near the free side, which results in a coarsely grained microstructure with Fe dendritic inclusions and overall variation in microstructure across the ribbon thickness. In addition, because a epitaxy exists between the Fe phase and the 2-14-1, the so-formed coarse 2-14-1 grains may be textured. C-axis texturing was observed in under quenched ribbons. As a constraint to solidification models in this system, the cause and characteristics of this phenomenon has been studied in detail to test the authors proposed model, and agreement has been found. An extension has also been made to understand the solidification process when TiC is added, which suggests that Ti and C slow down the growth front of both Fe and 2-14-1 phase.

  12. The status of Chinese permanent magnet industry and R&D activities

    Science.gov (United States)

    Dong, Shengzhi; Li, Wei; Chen, Hongsheng; Han, Rui

    2017-05-01

    It has been 15 years since China dominated the rare earth permanent magnet market in 2001. The annual output of sintered Nd-Fe-B magnets in China reached a new record of 126,300 tonnages in 2015 while the output in 2001 is only 6,500 tonnages. The average growth rate from 2001 to 2015 is about 23.5% though the output in 2012 suffers a deep drop due to the well known rare earth crisis in 2011. Currently, the RE magnet production capability in China seems to be over developed compared to actual requirements. Needless to say the oversupply situation implies a hard time for RE magnet manufacturers due to the fierce competition but maybe a good time for the whole industry. The motivation for a company to develop new technology and more competitive products with better performance and/or lower costs is greatly enhanced. The objective of this paper is to give a general picture of Chinese REPM industry and market including the output capability, the status of competition, the development of magnet application and the market trend. Some new research hot points potentially being applied, for example the Cerium magnet, will be introduced as well.

  13. Production of Nd-Fe-B alloys by mechanical alloying; Mechanical alloying ni yoru Nd-Fe-B gokin no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T. [Chiba Inst. of Tech., Narashino (Japan)

    1998-07-01

    Nb-Fe-B system magnet known as a high performance permanent magnet is produced by powder metallurgy and quench solidification methods. At present, although for a magnetic powder for Nd-Fe-B magnet an isotropic powder coarsely crashed after conducting heat treatment to and Nd-Fe-B amorphous thin belt produced by melt-spin method, research and development on an anisotropic magnetic powder are being propagated earnestly for magnetic powder with high magnetic property alternating with this. For a new producing method of magnetic powder alternating with the melt spin method, manufacturing methods using mechanical alloying method and using hydrogen storing feature of the Nd-Fe-B alloy called HDDR method are studied. In this study, mechanical alloying of mixed powders of Nd, Fe and B was conducted under hydrogen or nitrogen atmosphere to investigate the reaction to atmospheric gas such as hydrogen, nitrogen and so forth. And, by conducting the obtained powders to vacuum treatment, it was also investigated if Nd2Fe14B ferromagnetic phase formed or not. 9 refs., 6 figs.

  14. Magnetic forces produced by rectangular permanent magnets in static microsystems.

    Science.gov (United States)

    Gassner, Anne-Laure; Abonnenc, Mélanie; Chen, Hong-Xu; Morandini, Jacques; Josserand, Jacques; Rossier, Joel S; Busnel, Jean-Marc; Girault, Hubert H

    2009-08-21

    Finite element numerical simulations were carried out in 2D geometries to map the magnetic field and force distribution produced by rectangular permanent magnets as a function of their size and position with respect to a microchannel. A single magnet, two magnets placed in attraction and in repulsion have been considered. The goal of this work is to show where magnetic beads are preferentially captured in a microchannel. These simulations were qualitatively corroborated, in one geometrical case, by microscopic visualizations of magnetic bead plug formation in a capillary. The results show that the number of plugs is configuration dependent with: in attraction, one plug in the middle of the magnets; in repulsion, two plugs near the edges of the magnets; and with a single magnet, a plug close to the center of the magnet. The geometry of the magnets (h and l are the height and length of the magnets respectively) and their relative spacing s has a significant impact on the magnetic flux density. Its value inside a magnet increases with the h/l ratio. Consequently, bar magnets produce larger and more uniform values than flat magnets. The l/s ratio also influences the magnetic force value in the microchannel, both increasing concomitantly for all the configurations. In addition, a zero force zone in the middle appears in the attraction configuration as the l/s ratio increases, while with a single magnet, the number of maxima and minima goes from one to two, producing two focusing zones instead of only one.

  15. An adjustable focusing system for a 2 MeV H- ion beam line based on permanent magnet quadrupoles

    CERN Document Server

    Nirkko, M; Ereditato, A; Kreslo, I; Scampoli, P; Weber, M

    2012-01-01

    A compact adjustable focusing system for a 2 MeV H- RFQ Linac is designed, constructed and tested based on four permanent magnet quadrupoles (PMQ). A PMQ model is realised using finite element simulations, providing an integrated field gradient of 2.35 T with a maximal field gradient of 57 T/m. A prototype is constructed and the magnetic field is measured, demonstrating good agreement with the simulation. Particle track simulations provide initial values for the quadrupole positions. Accordingly, four PMQs are constructed and assembled on the beam line, their positions are then tuned to obtain a minimal beam spot size of (1.2 x 2.2) mm^2 on target. This paper describes an adjustable PMQ beam line for an external ion beam. The novel compact design based on commercially available NdFeB magnets allows high flexibility for ion beam applications.

  16. Design of magnet arrays for permanent magnetic linear motor

    Institute of Scientific and Technical Information of China (English)

    Junhong MAO; Junhang LUO; Qiang JIANG; Youbai XIE

    2008-01-01

    An iron-less single side permanent magnetic linear motor structure is presented,and two-dimensional analytical formulae for its magnetic field are deduced to design the types of magnetic arrays,the thickness of permanent magnet,and the duty ratio of magnet arrays,etc.With certain design parameters,conventional arrays are used instead of a piecewise Halbach arrays,and the machining and assembling of the motor are greatly simplified.Calculation results coincide with that of ANSYS.The analytical formulae can be used in designing cored linear motors by modifying boundary conditions.A linear motor driven bench with a single degree of freedom is realized,where the travel reaches 27 mm,the mass of the moving parts is 1.4 kg,and the maximum acceleration iS 11.5 m/s2.

  17. TEM observation of sintered permanent magnetic strontium ferrite

    Institute of Scientific and Technical Information of China (English)

    YU Hongya; LIU Zhengyi; ZENG Dechang

    2006-01-01

    Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. Themagnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxidephase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.

  18. Performance of repulsive type magnetic bearing system under nonuniform magnetization of permanent magnet

    OpenAIRE

    Ohji, T.; Mukhopadhyay, S. C.; Iwahara, Masayoshi; Yamada, Sotoshi

    2000-01-01

    Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, the...

  19. Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

    Science.gov (United States)

    Wang, Zexuan; Ju, Jinyun; Wang, Jinzhi; Yin, Wenzong; Chen, Renjie; Li, Ming; Jin, Chaoxiang; Tang, Xu; Lee, Don; Yan, Aru

    2016-12-01

    Ultrafine-grained die-upset Nd-Fe-B magnets are of importance because they provide a wide researching space to redesign the textured structures. Here is presented a route to obtain a new die-upset magnet with substantially improved magnetic properties. After experiencing the optimized heat treatment, both the coercivity and remanent magnetization of the Dy-Cu press injected magnets increased substantially in comparison with those of the annealed reference magnets, which is distinct from the reported experimental results on heavy rare-earth diffusion. To study the mechanism, we analyzed the texture evolution in high-temperature annealed die-upset magnets, which had significant impact on the improvement of remanent magnetization. On basis of the results, we find that the new structures are strongly interlinked with the initial structures. With injecting Dy-Cu eutectic alloy, an optimized initial microstructure was achieved in the near-surface diffused regions, which made preparations for the subsequent texture improvement. Besides, the Dy gradient distribution of near-surface regions of the Dy-Cu press injected magnets was also investigated. By controlling the initial microstructure and subsequent diffusion process, a higher performance magnet is expected to be obtained.

  20. Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment.

    Science.gov (United States)

    Wang, Zexuan; Ju, Jinyun; Wang, Jinzhi; Yin, Wenzong; Chen, Renjie; Li, Ming; Jin, Chaoxiang; Tang, Xu; Lee, Don; Yan, Aru

    2016-12-06

    Ultrafine-grained die-upset Nd-Fe-B magnets are of importance because they provide a wide researching space to redesign the textured structures. Here is presented a route to obtain a new die-upset magnet with substantially improved magnetic properties. After experiencing the optimized heat treatment, both the coercivity and remanent magnetization of the Dy-Cu press injected magnets increased substantially in comparison with those of the annealed reference magnets, which is distinct from the reported experimental results on heavy rare-earth diffusion. To study the mechanism, we analyzed the texture evolution in high-temperature annealed die-upset magnets, which had significant impact on the improvement of remanent magnetization. On basis of the results, we find that the new structures are strongly interlinked with the initial structures. With injecting Dy-Cu eutectic alloy, an optimized initial microstructure was achieved in the near-surface diffused regions, which made preparations for the subsequent texture improvement. Besides, the Dy gradient distribution of near-surface regions of the Dy-Cu press injected magnets was also investigated. By controlling the initial microstructure and subsequent diffusion process, a higher performance magnet is expected to be obtained.

  1. Design of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Tim

    2013-10-15

    The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. It is originally designed and built for ultrafast electron diffraction (UED) within the framework of the Center for Free-Electron Laser Science (CFEL). Additionally, two future experiments are planned at REGAE. First, an external injection experiment for Laser Wakefield Acceleration (LWA) will be performed in the framework of the LAOLA collaboration (LAboratory fOr Laser- and beam-driven plasma Acceleration). This experiment will provide a method for the reconstruction of the electric field distribution within a linear plasma wakefield. Second, a time resolving high energy Transmission Electron Microscope (TEM) will be implemented. Among others it is designed to allow for living cell imaging. Both experiments require strong focusing magnets inside the new target chamber at REGAE. Permanent magnetic solenoids (PMSs) can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. The present thesis deals with the design of such strong focusing PMSs. Since short and strong solenoids, as required for REGAE, exhibit a distinct non-linearity, the induced emittance growth is relatively large. This emittance growth is investigated and minimized for different set-ups with axially and radially magnetized annular magnets. Furthermore a magnetic shielding is developed. Together with a mechanical lifting system it assures that magnetic leakage fields do not disturb experiments, where the PMSs are removed from the beamline.

  2. Permanent magnetic toroidal drive with half stator

    Directory of Open Access Journals (Sweden)

    Lizhong Xu

    2017-01-01

    Full Text Available A permanent magnetic toroidal drive with a half stator is proposed that avoids noise and mechanical vibrations. The effects of the system parameters on the output torque of the drive were investigated. A model machine was designed and produced. The output torque and speed fluctuation of the drive system were measured, and the calculated and measured output torque were compared. The tests demonstrated that the drive system could operate continuously without noise, and the system achieved a given speed ratio. The drive system had high load-carrying ability and a maximum output torque of 0.15 N m when certain parameter values were used.

  3. Recent Advances on Permanent Magnet Machines

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2012-01-01

    This paper overviews advances on permanent magnet(PM) brushless machines over last 30 years,with particular reference to new and novel machine topologies.These include current states and trends for surface-mounted and interior PM machines,electrically and mechanically adjusted variable flux PM machines including memory machine,hybrid PM machines which uniquely integrate PM technology into induction machines,switched and synchronous reluctance machines and wound field machines,Halbach PM machines,dual-rotor PM machines,and magnetically geared PM machines,etc.The paper highlights their features and applications to various market sectors.

  4. Strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, Klaus

    1988-01-01

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

  5. Permanent superconducting magnets for space applications

    Science.gov (United States)

    Weinstein, Roy

    1994-01-01

    Work has been done to develop superconducting trapped field magnets (TFM's) and to apply them to a bumper-tether device for magnetic docking of spacecraft. The quality parameters for TFM's are J(c), the critical current of the superconductor, and d, the diameter of the superconducting tile. During this year we have doubled d, for production models, from 1 cm to 2 cm. This was done by means of seeding, an improved temperature profile in processing, and the addition of 1 percent Pt to the superconductor chemistry. Using these tiles we have set increasing records for the fields' permanent magnets. Magnets fabricated from old 1 cm tiles trapped 1.52 Tesla at 77K, 4.0T at 65K and 7.0T at 55K. The second of these fields broke a 17 year old record set at Stanford. The third field broke our own record. More recently using 2 cm tiles, we have trapped 2.3T at 77K, and 5.3T at 65K. We expect to trap lOT at 55K in this magnet in the near future. We have also achieved increases in J(c) using a method we developed for seeding U-235, and subsequently bombarding with neutrons. This method doubles J(c). We have not yet fabricated magnets from these tiles. During this year we have increased production yields from 15 percent to 95 percent. We have explored the properties of a magnetic bumper-tether for spacecraft. We have measured the bumper forces, and their dependence on time, distance, and the field of the ordinary ferromagnet (used together with a TFM). We have accounted for 85 percent of the collision energy, and its transformation to magnetic energy and heat energy. We have learned to control the relative bumper and tether forces by controlling TFM and ferromagnetic field strengths.

  6. Microstructural investigation of Nd-rich phase in sintered Nd-Fe-B magnets through electron microscopy

    Institute of Scientific and Technical Information of China (English)

    付新; 韩小磊; 杜志伟; 冯海波; 李岩峰

    2013-01-01

    The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron (BSE) imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2Fe14B matrix. Through selected area electron diffraction (SAED) analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic (FCC) structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2Fe14B matrix grains, such as (002)Nd2Fe14B//(200)FCC_Nd-rich [120] Nd2Fe14B//[001]FCC_Nd-rich, (002)Nd2Fe14B//( 220 )FCC_Nd-rich [110] Nd2Fe14B//[112]FCC_Nd-rich, as well as (011)Nd2Fe14B//(131)FCC_Nd-rich [111] Nd2Fe14B//[114]FCC_Nd-rich, which could be attributed to minimising interfacial energy. The combination of high-resolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd-rich grain were observed.

  7. Adjustable permanent magnet assembly for NMR and MRI

    Science.gov (United States)

    Pines, Alexander; Paulsen, Jeffrey; Bouchard, Louis S; Blumich, Bernhard

    2013-10-29

    System and methods for designing and using single-sided magnet assemblies for magnetic resonance imaging (MRI) are disclosed. The single-sided magnet assemblies can include an array of permanent magnets disposed at selected positions. At least one of the permanent magnets can be configured to rotate about an axis of rotation in the range of at least +/-10 degrees and can include a magnetization having a vector component perpendicular to the axis of rotation. The single-sided magnet assemblies can further include a magnet frame that is configured to hold the permanent magnets in place while allowing the at least one of the permanent magnets to rotate about the axis of rotation.

  8. Simulation on Magnetic Field Characteristics of Permanent-Magnet Seed-Metering Device

    OpenAIRE

    Wang, Jing; Hu, Jianping; Wang, Qirui; Wang, Xun

    2011-01-01

    Part 1: Simulation, Optimization, Monitoring and Control Technology; International audience; The cylindrical permanent magnet is the core part of the permanent-magnet seed-metering device, it can absorb single magnetic powder coated seed. The first, the magnetic induction intensity model of any point in the cylindrical permanent magnet external was established based on the equivalent current model of permanent magnet. The second, the mathematical formula was derived using the Biot-Savart law ...

  9. Forces between arrays of permanent magnets of basic geometric shapes

    DEFF Research Database (Denmark)

    Vokoun, D.; Beleggia, Marco

    2014-01-01

    We provide formulas for evaluating the magnetic force between two permanent magnet arrays, regularly spaced over a square lattice. We focus on three basic shapes of magnets constituting the arrays: cylinder, sphere and rectangular prism. When the lattice parameter is large, the expressions can...... be used to calculate the force between two single magnets in a computationally efficient way. The calculations are validated experimentally by measuring the attraction force between two single permanent magnets, where we demonstrate a fair agreement within about 15%....

  10. Advanced optimization of permanent magnet wigglers using a genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Hajima, Ryoichi [Univ. of Tokyo (Japan)

    1995-12-31

    In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms.

  11. Application of permanent magnets in accelerators and electron storage rings

    Science.gov (United States)

    Halbach, K.

    1985-04-01

    The use of permanent-magnet systems in high-energy accelerators and as sources of synchrotron radiation in electron-storage rings is discussed in a review of recent experimental investigations. Consideration is given to the generic advantages of permanent magnets over electromagnets (higher field strength per magnet size) in small-scale configurations; the magnetic properties of some charge-sheet-equivalent-permanent-magnet materials (CSEMs); and the design of pure-CSEM and CSEM-Fe-hybrid multipole magnetic lenses, dipoles, and undulator/wiggler systems for use in free-electron lasers and the production of elliptically polarized synchrotron light. Drawings and diagrams are provided.

  12. Magnetic Performance of a Nanocomposite Permanent Material

    Institute of Scientific and Technical Information of China (English)

    LIU Min; HAN Guang-Bing; GAO Ru-Wei

    2011-01-01

    @@ We build a sandwiched structure model in which the intergranular phase(IP) is homogeneously distributed between soft and hard magnetic grains, and gives a continuously anisotropic expression of the coupling part under the assumption that the IP weakens the intergrain exchange-coupling interaction.Based on the idea that the hardening mechanism is of the pinning type, we calculate the effect of the IP's thickness d and its anisotropy constant K1(0) on the intrinsic coercivity of a nanocomposite permanent material.The calculated results indicate that the domain wall goes twice through irreversible domain wall displacement during the process of moving from soft to hard magnetic grains, and the intrinsic coercivity increases with increasing d, but decreases with increasing K1(0).When d and K1(0) take 2nm and 0.7Kh, respectively, with Kh being the anisotropy constant in the inner part of the hard magnetic grain, the calculated intrinsic coercivity is in good agreement with the experimental data.

  13. Distributed generation induction and permanent magnet generators

    CERN Document Server

    Lai, L

    2007-01-01

    Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generators (IGs) are the cheapest and most commonly used technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples o better demonstrate how the integration of energy sources can be accomplished. The book also provides the ...

  14. Rotor for a line start permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Melfi, Mike; Schiferl, Rich; Umans, Stephen

    2017-07-11

    A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.

  15. The Effect of Grinding and Roasting Conditions on the Selective Leaching of Nd and Dy from NdFeB Magnet Scraps

    Directory of Open Access Journals (Sweden)

    Ho-Sung Yoon

    2015-07-01

    Full Text Available The pretreatment processes consisting of grinding followed by roasting were investigated to improve the selective leaching of Nd and Dy from neodymium-iron-boron (NdFeB magnet scraps. The peaks of Nd(OH3 and Fe were observed in XRD results after grinding with NaOH as the amount of water addition increased to 5 cm3. These results indicate that the components of Nd and Fe in NdFeB magnet could be changed successfully into Nd(OH3 and Fe, respectively. In the roasting tests using the ground product, with increasing roasting temperature to 500 °C, the peaks of Nd(OH3 and Fe disappeared while those of Nd2O3 and Fe2O3 were shown. The peaks of NdFeO3 in the sample roasted at 600 °C were observed in the XRD pattern. Consequently, 94.2%, 93.1%, 1.0% of Nd, Dy, Fe were leached at 400 rpm and 90 °C in 1 kmol·m−3 acetic acid solution with 1% pulp density using a sample prepared under the following conditions: 15 in stoichiometric molar ratio of NaOH:Nd, 550 rpm in rotational grinding speed, 5 cm3 in water addition, 30 min in grinding time, 400 °C and 2 h in roasting temperature and time. The results indicate that the selective leaching of Nd and Dy from NdFeB magnet could be achieved successfully by grinding and then roasting treatments.

  16. Analysis of Permanent Magnets Bearings in Flywheel Rotor Designs

    Directory of Open Access Journals (Sweden)

    Prince Owusu-Ansah

    2016-04-01

    Full Text Available This paper discusses analysis of permanent magnet bearing in flywheel rotor designs. This work focuses on the advantages of using permanent magnets in flywheel rotor design as compared to that of the convectional mode of levitating the rotor position. The use of permanent magnet in magnetic bearing design to generate the steady state position of the magnetic field results in less variation of the force exerted on the rotor when it deviates from the nominal position than when an electrical coil is used for the same purpose. Theresults of the analysis shows that the magnetic bearing dynamics as well as its load carryingcapacity improves when the rotor is offset from its central position. The use of permanent magnet compared to current-carrying coils results in smaller overall size of magnetic bearing leading to a more compact system design resulting in improved rotordynamic performance

  17. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  18. Permanent magnet quadrupoles for the CLIC Drive Beam decelerator

    CERN Document Server

    Shepherd, Ben; Collomb, Norbert

    2012-01-01

    STFC in collaboration with CERN has developed a new type of adjustable permanent magnet based quadrupole for the CLIC Drive Beam Decelerator. It uses vertical movement of the permanent magnets to achieve an integrated gradient range of 3.6-14.6T, which will allow it to be used for the first 60% of the decelerator line. Construction of a prototype of this magnet has begun; following this, it will be measured magnetically at CERN and Daresbury Laboratory.

  19. HDDR法制备NdFeB永磁体的高矫顽力研究%Study on the Mechanism of the High Coercivity of NdFeB Magnets Prepared by HDDR Method

    Institute of Scientific and Technical Information of China (English)

    张朋越; 泮敏翔; 朱津津; 葛洪良; 孙浩; 金一彪

    2011-01-01

    采用X射线衍射分析、扫描电镜和BH测试仪分别研究HDDR法制备的NdFeB永磁体微结构、晶粒表面形貌及其磁性能.结果表明,HDDR法制备的磁粉再经1080℃高温真空烧结所获得的NdFeB永磁体,主要由四方相NdFeB(P42/mnm)和少量的富稀土相构成,扫描电镜相片显示主相平均晶粒尺寸约为12.3μm;采用Horta法计算得到样品(006)晶面的极密度因子约为3.5,表明该样品具有较高的c轴取向;不同温度下退磁曲线研究表明,室温下合金有较好的磁性能:磁能积(BH)=264 kJ/m,剩磁B=1.17 T,矫顽力达到H=2038 kA/m:随温度的升高,磁性能各参数都单调下降,特别是矫顽力降低最为显著,从295 K升温到448 K过程中其值下降了1496 KA/m;H(T)/M磊(T)与H/M(T)(Kronmüller-Plot)关系曲线研究表明,该合金的矫顽力机制为畴成核反转机制,其中微磁参数α和N分别为1.39和1.75,是决定该合金高矫顽力的关键因素.%The microstructure, surface morphology, and magnetic properties of the suttered NdFeB permanent magnet prepared by the HDDR method were analyzed by X-ray diffraction, scanning electron microscopy and BH magnetic measurement Microstructural studies show that NdFeB magnets which were firstly prepared by HDDR powder and then sintered at the higb-temperature of 1080 ℃ consist of a large amount of the tetragonal phase NdZFe14B (P42/mnm) and trace amount of rare earth-rich phase.SEM images indicate that the average grain size of the Nd2Fe14B phase is about 12.3 μm.The density factor of (006) crystal face of Nd2Fe14B phase is estimated as about 3.5 using Horta formula, suggesting that the sample has a strong c-axis orientation.The demagnetic curves at different temperatures show that at room temperature this sample has well magnetic properties, i.e.(BH)max 264 kJ/m3, remanence Br about 1.17 T, and cocrcive Hcj 2038 kA/m.With the temperature increasing, magnetic properties of the samples are monotonicly reduced

  20. A Novel Open-winding Permanent Magnetic Starter-generator

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to overcome the difficulties of voltage regulation, narrow speed range and low power factor of the traditional permanent magnetic generator applied in the vehicles, a novel open-winding permanent magnetic starter-generator (see Fig.l) is used to widen the speed range and improve the efficiency in the generation mode.

  1. Direct current force sensing device based on compressive spring, permanent magnet, and coil-wound magnetostrictive/piezoelectric laminate.

    Science.gov (United States)

    Leung, Chung Ming; Or, Siu Wing; Ho, S L

    2013-12-01

    A force sensing device capable of sensing dc (or static) compressive forces is developed based on a NAS106N stainless steel compressive spring, a sintered NdFeB permanent magnet, and a coil-wound Tb(0.3)Dy(0.7)Fe(1.92)/Pb(Zr, Ti)O3 magnetostrictive∕piezoelectric laminate. The dc compressive force sensing in the device is evaluated theoretically and experimentally and is found to originate from a unique force-induced, position-dependent, current-driven dc magnetoelectric effect. The sensitivity of the device can be increased by increasing the spring constant of the compressive spring, the size of the permanent magnet, and/or the driving current for the coil-wound laminate. Devices of low-force (20 N) and high-force (200 N) types, showing high output voltages of 262 and 128 mV peak, respectively, are demonstrated at a low driving current of 100 mA peak by using different combinations of compressive spring and permanent magnet.

  2. Permanent magnets in accelerators can save energy, space and cost

    DEFF Research Database (Denmark)

    Bødker, F.; Baandrup, L.O.; Hauge, N.

    2013-01-01

    Green Magnet® technology with close to zero electrical power consumption without the need for cooling water saves costs, space and natural resources. A compact dipole based on permanent magnets has been developed at Danfysik in collaboration with Sintex and Aarhus University. Our first Green Magnet...... coils permit fine tuning of the magnetic field. Magnetic field measurements and thermal stability tests show that the Green Magnet fully meets the magnetic requirements of the previously used electromagnet. A permanent 30° bending dipole is currently being development to demonstrate the use of Green...

  3. Investigation of Coercivity Mechanism for Nd-Fe-B Magnets Prepared by Combination of Strip-Casting with Hydrogen Decrepitation Techniques

    Institute of Scientific and Technical Information of China (English)

    李波; 胡季帆; 王东玲; 郭炳麟; 王新林

    2003-01-01

    The coercivity mechanism of Nd-Fe-B magnets prepared by combination of strip-casting with hydrogen decrepitation techniques was investigated. The microstructure of (Nd0.935Dy0.065)14.5Fe79.4B6.1 magnet was observed. The average grain size is about 6~12 μm. The magnetizing field dependence of the hardmagnetic properties for the (Nd0.935Dy0.065)14.5Fe79.4B6.1 and the temperature dependence of the coercivity for the Nd14.5Fe79.4B6.1 were investigated. Results show that the coercivity for magnets prepared by the combination of strip-casting with hydrogen decrepitation techniques is controlled by the nucleation mechanism.

  4. Improvement of the thermal stability of sintered Nd-Fe-B magnets by intergranular addition of Dy{sub 82.3}Co{sub 17.7}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaofeng; Guo, Shuai; Yan, Changjiang; Cai, Lingwen; Chen, Renjie; Yan, Aru, E-mail: aruyan@nimte.ac.cn [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang (China); Lee, Don [University of Dayton, Dayton, Ohio 45469 (United States)

    2014-05-07

    In this study, microstructure and magnetic properties of sintered Nd-Fe-B magnets with addition of Dy{sub 82.3}Co{sub 17.7} (wt. %) were investigated. By adding a small amount of Dy{sub 82.3}Co{sub 17.7}, the coercivity is improved greatly, and the irreversible loss is decreased sharply. The increase of Curie temperature suggests that Co atoms have entered into the 2:14:1 main phase. Microstructural analysis indicates that a well-developed core-shell structure was formed in the magnets with the addition of Dy{sub 82.3}Co{sub 17.7}. The improvement of magnetic properties can be attributed to the microstructural modification and the intrinsic properties' improvement.

  5. MAGNETIC STRUCTURE AND MAGNETIC IMAGING OF RE{sub 2}Fe{sub 14}B (RE=Nd,Pr) PERMANENT MAGNETS

    Energy Technology Data Exchange (ETDEWEB)

    ZHU,Y.; VOLKOV,V.V.

    2000-04-20

    This chapter aims to review the magnetic structures observed in the RE{sub 2}Fe{sub 14}B (RE = Nd, Pr) system using various TEM magnetic imaging techniques. The authors focus on studies of die-upset Nd-based permanent magnets conducted mainly at Brookhaven National Laboratory in the past several years. Investigations on Nd-Fe-B sintered magnets and single crystals, as well as Pr-Fe-B die-upset magnets also will be covered. In Sec.2 and Sec.3 they review the microstructure, including grain alignment and secondary phases of the materials, and grain boundary structure and composition of the intergranular phase. Sec.4 is devoted to the domain structure, such as the width of domain and domain wall and domain-wall energy. Monte Carlo simulation of the effects of demagnetization fields will be presented in Sec.5. In-situ experiments on the dynamic behavior of domain reorientation as a function of temperature, pinning, grain boundary nucleation related to coercivity under various fields are described in Sec.6. Finally, in Sec.7 the correlation between microstructure and properties are discussed.

  6. Permanent magnets in accelerators can save energy, space and cost

    DEFF Research Database (Denmark)

    Bødker, F.; Baandrup, L.O.; Hauge, N.

    2013-01-01

    Green Magnet® technology with close to zero electrical power consumption without the need for cooling water saves costs, space and natural resources. A compact dipole based on permanent magnets has been developed at Danfysik in collaboration with Sintex and Aarhus University. Our first Green Magnet...... Magnet technology in other accelerator systems like synchrotron light sources and transfer beamlines....

  7. Quasi-periodic layer structure of die-upset NdFeB magnets

    Institute of Scientific and Technical Information of China (English)

    LAI Bin; LI Yanfeng; WANG Huijie; LI Anhua; ZHU Minggang; LI Wei

    2013-01-01

    Isotropic magnets were prepared from melt-spun powders at different hot pressing temperatures from 550 to 700 ℃,then upset into fully dense anisotropic magnets at the same die-upsetting temperature of 850 ℃.Die-upset magnets had the characteristics of inhomogeneous microstructure,including well-aligned grains structure and nonaligned grains layers transverse to press direction,which was quasi-periodic layer structure with a total length of 5-15 μm.Nonaligned grains layers were mainly made of large grains and had higher Nd content.To clearly understand the formation of layer structure,the microstructure of isotropic precursors with different hot pressing temperatures and their subsequent die-upset magnets was investigated.A new interpretation for the formation of layer structure was proposed in this paper:the layer structure was correlated to the original ribbon interface which was divided into three types based on the contact forms.Because of the incomplete contact of neighboring ribbons,concentration of stress occurred in the contacted points and the Nd-rich phase was squeezed into interspaces at high temperature under stress.Due to the release of interfacial energy and the fluidity of enough Nd-rich liquid phases,the nonaligned layers with large grains formed both in hot compaction and subsequent hot deformation process.The layer structure affected the magnetic properties of die-upset magnets.With increase of the hot pressing temperature,the nonaligned grains layers became thicker,and the magnetic performance of die-upset magnets decreased.It was necessary to reduce the thickness of large grains layers for the preparation of high-performance die-upset magnets.

  8. Shimming with permanent magnets for the x-ray detector in a hybrid x-ray/ MR system.

    Science.gov (United States)

    Wen, Zhifei; Fahrig, Rebecca; Williams, Scott T; Pelc, Norbert J

    2008-09-01

    In this x-ray/MR hybrid system an x-ray flat panel detector is placed under the patient cradle, close to the MR volume of interest (VOI), where the magnetic field strength is approximately 0.5 T. Immersed in this strong field, several electronic components inside the detector become magnetized and create an additional magnetic field that is superimposed on the original field of the MR scanner. Even after linear shimming, the field homogeneity of the MR scanner remains disrupted by the detector. The authors characterize the field due to the detector with the field of two magnetic dipoles and further show that two sets of permanent magnets (NdFeB) can withstand the main magnetic field and compensate for the nonlinear components of the additional field. The ideal number of magnets and their locations are calculated based on a field map measured with the detector in place. Experimental results demonstrate great promise for this technique, which may be useful in many settings where devices with magnetic components need to be placed inside or close to an MR scanner.

  9. Relativistic Engine Based on a Permanent Magnet

    CERN Document Server

    Tuval, Miron

    2015-01-01

    Newton's third law states that any action is countered by a reaction of equal magnitude but opposite direction. The total force in a system not affected by external forces is thus zero. However, according to the principles of relativity a signal can not propagate at speeds exceeding the speed of light. Hence the action cannot be generated at the same time with the reaction due to the relativity of simultaneity, thus the total force cannot be null at a given time. The following is a continuation of a previous paper \\cite{Tuval} in which we analyzed the relativistic effects in a system of two current conducting loops. Here the analysis is repeated but one of the loops is replaced by a permanent magnet. It should be emphasized that although momentum can be created in the {\\bf material} part of the system as described in the following work momentum can not be created in the {\\bf physical} system, hence for any momentum that is acquired by matter an opposite momentum is attributed to the electromagnetic field.

  10. A Novel Permanent Magnetic Angular Acceleration Sensor

    Directory of Open Access Journals (Sweden)

    Hao Zhao

    2015-07-01

    Full Text Available Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2. Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  11. From permanent magnets to rechargeable hydride electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Willems, J.J.G.; Buschow, K.H.J.

    1987-02-15

    A brief historical survey is given of how the study of coercitivity mechanisms in SmCo/sub 5/ permanent-magnet materials eventually led to the discovery of the favourable hydrogen sorption properties of the compound LaNi/sub 5/. It is shown how continued research by many investigators dealing with a variety of different physical and chemical properties has resulted in an advanced understanding of some of the principles that govern hydrogen absorption and which are responsible for the changes in physical properties that accompany it. The problems associated with various applications of LaNi/sub 5/-based hydrogen-storage materials are also briefly discussed. A large part of this paper is devoted to the applicability of LaNi/sub 5/-type materials in batteries. Research in this area has resulted in the development of a new type of rechargeable battery: the nickel-hydride cell. This battery can be charged and discharged at high rates and is relatively insensitive to overcharging and overdischarging. Special attention is given to the nature of the electrode degradation process and the effect of composition variations in LaNi/sub 5/-related materials on the lifetime of the corresponding hydride electrodes when subjected to severe electrochemical charge-discharge cycles.

  12. A Novel Permanent Magnetic Angular Acceleration Sensor.

    Science.gov (United States)

    Zhao, Hao; Feng, Hao

    2015-07-03

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s(-2)). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  13. Efficient IEC permanent magnet motor; Effizienter IEC Permanent-Magnetmotor (3 kW) - Jahresbericht 2007

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M.; Salathe, D.; Biner, H. P.; Evequoz, B.

    2007-07-01

    This annual report for the Swiss Federal Office of Energy (SFOE) takes a look at the work done at the Swiss Universities of Applied Sciences in Lucerne and Valais and the Circle Motor Company in 2007 on the economic feasibility, efficiency and limitations of permanent magnet motors. The higher efficiency of permanent-magnet motors in comparison with asynchronous motors for powers of over 100 kW is noted. Work done on the integration of a 3 kW permanent-magnet motor in an IEC-Standard housing is described. The construction of an efficient permanent magnet motor drive and its testing at the Valais University of Applied Sciences is discussed. The high efficiencies obtained both for the motor and its drive electronics are noted.

  14. Research on Magnetic Model of Low Resistance Permanent Magnet Pipe Belt Conveyor

    Science.gov (United States)

    Wang, Shuang; Li, De-yong; Guo, Yong-cun

    2016-09-01

    In view of the feasibility of a new type of low resistance permanent magnet pipe belt conveyor, the magnetic properties of the permanent magnet magnetic pipe conveyor belt system are studied. Based on the molecular current hypothesis, the mathematical model of the three dimensional radial magnetic force of permanent magnet pipe conveyor belt was established. The mathematical model of the radial magnetic force was derived, and the influence factors of the radial magnetic force were derived. The finite element simulation of permanent magnet-magnetic pipe conveyor belt magnetic model was carried out, then the magnetic flux density distribution chart under the conditions of different remanence intensity of different permanent magnet and different lengths of the permanent magnets (along the transport direction) were obtained. The simulation results are consistent with the calculation results, which shows that the permanent magnet pipe belt conveyor is feasible. Under certain conditions, the radial magnetic force has nonlinear increase relations with residual magnetism of permanent magnet and the length of the permanent magnet (along the transport direction).

  15. NdFeB Magnets Aligned in a 9-T Superconducting Solenoid (asterisk)

    Science.gov (United States)

    Mulcahy, T. M.; Hull, J. R.

    2002-08-01

    Commercial-grade magnet powder (Magnequench UG) was uniaxial die-pressed into cylindrical compacts, while being aligned in the 1-T to 8-T DC field of a superconducting solenoid at Argonne National Laboratory. Then, the compacts were added to normal Magnequench UG production batches for sintering and annealing. The variations in magnet properties for different strengths of alignment fields are reported for 15.88-mm (5/8-in.) diameter compacts made with length-to-diameter (L/D) ratios in the range 3 0.25 and L 1. The best magnets were produced when the powder-filled die was inserted into the active field of the solenoid and then pressed. Improvements in the residual flux density of 8% and in the energy product of 16% were achieved by increasing the alignment field beyond the typical 2-T capabilities of electromagnets. The most improvement was achieved for the compacts with the smallest L/D ratio. The ability to make very strong magnets with small L/D, where self-demagnetization effects during alignment are greatest, would benefit most the production of near-final-shape magnets. Compaction of the magnet powder using a horizontal die and a continuously active superconducting solenoid was not a problem. Although the press was operated in the batch mode for this proof-of-concept study, its design is intended to enable automated production.

  16. Globally Optimal Segmentation of Permanent-Magnet Systems

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    Permanent-magnet systems are widely used for generation of magnetic fields with specific properties. The reciprocity theorem, an energy-equivalence principle in magnetostatics, can be employed to calculate the optimal remanent flux density of the permanent-magnet system, given any objective...... functional that is linear in the magnetic field. This approach, however, yields a continuously varying remanent flux density, while in practical applications, magnetic assemblies are realized by combining uniformly magnetized segments. The problem of determining the optimal shape of each of these segments...

  17. The effect of Nd-Cu diffusion during hot pressing and hot deformation on the coercivity and the deformation ability of Nd-Fe-B HDDR magnets

    Science.gov (United States)

    Wang, Haihang; Chen, Renjie; Yin, Wenzong; Zhu, Mingyuan; Tang, Xu; Wang, Zexuan; Jin, Chaoxiang; Ju, Jinyun; Lee, Don; Yan, Aru

    2017-09-01

    HDDR processed Nd-Fe-B powders blended with Nd-Cu powders were hot-pressed and then hot-deformed to obtain fully dense, anisotropic magnets. The microstructure evolution in hot-pressed and hot-deformed HDDR magnets was studied to illustrate the impact of Nd-Cu diffusion on coercivity and deformation ability. It was found that the coercivity and the deformation ability were improved significantly by Nd-Cu addition. The coercivity of hot-deformed magnets was increased from 3.81 kOe to 13.01 kOe after 2 wt% Nd-Cu additions and the annealing at 900 °C for 2 h. Scanning electron microscopy and transmission electron microscopy observations revealed that the variation in coercivity was attributed to the diffusion of Nd-Cu along the grain boundaries during hot pressing and hot deformation.

  18. Status and development tendency of rare-earth permanent magnet materials%稀土永磁材料的现状与发展趋势

    Institute of Scientific and Technical Information of China (English)

    胡伯平

    2014-01-01

    作为稀土最重要的应用领域之一,稀土永磁材料是支撑现代社会的重要基础功能材料,与人们的生活息息相关。近10余年来,全球烧结钕铁硼磁体毛坯产量年均增长率为20%,我国年均增长率为28%;全球粘结钕铁硼磁体产量年均增长率为7%,我国年均增长率为21%。2012年,我国烧结钕铁硼磁体毛坯产量和粘结钕铁硼磁体产量分别为8.3万吨和4400吨,达到历史最高。近两年,具有高使用温度和优异耐腐蚀性的烧结钐钴磁体和热压/热变形辐射钕铁硼取向环形磁体的产量也有所增长。低碳经济对烧结钕铁硼磁体的综合磁性能指标“(BH)max (MGOe)+Hcj(kOe)”提出了越来越高的要求,目前该指标已超过70;Tb/Dy晶界扩散提高Hcj成为烧结钕铁硼的新热点,已开发出多种扩散技术并用于批量生产。利用氦气气流磨并结合无氧工艺建成的无或低Tb/Dy生产线已经在日本投入运行。粘结磁体方面,各向同性钕铁硼磁粉的国产化进程在加快,(BH)max=15MGOe的高性能磁粉已经面市,成本及耐蚀性更优的快淬Sm-Fe-N磁粉也在大力研发中;HDDR处理的各向异性钕铁硼磁粉已经商品化。高性价比的各向异性磁体成形技术正在开发,挤出成形工艺可制备直径60mm、壁厚1mm的辐射取向薄壁环。为了进一步高效利用稀土,西方国家和中国正在积极开展稀土永磁材料的回收利用。丰富的稀土资源,广阔的应用市场,稀土永磁材料将迎来更加美好的前景。%As one of the most important application for rare earth, the rare-earth permanent magnet material, which closely relates to people’s daily life, is an important fundamental functional material to support modern society. For recent ten years, the average annual growth rate of sintered Nd-Fe-B magnets output is 20% for the whole world and 28% for China. The average annual growth rate of bonded Nd-Fe-B

  19. Corrosion Behaviour of a Silane Protective Coating for NdFeB Magnets in Dentistry

    Directory of Open Access Journals (Sweden)

    Luigi Calabrese

    2015-01-01

    Full Text Available The corrosion behavior of coated and uncoated Ni/Cu/Ni rare earth magnets was assessed at increasing steps with a multilayering silanization procedure. Magnets’ durability was analyzed in Fusayama synthetic saliva solution in order to evaluate their application in dental field. Corrosion performance was evaluated by using polarization and electrochemical impedance spectroscopy in synthetic saliva solution up to 72 hours of continuous immersion. The results show that the addition of silane layers significantly improved anticorrosion properties. The coating and aging effects, in synthetic saliva solution, on magnetic field were evaluated by means of cyclic force-displacement curves.

  20. Iron free permanent magnet systems for charged particle beam optics

    Energy Technology Data Exchange (ETDEWEB)

    Lund, S.M.; Halbach, K.

    1995-09-03

    The strength and astounding simplicity of certain permanent magnet materials allow a wide variety of simple, compact configurations of high field strength and quality multipole magnets. Here we analyze the important class of iron-free permanent magnet systems for charged particle beam optics. The theory of conventional segmented multipole magnets formed from uniformly magnetized block magnets placed in regular arrays about a circular magnet aperture is reviewed. Practical multipole configurations resulting are presented that are capable of high and intermediate aperture field strengths. A new class of elliptical aperture magnets is presented within a model with continuously varying magnetization angle. Segmented versions of these magnets promise practical high field dipole and quadrupole magnets with an increased range of applicability.

  1. Fracture in sintered Sm-Co permanent magnetic materials

    Institute of Scientific and Technical Information of China (English)

    LI; Anhua(李安华); DONG; Shengzhi(董生智); LI; Wei(李卫)

    2003-01-01

    The bending strength and fracture toughness of sintered Sm-Co permanent magnetic materials are measured. A scanning electron microscope equipped with an energy dispersive X-ray analysis system is employed to investigate the bending fractography. The fracture behavior and micromechanism are discussed. The fracture behavior of sintered Sm-Co permanent magnetic materials exhibits cleavage fracture. Some Sm-rich impurities are found in fracture plane, suggesting that the Sm-rich impurities help reduce the cleavage brittleness of sintered Sm-Co permanent magnetic materials. The possible methods for improving the strength and toughness are also proposed.

  2. Polydimethylsiloxane films doped with NdFeB powder: magnetic characterization and potential applications in biomedical engineering and microrobotics.

    Science.gov (United States)

    Iacovacci, V; Lucarini, G; Innocenti, C; Comisso, N; Dario, P; Ricotti, L; Menciassi, A

    2015-12-01

    This work reports the fabrication, magnetic characterization and controlled navigation of film-shaped microrobots consisting of a polydimethylsiloxane-NdFeB powder composite material. The fabrication process relies on spin-coating deposition, powder orientation and permanent magnetization. Films with different powder concentrations (10 %, 30 %, 50 % and 70 % w/w) were fabricated and characterized in terms of magnetic properties and magnetic navigation performances (by exploiting an electromagnet-based platform). Standardized data are provided, thus enabling the exploitation of these composite materials in a wide range of applications, from MEMS/microrobot development to biomedical systems. Finally, the possibility to microfabricate free-standing polymeric structures and the biocompatibility of the proposed composite materials is demonstrated.

  3. Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

    Directory of Open Access Journals (Sweden)

    Jui-Che Huang

    2017-06-01

    Full Text Available An in-vacuum undulator (IVU provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced–heat load, phase errors, and the deformation of support girders.

  4. Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

    Science.gov (United States)

    Huang, Jui-Che; Kitamura, Hideo; Yang, Chin-Kang; Chang, Cheng-Hsing; Chang, Cheng-Hsiang; Hwang, Ching-Shiang

    2017-06-01

    An in-vacuum undulator (IVU) provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs) has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced-heat load, phase errors, and the deformation of support girders.

  5. Multipactor Mitigation in Coaxial Lines by Means of Permanent Magnets

    CERN Document Server

    Gonzalez-Iglesias, D; Anza, S; Vague, J; Gimeno, B; Boria, V E; Raboso, D; Vicente, C; Gil, J; Caspers, F; Conde, L

    2014-01-01

    The main aim of this paper is the analysis of the feasibility of employing permanent magnets for the multipactor mitigation in a coaxial waveguide. First, the study of a coaxial line immersed in a uniform axial magnetic field shows that multipactor can be suppressed at any RF frequency if the external magnetic field is strong enough. Both theoretical simulations and experimental tests validate this statement. Next, multipactor breakdown of a coaxial line immersed in a hollow cylindrical permanent magnet is analyzed. Numerical simulations show that multipactor can be suppressed in a certain RF frequency range. The performed experimental test campaign demonstrates the capability of the magnet to avoid the multipactor electron multiplication process.

  6. Hydrogen Decrepitation Press-Less Process Recycling of NdFeB sintered magnets

    DEFF Research Database (Denmark)

    Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian

    2017-01-01

    in a graphite mold. Coercivities up to 534 kA/m were obtained in porous samples based on powder size d 100 μm. Adding a ball milling step resulted in full density isotropic magnets for d > 100 μm. The coercivity reached Hci = 957 kA/m being 86 % of the original N48M material without addition of rare earth...

  7. Composition-dependent magnetic properties of melt-spun La or/and Ce substituted nanocomposite NdFeB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, M.; Zhao, L.Z.; Zhang, C.; Jiao, D.L.; Zhong, X.C.; Liu, Z.W.

    2016-02-15

    Aiming at high-performance low-cost NdFeB magnets, the magnetic properties and microstructure for melt spun nanocrystalline (Nd{sub 1−x}M{sub x}){sub 10}Fe{sub 84}B{sub 6} (M=La, Ce, or La{sub 0.5}Ce{sub 0.5}; x=0–0.7) alloys were investigated. Relatively, LaCe-substituted alloys show high values of the remanent magnetization M{sub r}, the maximum energy product (BH){sub max} and the coercivity H{sub c}, up to 114 emu/g (1.07 T), 147 kJ/m{sup 3} and 471 kA/m, respectively, at x=0.1. The unusual increase in coercivity for the alloys with 10% La or 10% La{sub 0.5}Ce{sub 0.5} substitution is possibly attributed to the phase segregation in alloys with certain La or LaCe contents. The reduced Curie temperature and spin-reorientation temperature were obtained for La, Ce or LaCe substituted alloys. Transmission electron microscope analysis has revealed that a fine and uniform distributed grain structure leads to remanence enhancement for La{sub 0.5}Ce{sub 0.5} substituted alloys. The present results indicate that partially substituting Nd by La or/and Ce cannot only effectively reduce the cost of nanocrystalline NdFeB based magnetic powders but also can maintain a relatively good combination of magnetic properties.

  8. Comparison of Achievable Magnetic Fields with Superconducting and Cryogenic Permanent Magnet Undulators – A Comprehensive Study of Computed and Measured Values

    Energy Technology Data Exchange (ETDEWEB)

    Moog, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Dejus, R. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Sasaki, S. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-01-01

    Magnetic modeling was performed to estimate achievable magnetic field strengths of superconducting undulators (SCUs) and to compare them with those of cryogenically cooled permanent magnet undulators (CPMUs). Starting with vacuum (beam stay-clear) gaps of 4.0 and 6.0 mm, realistic allowances for beam chambers (in the SCU case) and beam liners (in the CPMU case) were added. (A 6.0-mm vacuum gap is planned for the upgraded APS). The CPMU magnetic models consider both CPMUs that use NdFeB magnets at ~150 K and PrFeB magnets at 77 K. Parameters of the magnetic models are presented along with fitted coefficients of a Halbach-type expression for the field dependence on the gap-to-period ratio. Field strengths for SCUs are estimated using a scaling law for planar SCUs; an equation for that is given. The SCUs provide higher magnetic fields than the highest-field CPMUs – those using PrFeB at 77 K – for period lengths longer than ~14 mm for NbTi-based SCUs and ~10 mm for Nb3Sn-based SCUs. To show that the model calculations and scaling law results are realistic, they are compared to CPMUs that have been built and NbTi-based SCUs that have been built. Brightness tuning curves of CPMUs (PrFeB) and SCUs (NbTi) for the upgraded APS lattice are also provided for realistic period lengths.

  9. On the Motion of the Field of a Permanent Magnet

    Science.gov (United States)

    Leus, Vladimir; Taylor, Stephen

    2011-01-01

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap…

  10. Fully permanent magnet atom chip for Bose-Einstein condensation

    NARCIS (Netherlands)

    T. Fernholz; R. Gerritsma; S. Whitlock; I. Barb; R.J.C. Spreeuw

    2008-01-01

    We describe a proof-of-principle experiment on a fully permanent magnet atom chip. We study ultracold atoms and produce a Bose-Einstein condensate. The magnetic trap is loaded efficiently by adiabatic transport of a magnetic trap via the application of uniform external fields. Radio frequency spectr

  11. Wide gap, permanent magnet biased magnetic bearing system

    Science.gov (United States)

    Boden, Karl

    1992-01-01

    The unique features and applications of the presented electrical permanent magnetic bearing system essentially result from three facts: (1) the only bearing rotor components are nonlaminated ferromagnetic steel collars or cylinders; (2) all radial and axial forces are transmitted via radial gaps; and (3) large radial bearing gaps can be provided with minimum electric power consumption. The large gaps allow for effective encapsulation and shielding of the rotors at elevated or low temperatures, corrosive or ultra clean atmosphere or vacuum or high pressure environment. Two significant applications are described: (1) a magnetically suspended x ray rotary anode was operated under high vacuum conditions at 100 KV anode potential, 600 C temperature at the rotor collars and speed 18000 rpm with 13 mm radial bearing gap; and (2) an improved Czochralski type crystal growth apparatus using the hot wall method for pulling GaAs single crystals of low dislocation density. Both crystal and crucible are carried and transported by magnetically suspended shafts inside a hermetically sealed housing at 800 C shaft and wall temperature. The radial magnetic bearing gap measures 24 mm.

  12. Single Phase Permanent Magnet Low Speed Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Gao Lianxue

    2013-04-01

    Full Text Available In order to acquire a better cognition to the single phase permanent magnet low speed synchronous motor and validate the correctness of the motor mathematical model, the performances of the motor are tested with the single phase permanent magnet low speed synchronous motor whose type is 70TDY4, the corresponding simulations are done too. The resistance and the inductance of the single phase permanent magnet low speed synchronous motor are measured. According to the data of experiments and simulations, the static characteristics of the single phase permanent magnet low speed synchronous motor with the changes of the phase shift resistance and the phase shift capacitance are analysed, the results of experiments and simulations prove the correctness of the mathematics model.

  13. Design of Permanent Magnet Synchronous Generators for Wave Power Generation

    Institute of Scientific and Technical Information of China (English)

    方红伟; 王丹

    2016-01-01

    In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embed-ded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coeffi-cient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.

  14. Passive control of Permanent Magnet Synchronous Motor chaotic systems

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Jia-jun; ZHAO Guang-zhou

    2005-01-01

    Permanent Magnet Synchronous Motor model can exhibit a variety of chaotic phenomena under some choices of system parameters and external input. Based on the property of passive system, the essential conditions were studied, by which Permanent Magnet Synchronous Motor chaotic system could be equivalent to passive system. Using Lyapunov stability theory, the convergence condition deciding the system's characters was discussed. In the convergence condition area, the equivalent passive system could be globally asymptotically stabilized by smooth state feedback.

  15. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    OpenAIRE

    Li Hai Xia; Cao Yang

    2016-01-01

    This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  16. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    Directory of Open Access Journals (Sweden)

    Li Hai Xia

    2016-01-01

    Full Text Available This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  17. Effect of microstructure changes on magnetic properties of spark plasma sintered Nd-Fe-B powders

    Directory of Open Access Journals (Sweden)

    Michalski B.

    2013-01-01

    Full Text Available In this study the SPS method was applied for low RE content (8,5% at. and high RE content (13,5 % at. MQ powders. The powders were sintered in a wide range of temperature, for 5 min., under pressure of 35 MPa. The low RE content grade, densified reluctantly and gained the density close to the theoretical value only for 850 °C. The coercivity decreased gradually with increasing sintering temperature. On the other hand, the densification of the higher RE content grade powder occurred much easier and the coercivity, close to the theoretical value, was achieved already at 650 °C. The coercivity of this material also decreased with increasing sintering temperature. Microstructural studies revealed that the SPS sintering process leads to partial decomposition of the Nd2Fe14B phase. The proportion of the RE-rich and iron phases increases parallel to the increasing sintering temperature. On the basis of the current results one can conclude that fabrication of high density MQ powders based magnets by the SPS method is possible, however the powders having higher RE content should be used for this purpose and the sintering temperature as low as possible, related to density, should be kept.

  18. Permanent magnet with MgB{sub 2} bulk superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2014-07-21

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

  19. Design and analysis of an unconventional permanent magnet linear machine for energy harvesting

    Science.gov (United States)

    Zeng, Peng

    This Ph.D. dissertation proposes an unconventional high power density linear electromagnetic kinetic energy harvester, and a high-performance two-stage interface power electronics to maintain maximum power abstraction from the energy source and charge the Li-ion battery load with constant current. The proposed machine architecture is composed of a double-sided flat type silicon steel stator with winding slots, a permanent magnet mover, coil windings, a linear motion guide and an adjustable spring bearing. The unconventional design of the machine is that NdFeB magnet bars in the mover are placed with magnetic fields in horizontal direction instead of vertical direction and the same magnetic poles are facing each other. The derived magnetic equivalent circuit model proves the average air-gap flux density of the novel topology is as high as 0.73 T with 17.7% improvement over that of the conventional topology at the given geometric dimensions of the proof-of-concept machine. Subsequently, the improved output voltage and power are achieved. The dynamic model of the linear generator is also developed, and the analytical equations of output maximum power are derived for the case of driving vibration with amplitude that is equal, smaller and larger than the relative displacement between the mover and the stator of the machine respectively. Furthermore, the finite element analysis (FEA) model has been simulated to prove the derived analytical results and the improved power generation capability. Also, an optimization framework is explored to extend to the multi-Degree-of-Freedom (n-DOF) vibration based linear energy harvesting devices. Moreover, a boost-buck cascaded switch mode converter with current controller is designed to extract the maximum power from the harvester and charge the Li-ion battery with trickle current. Meanwhile, a maximum power point tracking (MPPT) algorithm is proposed and optimized for low frequency driving vibrations. Finally, a proof

  20. Two cylinder permanent magnet stirrer for liquid metals

    Science.gov (United States)

    Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

    2017-07-01

    To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

  1. Permanent magnet with MgB2 bulk superconductor

    Science.gov (United States)

    Yamamoto, Akiyasu; Ishihara, Atsushi; Tomita, Masaru; Kishio, Kohji

    2014-07-01

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB2) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (cryocoolers, making MgB2 bulks promising for the next generation of Tesla-class permanent-magnet applications.

  2. Contribution to permanent magnet excited dc linear actuators

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo, R.C.; Hanitsch, R. [Technische Univ. Berlin (Germany)

    1998-07-01

    In this paper an efficient method for the computation of magnetic fields and forces in dc linear actuators built with Sm{sub 2}Co{sub 17} - permanent magnet is presented. The results obtained show good agreement with measurements. (orig.)

  3. Variable-period permanent-magnet helical undulator

    OpenAIRE

    Jungho Mun; Young Uk Jeong; Vinokurov, Nikolay A.; Kitae Lee; Kyu-Ha Jang; Seong Hee Park; Min Yong Jeon; Sang-In Shin

    2014-01-01

    We realized a variable-period permanent-magnet helical undulator with high (∼1  T) field amplitude, which is almost constant over undulator periods of 23–26 mm. Each undulator period has four modular sections of iron poles and permanent magnets embedded in nonmagnetic disks with holes along the undulator axis. Modular plates undergo a longitudinal repulsive force from the magnetic field pressure and the spring coils between modular plates. The undulator period can thus be controlled by mechan...

  4. First-principles calculation of crystal field parameters of Dy ions substituted for Nd in Nd-Fe-B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, S; Moriya, H; Tsuchiura, H; Sakuma, A [Department of Applied Physics, Tohoku University, Sendai 980-8579 (Japan); Divis, M [Department of Condensed Matter, Charles University, FMF, Prague (Czech Republic); Novak, P, E-mail: tanaka@olive.apph.tohoku.ac.jp [Institute of Physics of ASCR, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic)

    2011-01-01

    We study the electronic structures of crystalline Nd{sub 2}Fe{sub 14}B, Dy{sub 2}Fe{sub 14}B and Dy-doped Nd-Fe-B, and estimate the crystal field parameter A{sup 0}{sub 2}(r{sup 2}) of the rare earth ions of these systems based on the first principles calculations. We find that the crystal field of the Dy ions is appreciably insensitive to its crystallographic location than that of Nd ions.

  5. System Cost Analysis for an Interior Permanent Magnet Motor

    Energy Technology Data Exchange (ETDEWEB)

    Peter Campbell

    2008-08-01

    The objective of this program is to provide an assessment of the cost structure for an interior permanent magnet ('IPM') motor which is designed to meet the 2010 FreedomCAR specification. The program is to evaluate the range of viable permanent magnet materials for an IPM motor, including sintered and bonded grades of rare earth magnets. The study considers the benefits of key processing steps, alternative magnet shapes and their assembly methods into the rotor (including magnetization), and any mechanical stress or temperature limits. The motor's costs are estimated for an annual production quantity of 200,000 units, and are broken out into such major components as magnetic raw materials, processing and manufacturing. But this is essentially a feasibility study of the motor's electromagnetic design, and is not intended to include mechanical or thermal studies as would be done to work up a selected design for production.

  6. Lunar magnetic field - Permanent and induced dipole moments

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Schubert, G.

    1974-01-01

    Apollo 15 subsatellite magnetic field observations have been used to measure both the permanent and the induced lunar dipole moments. Although only an upper limit of 1.3 x 10 to the 18th gauss-cubic centimeters has been determined for the permanent dipole moment in the orbital plane, there is a significant induced dipole moment which opposes the applied field, indicating the existence of a weak lunar ionosphere.

  7. Design and characterization of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, M., E-mail: max.hachmann@desy.de [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Flöttmann, K. [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Gehrke, T. [Deutsches Krebsforschungszentrum DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Mayet, F. [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany)

    2016-09-01

    REGAE is a small electron linear accelerator at DESY. In order to focus short and low charged electron bunches down to a few μm permanent magnetic solenoids were designed, assembled and field measurements were done. Due to a shortage of space close to the operation area an in-vacuum solution has been chosen. Furthermore a two-ring design made of wedges has been preferred in terms of beam dynamic issues. To keep the field quality of a piecewise built magnet still high a sorting algorithm for the wedge arrangement including a simple magnetic field model has been developed and used for the construction of the magnets. The magnetic field of these solenoids has been measured with high precision and compared to simulations. - Highlights: • presenting a two-ring radially magnetized permanent magnetic solenoid design. • development of a analytical field description and field quality factor. • development of a sorting algorithm for permanent magnetic pieces to form a magnet. • performing a high-precision field measurement of a high gradient field.

  8. Design, manufacture and measurements of permanent dipole magnets for DIRAC

    CERN Document Server

    Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D

    2013-01-01

    The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.

  9. Fast Neutron Damage Studies on NdFeB Materials

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.; Spencer, J.; Wolf, Z.; /SLAC; Baldwin, A.; Pellett, D.; Boussoufi, M.; /UC, Davis

    2005-05-17

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) since both accelerator and detectors will be subjected to large fluences of hadrons, leptons and {gamma}'s over the life of the facility [1]. While the linacs will be superconducting, there are still many uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the situation for rare earth, permanent magnet materials was presented at PAC03 [2]. Our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC04 [3]. We have extended the doses, included other manufacturer's samples, and measured induced radioactivities which are discussed in detail.

  10. Fast Neutron Damage Studies on NdFeB Materials

    CERN Document Server

    Spencer, James; Baldwin, A; Boussoufi, Moe; Pellet, David; Volk, James T; Wolf, Zachary

    2005-01-01

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas over the life of the facility. Although the linacs will be superconducting, there are still many potential uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the radiation damage situation for rare earth permanent magnet materials was presented at PAC2003 and our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC2004 where the damage appeared proportional to the distances between the effective operating points and Hc. Here we have extended those doses and included more commercial samples together with the induced radioactivities associated with their respective dopants. Hall probe data for the external induction distributions are compared with vector magnetizatio...

  11. Effect of permanent-magnet irregularities in levitation force measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J. R.

    1999-10-14

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.

  12. Effect of permanent-magnet irregularities in levitation force measurements

    Science.gov (United States)

    Hull, John R.

    2000-06-01

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a non-negligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analogue of Earnshaw's theorem, in which the vertical stiffness is equal to the sum of the horizontal stiffness at the field-cooling position, independent of the angular distribution of magnetic moments within the PM.

  13. Effect of permanent-magnet irregularities in levitation force measurements

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2000-06-01

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a non-negligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analogue of Earnshaw's theorem, in which the vertical stiffness is equal to the sum of the horizontal stiffness at the field-cooling position, independent of the angular distribution of magnetic moments within the PM. (author)

  14. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  15. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  16. Asynchronous slip-ring motor synchronized with permanent magnets

    Directory of Open Access Journals (Sweden)

    Glinka Tadeusz

    2017-03-01

    Full Text Available The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM – Fig. 3, and the Linear Permanent Magnet (IPM – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.

  17. Proposal of Permanent Magnet Repulsive Maglev Transportation System

    Science.gov (United States)

    Moriyama, Shin-Ichi

    This paper describes a maglev transportation system for automobile. The track is an array of permanent magnet blocks, and the levitating body is the bedplate which consists of permanent magnet plates, propulsion coils, levitation coils and guidance coils. The feature of this system is that the automobile equipped with the bedplate is free to approach into the track or to swerve from the track by using four wheels with the lift. The force acting on the levitating body is calculated on the assumption that each permanent magnet can be expressed as a surface current. From the calculation results, it is proven that the automobile of 4.35m length, 1.8m width and 1700kg weight can run at speed of 500km/h against the air resistance force of 3704N on the condition that the battery has an output of 337.5V and a capacity of 190Ah.

  18. Microstructure and magnetic properties of backward extruded NdFeB ring magnets by the CAPA process

    Science.gov (United States)

    Kim, Hyoung-Tae; Kim, Yoon-Bae

    2004-06-01

    The inhomogeneity in microstructure and magnetic properties of a ring magnet prepared by backward extrusion with a current-applied pressure-assisted process has been investigated. The initial part (top part) of a ring magnet prepared by back extrusion shows a high coercivity which is comparable to the raw powder. It exhibits isotropic characteristics along the three orthogonal directions probably due to small deformation. The last part (bottom part) of the ring magnet has a a low coercivity with large grains because high current flows through the pressurized punches during the whole deformation process as to increase the temperature and grain growth. The middle part is under an appropriate deformation with short time exposure at high temperature, therefore it maintains a relatively high remanent polarization with high coercivity.

  19. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  20. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  1. Analysis and Design of Hybrid Excitation Permanent Magnet Synchronous Generators

    Institute of Scientific and Technical Information of China (English)

    JIN Wan-bing; ZHANG Dong; AN Zhong-liang; TAN Ren-yuan

    2006-01-01

    On the basis of a conventional permanent magnet (PM) synchronous generator's construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator (HEPMSG) is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.

  2. Motor Integrated Permanent Magnet Gear in a Battery Electrical Vehicle

    DEFF Research Database (Denmark)

    Frandsen, Tommy; Mathe, Laszlo; Berg, Nick Ilsø

    2015-01-01

    This paper presents the physical construction and test results of two new demonstrators of a Motor Integrated Permanent Magnet Gear (MIPMG), which is a second version of an already tested demonstrator. The demonstrators will be used as traction units for a Battery Electrical Vehicle (BEV) and the......This paper presents the physical construction and test results of two new demonstrators of a Motor Integrated Permanent Magnet Gear (MIPMG), which is a second version of an already tested demonstrator. The demonstrators will be used as traction units for a Battery Electrical Vehicle (BEV...

  3. Permanent magnets composed of high temperature superconductors

    Science.gov (United States)

    Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

    1991-01-01

    A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

  4. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Directory of Open Access Journals (Sweden)

    Jikai Si

    2014-01-01

    Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  5. Design and analysis of tubular permanent magnet linear wave generator.

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  6. A modified Rogowski coil for measurements of hybrid permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Bertsche, K.

    1996-08-01

    For large permanent magnets, as proposed for the Fermilab Recycler Ring, it may be important to quickly verify that the magnet`s strength is correct. This may be important, for example, if a magnet is suspected of having changed due to some sort of accident. The field strength of a pure dipole can be readily measured with a Hall probe, but for indexed dipoles and for quadrupoles a Hall probe will not give very accurate results without precise positioning. We have investigated a different approach, the use of a modified Rogowski coil to measure the magnetic potential of each pole. As long as magnet geometry is fixed and known, measurement of the magnetic potential at each pole gives a good measurement of field strength even for magnets with large quadrupole components. The construction and use of such a coil and the precision of measurements made with it will be discussed. 4 refs., 5 figs.

  7. CALCULATION OF INDUCTANCE OF THE INTERIOR PERMANENT MAGNET SYNCHRONOUS MOTOR

    Directory of Open Access Journals (Sweden)

    Phyong Le Ngo

    2017-01-01

    Full Text Available Interior permanent magnet synchronous motor (IPMSM refers to salient-pole synchronous motors, characterized by inequality of inductances of longitudinal (d and transverse (q axes. Electromagnetic torque of IPMSM consists of two components: active torque and reactive torque; the latter depends on inductances of d and q axes. An analytical method to calculate own inductances and mutual inductances of a three-phase IPMSM is presented. Distributed windings of the stator are substituted by equivalent sine distributed windings. An interior permanent magnets rotor is substituted by an equivalent salient-pole rotor. Sections of a magnetic circuit comprising interior permanent magnets, air barriers and steel bridges are substituted by equivalent air-gap. The expressions of the magnetic induction created by current of the stator windings at each point of the air gap as well as of magnetic flux linkage of the stator windings have been obtained. The equations of the self-inductances of phases A, B, C, and of inductance of mutual induction are determined from magnetic flux linkage. The inductance of the d and q axes have been obtained as a result of transformation of the axes abc–dq. The results obtained with the use of the proposed analytical method and the finite element method are presented in the form of a graph; the calculations that have been obtained by these two methods were compared. 

  8. Performance characterization of a permanent-magnet helicon plasma thruster

    Science.gov (United States)

    Takahashi, Kazunori; Charles, Christine; Boswell, Rod

    2012-10-01

    Helicon plasma thrusters operated at a few kWs of rf power is an active area of an international research. Recent experiments have clarified part of the thrust-generation mechanisms. Thrust components which have been identified include an electron pressure inside the source region and a Lorentz force due to an electron diamagnetic drift current and a radial component of the applied magnetic field. The use of permanent magnets (PMs) instead of solenoids is one of the solutions for improving the thruster efficiency because it does not require electricity for the magnetic nozzle formation. Here the thrust imparted from a permanent-magnet helicon plasma thruster is directly measured using a pendulum thrust balance. The source consists of permanent magnet (PM) arrays, a double turn rf loop antenna powered by a 13.56 MHz rf generator and a glass source tube. The PM arrays provide a magnetic nozzle near the open exit of the source and two configurations, which have maximum field strengths of about 100 and 270 G, are tested. A thrust of 15 mN, specific impulse of 2000 sec and a thrust efficiency of 8 percent are presently obtained for 2 kW of input power, 24 sccm flow rate of argon and the stronger magnetic field configuration.

  9. Unsupervised Data Mining in nanoscale X-ray Spectro-Microscopic Study of NdFeB Magnet.

    Science.gov (United States)

    Duan, Xiaoyue; Yang, Feifei; Antono, Erin; Yang, Wenge; Pianetta, Piero; Ermon, Stefano; Mehta, Apurva; Liu, Yijin

    2016-09-29

    Novel developments in X-ray based spectro-microscopic characterization techniques have increased the rate of acquisition of spatially resolved spectroscopic data by several orders of magnitude over what was possible a few years ago. This accelerated data acquisition, with high spatial resolution at nanoscale and sensitivity to subtle differences in chemistry and atomic structure, provides a unique opportunity to investigate hierarchically complex and structurally heterogeneous systems found in functional devices and materials systems. However, handling and analyzing the large volume data generated poses significant challenges. Here we apply an unsupervised data-mining algorithm known as DBSCAN to study a rare-earth element based permanent magnet material, Nd2Fe14B. We are able to reduce a large spectro-microscopic dataset of over 300,000 spectra to 3, preserving much of the underlying information. Scientists can easily and quickly analyze in detail three characteristic spectra. Our approach can rapidly provide a concise representation of a large and complex dataset to materials scientists and chemists. For example, it shows that the surface of common Nd2Fe14B magnet is chemically and structurally very different from the bulk, suggesting a possible surface alteration effect possibly due to the corrosion, which could affect the material's overall properties.

  10. Unsupervised Data Mining in nanoscale X-ray Spectro-Microscopic Study of NdFeB Magnet

    Science.gov (United States)

    Duan, Xiaoyue; Yang, Feifei; Antono, Erin; Yang, Wenge; Pianetta, Piero; Ermon, Stefano; Mehta, Apurva; Liu, Yijin

    2016-01-01

    Novel developments in X-ray based spectro-microscopic characterization techniques have increased the rate of acquisition of spatially resolved spectroscopic data by several orders of magnitude over what was possible a few years ago. This accelerated data acquisition, with high spatial resolution at nanoscale and sensitivity to subtle differences in chemistry and atomic structure, provides a unique opportunity to investigate hierarchically complex and structurally heterogeneous systems found in functional devices and materials systems. However, handling and analyzing the large volume data generated poses significant challenges. Here we apply an unsupervised data-mining algorithm known as DBSCAN to study a rare-earth element based permanent magnet material, Nd2Fe14B. We are able to reduce a large spectro-microscopic dataset of over 300,000 spectra to 3, preserving much of the underlying information. Scientists can easily and quickly analyze in detail three characteristic spectra. Our approach can rapidly provide a concise representation of a large and complex dataset to materials scientists and chemists. For example, it shows that the surface of common Nd2Fe14B magnet is chemically and structurally very different from the bulk, suggesting a possible surface alteration effect possibly due to the corrosion, which could affect the material’s overall properties. PMID:27680388

  11. Unsupervised Data Mining in nanoscale X-ray Spectro-Microscopic Study of NdFeB Magnet

    Science.gov (United States)

    Duan, Xiaoyue; Yang, Feifei; Antono, Erin; Yang, Wenge; Pianetta, Piero; Ermon, Stefano; Mehta, Apurva; Liu, Yijin

    2016-09-01

    Novel developments in X-ray based spectro-microscopic characterization techniques have increased the rate of acquisition of spatially resolved spectroscopic data by several orders of magnitude over what was possible a few years ago. This accelerated data acquisition, with high spatial resolution at nanoscale and sensitivity to subtle differences in chemistry and atomic structure, provides a unique opportunity to investigate hierarchically complex and structurally heterogeneous systems found in functional devices and materials systems. However, handling and analyzing the large volume data generated poses significant challenges. Here we apply an unsupervised data-mining algorithm known as DBSCAN to study a rare-earth element based permanent magnet material, Nd2Fe14B. We are able to reduce a large spectro-microscopic dataset of over 300,000 spectra to 3, preserving much of the underlying information. Scientists can easily and quickly analyze in detail three characteristic spectra. Our approach can rapidly provide a concise representation of a large and complex dataset to materials scientists and chemists. For example, it shows that the surface of common Nd2Fe14B magnet is chemically and structurally very different from the bulk, suggesting a possible surface alteration effect possibly due to the corrosion, which could affect the material’s overall properties.

  12. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation performance...... of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure properties...

  13. Optimal Design Solutions for Permanent Magnet Synchronous Machines

    Directory of Open Access Journals (Sweden)

    POPESCU, M.

    2011-11-01

    Full Text Available This paper presents optimal design solutions for reducing the cogging torque of permanent magnets synchronous machines. A first solution proposed in the paper consists in using closed stator slots that determines a nearly isotropic magnetic structure of the stator core, reducing the mutual attraction between permanent magnets and the slotted armature. To avoid complications in the windings manufacture technology the stator slots are closed using wedges made of soft magnetic composite materials. The second solution consists in properly choosing the combination of pole number and stator slots number that typically leads to a winding with fractional number of slots/pole/phase. The proposed measures for cogging torque reduction are analyzed by means of 2D/3D finite element models developed using the professional Flux software package. Numerical results are discussed and compared with experimental ones obtained by testing a PMSM prototype.

  14. Rational design of the exchange-spring permanent magnet.

    Science.gov (United States)

    Jiang, J S; Bader, S D

    2014-02-12

    The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

  15. The permanent and induced magnetic dipole moment of the moon

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Lichtenstein, B. R.; Schubert, G.

    1974-01-01

    Magnetic field observations with the Apollo 15 subsatellite have been used to deduce the components of both the permanent and induced lunar dipole moments in the orbital plane. The present permanent lunar magnetic dipole moment in the orbital plane is less than 1.3 times ten to the eighteenth power gauss-cu cm. Any uniformly magnetized near surface layer is therefore constrained to have a thickness-magnetization product less than 2.5 emu-cm per g. The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85. Combining this with recent measures of the ratio of the relative field strength at the ALSEP and Explorer 35 magnetometers indicates that the global lunar permeability relative to the plasma in the geomagnetic tail lobes is between 1.008 and 1.03.

  16. Preferred Orientation in Nanocomposite Permanent Magnet Materials

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Melt-spun (Nd11.4Fe82.9B5.7)0.99M1 ribbons (M=Zr, Nb, Ga, Zr+Ga, Nb+Ga) were prepared by melt-spinning technique. Ga addition is found to be effective for the orientation of c-axis of Nd2Fe14B grains perpendicular to the ribbon plane. Better magnetic properties can be achieved by adding both the two kinds of elements Zr+Ga, Nb+Ga, and it is found that the preferred orientation is further improved. The alignment degree changes with ribbon thickness and is highest when ribbon thickness is 120 μm. Heat treatment can improve the texture degree, but lead to coarser grains. Cryogenic treatment is first applied for the treatment of nanocomposite Nd2Fe14B/α-Fe melt-spun ribbons. The effects on magnetic properties and texture degree of nanocomposite magnets after cryogenic treatment were studied. The result shows that cryogenic treatment is beneficial to the enhancement of texture degree of melt-spun ribbon and the grain size has no obvious change.

  17. Effect of Titanium Substitution on Magnetic Properties and Microstructure of Nanocrystalline Monophase Nd-Fe-B Magnets

    Directory of Open Access Journals (Sweden)

    Wang Cong

    2012-01-01

    Full Text Available Nd12.3Fe81.7−xTixB6.0  (x=0.5–3.0 ribbons have been prepared by rapid quenching and subsequent annealing treatment. Effect of Ti substitution and annealing treatment on the microstructure, magnetic properties, and crystallization behavior of the ribbons was systematically investigated by the methods of differential scanning calorimeter (DSC, X-ray diffraction (XRD, transmission electron microscopy (TEM, and vibrating sample magnetometer (VSM. It is found that Ti addition may increase the crystallization temperature and stabilize the amorphous phase. Ti element inhibits the grain growth during crystallization process and finally refines the microstructure. The exchange coupling interactions and magnetic properties of the ribbons increase with increasing x from 0.5 to 1 and then decrease with further increasing x≥1.5. Optimum magnetic properties with (BHmax⁡=151.6 kJ/m3, Hci=809.2 kA/m, Jr=1.02 T are achieved in the Nd12.3Fe80.7Ti1B6.0 ribbons annealed at 600°C for 10 min.

  18. Study of a Mini-Actuator with Permanent Magnets

    Directory of Open Access Journals (Sweden)

    PETRESCU, C.

    2009-10-01

    Full Text Available The paper presents an analytical method for the determination of the magnetic force produced by a mini - actuator with permanent magnets. The results are compared with those obtained by performing a numerical field analysis with COMSOL Multiphysics, showing a very good agreement. The study reveals that the actuator has two equilibrium points, one of which is stable and the other one unstable.

  19. Structural looseness investigation in slow rotating permanent magnet generators

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Mijatovic, Nenad; Sweeney, Christian Walsted;

    2016-01-01

    Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while...

  20. The permanent magnet propulsion motor: from infancy to adolescence

    Energy Technology Data Exchange (ETDEWEB)

    Voyce, J.E. [Royal Navy (United Kingdom); Husband, S.M. [Rolls-Royce Strategic Research Centre (United Kingdom); Mattick, D.J. [Rolls-Royce Marine (United Kingdom)

    2000-07-01

    This paper presents an update on the Permanent Magnet Propulsion Motor (PMPM) Technical Demonstrator Programme (TDP). It looks at the history behind the TDP before concentrating on the design and development of the motor. The paper highlights the manufacturing processes involved in building such a novel design, and the motor testing programme, both complete and forthcoming at the time of writing the paper. (authors)

  1. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...

  2. Compact ECR ion source with permanent magnets for Carbon therapy

    NARCIS (Netherlands)

    Muramatsu, M; Kitagawa, A; Sakamoto, Y; Sato, Y; Yamada, S; Ogawa, H; Drentje, AG; Biri, S; Yoshida, Y

    Ion sources for the medical facilities should have the following characteristics of easy maintenance, low electric power, good stability, and long operation time without trouble (1 year or longer). For this, a 10 GHz compact electron cyclotron resonance ion source (ECRIS) with all permanent magnets

  3. Modeling of Exterior Rotor Permanent Magnet Machines with Concentrated Windings

    NARCIS (Netherlands)

    Vu Xuan, H.

    2012-01-01

    In this thesis modeling, analysis, design and measurement of exterior rotor permanent magnet (PM) machines with concentrated windings are dealt with. Special attention is paid to slotting effect. The PM machine is integrated in flywheel and used for small-scale ship application. Analytical model and

  4. Combinatorial investigation of rare-earth free permanent magnets

    Science.gov (United States)

    Fackler, Sean Wu

    The combinatorial high throughput method allows one to rapidly study a large number of samples with systematically changing parameters. We apply this method to study Fe-Co-V alloys as alternatives to rare-earth permanent magnets. Rare-earth permanent magnets derive their unmatched magnetic properties from the hybridization of Fe and Co with the f-orbitals of rare-earth elements, which have strong spin-orbit coupling. It is predicted that Fe and Co may also have strong hybridization with 4d and 5d refractory transition metals with strong spin-orbit coupling. Refractory transition metals like V also have the desirable property of high temperature stability, which is important for permanent magnet applications in traction motors. In this work, we focus on the role of crystal structure, composition, and secondary phases in the origin of competitive permanent magnetic properties of a particular Fe-Co-V alloy. Fe38Co52V10, compositions are known as Vicalloys. Fe-CoV composition spreads were sputtered onto three-inch silicon wafers and patterned into discrete sample pads forming a combinatorial library. We employed highthroughput screening methods using synchrotron X-rays, wavelength dispersive spectroscopy, and magneto-optical Kerr effect (MOKE) to rapidly screen crystal structure, composition, and magnetic properties, respectively. We found that in-plane magnetic coercive fields of our Vicalloy thin films agree with known bulk values (300 G), but found a remarkable eight times increase of the out-of-plane coercive fields (˜2,500 G). To explain this, we measured the switching fields between in-plane and out-of-plane thin film directions which revealed that the Kondorsky model of 180° domain wall reversal was responsible for Vicalloy's enhanced out-of-plane coercive field and possibly its permanent magnetic properties. The Kondorsky model suggests that domain-wall pinning is the origin of Vicalloy's permanent magnetic properties, in contrast to strain, shape, or

  5. Performance Comparison of Permanent Magnet Linear Actuators of Different Mover Types

    DEFF Research Database (Denmark)

    Ritchie, Ewen; Hinov, K.; Yatchev, I.

    2006-01-01

    A comparative study of permanent magnet linear actuators with different location of the permanent magnet is reported. Three mover types are considered - soft magnetic mover, permanent magnet mover and hybrid mover. Force-stroke characteristics are obtained with the help of finite element models...

  6. Interaction domains in permanent-magnetic rare-earth transition-metal compounds; Wechselwirkungsdomaenen in permanentmagnetischen Seltenerd-Uebergangsmetall-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Thielsch, Juliane

    2015-02-05

    In the framework of this dissertation the phenomenon of the interaction domains was studied both experimentally and by means of micromagnetic simulation. Object of the study were one-phase NdFeB magnets, which were fabricated from commercial MQU-F powders of the Magnequench Inc. company by hot pressing and subsequent warm deformation in the IWF Dresden. Additionally via the same fabrication way also composite samples of NdFeB and Fe with different original particle sizes ere obtained and studied. Supported wer the experimental works by simulations with the FEMME software package, which is based on a hybrid finite-element method/boundary-element method.

  7. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    Science.gov (United States)

    Hull, J. R.; Rossing, T. D.; Mulcahy, T. M.; Uherka, K. L.

    1992-10-01

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss 'coefficient of friction' for thrust bearings of this type can be as low as 8 x 10(exp -6). While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K (Delta B)(sup 3)/J(sub c) where K is a geometric coefficient, Delta B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J(sub c) is the critical current density of the HTS. It is clear that a small decrease in Delta B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of Delta B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing Delta B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  8. Rotating permanent magnet excitation for blood flow measurement.

    Science.gov (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  9. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field.

    Science.gov (United States)

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L; Miloushev, Vesselin; Poot, Alex J; Truong, Steven; Alvarez, Julio A; Aldeborgh, Hannah N; Keshari, Kayvan R

    2016-09-06

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting (13)C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  10. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field

    Science.gov (United States)

    Tee, Sui Seng; Digialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L.; Miloushev, Vesselin; Poot, Alex J.; Truong, Steven; Alvarez, Julio A.; Aldeborgh, Hannah N.; Keshari, Kayvan R.

    2016-09-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting 13C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  11. Bearingless Permanent Magnet Synchronous Motor using Independent Control

    Directory of Open Access Journals (Sweden)

    Normaisharah Mamat

    2015-06-01

    Full Text Available Bearingless permanent magnet synchronous motor (BPMSM combines the characteristic of the conventional permanent magent synchronous motor and magnetic bearing in one electric motor. BPMSM is a kind of high performance motor due to having both advantages of PMSM and magnetic bearing with simple structure, high efficiency, and reasonable cost. The research on BPMSM is to design and analyse BPMSM by using Maxwell 2-Dimensional of ANSYS Finite Element Method (FEM. Independent suspension force model and bearingless PMSM model are developed by using the method of suspension force. Then, the mathematical model of electromagnetic torque and radial suspension force has been developed by using Matlab/Simulink. The relation between force, current, distance and other parameter are determined. This research covered the principle of suspension force, the mathematical model, FEM analysis and digital control system of bearingless PMSM. This kind of motor is widely used in high speed application such as compressors, pumps and turbines.

  12. Study of Permanent Magnet Focusing for Astronomical Camera Tubes

    Science.gov (United States)

    Long, D. C.; Lowrance, J. L.

    1975-01-01

    A design is developed of a permanent magnet assembly (PMA) useful as the magnetic focusing unit for the 35 and 70 mm (diagonal) format SEC tubes. Detailed PMA designs for both tubes are given, and all data on their magnetic configuration, size, weight, and structure of magnetic shields adequate to screen the camera tube from the earth's magnetic field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the magnetic field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application.

  13. Pure-type superconducting permanent-magnet undulator.

    Science.gov (United States)

    Tanaka, Takashi; Tsuru, Rieko; Kitamura, Hideo

    2005-07-01

    A novel synchrotron radiation source is proposed that utilizes bulk-type high-temperature superconductors (HTSCs) as permanent magnets (PMs) by in situ magnetization. Arrays of HTSC blocks magnetized by external magnetic fields are placed below and above the electron path instead of conventional PMs, generating a periodic magnetic field with an offset. Two methods are presented to magnetize the HTSCs and eliminate the field offset, enabling the HTSC arrays to work as a synchrotron radiation source. An analytical formula to calculate the peak field achieved in a device based on this scheme is derived in a two-dimensional form for comparison with synchrotron radiation sources using conventional PMs. Experiments were performed to demonstrate the principle of the proposed scheme and the results have been found to be very promising.

  14. Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children.

    Science.gov (United States)

    Terada, Y; Kono, S; Ishizawa, K; Inamura, S; Uchiumi, T; Tamada, D; Kose, K

    2013-05-01

    We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming.

  15. Neodymium as the main feature of permanent magnets from hard disk drives (HDDs).

    Science.gov (United States)

    München, Daniel Dotto; Veit, Hugo Marcelo

    2017-03-01

    As a way to manage neodymium-iron-boron (NdFeB) magnets wasted in end-of-life hard disk drives (HDDs), a waste characterization is needed prior to a recycling process. Due to their magnetic properties, NdFeB magnets are essential in technological applications nowadays, thus causing an increase in the industrial demand for rare earth metals. However, these metals have a short supply, since they are difficult to obtain from ores, creating a critical market. In this work, a study of the characterization of sintered neodymium-iron-boron magnets was undertaken by qualitatively and quantitatively uncovering the neodymium recovery potential from this type of electronic waste. From the collection and disassembly of hard disk drives, in which the magnet represents less than 3% of the total weight, an efficient demagnetization process was proceeded at 320°C. Then, the magnet was ground and screened for an X-ray diffraction (XRD) analysis, which showed the Nd2Fe14B tetragonal phase as the dominant constituent of the sample. An analysis was also carried out in a scanning electron microscope (SEM) and an inductively coupled plasma optical emission spectrometer (ICP-OES), where the magnet composition showed 21.5wt% of neodymium and 65.1wt% of iron, among other chemicals. This Nd content is higher than the one found in Nd ores, enhancing the recyclability and the importance of waste management.

  16. Development of a miniature permanent magnetic circuit for nuclear magnetic resonance chip

    Science.gov (United States)

    Lu, Rongsheng; Yi, Hong; Wu, Weiping; Ni, Zhonghua

    2013-07-01

    The existing researches of miniature magnetic circuits focus on the single-sided permanent magnetic circuits and the Halbach permanent magnetic circuits. In the single-sided permanent magnetic circuits, the magnetic flux density is always very low in the work region. In the Halbach permanent magnetic circuits, there are always great difficulties in the manufacturing and assembly process. The static magnetic flux density required for nuclear magnetic resonance(NMR) chip is analyzed based on the signal noise ratio(SNR) calculation model, and then a miniature C-shaped permanent magnetic circuit is designed as the required magnetic flux density. Based on Kirchhoff's law and magnetic flux refraction principle, the concept of a single shimming ring is proposed to improve the performance of the designed magnetic circuit. Using the finite element method, a comparative calculation is conducted. The calculation results demonstrate that the magnetic circuit improved with a single shimming has higher magnetic flux density and better magnetic field homogeneity than the one improved with no shimming ring or double shimming rings. The proposed magnetic circuit is manufactured and its experimental test platform is also built. The magnetic flux density measured in the work region is 0.7 T, which is well coincided with the theoretical design. The spatial variation of the magnetic field is within the range of the instrument error. At last, the temperature dependence of the magnetic flux density produced by the proposed magnetic circuit is investigated through both theoretical analysis and experimental study, and a linear functional model is obtained. The proposed research is crucial for solving the problem in the application of NMR-chip under different environmental temperatures.

  17. Performance of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

    2005-01-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

  18. Magnetic separation of general solid particles realised by a permanent magnet

    Science.gov (United States)

    Hisayoshi, K.; Uyeda, C.; Terada, K.

    2016-12-01

    Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

  19. NdFeB磁体表面镀铝膜层退镀液配方的研究%Study on formulation of stripping solution for aluminum coating on surface of NdFeB magnet

    Institute of Scientific and Technical Information of China (English)

    陈梓赫; 代明江; 胡芳; 林松盛; 侯惠君

    2015-01-01

    A highly efficient and stable solution for stripping aluminum coating from the surface of NdFeB magnet was developed based on NaOH as corrosion agent with auxiliary salt, surfactant, coordination agent, and corrosion inhibitor. The content of aluminum coating on surface of NdFeB and the weight loss of substrate were used as performance evaluation indexes. The optimal stripping process was determined by orthogonal test as follows: NaOH 10 g/L, Na2CO330 g/L, sodium dodecyl benzene sulfonate 6 g/L, EDTA-2Na 4 g/L, and hexamethylenetetramine 4 g/L. A 12-µm thick aluminum coating on surface of NdFeB substrate can be stripped completely by using the optimized stripping solution at room temperature for 3 min. After stripping, the remanence, coercive force, and maximum magnetic energy product of the substrate are changed only by 1.27%, 1.25%, and 0.47%, respectively. The stripping shows less damage to magnetic properties. The mechanism of stripping aluminum coating on NdFeB surface was discussed.%用 NaOH 作腐蚀剂,添加辅助盐、表面活性剂、配位剂和缓蚀剂,研制了一种高效稳定的 NdFeB 表面镀铝膜退镀液。以NdFeB试样表面的铝含量和基体失重量作为性能评定指标,通过正交试验确定了优化的退镀液配方为:NaOH 10 g/L,Na2CO330 g/L,十二烷基苯磺酸钠6 g/L,EDTA-2Na 4 g/L,六次甲基四胺4 g/L。优化的退镀液在室温条件下退镀3 min,即可把NdFeB基体上约12μm厚的铝膜退除干净,而且退镀后基体的剩磁、矫顽力和最大磁能积仅分别变化1.27%、1.25%和0.47%,磁性能损伤较小。探讨了NdFeB表面镀铝膜层的退镀机理。

  20. Sensorless operation of surface mount permanent magnet AC (PMAC) motors

    Energy Technology Data Exchange (ETDEWEB)

    Toliyat, H.A.; Rahman, K.M.; Shet, D.S.

    1999-12-01

    A sensorless field oriented control scheme for surface mount permanent magnet ac (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet ac motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Results are presented to show the effectiveness of the new controller, and it is also shown that the position error is negligible.

  1. FUZZY FAULT DETECTION FOR PERMANENT MAGNET SYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    N. Selvaganesan

    2011-07-01

    Full Text Available Faults in engineering systems are difficult to avoid and may result in serious consequences. Effective fault detection and diagnosis can improve system reliability and avoid expensive maintenance. In this paper fuzzy system based fault detection scheme for permanent magnet synchronous generator is proposed. The sequence current components like positive and negative sequence currents are used as fault indicators and given as inputs to fuzzy fault detector. Also, the fuzzy inference system is created and rule base is evaluated, relating the sequence current component to the type of faults. These rules are fired for specific changes in sequence current component and the faults are detected. The feasibility of the proposed scheme for permanent magnet synchronous generator is demonstrated for different types of fault under various operating conditions using MATLAB/Simulink.

  2. A New Torque Control System of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Evstratov Andrey

    2017-01-01

    Full Text Available The article describes a new approach to control of permanent magnet synchronous motor drive based on the analysis of the electromechanical transformation. The proposed control system provides quick response and low ripple of the motor torque and flux. To synthesis this control system, the authors put the electromagnetic torque and the modulus of stator flux vector as controlled values and use the Lyapunov’s second method. In addition, the stator voltage constriction and ability of low-pass filtration are taken into account. The investigation of the proposed control system has carried out with the simulation and the experimental research which have confirmed that the proposed control system correspond to all above-mentioned control tasks and the permanent magnet synchronous motor controlled under this system may be recommended to use in robotics.

  3. Study on cogging force of permanent magnet linear synchronous motor

    Institute of Scientific and Technical Information of China (English)

    SHANGGUAN Xuan-feng; YUAN Shi-ying; LI Qing-fu

    2005-01-01

    Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force,and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at different position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods,namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.

  4. New Cogging Torque Reduction Methods for Permanent Magnet Machine

    Science.gov (United States)

    Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

    2017-08-01

    Permanent magnet type motors (PMs) especially permanent magnet synchronous motor (PMSM) are expanding its limbs in industrial application system and widely used in various applications. The key features of this machine include high power and torque density, extending speed range, high efficiency, better dynamic performance and good flux-weakening capability. Nevertheless, high in cogging torque, which may cause noise and vibration, is one of the threat of the machine performance. Therefore, with the aid of 3-D finite element analysis (FEA) and simulation using JMAG Designer, this paper proposed new method for cogging torque reduction. Based on the simulation, methods of combining the skewing with radial pole pairing method and skewing with axial pole pairing method reduces the cogging torque effect up to 71.86% and 65.69% simultaneously.

  5. Photovoltaic-wind hybrid system for permanent magnet DC motor

    Science.gov (United States)

    Nasir, M. N. M.; Lada, M. Y.; Baharom, M. F.; Jaafar, H. I.; Ramani, A. N.; Sulaima, M. F.

    2015-05-01

    Hybrid system of Photovoltaic (PV) - Wind turbine (WT) generation has more advantages and reliable compared to PV or wind turbine system alone. The aim of this paper is to model and design hybrid system of PV-WT supplying 100W permanent-magnet dc motor. To achieve the objective, both of PV and WT are connected to converter in order to get the same source of DC supply. Then both sources were combined and straightly connected to 100W permanent magnet dc motor. All the works in this paper is only applied in circuit simulator by using Matlab Simulink. The output produced from each converter is expected to be suit to the motor specification. The output produced from each renewable energy system is as expected to be high as it can support the motor if one of them is breakdown

  6. Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

    Directory of Open Access Journals (Sweden)

    Lee J.-G.

    2015-06-01

    Full Text Available The effect of the desorption-recombination temperature on the microstructure and magnetic properties of hydrogenation-disproportionation-desorption-recombination (HDDR processed Nd-Fe-B powders was studied. The NdxB6.4Ga0.3Nb0.2Febal (x=12.5-13.5, at.% casting alloys were pulverized after homogenizing annealing, and then subjected to HDDR treatment. During the HDDR process, desorption-recombination (DR reaction was induced at two different temperature, 810°C and 820°C. The higher Nd content resulted in enhanced coercivity of the HDDR powder, and which was attributed to the thicker and more uniform Nd-rich phase along grain boundaries. But this uniform Nd-rich phase induced faster grain growth. The remanence of the powder DR-treated at 820°C is higher than that DR-treated at 810°C. In addition, it was also confirmed that higher DR temperature is much more effective to improve squareness.

  7. Cogging torque reduction for interior permanent magnet synchronous motors

    OpenAIRE

    Tost Candel, Miquel

    2015-01-01

    Interior permanent magnet synchronous machines show a good range of behaviours, which make these kinds of machines good candidates for an electromechanical energy conversion. However, in order to improve their accuracy in their torque responses, the cogging torque and torque ripple phenomena should be mitigated to obtain better performance of the machine. In order to reduce the cogging torque and torque ripple, control techniques as well as geometric parameters of the machine have to be im...

  8. Studies Directed Toward New and Improved Permanent Magnet Materials.

    Science.gov (United States)

    1994-09-28

    electric motors and generators. At present there are only 3 permanent magnet materials in widespread use - SmCo5, Nd2Fe14B and SmCo5-Sm2Co17. Each has...a third of the effort has been devoted to effecting improvements in existing materials which occur in the SmCo5 or Nd2Fe14B structures. Materials

  9. Induction Motors Versus Permanent-Magnet Actuators for Aerospace Applications

    OpenAIRE

    Kakosimos, Panagiotis E.; Sarigiannidis, Athanasios G.; Beniakar, Minos E.; Kladas, Antonios G.; Gerada, C

    2014-01-01

    This paper introduces a comparative study on the design of aerospace actuators concerning Induction Motor (IM) and Permanent Magnet Motor (PMM) technologies. In the analysis undertaken, the two candidate configurations are evaluated in terms of both their electromagnetic and thermal behavior in a combined manner. On a first step, the basic dimensioning of the actuators and their fundamental operational characteristics are determined via a time-stepping Finite Element (FE) analysis. The consid...

  10. Permanent magnet brushless motor control based on ADRC

    Directory of Open Access Journals (Sweden)

    Li Xiaokun

    2016-01-01

    Full Text Available Permanent magnet brushless motor is a nonlinear system with multiple variables, the mathematical model of Permanent magnet brushless motor is difficult to establish, and since that the classic PID control is hard to precisely control the motor. Active disturbance rejection control (ADRC technique is a new nonlinear controller which does not depend on the system model. It is starting from the classic PID control, and establishing the loop control system by error negative feedback, the ESO(extended state observer observing system which comes from the observer theory of modern control theory to observe internal and external perturbations. ADRC inherits the advantages of PID with little overshoot, high convergence speed, high accuracy, strong anti-interference ability and other characteristics, and it has a strong disturbance adaptability and robustness as for the uncertainty perturbation and their internal disturbance of control objects. Therefore, This paper attempts to use Active disturbance rejection control(ADRC, in order to improve the control of permanent magnet brushless motor. In this design of control system, the simulation of the system is realized based on MATLAB, and then the discrete control algorithm is transplanted to the embedded system to control the permanent magnet brushless DC motor (PMBLDCM. The control system is implemented on the DSP-F28335 digital signal processor, and the DSP also provides the functions like voltage and current AD sampling, PWM driver generation, speed and rotor position calculation, etc. The simulation and experiment results indicate that, the system has good dynamic performance and anti-disturbance performance.

  11. Speed Regulator for Permanent Magnet DC Boring Machine

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper a variable-speed system for a loaded permanent magnet direct current boring machine (PMDCBM) is described in details. The voltage adjustment of PMDCBM is accomplished by means of solid state switch with a high gain Darlington transistor. The device designed possesses good variable speed characteristic and Iow loss at low speed. The speed can be regulated automatically to hold at an ideal value according to the load.

  12. UCLA-KIAE focusing permanent magnet undulator for SASE experiment

    Science.gov (United States)

    Osmanov, N.; Tolmachev, S.; Varfolomeev, A.; Varfolomeev, A. A.; Frigola, P.; Hogan, M.; Pellegrini, C.; Carr, R.; Lidia, S.

    1998-02-01

    A description of a new 2 m undulator is presented which was specially designed and manufactured for a SASE mode FEL experiment. It is a one section two plane focusing permanent magnet construction. The uniform period length is 2.06 cm, total number of periods is 98. The peak field on the axis is 5.4 kG for a 5 mm gap.

  13. Cogging torque mitigation of modular permanent magnet machines

    OpenAIRE

    Li, G. J.; Ren, B.; Zhu, Z-Q.; Li, Y X; Ma, J.

    2015-01-01

    This paper proposes a novel cogging torque mitigation method for modular permanent magnet (PM) machines with flux gaps in alternate stator teeth. The slot openings of the modular PM machines are divided into two groups in a special way. By shifting the slot openings of two groups in opposite directions with the same angle, the machine cogging torque can be significantly reduced. Analytical formula of the desired shift angle is derived, and can be applicable to other modular machines with diff...

  14. Modular Permanent Magnet Machines with Alternate Teeth Having Tooth Tips

    OpenAIRE

    Li, G. J.; Zhu, Z.Q.; Foster, M. P.; Stone, D. A.; Zhan, H.L.

    2015-01-01

    This paper presents single layer modular permanent magnet machines with either wound or unwound teeth with tooth tips. The structures with wound teeth having tooth tips are suitable for modular machines with slot number higher than pole number to compensate for the drop in winding factor due to the flux gaps in alternate stator teeth, accordingly to maintain or even to increase their average torques. However, the structures with unwound teeth having tooth tips are suitable for modular machine...

  15. A permanent magnet electron beam phase-shifter

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, G.A. E-mail: trower@naxs.net; Ermakov, A.N.; Pakhomov, N.I.; Semyachkin, V.K.; Shvedunov, V.I.; Skachkov, V.S.; Tyurin, S.A

    2004-05-21

    We describe here the design and construction of a permanent magnet-based electron beam phase-shifter now operating in our 70 MeV Race-Track Microtron (P. Lucas, S. Webber (Eds.), Proceedings of the 2001 Particle Accelerator Conference, Vol. 4, IEEE, Piscataway, NJ, 2001, p. 2596; L. Gennary (Ed.), Proceedings of the 1995 Particle Accelerator Conference, Vol. 2, IEEE, Piscataway, NJ, 1996, p. 807)

  16. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

  17. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... a set of static magnetic filed analysis is carried out and then the electric circuit and mechanical motion equations are solved employing bi-cubic spline approximations of the field analysis results. The results show that the proposed decoupled model is of satisfactory accuracy and gives more...

  18. Permanent magnetic ferrite based power-tunable metamaterials

    Science.gov (United States)

    Zhang, Guanqiao; Lan, Chuwen; Gao, Rui; Zhou, Ji

    2017-08-01

    Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated in this research. Scattering parameter measurements confirm a shift in resonant frequency in correlation to changes in incident electromagnetic power within microwave frequency band. The tunable phenomenon represented by a blue-shift in transmission spectra in the metamaterials array can be attributed to a decrease in saturation magnetization resulting from FMR-induced temperature elevation upon resonant conditions. This power-dependent behavior offers a simple and practical route towards dynamically fine-tunable ferrite metamaterials.

  19. A clip-on Zeeman slower using toroidal permanent magnets.

    Science.gov (United States)

    Krzyzewski, S P; Akin, T G; Dahal, Parshuram; Abraham, E R I

    2014-10-01

    We present the design of a zero-crossing Zeeman slower for (85)Rb using rings of flexible permanent magnets. The design is inexpensive, requires no power or cooling, and can be easily attached and removed for vacuum maintenance. We show theoretically that such a design can reproduce a magnetic field profile of a standard zero-crossing Zeeman slower. Experimental measurements of a prototype and comparisons to theoretical simulations demonstrate the feasibility of the design and point toward future improvements. Simulations show an atom flux similar to other Zeeman slowers.

  20. Quasi permanent superconducting magnet of very high field

    Science.gov (United States)

    Ren, Y.; Liu, J.; Weinstein, R.; Chen, I. G.; Parks, D.; Xu, J.; Obot, V.; Foster, C.

    1993-01-01

    We report on persistent field in a quasi-permanent magnet made of high temperature superconductor. The material has an average of 40 percent molar excess of Y, relative to Y1Ba2Cu3O7 and has been irradiated with high energy light ions at 200 MeV. The magnet, which traps 1.52 T at 77.3 K, traps nearly 4 T at 64.5 K. No evidence of giant flux jump or sample cracking was observed.

  1. Multipole shimming of permanent magnets using harmonic corrector rings.

    Science.gov (United States)

    Jachmann, R C; Trease, D R; Bouchard, L-S; Sakellariou, D; Martin, R W; Schlueter, R D; Budinger, T F; Pines, A

    2007-03-01

    Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.

  2. Normal and abnormal grain growth in fine-grained Nd-Fe-B sintered magnets prepared from He jet milled powders

    Science.gov (United States)

    Bittner, F.; Woodcock, T. G.; Schultz, L.; Schwöbel, C.; Gutfleisch, O.; Zickler, G. A.; Fidler, J.; Üstüner, K.; Katter, M.

    2017-03-01

    Fine-grained, heavy rare earth free Nd-Fe-B sintered magnets were prepared from He jet milled powders with an average particle size of 1.5 μm by low temperature sintering at 920 °C or 980 °C. A coercivity of >1600 kA/m was achieved for an average grain size of 1.68 μm. Transmission electron microscopy showed that the distribution and composition of intergranular and grain boundary junction phases was similar to that in conventionally processed magnets. Microstructural analysis on different length scales revealed the occurrence of abnormal grain growth, which is unexpected for sintering temperatures below 1000 °C. A larger area fraction of abnormal grains was observed in the sample sintered at 920 °C compared to that sintered at 980 °C. Microtexture investigation showed a better crystallographic alignment of the abnormal grains compared to the fine-grained matrix, which is explained by a size dependent alignment of the powder particles during magnetic field alignment prior to sintering. Slightly larger particles in the initial powder show a better alignment and will act as nucleation sites for abnormal grain growth. Magneto-optical Kerr investigations confirmed the lower switching field of the abnormal grains compared to the fine-grained matrix. The demagnetisation curve of the sample sintered at 920 °C showed reduced rectangularity and this was attributed to a cooperative effect of the larger fraction of abnormal grains with low switching field and, as a minor effect, a reduced degree of crystallographic texture in this sample compared to the material sintered at 980 °C, which did not show the reduced rectangularity of the demagnetisation curve.

  3. Two dimensional model of a permanent magnet spur gear

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif; Andersen, Torben Ole; Rasmussen, Peter Omand

    2005-01-01

    This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear...... is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis...... of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses...

  4. Practical Aspects of Modern and Future Permanent Magnets

    Science.gov (United States)

    McCallum, R. W.; Lewis, L.; Skomski, R.; Kramer, M. J.; Anderson, I. E.

    2014-07-01

    The mandate to reduce greenhouse gases will require highly efficient electric machines for both power generation and traction motor applications. Although permanent magnet electric machines utilizing Nd2Fe14B-based magnets provide obvious power-to-weight advantages over induction machines, the limited availability and high price of the rare earth (RE) metals make these machines less favorable. Of particular concern is the cost and supply criticality of Dy, a key RE element that is required to improve the high-temperature performance of Nd-based magnetic alloys for use in generators and traction motors. Alternatives to RE-based alloys do exist, but they currently lack the energy density necessary to replace Nd-based magnets. Many of these compounds have been known for decades, but serious interest in their development waned once compounds based on RE elements were discovered. In this review, intrinsic and extrinsic materials factors that impact the optimization of both existing and potential future permanent magnets for energy applications are examined in light of new insights gained from renewed examination.

  5. Inspired by nature: investigating tetrataenite for permanent magnet applications.

    Science.gov (United States)

    Lewis, L H; Mubarok, A; Poirier, E; Bordeaux, N; Manchanda, P; Kashyap, A; Skomski, R; Goldstein, J; Pinkerton, F E; Mishra, R K; Kubic, R C; Barmak, K

    2014-02-12

    Chemically ordered L10-type FeNi, also known as tetrataenite, is under investigation as a rare-earth-free advanced permanent magnet. Correlations between crystal structure, microstructure and magnetic properties of naturally occurring tetrataenite with a slightly Fe-rich composition (~ Fe55Ni44) obtained from the meteorite NWA 6259 are reported and augmented with computationally derived results. The tetrataenite microstructure exhibits three mutually orthogonal crystallographic variants of the L10 structure that reduce its remanence; nonetheless, even in its highly unoptimized state tetrataenite provides a room-temperature coercivity of 95.5 kA m(-1) (1200 Oe), a Curie temperature of at least 830 K and a largely temperature-independent anisotropy that preliminarily point to a theoretical magnetic energy product exceeding (BH)max = 335 kJ m(-3) (42 MG Oe) and approaching those found in today's best rare-earth-based magnets.

  6. Torque Characteristics of Saturated Permanent-Magnet Synchronous Motors

    Science.gov (United States)

    Takahashi, Akeshi; Kikuchi, Satoshi; Wakui, Shinichi; Mikami, Hiroyuki; Ide, Kazumasa; Shima, Kazuo

    The evaluation of torque characteristics in a saturated magnetic field for permanent-magnet (PM) synchronous motors is presented. The torque saturation characteristics of non-salient and salient pole machines are investigated by finite element analysis and measurement. Thus, it is found that the torque saturation originates in the magnetic saturation in both the stator teeth, which are located on the leading position toward the direct axis, and in the stator back yoke, which is located on the lagging position toward the direct axis. This mechanism can also explain the reason for the significant torque saturation in the salient-pole machine; the higher inductance of the quadrature axis of the salient-pole machine causes a significant magnetic saturation in the stator back yoke. Therefore, less saliency or a wider back yoke can improve the torque saturation.

  7. Optimization of Magnet Arrangement in Double-Layer Interior Permanent-Magnet Motors

    Science.gov (United States)

    Yamazaki, Katsumi; Kitayuguchi, Kazuya

    The arrangement of permanent magnets in double-layer interior permanent-magnet motors is optimized for variable-speed applications. First, the arrangement of magnets is decided by automatic optimization. Next, the superiority of the optimized motor is discussed by the d- and q-axis equivalent circuits that consider the magnetic saturation of the rotor core. Finally, experimental verification is carried out by using a prototype motor. It is confirmed that the maximum torque of the optimized motor under both low speed and high speed conditions are higher than those of conventional motors because of relatively large q-axis inductance and small d-axis inductance.

  8. High-Performance Permanent Magnets for Energy-Efficient Devices

    Science.gov (United States)

    Hadjipanayis, George

    2012-02-01

    Permanent magnets (PMs) are indispensable for many commercial applications including the electric, electronic and automobile industries, communications, information technologies and automatic control engineering. In most of these applications, an increase in the magnetic energy density of the PM, usually presented via the maximum energy product (BH)max, immediately increases the efficiency of the whole device and makes it smaller and lighter. Worldwide demand for high performance permanent magnets has increased dramatically in the past few years driven by hybrid and electric cars, wind turbines and other power generation systems. New energy challenges in the world require devices with higher energy efficiency and minimum environmental impact. The potential of 3d-4f compounds which revolutionized the PM science and technology is almost fully utilized, and the supply of 4f rare earth elements does not seem to be much longer assured. This talk will address the major principles guiding the development of PMs and overview state-of-the-art theoretical and experimental research. Recent progress in the development of nanocomposite PMs, consisting of a fine (at the scale of the magnetic exchange length) mixture of phases with high magnetization and large magnetic hardness will be discussed. Fabrication of such PMs is currently the most promising way to boost the (BH)max, while simultaneously decreasing, at least partially, the reliance on the rare earth elements. Special attention will be paid to the impact which the next-generation high-(BH)max magnets is expected to have on existing and proposed energy-saving technologies.

  9. Discrete Current Control Strategy of Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2013-01-01

    Full Text Available A control strategy of permanent magnet synchronous motors (PMSMs, which is different from the traditional vector control (VC and direct torque control (DTC, is proposed. Firstly, the circular rotating magnetic field is analyzed on the simplified model and discredited into stepping magnetic field. The stepping magnetomotive force will drive the rotor to run as the stepping motor. Secondly, the stator current orientation is used to build the control model instead of rotor flux orientation. Then, the discrete current control strategy is set and adopted in positioning control. Three methods of the strategy are simulated in computer and tested on the experiment platform of PMSM. The control precision is also verified through the experiment.

  10. Innovative Sensors for Pipeline Crawlers: Rotating Permanent Magnet Inspection

    Energy Technology Data Exchange (ETDEWEB)

    J. Bruce Nestleroth; Richard J. Davis; Stephanie Flamberg

    2006-09-30

    Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. Current inspection systems that are propelled through the pipeline by the product flow cannot be used to inspect all pipelines because of the various physical barriers they may encounter. To facilitate inspection of these ''unpiggable'' pipelines, recent inspection development efforts have focused on a new generation of powered inspection platforms that are able to crawl slowly inside a pipeline and can maneuver past the physical barriers that limit internal inspection applicability, such as bore restrictions, low product flow rate, and low pressure. The first step in this research was to review existing inspection technologies for applicability and compatibility with crawler systems. Most existing inspection technologies, including magnetic flux leakage and ultrasonic methods, had significant implementation limitations including mass, physical size, inspection energy coupling requirements and technology maturity. The remote field technique was the most promising but power consumption was high and anomaly signals were low requiring sensitive detectors and electronics. After reviewing each inspection technology, it was decided to investigate the potential for a new inspection method. The new inspection method takes advantage of advances in permanent magnet strength, along with their wide availability and low cost. Called rotating permanent magnet inspection (RPMI), this patent pending technology employs pairs of permanent magnets rotating around the central axis of a cylinder to induce high current densities in the material under inspection. Anomalies and wall thickness variations are detected with an array of sensors that measure local changes in the magnetic field produced by the induced current flowing in the material. This inspection method is an alternative to the common concentric coil remote field technique that induces

  11. A SQP optimization method for shimming a permanent MRI magnet

    Institute of Scientific and Technical Information of China (English)

    Zhe Jin; Xing Tang; Bin Meng; Donglin Zu; Weimin Wang

    2009-01-01

    Based on the sequential quadratic programming (SQP) method, a new approach is presented in this paper to gain a uniform magnetic field for a permanent MRI magnet with biplanar poles. First, the adopted shimming piece is modeled as a magnetic dipole moment to calculate its effect on the background field over the imaging region of interest. Then, the SQP method is utilized to determine the ideal solution for the shimming equation. Finally, the ideal solution is discrete, and the quantization error control technique is used for special cases. This new method helps to reduce the inhomogeneity from 1234.5 ppm to 21.4 ppm over a 36 cm diameter spherical volume (DSV), within hours in practical shimming work.

  12. Virtual test system for permanent-magnet DC motor

    Institute of Scientific and Technical Information of China (English)

    崔淑梅; 王悦; 柴凤; 吴红星; 刘宝廷; 程树康

    2003-01-01

    In order to obtain the primary parameters and operating characteristics of a DC motor without directlymeasuring its torque and rational speed, it is proposed to use a PC and a data acquisition card to acquire boththe dynamic and static data of armature current to establish the performance of a DC permanent-magnet motor.The accuracy and validity of this virtual test system proposed were verified by comparing the measurements madewith the system proposed with the measurements made with conventional torque meters. It is concluded from theresults of comparison that from the mathematic model established for the DC permant-magnet motors, both majorparameters and operating characteristics can be directly established for the DC motors without measuring theirtorques and rotational speed, a perfect on-line measurement and test system has been established for the DCpermanent-magnet motors using the theory of virtual test system. The system proposed features shorter test time,higher efficiency and lower cost.

  13. Simulation of magnetic induction distribution in a coaxial linear motor with axial and radial direction of permanent magnets magnetization

    Directory of Open Access Journals (Sweden)

    G.M. Golenkov

    2014-03-01

    Full Text Available The paper presents results of computer simulation and experimental study of magnetic induction distribution in a coaxial linear motor air gap throughout the length of the runner active part at different heights of the air gap between the runner and the inductor magnetic core for motors with axial and radial direction of the permanent magnets magnetization.

  14. Design method and magnetic field analysis of axial-magnetized permanent magnet micromotor

    Institute of Scientific and Technical Information of China (English)

    YANG Jiewei; WU Yihui; JIA Hongguang; ZHANG Ping; WANG Shurong

    2007-01-01

    To investigate the impact of size on its performance in designing an axial-magnetized permanent magnet micromotor,the finite element method is adopted to simulate the magnetic field of the dual rotor motor,and the flux density wave form distributed in the airgap is obtained.The influence of the external dimensions,pole numbers and magnet thicknesses of the rotor,and the airgap distances on the flux density,are analyzed and analytical results are given.With the increase of the airgap distance,the flux density under more poles reduces more quickly than under fewer poles.With the increase of the magnet thickness,the flux density is a rising curve,and after the magnet thickness attains a certain point,the flux density is almost a constant.While reducing the diameter of the rotor,the decrease of the flux density slows down as magnet thickness is reduced.To avoid having a seriously distorted waveform,the distance between inner and outer radii of the rotor must be larger than 1.5 millimeter.Results of the magnetic field analysis can guide a microminiaturization of the motor.Moreover,the results are analyzed theoretically and the simulated values are almost consistent with the experimental values.

  15. [Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

    Science.gov (United States)

    Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

    2014-10-01

    In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

  16. Toroidal-Core Microinductors Biased by Permanent Magnets

    Science.gov (United States)

    Lieneweg, Udo; Blaes, Brent

    2003-01-01

    The designs of microscopic toroidal-core inductors in integrated circuits of DC-to-DC voltage converters would be modified, according to a proposal, by filling the gaps in the cores with permanent magnets that would apply bias fluxes (see figure). The magnitudes and polarities of the bias fluxes would be tailored to counteract the DC fluxes generated by the DC components of the currents in the inductor windings, such that it would be possible to either reduce the sizes of the cores or increase the AC components of the currents in the cores without incurring adverse effects. Reducing the sizes of the cores could save significant amounts of space on integrated circuits because relative to other integrated-circuit components, microinductors occupy large areas - of the order of a square millimeter each. An important consideration in the design of such an inductor is preventing magnetic saturation of the core at current levels up to the maximum anticipated operating current. The requirement to prevent saturation, as well as other requirements and constraints upon the design of the core are expressed by several equations based on the traditional magnetic-circuit approximation. The equations involve the core and gap dimensions and the magnetic-property parameters of the core and magnet materials. The equations show that, other things remaining equal, as the maximum current is increased, one must increase the size of the core to prevent the flux density from rising to the saturation level. By using a permanent bias flux to oppose the flux generated by the DC component of the current, one would reduce the net DC component of flux in the core, making it possible to reduce the core size needed to prevent the total flux density (sum of DC and AC components) from rising to the saturation level. Alternatively, one could take advantage of the reduction of the net DC component of flux by increasing the allowable AC component of flux and the corresponding AC component of current

  17. Sample Size Effect of Magnetomechanical Response for Magnetic Elastomers by Using Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tsubasa Oguro

    2017-01-01

    Full Text Available The size effect of magnetomechanical response of chemically cross-linked disk shaped magnetic elastomers placed on a permanent magnet has been investigated by unidirectional compression tests. A cylindrical permanent magnet with a size of 35 mm in diameter and 15 mm in height was used to create the magnetic field. The magnetic field strength was approximately 420 mT at the center of the upper surface of the magnet. The diameter of the magnetoelastic polymer disks was varied from 14 mm to 35 mm, whereas the height was kept constant (5 mm in the undeformed state. We have studied the influence of the disk diameter on the stress-strain behavior of the magnetoelastic in the presence and in the lack of magnetic field. It was found that the smallest magnetic elastomer with 14 mm diameter did not exhibit measurable magnetomechanical response due to magnetic field. On the opposite, the magnetic elastomers with diameters larger than 30 mm contracted in the direction parallel to the mechanical stress and largely elongated in the perpendicular direction. An explanation is put forward to interpret this size-dependent behavior by taking into account the nonuniform field distribution of magnetic field produced by the permanent magnet.

  18. Analysis of Vibration and Acoustic Noise in Permanent Magnet Motors.

    Science.gov (United States)

    Hwang, Sangmoon

    The drive motor is a frequent source of vibration and acoustic noise in many precision spindle motors. One of the electromagnetic sources of vibration in permanent magnet motors is the torque ripple, consisting of the reluctance torque and electromagnetic torque fluctuation. This type of vibration is becoming more serious with the advent of new high-grade magnets with increased flux density. Acoustic noise of electromagnetic origin is difficult to predict and its exact mechanism is unclear. The mechanism of noise generation should be revealed to design a quieter motor which is the modern customer's demand. For motor operation at low speeds and loads, torque ripple due to the reluctance torque is often a source of vibration and control difficulty. The reluctance torque in a motor was calculated from the flux density by a finite element method and the Maxwell stress method. Effects of design parameters, such as stator slot width, permanent slot width, airgap length and magnetization direction, were investigated. Magnet pole shaping, by gradually decreasing the magnet thickness toward edges, yields a sinusoidal shape of the reluctance torque with reduced harmonics, thus reducing the vibration. This dissertation also presents two motor design techniques: stator tooth notching and rotor pole skewing with magnet pole shaping, and the effect of each method on the output torque. The analysis shows that the reluctance torque can be nearly eliminated by the suggested designs, with minimal sacrifice of the output torque. In permanent magnet DC motors, the most popular design type is the trapezoidal back electro-motive force (BEMF), for switched DC controllers. It is demonstrated that the output torque profile of one phase energized is qualitatively equivalent to the BEMF profile for motors with reduced reluctance torque. It implies that design of BEMF profile is possible by magnetic modeling of a motor, without expensive and time-consuming experiments for different designs

  19. 低碳经济下钕铁硼永磁体防护新技术%Low-carbon Economy and Corrosion Protection of NdFeB Magnets by New Surface Coatings

    Institute of Scientific and Technical Information of China (English)

    金莹; 曹美蓉; 刘素芬

    2012-01-01

    Low carbon economy is the trend of economic development in the world today. It is the in- evitable choice of sustainable development for human societies. Characterized and summarized are the surface protection technologies, electroplating and vapor deposition, for Nd-Fe-B magnets. There are, however, existing environmental problems such as pollution for the former. In the present paper, we have reviewed the current status of surface protection techniques for Nd-Fe-B magnets. The main is- sues of vapor technology are emphasized on the principles, the characteristics, and its applications. It is finally pointed out that the efficient, clean, and environment friendly physical vapor deposition (PVD) will likely be one of the best choices for the surface protection for Nd-Fe-B magnets.%发展低碳经济是当今世界经济发展的潮流,是人类可持续发展的必然选择。针对NdFeB永磁体各种防护保护技术的特点,概述了钕铁硼永磁体表面防护处理常见方法———电镀,存在的环保和污染问题。论述了气相沉积技术原理、特点以及在钕铁硼永磁体表面防护处理上的应用。提出了气相沉积金属镀层需要解决的主要问题,而高效、清洁、环保的气相沉积技术是今后钕铁硼永磁体防护热点方向之一。

  20. Self-suspended permanent magnetic FePt ferrofluids

    KAUST Repository

    Dallas, Panagiotis

    2013-10-01

    We present the synthesis and characterization of a new class of self-suspended ferrofluids that exhibit remanent magnetization at room temperature. Our system relies on the chemisorption of a thiol-terminated ionic liquid with very low melting point on the surface of L10 FePt nanoparticles. In contrast, all types of ferrofluids previously reported employ either volatile solvents as the suspending media or superparamagnetic iron oxide nanoparticles (that lacks permanent magnetization) as the inorganic component. The ferrofluids do not show any sign of flocculation or phase separation, despite the strong interactions between the magnetic nanoparticles due to the strong chemisorption of the ionic liquid as evidenced by Raman spectroscopy and thermal analysis. Composites with high FePt loading (40 and 70. wt%) exhibit a pseudo solid-like rheological behavior and high remanent magnetization values (10.1 and 12.8. emu/g respectively). At lower FePt loading (12. wt%) a liquid like behavior is observed and the remanent and saturation magnetization values are 3.5 and 6.2. emu/g, respectively. The magnetic and flow properties of the materials can be easily fine tuned by controlling the type and amount of FePt nanoparticles used. © 2013 Elsevier Inc.

  1. Slip Torque Investigation and Magnetic Redesign of Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Frandsen, Tommy Vestergaard; Rasmussen, Peter Omand

    2015-01-01

    This paper presents an investigation of 20% difference between the measured and calculated slip torque of a Motor Integrated Permanent Magnet Gear (MIPMG) prototype. The High Speed (HS) side of the Magnetic Gear (MG) was fixed by loading the motor when conducting the slip torque measurement...

  2. Improving torque per kilogram magnet of permanent magnet couplings using finite element analysis

    DEFF Research Database (Denmark)

    Högberg, Stig; Jensen, Bogi Bech; Bendixen, Flemming Buus

    2013-01-01

    This paper presents the methodology and subsequent findings of a performance-improvement routine that employs automated finite element (FE) analysis to increase the torque-per-kilogram-magnet (TPKM) of a permanent magnet coupling (PMC). The routine is applied to a commercially available cylindrical...

  3. Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

    Science.gov (United States)

    Smid, Pieter; Shcherbakov, Valeriy; Petersen, Nikolai

    2015-09-01

    Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain. This will cause the bacterium to be rotated and aligned with the external field. The swimming direction of magnetotactic bacteria can be controlled with external magnetic fields, which makes it convenient to study them under a light microscope. Usually, a special set of coils arranged around a light microscope is used to control the swimming magnetotactic bacteria. Here, we present a simple mechanical system with a permanent magnet, which produces a rotating magnetic field of nearly constant amplitude in the focal plane of a light microscope. The device is placed beside the light microscope and easily adaptable to almost any microscope and thus convenient for field experiments. To describe the trajectories qualitatively, a theoretical model of the trajectories is presented. This device can be used to control the swimming direction of magnetotactic bacteria and also for studying their magnetic and hydrodynamic properties.

  4. Prediction and analysis of magnetic forces in permanent magnet brushless dc motor with rotor eccentricity

    Science.gov (United States)

    Liu, Z. J.; Li, J. T.; Jabbar, M. A.

    2006-04-01

    In design of permanent magnet motors for high-precision applications, it is sometimes necessary, early in the design stage, to have a detailed analysis of the effect of rotor eccentricity that may result from manufacturing imperfectness or use of fluid dynamic or aerodynamic bearings. This paper presents an analytical model for electromagnetic torque and forces in permanent magnet motors with rotor eccentricity. The model gives an insight to the relationship between the effect of the eccentricity and the other motor design parameters on the electromagnetic forces. It is shown that the calculated magnetic forces obtained from this model agree well with those obtained from numerical simulations that are very computationally demanding.

  5. Permanent Magnetic Synchronous Motor Control System Based on ADRC

    Directory of Open Access Journals (Sweden)

    Song Wang

    2013-06-01

    Full Text Available Permanent magnetic synchronous motor (PMSM is a strong coupling and non-linear system. In the PMSM speed-regulation system, PID controller is the conventional one, it is difficult to decide the parameters of PID. Moreover, the performance of PID controller is not very well in large disturbance. In the paper, the Active Disturbance Rejection Controller (ADRC is applied to the PMSM speed-regulation system. The result of simulations and experiments show that this algorithm has better anti-load-disturbance performance than PID controller.

  6. Axial Permanent Magnet Generator for Wearable Energy Harvesting

    DEFF Research Database (Denmark)

    Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad

    2016-01-01

    An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable...... in order to reduce the rotor inertia and to reduce losses. Analytical models and finite element simulations were employed for the analyses of both generator types, and verified experimentally by prototypes. The results suggested that a generator of this size and power rating (20 mm radius, and 5 m...

  7. Modelling of Permanent Magnet Synchronous Motor Incorporating Core-loss

    Directory of Open Access Journals (Sweden)

    K. Suthamno

    2012-08-01

    Full Text Available This study proposes a dq-axis modelling of a Permanent Magnet Synchronous Motor (PMSM with copper-loss and core-loss taken into account. The proposed models can be applied to PMSM control and drive with loss minimization in simultaneous consideration. The study presents simulation results of direct drive of a PMSM under no-load and loaded conditions using the proposed models with MATLAB codes. Comparisons of the results are made among those obtained from using PSIM and SIMULINK software packages. The comparison results indicate very good agreement.

  8. A strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, K.

    1987-01-30

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles. 4 figs.

  9. Magnetization reversal processes of isotropic permanent magnets with various inter-grain exchange interactions

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We performed a large-scale micromagnetics simulation on a supercomputing system to investigate the properties of isotropic nanocrystalline permanent magnets consisting of cubic grains. In the simulation, we solved the Landau–Lifshitz–Gilbert equation under a periodic boundary condition for accurate calculation of the magnetization dynamics inside the nanocrystalline isotropic magnet. We reduced the inter-grain exchange interaction perpendicular and parallel to the external field independently. Propagation of the magnetization reversal process is inhibited by reducing the inter-grain exchange interaction perpendicular to the external field, and the coercivity is enhanced by this restraint. In contrast, when we reduce the inter-grain exchange interaction parallel to the external field, the coercivity decreases because the magnetization reversal process propagates owing to dipole interaction. These behaviors show that the coercivity of an isotropic permanent magnet depends on the direction of the inter-grain exchange interaction.

  10. A compact permanent magnet cyclotrino for accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Young, A.T.; Clark, D.J.; Kunkel, W.B.; Leung, K.N.; Li, C.Y. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    The authors describe the development of a new instrument for the detection of trace amounts of rare isotopes, a Cyclotron Mass Spectrometer (CMS). A compact low energy cyclotron optimized for high mass resolution has been designed and has been fabricated. The instrument has high sensitivity and is designed to measure carbon-14 at abundances of < 10{sup {minus}12}. A novel feature of the instrument is the use of permanent magnets to energize the iron poles of the cyclotron. The instrument uses axial injection, employing a spiral inflector. The instrument has been assembled and preliminary measurements of the magnetic field show that it has a uniformity on the order of 2 parts in 10{sup 4}.

  11. Plasma Diagnostic and Performance of a Permanent Magnet Hall Thruster

    CERN Document Server

    Ferreira, J L; Rego, I D S; Ferreira, I S; Ferreira, Jose Leonardo; Souza, Joao Henrique Campos De; Rego, Israel Da Silveira; Ferreira, Ivan Soares

    2004-01-01

    Electric propulsion is now a sucessfull method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Plasma Thruster, so called Hall Thruster or SPT (stationary plasma thruster) were primarily conceived in USSR (the ancient Soviet Union) and now it is been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work, we show plasma characteristics and performance of a Hall Thruster designed with an innovative concept which uses an array of permanent magnets, instead of an eletromagnet, to produce a radial magnetic field inside its cylindrical plasma drift channel. Within this new concept, we expect to develop a Hall Thruster within power consuption that will scale up to small and medium size satellites. A plasma density and temperature space profiles inside and outside the thruster channel will be shown. Space plasma potential, ion temperat...

  12. Torque analysis for double-stator permanent-magnet motor

    Institute of Scientific and Technical Information of China (English)

    柴凤; 程树康; 崔淑梅

    2002-01-01

    In addition to the characteristics of a conventional motor, a novel direct-drive double-stator perma-nent-magnet brushless motor proposed can operate in the state of either a generator or a motor as appropriate.Through numerical calculation and analysis, the output torque of double-stator permanent-magnet brushless motor of the same volume as the traditional machine is discussed, and the reduction of torque ripple by using the structure features of this motor is investigated. The results indicate that lower torque ripple under the condition of ideal effective torque can be obtained by the rational design of motor. The prototype motors tested show that this kind of motor structure has a higher power density.

  13. An improved iron loss estimation for permanent magnet brushless machines

    CERN Document Server

    Fang, D

    1999-01-01

    This paper presents an improved approach for predicting iron losses in permanent magnet brushless machines. The new approach is based on the fundamental concept that eddy current losses are proportional to the square of the time rate of change of flux density. Expressions are derived for predicting hysteresis and eddy current losses in the stator teeth and yoke. The so-called anomalous or excess losses, caused by the induced eddy current concentration around moving magnetic domain walls and neglected in the conventional core loss calculation, are also included in the proposed approach. In addition, the model is also capable of accounting for the stator skewing, if present. The core losses obtained from the proposed approach are compared with those measured on an existing PM motor at several operating speeds, showing very good agreement. (14 refs).

  14. Improvement of the levitation stability of the HTSC-permanent magnet hybrid bearing by using the new arrangement of the permanent magnet

    Science.gov (United States)

    Sukedaia, M.; Emoto, K.; Sugiyama, R.; Ohashi, S.

    The hybrid magnetic bearing using permanent magnets and the high temperature superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. Although the previous configuration improves the load weight of the rotor, levitation and guidance stability has been decreased because of the repulsive force of the permanent magnet. Three-dimensional numerical analysis of the system has been undertaken to reduce lateral force which decreases lateral stability of the rotor. From the results, effective arrangement of the hybrid system is given. Increment of the load weight is confirmed. Influence of the hybrid system on the pinning force between the HTSC and the permanent magnet is shown to be smaller than previous one.

  15. Results of using permanent magnets to suppress Josephson noise in the KAPPa SIS receiver

    Science.gov (United States)

    Wheeler, Caleb H.; Neric, Marko; Groppi, Christopher E.; Underhill, Matthew; Mani, Hamdi; Weinreb, Sander; Russell, Damon S.; Kooi, Jacob W.; Lichtenberger, Arthur W.; Walker, Christopher K.; Kulesa, Craig

    2016-07-01

    We present the results from the magnetic field generation within the Kilopixel Array Pathfinder Project (KAPPa) instrument. The KAPPa instrument is a terahertz heterodyne receiver using a Superconducting-Insulating- Superconducting (SIS) mixers. To improve performance, SIS mixers require a magnetic field to suppress Josephson noise. The KAPPa test receiver can house a tunable electromagnet used to optimize the applied magnetic field. The receiver is also capable of accommodating a permanent magnet that applies a fixed field. Our permanent magnet design uses off-the-shelf neodymium permanent magnets and then reshapes the magnetic field using machined steel concentrators. These concentrators allow the use of an unmachined permanent magnet in the back of the detector block while two small posts provide the required magnetic field across the SIS junction in the detector cavity. The KAPPa test receiver is uniquely suited to compare the permanent magnet and electromagnet receiver performance. The current work includes our design of a `U' shaped permanent magnet, the testing and calibration procedure for the permanent magnet, and the overall results of the performance comparison between the electromagnet and the permanent magnet counterpart.

  16. Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2016-03-01

    Full Text Available In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded.

  17. Improvement of the Levitation Characteristics in the Magnetic Bearing System Using HTSC-Permanent Magnet Hybrid Structure

    Science.gov (United States)

    Ohashi, Shunsuke

    Magnetic bearing using pining force of a permanent magnet and a high-temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pining force of the superconductor. The experimental device is developed. A ring type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. A bulk superconductor shows better characteristics both levitation and lateral stability than ring one. Levitation force of the hybrid system becomes about twice as large as that of the no-hybrid one. Although repulsive force of the permanent magnet decreases lateral stability of the system, its influence becomes small by choosing adequate position of the permanent magnets and the superconductor.

  18. Analysis and Design Optimization of a Coaxial Surface-Mounted Permanent-Magnet Magnetic Gear

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Wang, Chao

    2014-01-01

    This paper presents the analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear. The magnetic field distribution in the coaxial magnetic gear is calculated analytically in the polar coordinate system and then validated by the finite element method (FEM......) algorithm is employed to optimize the studied magnetic gear. Given that the torque capability and material cost conflict with each other, both of them are set as the optimization objectives in this paper. Different weight factors may be chosen for the two objectives so that more attention can be placed...

  19. Characteristics Analysis of Square Wave BLDC Motor Considering Magnetization Distribution of Permanent Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Byung Il; Park, Seung Chan [Hanyang University (Korea, Republic of); Im, Tae Bin [Korea Electronics Technology Institute (Korea, Republic of); Kang, Young Gyu [Samsung Electro-Mechanics R and D Center (Korea, Republic of)

    1998-04-01

    This paper deals with the characteristics analysis of a permanent magnet brushless DC(BLDC) motor. The analysis method is to utilize the time-stepped finite element method considering the square wave voltage of MOS FET inverter. The system matrix that unknown parameters are magnetic vector potentials at nodes and phases currents is constructed through the finite element formulation and circuit equations, and then solved by bi-conjugate gradient(BCG) method. The analyzed model has a inner rotor which is consisted of a permanent magnet of ring shape and a laminated steel core. The current carrying free-wheeling diode of inverter is neglected because of low value of the winding inductance of motor. The magnetization distribution in the permanent magnet i determined by solving inverse problem that the calculated flux densities values on the surface of the permanent magnet are led to the same values that measured by gauss meter. And then, torque and phase currents, which are calculated by finite element analysis are compared with experimental values. (author). 12 refs., 17 figs., 2 tabs.

  20. Magnetic properties of Nd-Fe-B magnets sintered using granulated powders by spray drying method. 3; Spray zoryufun wo mochiita Nd-Fe-B shoketsu jishaku no jiki tokusei. 3

    Energy Technology Data Exchange (ETDEWEB)

    Kishimoto, Y. [Sumitomo Metal Industries Ltd., Osaka (Japan); Yamashita, O. [Sumitomo Special Metals Co. Ltd., Osaka (Japan)

    1997-08-15

    Using two kinds of polymers with different tensile strengths and plasticizer as binders for the spray drying method of Nd2Fe14B rare earth system alloy powder, the relation between binder composition and powder characteristics or sintered magnet characteristics was studied. The binder polymers with high tensile strength improved the binding strength between alloy powders, and formed the secondary grain powder with a flowability superior in granulation. An increase in residual carbon was controlled to 200-300ppm by decarbonization at 673K for 0.5h. Reduction of an oxygen content in granulated powders was important for improving magnet characteristics. Magnet characteristics of sintered bodies were largely dependent on the amount of added plasticizer. The higher flexibility of binders due to addition of more amount of plasticizer reduced the binding strength between alloy powders and slightly reduced the flowability, however, improved magnet characteristics. The binder composed of PVA of 0.2wt% and plasticizer (glycerine) of 0.09wt% was most suitable. 4 refs., 7 figs., 1 tab.

  1. Effect of Hot-deformed Temperature on Magnetic Properties of Nanograin Nd-Fe-B Magnets%热变形温度对纳米晶Nd-Fe-B磁体性能的影响

    Institute of Scientific and Technical Information of China (English)

    赖彬; 刘国军; 王会杰; 潘伟; 朱明刚

    2011-01-01

    为了研究纳米晶Nd-Fe-B磁体的热变形机理,在不同温度下对快淬粉进行热压热变形处理.通过分析不同温度下热变形过程中应力和磁体应变的变化,以及磁性能和SEM测试,研究了温度对热变形磁体性能和微观结构的影响,分析了热变形过程的热变形机理.结果表明,纳米晶磁体存在最佳的热压温度和热变形温度.当热压温度为550℃,热变形温度为850℃,磁体的剩磁和磁能积最大值,分别为1.343 T和344.7kJ/m3.纳米晶Nd-Fe-B磁体的热变形过程塑变应力和温度的关系满足:ln σ∝1/T.%Full dense anisotropic magnets are prepared from commercial MQ powders by hot-pressing and subsequent hot deformation with different temperature in order to study the hot-deformation mechanism of nanograin Nd-Fe-B magnets. Effect of temperature during hot-pressing and hot deformation process on magnetic properties and microstructure of Nd-Fe-B magnets is investigated by magnetic measurement and scanning electron microscopy (SEM).The mechanism of hot deformation is studied by analyzing the values of stresses and strains recorded during hot deformation process. The largest remanence (Br = 1. 343 T ) and maximum energy product ( (BH)max = 344. 7 kJ/m3)are obtained with the hot-pressing temperature 550 ℃ and hot deformation temperature 850 ℃. In the hot deformation process the relationship of stresses and temperature satisfies this equation: 1nσ ∝ 1/T

  2. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic fiel

  3. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  4. Experimental Investigation and Thermodynamic Modeling of the B2O3-FeO-Fe2O3-Nd2O3 System for Recycling of NdFeB Magnet Scrap

    Science.gov (United States)

    Jakobsson, Lars Klemet; Tranell, Gabriella; Jung, In-Ho

    2016-07-01

    NdFeB magnet scrap is an alternative source of neodymium that could have a significantly lower impact on the environment than current mining and extraction processes. Neodymium can be readily oxidized in the presence of oxygen, which makes it easy to recover neodymium in oxide form. Thermochemical data and phase diagrams for neodymium oxide containing systems is, however, very limited. Thermodynamic modeling of the B2O3-FeO-Fe2O3-Nd2O3 system was hence performed to obtain accurate phase diagrams and thermochemical properties of the system. Key phase diagram experiments were also carried out for the FeO-Nd2O3 system in saturation with iron to improve the accuracy of the present modeling. The modified quasichemical model was used to describe the Gibbs energy of the liquid oxide phase. The Gibbs energy functions of the liquid phase and the solids were optimized to reproduce all available and reliable phase diagram data, and thermochemical properties of the system. Finally the optimized database was applied to calculate conditions for selective oxidation of neodymium from NdFeB magnet waste.

  5. Experimental Investigation and Thermodynamic Modeling of the B2O3-FeO-Fe2O3-Nd2O3 System for Recycling of NdFeB Magnet Scrap

    Science.gov (United States)

    Jakobsson, Lars Klemet; Tranell, Gabriella; Jung, In-Ho

    2017-02-01

    NdFeB magnet scrap is an alternative source of neodymium that could have a significantly lower impact on the environment than current mining and extraction processes. Neodymium can be readily oxidized in the presence of oxygen, which makes it easy to recover neodymium in oxide form. Thermochemical data and phase diagrams for neodymium oxide containing systems is, however, very limited. Thermodynamic modeling of the B2O3-FeO-Fe2O3-Nd2O3 system was hence performed to obtain accurate phase diagrams and thermochemical properties of the system. Key phase diagram experiments were also carried out for the FeO-Nd2O3 system in saturation with iron to improve the accuracy of the present modeling. The modified quasichemical model was used to describe the Gibbs energy of the liquid oxide phase. The Gibbs energy functions of the liquid phase and the solids were optimized to reproduce all available and reliable phase diagram data, and thermochemical properties of the system. Finally the optimized database was applied to calculate conditions for selective oxidation of neodymium from NdFeB magnet waste.

  6. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Y.; Sukedai, M. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetic bearing has been developed. In the hybrid system, effect of the pinning force becomes smaller. Influence of the vibration and the gradient angle in the resonance state is large. The resonance frequency becomes small in the hybrid bearing system. The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  7. Motor Integrated Permanent Magnet Gear with a Wide Torque-Speed Range

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Matzen, Torben N.; Jahns, T. M.

    2009-01-01

    This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process of t...... may be useful as a direct drive wheel motor for EV's and no liquid cooling system is required....

  8. Accelerated Testing of High Temperature Permanent Magnets for Spacecraft Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High temperature permanent magnet materials play an important role in NASA's space missions in electric propulsion, energy generation and storage and other...

  9. Influence of NdFeB Fillers on Tensile and Electromagnetic Properties of Natural Rubber

    Directory of Open Access Journals (Sweden)

    Puripat LERTSURAWAT

    2009-06-01

    Full Text Available Tensile and electromagnetic properties of hard magnetic natural rubber composites were studied. In a fabrication stage, neodymium-iron-boron (NdFeB magnets were recycled from electronic wastes, broken and then ball-milled for 1 - 3 h. The NdFeB powder was then incorporated into natural rubber (NR by a 2-roll mill technique. Since the NdFeB powder behaved as a non-reinforced filler, thus, it inhibited cross-linking and stress-induced recrystallization. Therefore, the cure time and the tensile strength of the NdFeB-NR composites were reduced compared to the control sample without magnetic fillers. The addition of NdFeB fillers improved the electrical permittivity of NR and the magnetic moment in NdFeB-NR composites could be measured by a fluxmeter.

  10. Recycling as a strategy against rare earth element criticality: a systemic evaluation of the potential yield of NdFeB magnet recycling.

    Science.gov (United States)

    Rademaker, Jelle H; Kleijn, René; Yang, Yongxiang

    2013-09-17

    End-of-life recycling is promoted by OECD countries as a promising strategy in the current global supply crisis surrounding rare earth elements (REEs) so that dependence on China, the dominant supplier, can be decreased. So far the feasibility and potential yield of REE recycling has not been systematically evaluated. This paper estimates the annual waste flows of neodymium and dysprosium from permanent magnets, the main deployment of these critical REEs, during the 2011-2030 period. The estimates focus on three key permanent magnet waste flows: wind turbines, hybrid and electric vehicles, and hard disk drives (HDDs) in personal computers (PCs). This is a good indication of the end-of-life recycling of neodymium and dysprosium maximum potential yield. Results show that for some time to come, waste flows from permanent magnets will remain small relative to the rapidly growing global REE demand. Policymakers therefore need to be aware that during the next decade recycling is unlikely to substantially contribute to global REE supply security. In the long term, waste flows will increase sharply and will meet a substantial part of the total demand for these metals. Future REE recycling efforts should, therefore, focus on the development of recycling technology and infrastructure.

  11. A simple, small and low cost permanent magnet design to produce homogeneous magnetic fields.

    Science.gov (United States)

    Manz, B; Benecke, M; Volke, F

    2008-05-01

    A new portable, pocket-size NMR probe based on a novel permanent magnet arrangement is presented. It is based on a Halbach-type magnet design which mimics the field of a spherical dipole by using cylindrical bar and ring magnets. The magnet system is made up of only three individual magnets, and most field calculations and optimisations can be performed analytically. A prototype system has been built using a set of small, off the shelf commercially available permanent magnets. Proton linewidths of 50 ppm FWHM could be achieved at a field strength of 1T. Calculations show that with custom-sized permanent magnets, linewidths of less than 1 ppm can be achieved over sample volumes of up to 1 mm3, which would in theory enable chemical shift resolved proton spectroscopy on mass-limited samples. But even with the achieved linewidth of 50 ppm, this can be a useful portable sensor for small amounts of liquid samples with restricted molecular mobility, like gels, polymers or high viscosity liquids.

  12. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Science.gov (United States)

    Morii, Y.; Sukedai, M.; Ohashi, S.

    2011-11-01

    The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  13. Basic Characteristics of the Propulsion System in the Permanent Magnet-HTSC Hybrid Magnetic Conveyance System

    Science.gov (United States)

    Ohashi, Shunsuke; Kumano, Daiki; Goto, Yasuyuki

    The Hybrid magnetically levitated transportation system has been developed. The magnetic rail is set on the ground, and the carrier with permanent magnets and high-Tc superconductors (HTSC) levitates on the rail. Repulsive force of permanent magnet is introduced to support load weight. Pinning force of the HTSC is used to support weight of the frame of the carrier and to achieve lateral stability of the carrier. In this paper, propulsion system of the conveyance system is studied. Propulsion function is installed on the carrier body. Magnetic gradient is used to get propulsion force. Propulsion force of the system is little. So propulsion rail system is introduced. Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Enough propulsion force is given. Influence of the propulsion system on the levitation and guidance system is measured. Stability of levitation and guidance system is enough even when propulsion system is operated.

  14. Innovative Sensors for Pipeline Crawlers: Rotating Permanent Magnet Inspection

    Energy Technology Data Exchange (ETDEWEB)

    J. Bruce Nestleroth; Richard J. Davis; Stephanie Flamberg

    2006-09-30

    Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. Current inspection systems that are propelled through the pipeline by the product flow cannot be used to inspect all pipelines because of the various physical barriers they may encounter. To facilitate inspection of these ''unpiggable'' pipelines, recent inspection development efforts have focused on a new generation of powered inspection platforms that are able to crawl slowly inside a pipeline and can maneuver past the physical barriers that limit internal inspection applicability, such as bore restrictions, low product flow rate, and low pressure. The first step in this research was to review existing inspection technologies for applicability and compatibility with crawler systems. Most existing inspection technologies, including magnetic flux leakage and ultrasonic methods, had significant implementation limitations including mass, physical size, inspection energy coupling requirements and technology maturity. The remote field technique was the most promising but power consumption was high and anomaly signals were low requiring sensitive detectors and electronics. After reviewing each inspection technology, it was decided to investigate the potential for a new inspection method. The new inspection method takes advantage of advances in permanent magnet strength, along with their wide availability and low cost. Called rotating permanent magnet inspection (RPMI), this patent pending technology employs pairs of permanent magnets rotating around the central axis of a cylinder to induce high current densities in the material under inspection. Anomalies and wall thickness variations are detected with an array of sensors that measure local changes in the magnetic field produced by the induced current flowing in the material. This inspection method is an alternative to the common concentric coil remote field technique that induces

  15. Phase Formation and Magnetic Properties of Nanocomposite Nd-Fe-B Adjusted by Small Amount of Dy and Co

    Institute of Scientific and Technical Information of China (English)

    T S Jang; T W Lim; H S Aum; D H Lee; M B Kim

    2004-01-01

    In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14B/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84B7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14B was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3B was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3B was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14B in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14B. Moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14B in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ~ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ~ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5B7 alloy annealed for 12 min at 725 ℃were iHc=4.85 kOe, Br= 11.32 kG, (BH)max = 15.73 MGOe, and mr=0.73.

  16. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three......-phase radial-flux PM synchronous generator with a back-to-back power converter is presented. The design optimization is adopted with a genetic algorithm forminimizing generator system cost. To demonstrate the effectiveness of the developed electromagnetic design model, the optimization results of a 500-k......W direct-drive PM generator and a 1.5-MW multibrid PM generator with various gear ratios are, respectively, compared with those from other methods. Then, the optimal design approach is further employed for a range from 750 kW up to 10 MW. The optimization results of PM generator systems including direct...

  17. A double-sided linear primary permanent magnet vernier machine.

    Science.gov (United States)

    Du, Yi; Zou, Chunhua; Liu, Xianxing

    2015-01-01

    The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM) vernier (DSLPPMV) machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed.

  18. Zeeman slowers for strontium based on permanent magnets

    Science.gov (United States)

    Hill, Ian R.; Ovchinnikov, Yuri B.; Bridge, Elizabeth M.; Curtis, E. Anne; Gill, Patrick

    2014-04-01

    We present the design, construction, and characterization of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimized for operation with deceleration related to the local laser intensity (by the parameter ɛ), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to ≈18% are realized and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to space-borne application. For 88Sr we achieve a slow-atom flux of around 6 × 109 atoms s-1 at 30 ms-1, loading approximately 5 × 108 atoms in to a magneto-optical-trap, and capture all isotopes in approximate relative natural abundances.

  19. Zeeman Slowers for Strontium based on Permanent Magnets

    CERN Document Server

    Hill, Ian R; Bridge, Elizabeth M; Curtis, E Anne; Gill, Patrick

    2014-01-01

    We present the design, construction, and characterisation of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimised for operation with deceleration related to the local laser intensity (by the parameter $\\epsilon$), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to $\\approx$ $18$ $%$ are realised and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to spaceborne application. For $^{88}$Sr we achieve a slow-atom flux of around $6\\times 10^9$ atoms$\\,$s$^{-1}$ at $30$ ms$^{-1}$, loading approximately $5\\times 10^8$ atoms in to a magneto-optical-trap (MOT), and capture all isotopes in approximate relative natural abundances.

  20. A Double-Sided Linear Primary Permanent Magnet Vernier Machine

    Directory of Open Access Journals (Sweden)

    Yi Du

    2015-01-01

    Full Text Available The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM vernier (DSLPPMV machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed.

  1. Economic viability, applications and limits of efficient permanent magnet motors - Summary and update; Wirtschaftlichkeit, Anwendungen und Grenzen von effizienten Permanent-Magnet-Motoren - Zusammenfassung und Update - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [Hochschule Westschweiz, Delemont (Switzerland); Salathe, D. [Hochschule Luzern Technik und Architektur, Horw (Switzerland)

    2009-06-15

    This final report for the Swiss Federal Office of Energy (SFOE), takes a look at the economic viability, applications and limits of efficient permanent magnet motors. Permanent magnet motors are compared with standard IEC asynchronous motors. In a theoretical part of the report, it is discussed how the increasing size of the motor influences efficiency, weight, volume and power. The results of practical tests carried out on six motors are presented. Three standard motors with varying efficiency were compared with three permanent-magnet motors for the power range around 3 kW. Market-oriented considerations concerning permanent-magnet motors are discussed. Operational criteria for the choice of the type of motor to be used are also examined.

  2. Computing the External Magnetic Scalar Potential due to an Unbalanced Six-Pole Permanent Magnet Motor

    Energy Technology Data Exchange (ETDEWEB)

    Selvaggi J, Salon S, Kwon O, Chari MVK

    2007-02-12

    The accurate computation of the external magnetic field from a permanent magnet motor is accomplished by first computing its magnetic scalar potential. In order to find a solution which is valid for any arbitrary point external to the motor, a number of proven methods have been employed. Firstly, A finite element model is developed which helps generate magnetic scalar potential values valid for points close to and outside the motor. Secondly, charge simulation is employed which generates an equivalent magnetic charge matrix. Finally, an equivalent multipole expansion is developed through the application of a toroidal harmonic expansion. This expansion yields the harmonic components of the external magnetic scalar potential which can be used to compute the magnetic field at any point outside the motor.

  3. Design and Maxwell 3D simulation of small permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    Zhang Guangcai; Xu Yajie; Chang Yan; Chen Qiaoyan; Yang Xiaodong

    2014-01-01

    According to the magnetic circuit design theory and performance requirements of magnetic field, an H-type permanent magnetic actuator that generates uniform magnetic field larger than 0.4 T in the interested re- gion has been designed in this paper. The static magnetic field simulation analysis was done by Ansoft' s Max- well three-dimensional (3D) software. The simulation results showed that the magnetic field of this system can meet the requirements, and this permanent magnetic actuator designed in this paper can be used in small nuclear magnetic resonance (NMR) svstem.

  4. Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field

    Science.gov (United States)

    Huber, C.; Abert, C.; Bruckner, F.; Pfaff, C.; Kriwet, J.; Groenefeld, M.; Teliban, I.; Vogler, C.; Suess, D.

    2017-08-01

    Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.

  5. The study, design and testing of a linear oscillating generator with moving permanent magnets

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros (Pop

    2015-12-01

    Full Text Available This paper presents a study, design and testing of a Linear Oscillating Generator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally it has been shown the comparative analysis between the linear oscillating generator with moving permanent magnets in no load operation and load operation.

  6. Analysis of a Permanent-Magnet Brushless DC Motor with Fixed Dimensions

    Science.gov (United States)

    Brakanskis, Uldis; Dirba, Janis; Kukjane, Ludmila; Drava, Viesturs

    2010-01-01

    The purpose of this paper is to describe the analysis of a permanent-magnet brushless DC motor with fixed outer diameter and active zone length. The influence of air gap, material of permanent magnets and their size on the magnetic flux density of the machine and magnetic flux is analyzed. The work presents the calculations of two programs, the comparison of the results and the most suitable combination of factors that has been found.

  7. Analytical Calculation of the Magnetic Field distribution in a Flux-Modulated Permanent-Magnet Brushless Motor

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Chen, Zhe

    2015-01-01

    This paper presents a rapid approach to compute the magnetic field distribution in a flux-modulated permanent-magnet brushless motor. Partial differential equations are used to describe the magnet field behavior in terms of magnetic vector potentials. The whole computational domain is divided int...... magnetic field with those calculated by finite element method....

  8. Levitation and Guidance Characteristics of the Permanent magnet-HTSC Hybrid Magnetic Conveyance System

    Science.gov (United States)

    Ohashi, Shunsuke; Dodo, Daiki

    Hybrid magnetically levitated transportation system has been developed. The magnetic rail is set on the ground, and the carrier with permanent magnets and high-Tc superconductors (HTSC) levitates on the rail. In this system, pinning force of HTSC and repulsive force of permanent magnet is combined. Repulsive force of permanent magnet is introduced to support weight. Pinning force is used to support weight of the frame of the carrier and to achieve lateral stability of the carrier. To decrease influence of weight on the levitation gap of the carrier, the weight stage is fixed to the carrier frame by linear sliders, and moves freely for vertical direction. As a result, there is little influence on levitation gap of the carrier. Basic levitation and guidance characteristics of the system are shown. Repulsive force generates very large levitation force. It also generates unstable lateral force. Weight added to the carrier has some influence on lateral stability. Although lateral position recovery force by pinning effect decreases at a heavier weight, the carrier shows enough force to keep lateral stability.

  9. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  10. Influence of End-Effects on Static Torque Performance of Misaligned Cylindrical Permanent Magnet Couplings

    DEFF Research Database (Denmark)

    Högberg, Stig; Hansen, Hilary; Jensen, Bogi Bech;

    2014-01-01

    Permanent magnet couplings are widely used in applications requiring torque to be transmitted through an air- gap. The aim of this study is to observe and explain the effect of radial and axial misalignment in a 12-pole, cylindrical permanent magnet coupling. Pull-out torque was measured for two...

  11. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a d

  12. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a

  13. Optimal Design of Stator Interior Permanent Magnet Machine with Minimized Cogging Torque for Wind Power Application

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, Ming

    2008-01-01

    This paper proposes a new approach to minimize the cogging torque of a stator interior permanent magnet (SIPM) machine. The optimization of stator slot gap and permanent magnet is carried out and the cogging torque ripple is analyzed by using finite element analysis. Experiments on a prototype...

  14. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T., E-mail: tsubasa@oshima-k.ac.jp; Wada, H.; Furuse, M. [National Institute of Technology, Oshima College, 1091-1 Komatsu, Suouoshima, Oshima, Yamaguchi 742-2193 (Japan); Asaji, T. [National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630 (Japan)

    2016-02-15

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar{sup 4+} ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  15. Magnetized sheath near positively biased wall between two permanent magnetic plates

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Wei, Zi-an; Ma, J. X., E-mail: jxma@ustc.edu.cn; Jiang, Zheng-qi; Wu, Fei [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Key Laboratory of Geospace Environment, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-06-15

    The characteristics of magnetized electron sheath near a positively biased conducting wall parallel to magnetic field formed between two permanent magnetic plates were experimentally investigated in a double plasma device. The magnetic field strength between the magnetic plates is about 1200 G which is sufficient to magnetize the plasma such that the ion gyroradius is comparable to the electron Debye length. A virtual cathode (or potential dip) structure was found between the electron-rich sheath and bulk plasma. For a given neutral gas pressure, the potential minimum (dip position) remains almost the same for different positive biases on the wall. For a given bias on the wall, however, the electron sheath thickness and the potential drop from the bulk plasma to the dip decrease with the increase of the neutral gas pressure. In addition, the electron sheath and potential dip appear to be wider and deeper in the downstream side of the wall.

  16. Specification Requirement for Thermal Stability of Sintered NdFeB Materials for Electrical Machines

    Institute of Scientific and Technical Information of China (English)

    Lin Yan; Jiang Daiwei; Chen Lixiang; Chen Hailing; Bi Haitao; Tang Renyuan

    2004-01-01

    Based on IEC standards and Chinese national standards of sintered NdFeB materials, in the paper the hightemperature, room-temperature properties and thermal stability of about one hundred samples of NdFeB materials for electrical machines were measured and analyzed.These materials are produced by ten representative manufactories in China.Combined with the analysis results, the paper points out that the magnetic properties of sintered NdFeB materials for electrical machines should meet not only the specific values in standards, such as Br, (BH)max ,HcJ ,but also the requirement of temperature coefficients a (Br) , a (HcJ).

  17. First Ever Storage of Ultracold Neutrons in a Magnetic Trap Made of Permanent Magnets.

    Science.gov (United States)

    Ezhov, V F; Andreev, A Z; Glushkov, A A; Glushkov, A G; Groshev, M N; Knyazkov, V A; Krygin, G B; Ryabov, V L; Serebrov, A P; Bazarov, B A; Geltenbort, P; Hartman, F J; Paul, S; Picker, R; Zimmer, O; Kovrizhnykh, N A

    2005-01-01

    Further improvement in the accuracy of any neutron lifetime experiment by means of ultracold neutrons (UCN) in material bottles is limited due to unavoidable systematic effects when the UCN are reflected from the walls. However, such effects can be excluded in principle if magnetic trapping of UCN is used. The storage of UCN in a small magnetic trap made of permanent magnets was demonstrated for the first time ever. The measured storage time in this feasibility study was (882 ± 16) s. At this level of accuracy no depolarization was observed.

  18. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  19. Large-Area Permanent-Magnet ECR Plasma Source

    Science.gov (United States)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired because it is associated with erosion and contamination. The electron temperature is low and does not vary appreciably with power.

  20. High-gradient permanent magnet apparatus and its use in particle collection

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Mengdawn; Ludtka, Gerard Michael; Avens, Larry R.

    2016-07-12

    A high-gradient permanent magnet apparatus for capturing paramagnetic particles, the apparatus comprising: (i) at least two permanent magnets positioned with like poles facing each other; (ii) a ferromagnetic spacer separating the like poles; and (iii) a magnetizable porous filling material in close proximity to the at least two permanent magnets. Also described is a method for capturing paramagnetic particles in which a gas or liquid sample containing the paramagnetic particles is contacted with the high-gradient permanent magnet apparatus described above; wherein, during the contacting step, the gas or liquid sample contacts the magnetizable porous filling material of the high-gradient permanent magnet apparatus, and at least a portion of the paramagnetic particles in the gas or liquid sample is captured on the magnetizable porous filling material.

  1. Passive control of Permanent Magnet Synchronous Motor chaotic system based on state observer

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Qiao

    2006-01-01

    Passive system theory was applied to propose a new passive control method with nonlinear observer of the Permanent Magnet Synchronous Motor chaotic system. Through constructing a Lyapunov function, the subsystem of the Permanent Magnet Synchronous Motor chaotic system could be proved to be globally stable at the equilibrium point. Then a controller with smooth state feedback is designed so that the Permanent Magnet Synchronous Motor chaotic system can be equivalent to a passive system.To get the state variables of the controller, the nonlinear observer is also studied. It is found that the outputs of the nonlinear observer can approximate the state variables of the Permanent Magnet Synchronous Motor chaotic system if the system's nonlinear function is a globally Lipschitz function. Simulation results showed that the equivalent passive system of Permanent Magnet Synchronous Motor chaotic system could be globally asymptotically stabilized by smooth state feedback in the observed parameter convergence condition area.

  2. Processing of alnico permanent magnets by advanced directional solidification methods

    Science.gov (United States)

    Zou, Min; Johnson, Francis; Zhang, Wanming; Zhao, Qi; Rutkowski, Stephen F.; Zhou, Lin; Kramer, Matthew J.

    2016-12-01

    Advanced directional solidification methods have been used to produce large (>15 cm length) castings of Alnico permanent magnets with highly oriented columnar microstructures. In combination with subsequent thermomagnetic and draw thermal treatment, this method was used to enable the high coercivity, high-Titanium Alnico composition of 39% Co, 29.5% Fe, 14% Ni, 7.5% Ti, 7% Al, 3% Cu (wt%) to have an intrinsic coercivity (Hci) of 2.0 kOe, a remanence (Br) of 10.2 kG, and an energy product (BH)max of 10.9 MGOe. These properties compare favorably to typical properties for the commercial Alnico 9. Directional solidification of higher Ti compositions yielded anisotropic columnar grained microstructures if high heat extraction rates through the mold surface of at least 200 kW/m2 were attained. This was achieved through the use of a thin walled (5 mm thick) high thermal conductivity SiC shell mold extracted from a molten Sn bath at a withdrawal rate of at least 200 mm/h. However, higher Ti compositions did not result in further increases in magnet performance. Images of the microstructures collected by scanning electron microscopy (SEM) reveal a majority α phase with inclusions of secondary αγ phase. Transmission electron microscopy (TEM) reveals that the α phase has a spinodally decomposed microstructure of FeCo-rich needles in a NiAl-rich matrix. In the 7.5% Ti composition the diameter distribution of the FeCo needles was bimodal with the majority having diameters of approximately 50 nm with a small fraction having diameters of approximately 10 nm. The needles formed a mosaic pattern and were elongated along one crystal direction (parallel to the field used during magnetic annealing). Cu precipitates were observed between the needles. Regions of abnormal spinodal morphology appeared to correlate with secondary phase precipitates. The presence of these abnormalities did not prevent the material from displaying superior magnetic properties in the 7.5% Ti composition

  3. Analysis and Design Optimization of a Coaxial Surface-Mounted Permanent-Magnet Magnetic Gear

    Directory of Open Access Journals (Sweden)

    Xiaoxu Zhang

    2014-12-01

    Full Text Available This paper presents the analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear. The magnetic field distribution in the coaxial magnetic gear is calculated analytically in the polar coordinate system and then validated by the finite element method (FEM. The analytical field solution allows the prediction of the magnetic torque, which is formulated as a function of design parameters. The impacts of key design parameters on the torque capability are then studied and some significant observations are summarized. Furthermore, the particle swarm optimization (PSO algorithm is employed to optimize the studied magnetic gear. Given that the torque capability and material cost conflict with each other, both of them are set as the optimization objectives in this paper. Different weight factors may be chosen for the two objectives so that more attention can be placed on one or another. The results shows that the highest torque density of 157 kNm/m3 is achieved with the consideration focusing on the torque capability only, then the highest torque per permanent magnet (PM consumption could be improved to 145 Nm/kg by taking the material cost into account. By synthesizing the torque capability and material cost, a 124 kNm/m3 of torque density and a 128 Nm/kg of torque per PM consumption could be achieved simultaneously by the optimal design.

  4. Nb含量对烧结NdFeB永磁体磁性能及显微结构的影响%INVESTIGATIONS ON THE MAGNETIC PROPERTIES AND MICROSTRUCTURES OF SINTERED NdFeB MAGNETS WITH DIFFERENT Nb ADDITIONS

    Institute of Scientific and Technical Information of China (English)

    成问好; 李卫; 李传健

    2001-01-01

    对Nd33.0Fe65.9-xNbxB1.1(wt%,x=0,0.3,0.6,1.0,1.5,2.0)系列烧结永磁体的磁性能、组织形貌以及磁性能与组织形貌间的关系进行了系统研究.研究发现,不含Nb的NdFeB磁体晶粒的大小、形状差异非常大.这种结构使NdFeB磁体的磁性能恶化.添加一定量的Nb元素后,磁体的组织结构变得均匀一致.当Nb含量小于1.0时磁体矫顽力、剩磁、磁能积均比相应不含Nb的磁体高.其原因是Nb使NdFeB磁体的晶粒变得均匀一致,密度提高.Nb对NdFeB磁体的绝大部分磁性能的影响均与Nb使NdFeB磁体的晶粒得到均匀化有关.%The magnetic properties and microstructures of a series of sintered magnets Nd33.0Fe65.9-xNbxB1.1(wt%,x=0,0.3,0.6,1.0,1.5,2.0) as well as their relations were investigated in detail. It was found that the grain size of NdFeB magnet without Nb addition was quiet different from each other and the shape of the grains was very irregular, which led to the deterioration of the magnetic properties. The microstructures of the magnets with proper Nb addition became homogeneous and the final size of the grain after annealing was very fine, and, correspondingly, the density of the final magnet was increased to a higher level. Magnetic measurements showed that the coercivity iHc, magnetic remanence Br and energy product (BH)max of the magnet with Nb additions below 1.0wt% were generally higher than those of their Nb-free counterparts. The effect of Nb on the magnetic properties originated mainly from the homogenization of the microstructure due to Nb addition.

  5. Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

    Directory of Open Access Journals (Sweden)

    Michael W Vogel

    Full Text Available We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability.The finite element method (COMSOL® was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field.A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres.A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR and magnetic resonance imaging (MRI instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

  6. High Temperature, Permanent Magnet Biased, Fault Tolerant, Homopolar Magnetic Bearing Development

    Science.gov (United States)

    Palazzolo, Alan; Tucker, Randall; Kenny, Andrew; Kang, Kyung-Dae; Ghandi, Varun; Liu, Jinfang; Choi, Heeju; Provenza, Andrew

    2008-01-01

    This paper summarizes the development of a magnetic bearing designed to operate at 1,000 F. A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1,000 F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces with over one-half of the coils failed. The construction and design methodology of the bearing is outlined and test results are shown. The agreement between a 3D finite element, magnetic field based prediction for force is shown to be in good agreement with predictions at room and high temperature. A 5 axis test rig will be complete soon to provide a means to test the magnetic bearings at high temperature and speed.

  7. Electromagnetic Flux Analysis of Permanent Magnet Brushless DC Motor Using Magnet Software

    Directory of Open Access Journals (Sweden)

    G.R.Puttalakshmi

    2013-08-01

    Full Text Available Permanent Magnet Brushless DC (PMBLDC motors is emerging as a suitable motor for a number of drive applications in industrial and consumer products. Cogging torque is one of the important drawbacks of PMBLDC motor which results in shaft vibrations and noise. The focus of this work is to minimize the electromagnetic flux and cogging torque in PMBLDC by introducing structural design modifications. The performance of the machine is analyzed by varying the magnet pole shape, magnet pole width and by using magnetic material with different remenance value. For analyzing the performance of the machine, machine is modeled using Finite Element Analysis (FEA based software package Magnet. Cogging torque and average torque are taken as performance measures to determineoptimum pole shape and pole width.

  8. Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets.

    Science.gov (United States)

    Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi

    2016-11-29

    We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual magnets damaged by radiation. We show that the estimated flux-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the magnetization reversal and quantify the flux loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.

  9. Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets

    Science.gov (United States)

    Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi

    2016-11-01

    We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual magnets damaged by radiation. We show that the estimated flux-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the magnetization reversal and quantify the flux loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.

  10. A few simple classroom experiments with a permanent U-shaped magnet

    Science.gov (United States)

    Babović, Miloš; Babović, Vukota

    2017-01-01

    A few simple experiments in the magnetic field of a permanent U-shaped magnet are described. Among them, pin oscillations inside the magnet are particularly interesting. These easy to perform and amusing measurements can help pupils understand magnetic phenomena and mutually connect knowledge of various physics branches.

  11. Optimal current waveforms for brushless permanent magnet motors

    Science.gov (United States)

    Moehle, Nicholas; Boyd, Stephen

    2015-07-01

    In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.

  12. Permanent Magnet Synchronous Condenser with Solid State Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Ping; Muljadi, Eduard; Wu, Ziping; Gao, Wenzhong

    2015-10-05

    A synchronous condenser consists of a free-spinning wound-field synchronous generator and a field excitation controller. In this paper, we propose a synchronous generator that employs a permanent magnet synchronous generator (PMSG) instead of a wound-field machine. PMSGs have the advantages of higher efficiency and reliability. In the proposed configuration, the reactive power control is achieved by a voltage source converter connected in series with the PMSG and the grid. The converter varies the phase voltage of the PMSG so as to create the same effect of over or under excitation in a wound-field machine. The converter output voltage level controls the amount and the direction of the produced reactive power and the voltage's phase is kept in-phase with the grid voltage except a slight phase can be introduced so that some power can be drawn from the grid for maintaining the DC bus voltage level of the converter. Since the output voltage of the converter is only a fraction of the line voltage, its VA rating is only a fraction of the rating of the PMSG. The proposed scheme is shown to be effective by computer simulation.

  13. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  14. Thermal analysis of high speed permanent magnetic generator

    Institute of Scientific and Technical Information of China (English)

    LI WeiLi; ZHANG XiaoChen; CHENG ShuKang; CAO JunCi; ZHANG YiHuang

    2012-01-01

    High-speed permanent magnetic generators (HSPMG) are common and important power generation equipments used in distributed generation systems.A 100 kW level HSPMG is investigated in this paper,and it is fluid-thermal coupling analyzed.The transient 2D electromagnetic field while machine is under rated operating is analyzed by using the time-stepping FEM,from which the electromagnetic performances and the loss distributions are obtained.Then,an analysis model for fluid-solid temperature field analysis is established.Taking losses as the distributed heat sources,the 3D thermal field is coupling calculated.The variations of heat transfer coefficient and temperature of fluid in stator grooves along the axial direction,as well as the whole region 3D temperature distribution in HSPMG are obtained.Then,considering the variations of heat sources distributions and heat transfer conditions,3D temperature fields of HSPMG operating under different speeds are calculated,and the influences of machine operating speed on the HSPMG thermal performance are studied,based on which,the functions of machine temperature with operating speed and stator windings resistance are proposed.The obtained conclusions may provide a useful reference for the design and research of HSPMG.

  15. Characterization of the ELIMED prototype permanent magnet quadrupole system

    Science.gov (United States)

    Russo, A. D.; Schillaci, F.; Pommarel, L.; Romano, F.; Amato, A.; Amico, A. G.; Calanna, A.; Cirrone, G. A. P.; Costa, M.; Cuttone, G.; Amato, C.; De Luca, G.; Flacco, F. A.; Gallo, G.; Giove, D.; Grmek, A.; La Rosa, G.; Leanza, R.; Maggiore, M.; Malka, V.; Milluzzo, G.; Petringa, G.; Pipek, J.; Scuderi, V.; Vauzour, B.; Zappalà, E.

    2017-01-01

    The system described in this work is meant to be a prototype of a more performing one that will be installed at ELI-Beamlines in Prague for the collection of ions produced after the interaction Laser-target, [1]. It has been realized by the researchers of INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) and SIGMAPHI, a French company, using a system of Permanent Magnet Quadrupoles (PMQs), [2]. The final system that will be installed in Prague is designed for protons and carbons up to 60 MeV/u, around 10 times more than the energies involved in the present work. The prototype, shown in this work, has been tested in collaboration with the SAPHIR experimental facility group at LOA (Laboratoire d'Optique Appliqueé) in Paris using a 200 TW Ti:Sapphire laser system. The purpose of this work is to validate the design and the performances of this large and compact bore system and to characterize the beam produced after the interaction laser-target and its features. Moreover, the optics simulations have been compared with a real beam shape on a GAFChromic film. The procedure used during the experimental campaign and the most relevant results are reported here demonstrating a good agreement with the simulations and a good control on the beam optics.

  16. Research on an Improved Method for Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Yingpei Liu

    2014-01-01

    Full Text Available In permanent magnet synchronous motor (PMSM traditional vector control system, PI regulator is used in the speed loop, but it has some defects. An improved method of PMSM vector control is proposed in the paper. The active-disturbance rejection control (ADRC speed regulator is designed with the input signals of given speed and real speed and the output of given stator current q coordinate component. Then, in order to optimize ADRC controller, the least squares support vector machines (LSSVM optimal regression model is derived and successfully embedded in the ADRC controller. ADRC observation precision and dynamic response of the system are improved. The load disturbance effect on the system is reduced to a large extent. The system anti-interference ability is further improved. Finally, the current sensor CSNE151-100 is selected to sample PMSM stator currents. The voltage sensor JLBV1 is used to sample the stator voltage. The rotor speed of PMSM is measured by mechanical speed sensor, the type of which is BENTLY 330500. Experimental platform is constructed to verify the effectiveness of the proposed method.

  17. Permanent Magnet Synchronous Condenser with Solid State Excitation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P.; Muljadi, E.; Wu, Z.; Gao, W.

    2015-04-07

    A typical synchronous condenser (SC) consists of a free-spinning, wound-field synchronous generator and a field excitation controller. In this paper, we propose an SC that employs a permanent magnet synchronous generator (PMSG) instead of a wound-field machine. PMSGs have the advantages of higher efficiency and reliability. In the proposed configuration, the reactive power control is achieved by a voltage converter controller connected in series to the PMSG. The controller varies the phase voltage of the PMSG and creates the same effect on the reactive power flow as that of an over- or underexcited wound-field machine. The controller’s output voltage magnitude controls the amount of the reactive power produced by the SC. The phase of the controller’s output is kept within a small variation from the grid voltage phase. This small phase variation is introduced so that a small amount of power can be drawn from the grid into the controller to maintain its DC bus voltage. Because the output voltage of the controller is only a fraction of the line voltage, its VA rating is only a fraction of the rating of the PMSG. The proposed scheme is shown to be effective by computer simulations.

  18. Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

    Science.gov (United States)

    Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

    2017-03-01

    High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd–Fe–B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8–12 November 2016, Ha Long City, Vietnam.

  19. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Bo, E-mail: yebo@hubu.edu.cn [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Zhang, Wei [Department of Mechanical Engineering, Hubei University of Automotive Technology, Shiyan 442002 (China); Sun, Zhen-jun [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Guo, Lin [School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Deng, Chao [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Chen, Ya-qi [Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030 (China); Zhang, Hong-hai [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Liu, Sheng [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application. - Highlights: • A new magnetic control method for spiral-type wireless capsule endoscope is proposed. • Wireless capsule endoscope rotates synchronously with external permanent magnet. • The method controls the wireless capsule endoscope well in porcine small intestine. • Long control distance makes the method may be used in future medical application. • Experimental setup has great advantages: high cost performance and easy operation.

  20. Designing Model and Optimization of the Permanent Magnet for Joule Balance NIM-2

    CERN Document Server

    You, Qiang; Li, Zhengkun; Li, Shisong

    2016-01-01

    Permanent magnets with yokes are widely used in the watt and joule balances to measure the Planck constant for the forthcoming redefinition of the unit of mass, the kilogram. Recently, a permanent magnet system has been in consideration for a further practice of NIM-2, the generalized joule balance. In this paper, an analytical model to design the permanent magnet system is presented. The presented model can be solved to obtain the preliminary parameters and then is used as guidance for FEA software to optimize the parameters of such magnetic system. As an instance for the application of the designing model, the design of the permanent magnet system for NIM-2 is described and the special design of opening shape makes the misalignment of the top and middle yokes has little influence on the vertical component of the magnetic field.