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Sample records for ndfeb magnet scrap

  1. Liquid metal extraction of Nd from NdFeB magnet scrap

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yanchen [Iowa State Univ., Ames, IA (United States)

    1999-12-10

    This research involves using molten magnesium (Mg) to remove neodymium (Nd) from NdFeB magnet scrap by diffusion. The results show that liquid metal extraction of Nd may be a viable and inexpensive method for recovering the expensive rare earth element Nd for use in Mg castings.

  2. REE Recovery from End-of-Life NdFeB Permanent Magnet Scrap : A Critical Review

    NARCIS (Netherlands)

    Yang, Y.; Walton, A; Sheridan, R.; Güth, K.; Gauß, R.; Gutfleisch, O; Buchert, M; Steenari, B-M,; Van Gerven, T; Jones, PT; Binnemans, K

    2017-01-01

    NdFeB permanent magnets have different life cycles, depending on the applications: from as short as 2–3 years in consumer electronics to 20–30 years in wind turbines. The size of the magnets ranges from less than 1 g in small consumer electronics to about 1 kg in electric vehicles (EVs) and hybrid

  3. 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.

  4. Recycling of rare earth magnet scraps: Carbon and oxygen removal from Nd magnet scraps

    International Nuclear Information System (INIS)

    Saguchi, A.; Asabe, K.; Fukuda, T.; Takahashi, W.; Suzuki, R.O.

    2006-01-01

    The decarburization and deoxidation technique for permanent Nd-Fe-B magnet scrap is investigated. The carbon and oxygen contamination damage the magnetic properties. The carbon content decreased less than 0.001% by heating in air. The two stage deoxidation is applied, iron oxides are reduced by heating in hydrogen thereafter rare earth oxides are removed by Ca-reduction and leaching. The appropriate conditions for deoxidation in the Ca-reduction and suppressing the re-oxidation in the leaching are investigated. The heating pattern in Ca-reduction and the leaching condition for the mixture composed of Ca compounds and Nd-Fe-B alloy powder greatly affects the oxygen content of recycled material. The decarburized and deoxidized Nd-Fe-B magnet scrap can be recycled as alloying elements by melting

  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. MAGNETIC VISCOSITY IN NdFeB MAGNETS

    OpenAIRE

    Martinez , J.; Missell , F.

    1988-01-01

    The relaxation of the magnetization is calculated for isotropic and anisotropic magnets. For NdFeB magnets, the dependence of Sv on texture, above room temperature, is roughly consistent with the model, while the NdDyFeB magnets show no dependence upon texture.

  7. Production of NdFeB powders by HDDR from sintered magnets

    International Nuclear Information System (INIS)

    Janasi, S.R.; Rodrigues, D.; Landgraf, F.J.G.; Campos, M.F. de

    2010-01-01

    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 2 Fe 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)

  8. 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)

  9. Characterization of nanocomposite NdFeB permanent magnetic materials

    International Nuclear Information System (INIS)

    Mat Husin Salleh; Hussain, P.; Mohammad, M.; Abd Aziz Mohamed

    2005-01-01

    The following topics were discussed: Introduction to NdFeB magnet, grain size measurement using XRD (X-ray diffraction), FESEM , TEM (Transmission Electron Microscopy) and SANS (Small-angle Neutron Scattering). The objective of the project are to analyze the structure of nano-crystallite formed in the melt spun ribbons after annealing by XRD, FESEM,TEM and SANS, to study the magnetic properties of nano-composite NdFeB melt spun ribbons and their bonded magnet and possible usage in small motor to replace the conventional NdFeB bonded magnet

  10. Magnetic viscosity and texture in NdFeB magnets

    International Nuclear Information System (INIS)

    Martinez, J.C.; Missell, F.P.

    1988-01-01

    The dependence of the magnetic viscosity on texture can be used to study a model recently proposed by Givord and co-workers to describe the angular dependence of the coercive field in NdFeB magnets. We have measured the magnetic viscosity parameter S/sub v/ for samples of Magnequench (MQ) II and III as a function of magnetic field H and temperature T above room temperature. Near room temperature, S/sub v/ for MQ II is smaller than for MQ III, while for temperatures above ∼70 0 C, the opposite behavior is observed. This temperature dependence is discussed and compared with that observed in sintered NdFeB and NdDyFeB magnets

  11. Temperature compensation of NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Kim, S.H.; Doose, C.

    1997-01-01

    Permanent magnet blocks of NdFeB have a relatively high maximum energy product. Because of its relatively low Curie temperature, however, NdFeB has a large temperature coefficient for its residual induction. The temperature coefficients of the relative magnetic fields (ΔB/B)/ΔT in the air gap of NdFeB dipole magnets were reduced from -1.1 x 10 -3 /c to less than 2 x 10 -5 /degree C under operating temperatures of ± 6 C. This was achieved passively by using 1.25-mm-thick strips of 30%-Ni-Fe alloy as flux shunts for the NdFeB blocks. The magnets with soft-steel poles and flux-return yokes were assembled and measured in a temperature-controlled environment

  12. Anisotropic powder from sintered NdFeB magnets by the HDDR processing route

    Energy Technology Data Exchange (ETDEWEB)

    Sheridan, R.S.; Sillitoe, R.; Zakotnik, M.; Harris, I.R. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Williams, A.J., E-mail: a.j.williams@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2012-01-15

    Sintered NdFeB-based scrap magnets were recovered and processed using the HD and HDDR routes. The effects of varying the HDDR processing temperature were investigated (over the range 835-930 deg. C). The disproportion was carried out with a pressure ramp to a maximum of 1000 mbar hydrogen pressure with a 1 h hold time at each step and the optimum recombination conditions were set at 100 mbar with a 20 min hold time. Anisotropic NdFeB powder was produced in all cases with the best magnetic properties achieved at a processing temperature of 880 deg. C, producing powder with a remanence of 1.10({+-}0.02) T and an intrinsic coercivity of 800 ({+-}16) kA m{sup -1} and giving a (BH){sub max} of 129({+-}2.5) kJ m{sup -3}. - Highlights: > Production of anisotropic permanent magnet powder from scrap NdFeB magnets by HDDR. > Reaction pressure increases with increasing processing temperature. > Best magnetic properties achieved by processing at 880 deg. C.

  13. Anisotropic powder from sintered NdFeB magnets by the HDDR processing route

    International Nuclear Information System (INIS)

    Sheridan, R.S.; Sillitoe, R.; Zakotnik, M.; Harris, I.R.; Williams, A.J.

    2012-01-01

    Sintered NdFeB-based scrap magnets were recovered and processed using the HD and HDDR routes. The effects of varying the HDDR processing temperature were investigated (over the range 835-930 deg. C). The disproportion was carried out with a pressure ramp to a maximum of 1000 mbar hydrogen pressure with a 1 h hold time at each step and the optimum recombination conditions were set at 100 mbar with a 20 min hold time. Anisotropic NdFeB powder was produced in all cases with the best magnetic properties achieved at a processing temperature of 880 deg. C, producing powder with a remanence of 1.10(±0.02) T and an intrinsic coercivity of 800 (±16) kA m -1 and giving a (BH) max of 129(±2.5) kJ m -3 . - Highlights: → Production of anisotropic permanent magnet powder from scrap NdFeB magnets by HDDR. → Reaction pressure increases with increasing processing temperature. → Best magnetic properties achieved by processing at 880 deg. C.

  14. Recent development in bonded NdFeB magnets

    International Nuclear Information System (INIS)

    Ma, B.M.; Herchenroeder, J.W.; Smith, B.; Suda, M.; Brown, D.N.; Chen, Z.

    2002-01-01

    The magnetic properties of isotropic NdFeB powders used for bonded magnets are compared. The characteristics of two newly developed powders, namely MQP-13-9 and MQP-S-9-8 were compared with respect to existing powders. The advantages of spherical powders for injection molding were highlighted. Development targets for the 180 deg. C application and NdFeB nanocomposites were also discussed

  15. Laboratory scale fabrication of Nd-Fe-B sintered magnets

    International Nuclear Information System (INIS)

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

    1992-01-01

    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 k field, is confirmed

  16. 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.

  17. Magnetic viscosity and coercivity mechanisms in sintered and melt spun NdFeB

    International Nuclear Information System (INIS)

    Street, R.; Bingham, D.; Day, R.K.; Dunlop, J.B.

    1988-01-01

    Magnetic viscosity parameters kT/q(=Sv) of sintered and melt spun NdFeB vary with internal field. During initial magnetization of thermally demagnetized specimens signifiant viscosity occurs with melt spun NdFeB but is negligible with sintered NdFeB. Differences in mechanisms of magnetization account for this behaviour

  18. 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.

  19. In-situ magnetization of NdFeB magnets for permanent magnet machines

    International Nuclear Information System (INIS)

    Chang, L.; Eastham, T.R.; Dawson, G.E.

    1991-01-01

    In-situ magnetizers are needed to facilitate the assembly of permanent magnet machines and to remagnetize the magnets after weakening due to a fault condition. The air-core magnetizer in association with the silicon steel lamination structure of the rotor has advantages over its iron-core counterpart. This novel method has been used to magnetize the NdFeB magnets in a 30-hp permanent magnet synchronous motor. The magnetizing capability for different magnetizer geometries was investigated for the magnetization of NdFeB material. The design, testing, and operation of this magnetizer are reported in this paper

  20. Metal coordination in the high-temperature leaching of roasted NdFeB magnets with the ionic liquid betainium bis(trifluoromethylsulfonyl)imide

    OpenAIRE

    Orefice, Martina; Binnemans, Koen; Vander Hoogerstraete, Tom

    2018-01-01

    Ionic liquids are largely used to leach metals from primary (ores) and secondary sources (end-of-life products). However, dry ionic liquids with a carboxylic function on the cation have not yet been used to leach metals at temperature above 100 °C and under atmospheric pressure. The ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used in the dry state to recover neodymium, dysprosium and cobalt from NdFeB magnets and NdFeB production scrap. The magnets and the scra...

  1. 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.

  2. Metal Injection Molding (MIM) of NdFeB Magnets

    OpenAIRE

    Hartwig T.; Lopes L.; Wendhausen P.; Ünal N.

    2014-01-01

    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 ...

  3. Phase equilibrium of the system Ag-Fe-Nd, and Nd extraction from magnet scraps using molten silver

    International Nuclear Information System (INIS)

    Takeda, O.; Okabe, T.H.; Umetsu, Y.

    2004-01-01

    To develop a new recycling process, we examined the direct extraction of neodymium (Nd) metal from Nd-Fe-B magnet scraps using molten silver (Ag) as an extraction medium. Prior to the extraction experiment, the phase equilibrium of the system Ag-Fe-Nd was investigated to estimate the theoretical extraction limit. It was observed that the Fe/Nd 2 Fe 17 mixture equilibrates with the molten Ag-Nd alloy containing 50-52 mol% Nd (57-59 mass% Nd) at 1363 K. The experimental results were in good agreement with the thermodynamic calculation based on literature values. By reacting Nd-Fe-B magnet scraps with molten silver at 1273 K, more than 90% of the neodymium in the scrap was extracted, and an Ag-Nd alloy containing 40-50 mass% Nd was obtained. The neodymium in the Ag-Nd alloy was separated from silver as Nd 2 O 3 by oxidizing the obtained alloy in air. Although the wettability of Nd 2 O 3 with molten silver caused some difficulties in the separation of neodymium from silver, molten silver is shown to be an effective medium for neodymium extraction from magnet scrap

  4. Processing and physical metallurgy of NdFeB and other R.E. magnets

    International Nuclear Information System (INIS)

    Ormerod, J.

    1985-01-01

    The background to the developmetn of NdFeB-based permanent magnets is described. The processing of NdFeB permanent magnets is outlined and compared with the production of SmCo-based permanent magnets. Some metallographic observations of sintered NdFeB magnets are presented. Finally, the improvement and future development of NdFeB and related permanent magnet materials are discussed

  5. NdFeB permanent magnets with various Nd content

    Czech Academy of Sciences Publication Activity Database

    Žák, Tomáš; Talijan, N.; Ćosović, V.; Grujić, A.

    2008-01-01

    Roč. 113, č. 1 (2008), s. 279-282 ISSN 0587-4246. [Czech and Slovak Conference on Magnetism /13./ (CSMAG'07). Košice, 09.08.2007-12.08.2007] R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : NdFeB permanent magnets * Mossbauer effect * X-ray Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.321, year: 2008

  6. Development of NdFeB magnet through hydrogen decrepitation

    International Nuclear Information System (INIS)

    Akhtar, S.; Farooque, M.; Haider, A.; Ahmad, Z.

    2009-01-01

    Neodymium based magnets are the powerful permanent magnet of today. This paper will discuss iron based rare earth magnets. NdFeB sintered magnet material has been developed. The magnets are produced by powder metallurgy route involving hydrogen decrepitation technique for making fine powder. After melting and casting, the NdFeB alloy is subject to hydrogen atmosphere. Hydrogen slowly absorbs into the solid alloy and makes it brittle, which upon milling becomes fine powder. Hydrogen is then removed by placing the powder at temperature around 800 deg. C under vacuum. Then the powders are pressed under isostatic conditions and sintered at temperature range of 1020-1050 deg. C. Post sintering is done at 800 deg. C and 580 deg. C followed by quenching. Energy product in the range of 8 MGOe is achieved. (author)

  7. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 2 O 3 . • Diffusion coefficient determined to be 4 × 10 −13 cm 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 2 O 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 −13 cm 2 /sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated

  8. 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

  9. Corrosion behaviour of Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mummert, K.; El-Aziz, A.M.; Barkleit, G.; Schultz, L.; Rodewald, W.

    2000-01-01

    The corrosion behaviour of Nd-Fe-B permanent magnetic alloys as well as of single phases of these alloys have been investigated in sulphuric acid at room temperature and humid air at 150 C using mass loss and electrochemical techniques. Scanning electron microscopy and scanning probe microscopy were used to study the surface topography. The electrostatic surface potential was examined by scanning probe microscopy using tapping mode. A correlation between the electrostatic surface potential and the corrosion rate of these alloys was found. The higher the value of the electrostatic surface potential of the intergranular phases the higher is the corrosion sensitivity. The strength of the corrosion attack on the phases of sintered permanent magnetic alloys is as follows: Ferromagnetic phase < B-rich phase < Nd-rich phase. The differences in the chemical composition as well as in the preparation of these magnetic alloys have distinct influence on the corrosion resistance of the magnetic Nd-Fe-B alloys. (orig.)

  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. Zinc and resin bonded NdFeB magnets

    International Nuclear Information System (INIS)

    Leonowicz, M.; Kaszuwara, W.

    2002-01-01

    Zinc and resin bonded NdFeB magnets were processed. Basic magnetic parameters as well as compressive strength were evaluated versus annealing temperature and volume fraction of the bonding agent. For the zinc bonded magnets phase composition was investigated. The additional NdZn 5 phase was found in the Zn bonded magnets after annealing. Comparison of the Zn and resin bonded magnets reveals higher remanence for the former and higher coercivity for the latter. For the Zn and resin bonded magnets, 15 wt.% Zn / 370 o C and 7-10 wt.% resin were chosen as the optimal processing parameters. (author)

  12. 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.

  13. Plasma sprayed Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.; Bauser, S.; Liu, S.; Huang, M.

    2003-01-01

    This study demonstrated that the plasma spray deposition method is an alternative process for producing Nd-Fe-B magnets in addition to the two existing principal processes: the powder metallurgy process for producing sintered Nd-Fe-B magnets and the melt spinning process for bonded Nd-Fe-B magnets. Plasma spray is a potentially better process for producing magnetic parts with complicated shape, large area, thin thickness, small dimension, or unusual geometry. High intrinsic coercivity greater than 15 kOe was readily obtained for Nd 16 Dy 1 Fe 76 B 7 even in the as-deposited condition when the substrate was preheated. The plasma spray process contains only three steps: melting, crushing, and plasma spray, which is much simpler than the powder metallurgy and melt spinning processes. Without preheating the substrate, the coercivity was usually very low (∼0.1 kOe) in the as-deposited condition and it increased to 10 to >15 kOe after anneal. Evidence of magnetocrystalline anisotropy was observed in plasma sprayed Nd 15 Dy 1 Fe 77 B 7 magnets when the substrate was not preheated. It is believed that a crystal texture was developed during the plasma spray as a result of the existence of a temperature gradient in the solidifying melt

  14. Corrosion of NdFeB permanent magnet materials

    International Nuclear Information System (INIS)

    Warren, G.W.; Gao, G.; Li, Q.

    1991-01-01

    NdFeB is an important class of new magnetic materials, however corrosion resistance is a serious concern and literature on the electrochemical behavior of NdFeB is scarce. This paper reports the results of an electrochemical investigation of the corrosion behavior of sintered NdFeB magnets obtained from three manufacturers. Linear polarization (cyclic voltammetry) experiments were conducted in aqueous solutions ranging in pH from 0.7 to 13.5. A limited degree of passivation was observed in all solutions which is believed to be due to the formation of a complex Fe-Nd oxide and/or hydroxide film. The presence of a small amount of chloride ion, 10 to 100 ppm, shows only a slight effect, but higher concentrations (1000 ppm) cause a total breakdown in passivity and a dramatic increase in anodic current. The cathodic potential sweep shows an abrupt and unusual oxidation process, giving rise to an oxidation peak not commonly seen. This peak may result from dissolution of the film or preferential attack of intergranular phases

  15. Magnetic microstructure and magnetic properties of spark plasma sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.L., E-mail: hyl1019_lin@163.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wang, Y.; Hou, Y.H.; Wang, Y.L.; Wu, Y.; Ma, S.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Z.W.; Zeng, D.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Tian, Y.; Xia, W.X. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2016-02-01

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) technique using melt-spun ribbons as starting materials. A distinct two-zone structure with coarse grain zone and fine grain zone was formed in the SPSed magnets. Multi-domain particle in coarse grain zone and exchange interaction domain for fine grain zone were observed. Intergranular non-magnetic phase was favorable to improve the coercivity due to the enhancement of domain wall pinning effects and increased exchange-decouple. The remanent polarization of 0.83 T, coercivity of 1516 kA/m, and maximum energy product of 118 kJ/m{sup 3} are obtained for an isotropic magnet. - Highlights: • Nanocrystalline NdFeB magnets were prepared by spark plasma sintering technique. • Multi-domain particle and exchange interaction domain were observed. • Magnetic microstructure and their relation to the properties were investigated.

  16. 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 speci......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....

  17. Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

    Science.gov (United States)

    Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

    2015-08-18

    The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 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 2 gas. Expansion of the NdFeB crystal lattice in both ATF and H 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 2 Fe 14 B, reducing coercivity.

  19. Production for high thermal stability NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.Q. [College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, Shandong Province (China)], E-mail: iyy2000@163.com; Zhang, J.; Hu, S.Q.; Han, Z.D. [College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, Shandong Province (China); Yan, M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2008-04-15

    To improve sintered NdFeB magnets' thermal stability and magnetic properties, combined addition of elements Cu and Gd was investigated. It was found that with Gd addition increase to 1.0%, the temperature coefficient {alpha} improved from -0.15 to -0.05%/deg. C (maximum working temperature 120 deg. C), but the remanence and the maximum energy product linearly decreased. With addition of Cu in Gd-containing magnets the intrinsic coercivity increased greatly, and the remanence increased also because of their density improvement, and optimum Cu content was achieved at 0.2%. Microstructure analysis showed that most of the Cu distributed at grain boundaries and led to clear and smooth morphologies. Magnets with high thermal stability {alpha}=-0.05%/deg. C and magnetic properties were obtained with addition of Gd=0.8% and Cu=0.2%.

  20. Influences of Laser Spot Welding on Magnetic Property of a Sintered NdFeB Magnet

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2016-08-01

    Full Text Available Laser welding has been considered as a promising method to join sintered NdFeB permanent magnets thanks to its high precision and productivity. However, the influences of laser welding on the magnetic property of NdFeB are still not clear. In the present paper, the effects of laser power on the remanence (Br were experimentally investigated in laser spot welding of a NdFeB magnet (N48H. Results show that the Br decreased with the increase of laser power. For the same welding parameters, the Br of magnets, that were magnetized before welding, were much lower than that of magnets that were magnetized after welding. The decrease in Br of magnets after laser welding resulted from the changes in microstructures and, in turn, the deterioration of magnetic properties in the nugget and the heat affected zone (HAZ in a laser weld. It is recommended that the dimensions of nuggets and HAZ in laser welds of a NdFeB permanent magnet should be as small as possible, and the magnets should be welded before being magnetized in order to achieve a better magnetic performance in practical engineering applications.

  1. Environmental degradation of NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yan Gaolin [Wuhan University, School of Physics and Technology, Wuhan 430072 (China)], E-mail: gaolinyan@whu.edu.cn; McGuiness, P.J. [Jozef Stefan Institute (Slovenia); Farr, J.P.G.; Harris, I.R. [School of Metallurgy and Materials, University of Birmingham, Elms Road, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-06-10

    A mechanism for pitting of NdFeB magnet because of differential-aeration beneath a water droplet is proposed and observations of the localised corrosions are presented. NdFeB magnets exhibit general corrosion along the grain boundaries when etched in Viella's reagent. However, localised corrosion of these magnets results in a crater-like feature when corrosion is produced in an environmental chamber, e.g. when Nd{sub 16}Fe{sub 76}B{sub 8} magnets are corroded in the environmental chamber at 85 deg. C, relative humidity (RH): 80%. This is attributed to the condensation of water droplets on the surface of samples and the concentration gradient of oxygen dissolved in the droplets then influencing the corrosion process. It is thought that during the process of pitting, the high concentration of H{sup +} in the center of the pit accelerates the pit development; meanwhile, the cathodic Nd{sub 2}Fe{sub 14}B matrix phase absorbs the nascent hydrogen atoms. It is believed that pits start at the Nd-rich phase and then propagate along the grain boundaries.

  2. Influence of Demagnetization-Temperature on Magnetic Performance of Recycled Nd-Fe-B Magnets

    DEFF Research Database (Denmark)

    Högberg, Stig; Bendixen, Flemming Buus; Mijatovic, Nenad

    2015-01-01

    Recycling rare earth permanent magnets is becoming an important alternative source of supply of raw materials for neodymium-iron-boron (Nd-Fe-B) permanent magnets. This article documents a recycling case-study in which isotropic binder-free magnet powder is extracted and recycled from hermeticall...

  3. Magnetisation reversal on surface of Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Sun, H.; Woodward, R.; Street, R.

    1998-01-01

    Full text: Time dependent magnetisation processes on surface of isotropic and anisotropic Nd-Fe-B magnets were measured using a Magneto-Optic Magnetometer (MOM) and the data were analysed by means of the constitutive equation H = H(M, M). The surface magnetic viscosity parameter Λ (or fluctuation field H f ) was obtained. The activation volume v, which represents the volume of a negative magnetisation nuclei during a magnetisation reversal process was calculated from Λ. The results are compared with those of the corresponding bulk properties obtained by analysing the data measured using a Vibrating Sample Magnetometer (VSM). Similar to bulk materials, Λ for the surface magnetisation is nearly constant over a wide range of magnetisation for both isotropic and anisotropic Nd-Fe-B. However, the surface hysteresis loops are significantly different from the bulk materials, indicating a significant difference in the magnetisation reversal processes between the bulk and surface materials. The surface magnetisation reversal mechanism, its relation and influence to the bulk properties and therefore the performance of permanent magnet are discussed

  4. Effect of process on the magnetic properties of bonded NdFeB magnet

    International Nuclear Information System (INIS)

    Li, J.; Liu, Y.; Gao, S.J.; Li, M.; Wang, Y.Q.; Tu, M.J.

    2006-01-01

    The effects of magnetic separation, coupling treatment, lubricating treatment, preform and biaxial molding on the density and magnetic properties of bonded NdFeB magnet were investigated. The results demonstrate that magnetic separation separates the powders with low coercive force; coupling treatment improves the interfaces between the powders and the binders; decrease in volume fraction of the binder increases magnetic properties of the magnet; granular arrangement improves both the magnetic and mechanical properties when powders are arranged in certain size; lubricating treatment improves the formability of the magnet and preform and biaxial molding improves both density and magnetic properties greatly. Combining these methods, the density of the bonded NdFeB magnet can reach 6.52 g/cm 3 and the maximum energy product can reach 114 kJ/m 3

  5. Effect of process on the magnetic properties of bonded NdFeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Liu, Y. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)]. E-mail: liuying5536@163.com; Gao, S.J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Li, M. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Wang, Y.Q. [South-West Magnetic Science and Technology Developing Company, Mianyang, 621600 (China); Tu, M.J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)

    2006-04-15

    The effects of magnetic separation, coupling treatment, lubricating treatment, preform and biaxial molding on the density and magnetic properties of bonded NdFeB magnet were investigated. The results demonstrate that magnetic separation separates the powders with low coercive force; coupling treatment improves the interfaces between the powders and the binders; decrease in volume fraction of the binder increases magnetic properties of the magnet; granular arrangement improves both the magnetic and mechanical properties when powders are arranged in certain size; lubricating treatment improves the formability of the magnet and preform and biaxial molding improves both density and magnetic properties greatly. Combining these methods, the density of the bonded NdFeB magnet can reach 6.52 g/cm{sup 3} and the maximum energy product can reach 114 kJ/m{sup 3}.

  6. 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.

  7. Net Shape 3D Printed NdFeB Permanent Magnet

    OpenAIRE

    Jacimovic, J.; Binda, F.; 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...

  8. Improvement of the microstructure and magnetic properties of sintered NdFeB permant magnets

    International Nuclear Information System (INIS)

    Vial, F.; Rozendaal, E.; Sagawa, M.

    1998-01-01

    A correlation between sintered NdFeB process, microstructure of the products at each step of the process and magnetic properties has been established. To increase (BH) max of sintered NdFeB magnets, the total rare-earth content in the alloy has to be decreased and to keep coercivity as high as possible, the unavoidable oxygen pick-up has to be substantially reduced. The composition improvements tend to create a high sensitivity to form abnormal grain growth which can potentially occur during the sintering operation. Special attention has been given to characterising, understanding the mechanisms and solving this defect which could affect the magnetic properties. In addition, the composition and each step of the process have been optimised to improve magnetic properties, thermal stability and corrosion resistance of the NdFeB permanent magnets. These collaborative studies have resulted in a significant improvement of both remanence and coercivity of the sintered NdFeB permanent magnets, covering a wide coercivity range from 800 to 2500 kA/m (10 to 35 kOe) with respective associated energy products of 400 to 270 kJ/m3 (52 to 35 MGOe). (orig.)

  9. Hard magnetic property and δM(H) plot for sintered NdFeB magnet

    International Nuclear Information System (INIS)

    Gao, R.W.; Zhang, D.H.; Li, W.; Li, X.M.; Zhang, J.C.

    2000-01-01

    The hard magnetic properties and the interactions between the grains for sintered Nd 16 Fe 73 Co 5 B 6 magnets are investigated by using δM(H) plot technique. The results show that the δM(H) plot of NdFeB sintered magnet can explain the effects of the microstructure (size, shape and orientation of the grains) and the intergrain interactions on the hard magnetic properties of the magnet. However, the value of δM(H) is positive when the applied field is not strong enough, which means that the common δM(H) plot theory is not completely consistent with the sintered NdFeB magnet

  10. 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.

  11. Analysis of physical and magnetic properties of composite NdFeB bind with polyvinyl alcohol

    Science.gov (United States)

    Ramlan; Sardjono, P.; Muljadi; Setiabudidaya, D.; Gulo, F.

    2018-03-01

    The composite magnet NdFeB has been made using magnetic powder MQP-B and polyvinyl alcohol (PVA) as the binder. The mixing compositions of raw materials used are: 95 wt% NdFeB - 5 wt% PVA, 92.5 wt% NdFeB - 7.5 wt% PVA, 90 wt.% NdFeB - 10 wt% PVA, and 87.5 wt% NdFeB - 12.5 wt% PVA. Both raw materials are weighed according to the composition, and then mixed until homogeneous. Furthermore, pellet forming was made using dry pressing at 50 kgf/cm2 pressures and continued with drying at 100 °C and 10 mmbar for 4 hours. The characterization includes bulk density, hardness, compressive strength measurements, and magnetic properties testing. The characterization results show that the optimal composition of binder PVA is achieved at 5–7.5 wt% NdFeB composite magnet with following properties: bulk density = 5.21–5.25 g/cm3, hardness = 302.17 - 304.32 Hv, compressive strength = 25.17–3.17 kgf/cm2, magnetic flux = 1150-1170 Gauss, remanence = 70.90–74.97 emu/g or 4.7–5.0 kGauss, coercivity = 8.68–8.76 kOe, and energy product = 2.89–3.04 MgOe.

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

    OpenAIRE

    Liu, Wenfeng; Zhang, Mingang; Zhang, Kewei; Chai, Yuesheng

    2017-01-01

    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 per...

  13. 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.

  14. 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.

  15. [The cytotoxicity of N48 NdFeB magnets coated with titanium-nitride].

    Science.gov (United States)

    Cao, Xiao-Ming; Hou, Zhi-Ming; Chu, Ming

    2008-04-01

    To evaluate the effect of N48 NdFeB magnets coated with titanium-nitride on the growth and apoptosis of L929 mouse fibroblast cells, and to determine the material biocompatibility. The NdFeB magnets coated with titanium-nitride, bare NdFeB magnets and ordinary brackets were put into RPMI-1640 to prepare fusions. L929 mouse fibroblast cells were cultivated in the negative control liquid, positive control liquid, 100%, 50% and 25% sample fusions, respectively. The cell proliferation vitality was detected by MTT assay and the relative growth rate was calculated.Cell scatter diagrams of the negative control liquid, 100% titanium-nitride coated magnets fusion and bare magnets fusion were detected by flow cytometry Annexin V/PI double staining method. The ratios of normal cells, early apoptosis, advanced apoptosis and necrosis cells were calculated. The results were analyzed for paired t test using SPSS11.5 software package. The toxic levels of N48 NdFeB coated with titanium-nitride were ranked as 0-1. The toxic levels of bare magnets were ranked as 2. The cell scatter diagrams showed that there was no significant difference in living cell, early apoptosis and necrosis between magnets coated with titanium-nitride and control group. But there was significant difference between the bare magnets group and control group. The N48 NdFeB magnets coated with titanium-nitride have good biocompatibility.

  16. 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.

  17. NdFeB magnets for high-power motors

    International Nuclear Information System (INIS)

    Oswald, B.; Soell, M.; Berberich, A.

    1998-01-01

    The use of REM in electric motors especially in the case of servo drives is state of the art today. Whether permanent magnet types SmCo or NdFeB are also suitable for high power main drives has to be decided regarding criteria which apply to high power machines. In this paper operation characteristics of common electric motors and especially those of drives with controlled speed are presented. In the case of electric motors with REM, increased output power and high efficiency at the same time are to be expected in comparison to classical drives. This makes them attractive for a number of applications. However their speed range is restricted for fundamental reasons as normally weakening of field is not possible. It is to be expected that due to their advantages the use of permanent magnet motors for elevated output power also will increase. Besides other forms they can be used also as special design such as e.g. round or flat linear motors. Their power density (force density) makes them attractive for numerous applications in this form. A comparison between permanent magnet motors with superconducting motors made of bulk HTS material gives insight into the wide area of future design of electrical machines. (orig.)

  18. 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....... It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop...

  19. Microstructure, texture, and magnetic properties of backward extruded NdFeB ring magnets

    International Nuclear Information System (INIS)

    Gruenberger, W.; Hinz, D.; Schlaefer, D.; Schultz, L.

    1996-01-01

    Radially-oriented NdFeB ring magnets have been prepared by backward extrusion of melt-spun material. The average remanence measured in the radial direction reaches values above 1.2 T. Due to the inhomogeneity of the deformation, the magnetic properties and X-ray diffraction patterns revealed a gradual improvement of the alignment from the outer shell to regions near the inner surface of the ring. (orig.)

  20. Characterization of corrosion products from Nd-Fe-B magnets used in dental prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Saiki, Mitiko; Rogero, Sizue O.; Costa, Isolda; Dantas, Elisabeth; Oliveira, Mara C.L. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    2002-07-01

    A special group of magnets composed mainly by Nd-Fe-B has been widely used in dental applications as retentive devices for overdentures, due to their strong force and compactness. Dental materials should present high corrosion resistance and be innocuous to human tissues, however, Nd-Fe-B magnets are highly susceptible to corrosion. This work presents results obtained in the elemental analysis of Nd-Fe-B magnets and their corrosion products. The corrosion products were analyzed in the extracts of culture medium where the magnets had been immersed for 10 days at 37 deg C. Elements B, Co, Fe, La, Nd, Dy, Pr, Sm, Ho, Yb and Lu were found in the magnet and the analysis of extract indicated that Co, Fe and Nd are released from the magnet to the extract. Toxicity was also investigated in this extract using the neutral red uptake cytotoxicity assay. Acknowledgements: To FAPESP and CNPq for financial support. (author)

  1. Characterization of corrosion products from Nd-Fe-B magnets used in dental prostheses

    International Nuclear Information System (INIS)

    Saiki, Mitiko; Rogero, Sizue O.; Costa, Isolda; Dantas, Elisabeth; Oliveira, Mara C.L.

    2002-01-01

    A special group of magnets composed mainly by Nd-Fe-B has been widely used in dental applications as retentive devices for overdentures, due to their strong force and compactness. Dental materials should present high corrosion resistance and be innocuous to human tissues, however, Nd-Fe-B magnets are highly susceptible to corrosion. This work presents results obtained in the elemental analysis of Nd-Fe-B magnets and their corrosion products. The corrosion products were analyzed in the extracts of culture medium where the magnets had been immersed for 10 days at 37 deg C. Elements B, Co, Fe, La, Nd, Dy, Pr, Sm, Ho, Yb and Lu were found in the magnet and the analysis of extract indicated that Co, Fe and Nd are released from the magnet to the extract. Toxicity was also investigated in this extract using the neutral red uptake cytotoxicity assay. Acknowledgements: To FAPESP and CNPq for financial support. (author)

  2. Fabrication of NdFeB microstructures using a silicon molding technique for NdFeB/Ta multilayered films and NdFeB magnetic powder

    International Nuclear Information System (INIS)

    Jiang Yonggang; Fujita, Takayuki; Uehara, Minoru; Iga, Yuki; Hashimoto, Taichi; Hao, Xiuchun; Higuchi, Kohei; Maenaka, Kazusuke

    2011-01-01

    The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-μm-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 μm are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T. - Highlights: → We demonstrate the fabrication of micro-magnets using silicon molding processes. → NdFeB/Ta films are well filled in silicon trenches with a thickness of 12 μm. → The 12-μm-thick NdFeB/Ta magnetic film shows a retentivity of 1.3 T. → Magnetic structures as narrow as 20 μm are fabricated using NdFeB magnetic powder. → VSM measurement shows a retentivity of 0.37 T for patterned NdFeB magnetic powder.

  3. Fabrication of NdFeB microstructures using a silicon molding technique for NdFeB/Ta multilayered films and NdFeB magnetic powder

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yonggang, E-mail: yonggangj@gmail.com [School of Mechanical Engineering and Automation, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing 100191 (China); Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Fujita, Takayuki [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Uehara, Minoru [NEOMAX Co. Ltd., 2-15-17, Egawa, Shimamoto-Cho, Mishima-gun, Osaka 618-0013 (Japan); Iga, Yuki [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Hashimoto, Taichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Hao, Xiuchun; Higuchi, Kohei [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Maenaka, Kazusuke [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan)

    2011-11-15

    The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-{mu}m-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 {mu}m are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T. - Highlights: > We demonstrate the fabrication of micro-magnets using silicon molding processes. > NdFeB/Ta films are well filled in silicon trenches with a thickness of 12 {mu}m. > The 12-{mu}m-thick NdFeB/Ta magnetic film shows a retentivity of 1.3 T. > Magnetic structures as narrow as 20 {mu}m are fabricated using NdFeB magnetic powder. > VSM measurement shows a retentivity of 0.37 T for patterned NdFeB magnetic powder.

  4. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

    Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

    2017-08-08

    A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

  5. Feasibility of low-cost magnetic rail designs by integrating ferrite magnets and NdFeB magnets for HTS Maglev systems

    Science.gov (United States)

    Sun, R. X.; Deng, Z. G.; Gou, Y. F.; Li, Y. J.; Zheng, J.; Wang, S. Y.; Wang, J. S.

    2015-09-01

    Permanent magnet guideway (PMG) is an indispensable part of high temperature superconducting (HTS) Maglev systems. Present PMGs are made of NdFeB magnets with excellent performance and cost much. As another permanent magnet material, the ferrite magnet is weak at magnetic energy product and coercive force, but inexpensive. So, it is a possible way to integrate the ferrite and NdFeB magnets for cutting down the cost of present PMGs. In the paper, the equivalent on magnetic field intensity between ferrite magnets and NdFeB magnets was evaluated by finite element simulation. According to the calculation results, the magnetic field of the PMG integrating ferrite magnets and NdFeB magnets can be increased remarkably comparing with the pure ferrite PMG. It indicates that low-cost PMG designs by integrating the two permanent magnet materials are feasible for the practical HTS Maglev system.

  6. Improved magnetic properties and fracture strength of NdFeB by dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Yan, M. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mse_yanmi@dial.zju.edu.cn; Yu, L.Q. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Wu, J.M. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Cui, X.G. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2006-11-15

    Effects of the dehydrogenation of the hydrogen decrepitated (HD) powders on the magnetic properties and the fracture strength of sintered NdFeB magnets were studied. It was found that the lattice parameters and the crystal phase of NdFeB changed significantly with the various hydrogen contents of the resultant HD powders due to the different degrees of dehydrogenation. The magnetic properties and fracture strength increased with decreasing hydrogen content, reaching the maximum increases of 200% for both intrinsic coercivity and bending strength, which can be ascribed to the improved microstructure of the sintered NdFeB magnets. The hydrogen remaining in the HD powders diffused out and affected drastically the grain and grain boundaries by the hydrogen out-take channel during the subsequent sintering process.

  7. Improved magnetic properties and fracture strength of NdFeB by dehydrogenation

    International Nuclear Information System (INIS)

    Yan, M.; Yu, L.Q.; Wu, J.M.; Cui, X.G.

    2006-01-01

    Effects of the dehydrogenation of the hydrogen decrepitated (HD) powders on the magnetic properties and the fracture strength of sintered NdFeB magnets were studied. It was found that the lattice parameters and the crystal phase of NdFeB changed significantly with the various hydrogen contents of the resultant HD powders due to the different degrees of dehydrogenation. The magnetic properties and fracture strength increased with decreasing hydrogen content, reaching the maximum increases of 200% for both intrinsic coercivity and bending strength, which can be ascribed to the improved microstructure of the sintered NdFeB magnets. The hydrogen remaining in the HD powders diffused out and affected drastically the grain and grain boundaries by the hydrogen out-take channel during the subsequent sintering process

  8. 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.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered...

  10. Prediction of particle orientation in simple upsetting process of NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chao-Cheng; Hsiao, Po-Jen [Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Sanmin District, Kaohsiung 80778, Taiwan (China); You, Jr-Shiang; Chen, Yen-Ju; Chang, Can-Xun [Metal Forming Technology Section, Metal Processing R and D Department, Metal Industries Research and Development Centre, 1001 Kaonan Highway, Kaohsiung 81160, Taiwan (China)

    2013-12-16

    The magnetic properties of NdFeB magnets are strongly affected by crystallographic texture which is highly associated with particle orientation. This study proposed a method for predicting the particle orientation in the simple upsetting process of NdFeB magnets. The method is based on finite element simulation with flow net analysis. The magnets in a cylindrical form were compressed by two flat dies in a chamber filled with argon at 750°C. Three forming speeds were taken into account in order to obtain flow stress curves used in simulations. The micrographs of the cross sections of the deformed magnets show that the particle deformation significantly increases with the compression. The phenomenon was also predicted by the proposed method. Both simulated and experimental results show that the inhomogeneity of the texture of the NdFeB magnets can be increased by the simple upsetting process. The predicted particle orientations were in a good agreement with those examined in the deformed magnets. The proposed method for predicting particle orientations can also be used in other forming processes of NdFeB magnets.

  11. Prediction of particle orientation in simple upsetting process of NdFeB magnets

    International Nuclear Information System (INIS)

    Chang, Chao-Cheng; Hsiao, Po-Jen; You, Jr-Shiang; Chen, Yen-Ju; Chang, Can-Xun

    2013-01-01

    The magnetic properties of NdFeB magnets are strongly affected by crystallographic texture which is highly associated with particle orientation. This study proposed a method for predicting the particle orientation in the simple upsetting process of NdFeB magnets. The method is based on finite element simulation with flow net analysis. The magnets in a cylindrical form were compressed by two flat dies in a chamber filled with argon at 750°C. Three forming speeds were taken into account in order to obtain flow stress curves used in simulations. The micrographs of the cross sections of the deformed magnets show that the particle deformation significantly increases with the compression. The phenomenon was also predicted by the proposed method. Both simulated and experimental results show that the inhomogeneity of the texture of the NdFeB magnets can be increased by the simple upsetting process. The predicted particle orientations were in a good agreement with those examined in the deformed magnets. The proposed method for predicting particle orientations can also be used in other forming processes of NdFeB magnets

  12. The permanent NdFeB magnets in the circuits for magnetic filters and the first technological tests

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel; Mucha, Pavel

    2005-01-01

    Roč. 78, - (2005), s. 31-39 ISSN 0301-7516 R&D Projects: GA AV ČR IBS3046004 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic circuit * magnetic filter * rare earth magnets ( NdFeB ) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.965, year: 2005

  13. Radiation hardness of permanent magnets of NdFeB in high energy neutron fields

    International Nuclear Information System (INIS)

    Shchegolev, V.Yu.

    2003-01-01

    Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 %. Estimation of magnet 'life time' was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed. (author)

  14. Radiation Hardness of Permanent Magnets of NdFeB in High Energy Neutrons Field

    CERN Document Server

    Schegolev, V Yu

    2003-01-01

    Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 \\%. Estimation of magnet "life tim" was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed.

  15. Radiation hardness of permanent magnets of NdFeB in high energy neutron fields

    CERN Document Server

    Shchegolev, V Y

    2003-01-01

    Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 %. Estimation of magnet 'life time' was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed.

  16. Application of permanent magnets made from NdFeB powder and from mixtures of powders in DC motors

    International Nuclear Information System (INIS)

    Slusarek, B.; Dudzikowski, I.

    2002-01-01

    The paper presents the influence of magnetic properties of applied permanent magnets on the characteristics of DC motors excited with these magnets. In the factory-produced DC motors, excited with sintered ferrite magnets, authors replaced ferrite magnets with the dielectromagnets from NdFeB powder and from different mixtures of NdFeB and ferrite powders. The paper shows the increase of the power of the resultant DC motors according to the powders' content

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

    International Nuclear Information System (INIS)

    Lin, Min; Wang, Huijie; Zheng, Jingwu; Yan, Aru

    2015-01-01

    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 r and the (BH) 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

  18. Study of high-coercivity sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Bai, G. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Department of Mathematics and Physics, Xi' an Institute of Technology, Xi' an, 710032 (China); Gao, R.W. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China)]. E-mail: gaorwbox@sdu.edu.cn; Sun, Y. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Han, G.B. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Wang, B. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Baotou Rare Earth Research Institute, Batou 014030 (China)

    2007-01-15

    Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of {sub j} H {sub c}=25.6 kOe, B {sub r}=13.2 kG and (BH){sub max}=39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 deg. C) is -0.53% deg. C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors.

  19. Study of high-coercivity sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Bai, G.; Gao, R.W.; Sun, Y.; Han, G.B.; Wang, B.

    2007-01-01

    Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of j H c =25.6 kOe, B r =13.2 kG and (BH) max =39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 deg. C) is -0.53% deg. C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors

  20. NdFeB alloy as a magnetic electrode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang, J.; Shui, J.L.; Zhang, S.L.; Wei, X.; Xiang, Y.J.; Xie, S.; Zhu, C.F.; Chen, C.H.

    2005-01-01

    The search for a reliable indicator of state of charge and even the remaining energy of a lithium-ion cell is of great importance for various applications. This study was an exploratory effort to use magnetic susceptibility as the indicator. In this work, for the first time the change of ac susceptibility of cells was in situ monitored during charge-discharge process. A strong permanent magnetic material, NdFeB alloy, was investigated as an anode material for rechargeable lithium batteries. Both original and partially oxidized NdFeB powders were made into electrodes. Structural characterization was performed on the NdFeB electrodes by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. An alloy (core)-oxide (shell) structure was found for those partially oxidized samples. The electrochemical cycling of cells made of the NdFeB electrodes against lithium was measured. The first lithium intercalation capacity of a treated NdFeB can be up to about 831 mAh/g, while a rather reversible capacity of up to 352 mAh/g can be obtained. With a specially designed cell, we were able to monitor in situ the change of relative ac susceptibility during charge and/or discharge steps. A clearly monotonous relationship is found between the ac susceptibility of a cell and its depth-of-discharge (DOD). A mechanism based on skin effect and eddy current change is proposed to explain this susceptibility versus DOD relationship

  1. NdFeB alloy as a magnetic electrode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Shui, J.L. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Zhang, S.L. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Wei, X. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Xiang, Y.J. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Xie, S. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Zhu, C.F. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Chen, C.H. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China)]. E-mail: cchchen@ustc.edu.cn

    2005-04-05

    The search for a reliable indicator of state of charge and even the remaining energy of a lithium-ion cell is of great importance for various applications. This study was an exploratory effort to use magnetic susceptibility as the indicator. In this work, for the first time the change of ac susceptibility of cells was in situ monitored during charge-discharge process. A strong permanent magnetic material, NdFeB alloy, was investigated as an anode material for rechargeable lithium batteries. Both original and partially oxidized NdFeB powders were made into electrodes. Structural characterization was performed on the NdFeB electrodes by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. An alloy (core)-oxide (shell) structure was found for those partially oxidized samples. The electrochemical cycling of cells made of the NdFeB electrodes against lithium was measured. The first lithium intercalation capacity of a treated NdFeB can be up to about 831 mAh/g, while a rather reversible capacity of up to 352 mAh/g can be obtained. With a specially designed cell, we were able to monitor in situ the change of relative ac susceptibility during charge and/or discharge steps. A clearly monotonous relationship is found between the ac susceptibility of a cell and its depth-of-discharge (DOD). A mechanism based on skin effect and eddy current change is proposed to explain this susceptibility versus DOD relationship.

  2. Enhancement in (BHmax of PLD-made isotropic Nd-Fe-B thick film magnets deposited on Si substrates

    Directory of Open Access Journals (Sweden)

    M. Nakano

    2017-05-01

    Full Text Available Increase in Nd contents of a PLD-made isotropic Nd-Fe-B thick-film magnet enabled us to enhance the thickness of the film magnet deposited on a Si substrate because the linear expansion coefficient of Nd is an intermediate value between Nd2Fe14B and Si. The large amount of Nd, however, degraded the residual magnetic polarization and (BHmax. In the study, we reduced the Nd contents of each Nd-Fe-B film by inserting a Nd or a Nd-rich Nd-Fe-B buffer layer between a Nd-Fe-B film and a Si substrate in order to suppress the mechanical destruction together with the improvement in magnetic properties. It was found that the mechanical property of a Nd-Fe-B film comprising the Nd-Fe-B buffer layer in the thickness range from 10 to 60 μm was superior than that of a sample with the Nd buffer layer. Resultantly, an average (BHmax value of Nd-Fe-B films with each Nd-Fe-B buffer layer deposited on Si substrates could be enhanced by approximately 15 kJ/m3 compared to that of non-buffer-layered films.

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

    International Nuclear Information System (INIS)

    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 10 4 ppm and 4·10 4 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. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xia, M., E-mail: maxi@dtu.dk [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Abrahamsen, A.B. [Department of Wind Energy, DTU Risø campus, Technical University of Denmark, Roskilde (Denmark); Bahl, C.R.H. [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Veluri, B.; Søegaard, A.I. [Grundfos A/S, DK-8850 Bjerringbro (Denmark); Bøjsøe, P. [Holm Magnetics APS, 2800 Kongens Lyngby (Denmark); Millot, S. [FJ Industries A/S, 5863 Ferritslev (Denmark)

    2017-01-15

    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 10{sup 4} ppm and 4·10{sup 4} 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. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

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

    International Nuclear Information System (INIS)

    Suprapedi; Sardjono, P.; Muljadi

    2016-01-01

    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/cm 3 and 4.88 g/cm 3 . 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. (paper)

  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. Liquid coated melt-spun Nd-Fe-B powders for bonded magnets

    Science.gov (United States)

    Li, D.; Gaiffi, S.; Kirk, D.; Young, K.; Herchenroeder, J.; Berwald, T.

    1999-04-01

    The liquid coating (LC) has been employed to apply epoxy and lubricant over the surface of rapidly solidified Nd-Fe-B powder particles. The LC led to an improvement of physical and magnetic properties for the powders and magnets compared to the dry blending and the encapsulation methods. The LC powders have excellent flowability and can be used for bonded magnets requiring very close tolerances; further bonded magnets made using this powder posses higher strength.

  8. Coercivity of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering method

    Directory of Open Access Journals (Sweden)

    Tetsuji Saito

    2017-05-01

    Full Text Available The effects of Nd-Cu alloy powder addition on the microstructures and magnetic properties of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering (SPS method were investigated. The addition of a small amount of Nd-Cu alloy powder, up to 2%, significantly increased the coercivity of the Nd-Fe-B hot-deformed magnets without deteriorating the crystallographic alignment of the Nd2Fe14B phase. The Nd-Fe-B hot-deformed magnet with 2% Nd-Cu alloy powder had the same remanence value as the Nd-Fe-B hot-deformed magnet without Nd-Cu alloy powder addition, but the magnet with 2% Nd-Cu alloy powder exhibited higher coercivity and a higher maximum energy product than the magnet without Nd-Cu alloy powder addition.

  9. Preparation and properties of isotropic Nd-Fe-B bonded magnets with sodium silicate binder

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q.; Hu, R.J.; Yue, M., E-mail: yueming@bjut.edu.cn; Yin, Y.X.; Zhang, D.T.

    2017-08-01

    Graphical abstract: To improve the working temperature of bonded Nd-Fe-B magnets, the heat-resistant binder, sodium silicate, was used to prepare new type bonded Nd-Fe-B magnets. The three-dimensional Si-O-Si structure formed in the curing process has excellent strength; it can ensure that the bonded magnets have a certain shape and usable magnetic properties when working at 200 °C. - Highlights: • Sodium silicate enables bonded Nd-Fe-B magnets to be used for higher operation temperatures. • The sodium silicate bonded magnets exhibit usable maximum energy product of 4.057 MGOe at 200 °C. • The compressive strength of sodium silicate bonded magnets is twice bigger than that of epoxy resin bonded magnets. - Abstract: In present study, sodium silicate, a kind of heat-resistant binder, was used to prepare bonded Nd-Fe-B magnets with improved thermal stability and mechanical strength. Effect of curing temperature and curing time of the new binder to the magnetic properties, microstructure, and mechanical strength of the magnets was systematically investigated. Fracture surface morphology observation show that sodium silicate in bonded magnets could completely be cured at 175 °C for 40 min, and the magnets prepared under this condition exhibit optimal properties. They exhibit usable magnetic properties of B{sub r} of 4.66 kGs, H{sub cj} of 4.84 kOe, and (BH){sub max} of 4.06 MGOe at 200 °C. Moreover, the magnets possess high compressive strength of 63 MPa.

  10. Properties enhancement and recoil loop characteristics for hot deformed nanocrystalline NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z. W.; Huang, Y. L.; Hu, S. L.; Zhong, X. C.; Yu, H. Y.; Gao, X. X.

    2013-01-01

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) and SPS followed by HD using melt spun ribbons as the starting materials. The microstructure of SPSed and HDed magnets were analyzed. The effects of process including temperature and compression ratio on the microstructure and properties were investigated. High magnetic properties were obtained in anisotropic HDed magnets. The combination of Zn and Dy additions was successfully employed to improve the coercivity and thermal stability of the SPSed magnets. Open recoil loops were found in these magnets with Nd-rich composition and without soft magnetic phase for the first time. The relationship between the recoil loops and microstructure for SPS and HD NdFeB magnets were investigated. The investigations showed that the magnetic properties of SPS+HDed magnets are related to the extent of the aggregation of Nd-rich phase, which was formed during HD due to existence of porosity in SPSed precursor. Large local demagnetization fields induced by the Nd-rich phase aggregation leads to the open loops and significantly reduced the coercivity. By reducing the recoil loop openness, the magnetic properties of HDed NdFeB magnets were successfully improved. (author)

  11. 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

    1993-12-31

    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.

  12. On the angular dependence of the coercivity of NdFeB hard magnets

    International Nuclear Information System (INIS)

    Jahn, L.; Christoph, V.; Pastuschenko, J.S.

    1989-01-01

    In order to test the model assumptions on hard magnetic properties of sintered NdFeB magnets, a comparison of the measured and calculated values of the magnetization and remanence coercivities H C and H R , respectively, as a function of the angle between texture axis and external field θ in Nd 16 Fe 76 B 8 and (Nd 0.9 Tb 0.1 ) 16 Fe 76 B 8 is given and explained qualitatively

  13. The comparative study of Nd-Fe-B magnetic materials with different Nd content

    Czech Academy of Sciences Publication Activity Database

    Grujić, A.; Žák, Tomáš; Ćosović, V.; Stajić-Trošić, J.; Spasojević, V.; Talijan, N.

    2009-01-01

    Roč. 3, č. 5 (2009), s. 477-480 ISSN 1842-6573 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : Rapid quenched Nd-Fe-B alloy * Chemical composition * Phase composition * Magnetic properties * Performance permanent-magnets * Nanocrystalline composite * Alloys * Phase Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.451, year: 2009

  14. The effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mural, Zorjana; Kollo, Lauri; Xia, Manlong; Bahl, Christian R.H.; Abrahamsen, Asger Bech; Bez, Henrique Neves; Link, Joosep; Veinthal, Renno

    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. It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop 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/m 3 . The maximum working point and the Curie temperature of the developed magnets were 373 K and 623 K respectively. - Highlights: • Improvement of thermal stability of Nd-Fe-B magnets by introducing nano-TiC prior sintering is proposed. • The mechanism relies on nano-TiC particles behaving as grain growth inhibitors between thin RE-rich phase regions. • The concentration of up to 1 wt% of nano-TiC appears to increase coercivity without a significant decrease in remanence. • The maximum working point and the Curie temperature of the developed magnets are 373 K and 623 K respectively.

  15. 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.

  16. The effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Mural, Zorjana, E-mail: zorjana.mural@ttu.ee [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Kollo, Lauri [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Xia, Manlong; Bahl, Christian R.H. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Abrahamsen, Asger Bech [Department of Wind Energy, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Bez, Henrique Neves [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Link, Joosep [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Veinthal, Renno [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia)

    2017-05-01

    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. It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop 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/m{sup 3}. The maximum working point and the Curie temperature of the developed magnets were 373 K and 623 K respectively. - Highlights: • Improvement of thermal stability of Nd-Fe-B magnets by introducing nano-TiC prior sintering is proposed. • The mechanism relies on nano-TiC particles behaving as grain growth inhibitors between thin RE-rich phase regions. • The concentration of up to 1 wt% of nano-TiC appears to increase coercivity without a significant decrease in remanence. • The maximum working point and the Curie temperature of the developed magnets are 373 K and 623 K respectively.

  17. NdFeB magnets with zero temperature coefficient of induction

    International Nuclear Information System (INIS)

    Ma, B.M.; Narasimhan, K.S.V.L.; Hurt, J.C.

    1986-01-01

    Temperature compensation for the induction of NdFeB type magnets has been investigated. A computer assisted alloy selection method was adopted to identify composition of zero temperature coefficient of induction over -50 to 200 0 C. Selected alloys were processed into magnet by the conventional powder metallurgy method. The experimental temperature coefficient on the sintered magnet correlated with the prediction satisfactory. Holmium is an essential ingredient required for temperature compensation of NdFeB magnets. A magnet, (Nd/sub 0.23/Ho/sub 0.64/Dy/sub 0.13/)/sub 15/Fe/sub 79/B/sub 6/ with B/sub r/ of 7,700 Gauss, H/sub c/ of 7,700 Oe, H/sub ci/ of 20,600 Oe, Bh/sub max/ of 14.8 MGOe and temperature coefficient of -0.029% per 0 C over -50 to +150 was obtained

  18. 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

    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...

  19. 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.

  20. Corrosion behaviour of Nd-Fe-B magnets containing Co and Cr

    International Nuclear Information System (INIS)

    Pawlowska, G.; Bala, H.; Szymura, S.

    1993-01-01

    The effect of partial substitution of iron by Co and Cr on corrosion behaviour of Nd 16 Fe 76 B 8 permanent magnets has been investigated. Small additions of Cr (1 to 4%at) are enough to ensure maximal corrosion inhibition. Greater amount of Cr into Nd-Fe-B alloy (>8%at), against expectations, practically do not affect the corrosion behaviour and additionally, considerably worsen its magnetic properties. Corrosion tests have shown a distinct effect of cobalt addition on the inhibition of both acid corrosion and the abnormal dissolution process of the Nd-Fe-Co-B magnets. Cobalt additions inhibit the atmosphere corrosion of Nd-Fe-B permanent magnets, especially a salt-spray environment. (author). 6 refs, 4 figs, 1 tab

  1. Technological parameter effect on properties of sintered hard-magnetic type Nd-Fe-B materials

    International Nuclear Information System (INIS)

    Rastegaev, V.S.; Stepanova, G.I.; Gudim, Z.Yu.

    1989-01-01

    The effect of each technological operation on manufacturing hard magnets from Nd-Fe-B alloys on properties of sintered permanent magnets is studied. It is noted that violation of the metting regime can result in burn-up of boron and rare earths, and violation of the grinding mode-formation of nonmagnetic powder fractions, etc. Special attention is paid to material protection against oxidation by introducing passivating additions and creating of particular conditions for alloy sintering and heat treatment

  2. Nd-Fe-B sintered magnets fabrication by using atomized powders

    International Nuclear Information System (INIS)

    Goto, R; Sugimoto, S; Matsuura, M; Tezuka, N; Une, Y; Sagawa, M

    2011-01-01

    Nd-Fe-B sintered magnets are required to achieve high coercivity for improvement of their thermal stability. Dy is added to increase coercivity, however, this element decrease magnetization and energy products. Therefore, Dy-lean Nd-Fe-B sintered magnets with high coercivity are strongly demanded. To increase coercivity, it is necessary that microstructure of sintered magnets is consisted of both fine main phase particles and homogeneously distributed Nd-rich phases around the main phase. To meet those requirements, Nd-Fe-B atomized powders were applied to the fabrication process of sintered magnets. Comparing with the case of using strip casting (SC) alloys, jet-milled powders from atomized powders show homogeneous distribution of Nd-rich phase. After optimized thermal treatment, coercivities of sintered magnets from atomized powders and SC alloys reach 1050 kA·m-1 and 1220 kA·m-1, respectively. This difference in coercivity was due to initial oxygen concentration of starting materials. Consequently, Nd-rich phases became oxides with high melting points, and did not melt and spread during sintering and annealing.

  3. 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.

  4. Development of a phosphating process for corrosion protection in NdFeB magnets

    International Nuclear Information System (INIS)

    Silva, Adonis Marcelo Saliba

    2001-01-01

    NdFeB magnets are important materials, which produce better energy efficiency in electrical devices, but they are rather vulnerable to corrosion. In this study, a phosphating treatment for protection against corrosion of NdFeB magnets has been investigated. Phosphating is generally used as a pretreatment in the application of protective coatings. This treatment increases the corrosion assistance in defective areas of the coating as well as improves the adhesion between coating and substrate. A commercial NdFeB magnet produced by powder metallurgy has been used and the effect of the following parameters on phosphating was studied: time of phosphating; pH of phosphating solution; anodic polarization and molybdate addition to the phosphating solution. The results showed a significant increase in the corrosion resistance of magnets phosphated in a solution concentrated between 10-20 g/L NaH 2 PO 4 , pH in the range of 3 to 4.6, acidulated preferably with H 3 PO 4 at room temperature (20±1) deg C. Conversion coatings formed at solutions of pH 3.8 showed better corrosion resistance. Phosphating times longer than 4 hours increased the magnet corrosion resistance 10 to 20 times. This resistance improves with higher immersion times. Anodic polarization of the magnet in the range 200-400 mV SCE accelerated phosphating. Results indicated that molybdate interacts preferentially with Nd rich phase of the magnet. In addition to the newly developed technology in this work for NdFeB corrosion protection, two methodologies have been introduced to facilitate electrochemical analyses: selection of samples of similar electrochemical behavior, based on the current density after 200s of constant anodic polarization; and evaluation of the corrosion protection provided by conversion coatings by monitoring of gas evolution during corrosion in acid solution. (author)

  5. Magnetic and microstructural properties of thin NdFeB based films and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bommer, Lars; Goll, Dagmar [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

    2010-07-01

    The magnetic and microstructural properties of NdFeB and NdFeB/Fe thin films and nanostructures are presented. Samples with Cr buffer and protection layer (minimum thickness: d=50 nm) have been produced by ion beam sputtering at elevated temperatures (T{sub s}=700 C) using Al{sub 2}O{sub 3} and MgO(001) single crystal substrates. Films deposited on Al{sub 2}O{sub 3} substrates show c-axis growth in out-of-plane direction down to thicknesses of the NdFeB film of d=10 nm with coercivities up to {mu}{sub 0}H{sub c}=1 T. The texture of films deposited on MgO(001) substrates is less pronounced and films below d=20 nm show no hard magnetic behavior. For comparison, films were deposited at room temperature on Al{sub 2}O{sub 3} and MgO(001) followed by post-annealing in Ar atmosphere (T{sub pa}=525-650 C) leading to coercivities as high as {mu}{sub 0}H{sub c}=1.2 T but with isotropic behavior. By TEM images the grain structure of the NdFeB samples is studied. Bilayers of NdFeB (d=50 nm) and Fe (d=0-20 nm) show fully exchange coupled behavior. From the temperature dependence of the coercivity the microstructural parameters of all samples have been determined. Furthermore NdFeB periodical patterns were produced by means of electron beam lithography with dot sizes of 1000 nm and 500 nm, respectively.

  6. Comparison of properties of Nd-Fe-B and Sm-Co permanent magnets

    International Nuclear Information System (INIS)

    Ervens, W.

    1985-01-01

    In this paper permanent magnet materials on the basis of RECo and NdFeB are compared in terms of manufacturing processes, magnetic values at ambient and elevated temperatures, maximum operating temperatures and magnetization behaviour. At the present stage of development NdFeB-magnets are superior to the high coercivity RECo-magnets in their B/sub r/ - and (BH)/sub ma//sup -/ values at room temperature but are inferior to them at temperatures higher than 120 0 C

  7. Magnetization reversal mechanism of Nd-Fe-B films with perpendicular magnetic anisotropy

    International Nuclear Information System (INIS)

    Liu Xiaoxi; Ishida, Go; Morisako, Akimitsu

    2011-01-01

    The microstructure and magnetic properties of Nd-Fe-B films with thicknesses from 100 nm to 3 nm have been investigated. All the films show excellent perpendicular magnetic anisotropy with a squareness ratio of 1 in the perpendicular direction and almost zero coercivity in the in-plane direction. Of particular interest is that the initial magnetization curves sensitively depended on the film thickness. Films thicker than 15 nm show steep initial magnetization curve. Although the films have coercivities larger than 21 kOe, the films can be fully magnetized from the thermally demagnetized state with a field as small as 5 kOe. With the decrease of film thickness to 5 nm, the initial magnetization curve becomes flat. The evolution of initial magnetization curves with film thickness can be understood by the microstructure of the films. Films with thickness of 15 nm show close-packed grains without any intergranular phases. Such microstructures lead to steep initial magnetization curves. On the other hand, when the film thickness decreased to 3 nm, the film thickness became nonuniform. Such microstructure leads to flat initial magnetization curves.

  8. Multi-pole magnetization of NdFeB magnets for magnetic micro-actuators and its characterization with a magnetic field mapping device

    International Nuclear Information System (INIS)

    Toepfer, J.; Pawlowski, B.; Beer, H.; Ploetner, K.; Hofmann, P.; Herrfurth, J.

    2004-01-01

    Multi-pole magnetization of NdFeB plate magnets of thickness between 0.25 and 2 mm with a stripe pattern and a pole pitch of 2 or 1 mm was performed by pulse magnetization. The experimental conditions of the magnetization process were optimized to give a maximum surface flux density at the poles. The magnetic field distribution above the magnets was measured with a field mapping device that automatically scans the surface of the magnet with a Hall probe. It is demonstrated for different magnet geometries that the field mapping system is a useful device to study the magnetic surface pole structure. The characterization of the pole flux density of multi-pole NdFeB flat magnets is an important prerequisite for the application of these magnets in miniature actuators

  9. Coercivity degradation caused by inhomogeneous grain boundaries in sintered Nd-Fe-B permanent magnets

    Science.gov (United States)

    Chen, Hansheng; Yun, Fan; Qu, Jiangtao; Li, Yingfei; Cheng, Zhenxiang; Fang, Ruhao; Ye, Zhixiao; Ringer, Simon P.; Zheng, Rongkun

    2018-05-01

    Quantitative correlation between intrinsic coercivity and grain boundaries in three dimensions is critical to further improve the performance of sintered Nd-Fe-B permanent magnets. Here, we quantitatively reveal the local composition variation across and especially along grain boundaries using the powerful atomic-scale analysis technique known as atom probe tomography. We also estimate the saturation magnetization, magnetocrystalline anisotropy constant, and exchange stiffness of the grain boundaries on the basis of the experimentally determined structure and composition. Finally, using micromagnetic simulations, we quantify the intrinsic coercivity degradation caused by inhomogeneous grain boundaries. This approach can be applied to other magnetic materials for the analysis and optimization of magnetic properties.

  10. Magnetic viscosity, susceptibility and fluctuation fields in sintered NdFeB

    International Nuclear Information System (INIS)

    Tomka, G.J.; Bissell, P.R.; O'Grady, K.; Chantrell, R.W.

    1990-01-01

    Magnetic viscosity and irreversible susceptibility of a sample of anisotropic sintered NdFeB have been measured using a vibrating sample magnetometer. The fluctuation field as a function of local field is found to decrease with increasing demagnetizing field with a dip at the coercivity. This behavior is compared with an existing computer model based on a non-interacting system of fine, uniaxial, randomly oriented particles

  11. The demagnetising factors for bonded neodymium iron boron (NdFeB) magnets

    International Nuclear Information System (INIS)

    Wang, Z.

    2000-10-01

    Both analytical and computational methods have been, for the first time, employed to study the demagnetising factors for bonded magnets. The demagnetising factors for bonded NdFeB magnets are dependent on the external shape of the bonded magnet, the shapes of magnetic particles, the magnetic loading percentage and the distributions of magnetic particles. Particularly, it has been shown that the demagnetising factor along the length of an infinitely long bonded magnet is not equal to zero but that it also depends on the shapes of the magnetic particles, magnetic loading percentage and the distribution of magnetic particles. However, the sum of the demagnetising factors along the x, y and z directions is, as expected, unity for all bonded magnets. The demagnetising factor for a fully dense magnet, which is dependent only on the external shape of the magnet, can be considered as a special case of bonded magnets in which the magnetic loading is 100%. Simplified formulae for calculating the demagnetising factors for simple shaped magnets such as cuboid, cylindroid and ellipsoid shapes were obtained and the values are in reasonable agreement with precise analytical solutions. A Lorentz ''sphere'' concept has, for the first time, been employed to calculate the demagnetising factors for hollow magnets and bonded NdFeB magnets. The simplified formulae for hollow magnets and bonded magnets were derived. Computer programmes based on the basic energy method were developed and employed to calculate the demagnetising factors for bonded magnet models, such as a one-dimensional NdFeB ribbon array, two-dimensional bonded magnets and three-dimensional bonded magnets. A finite difference method and a finite element method have been, for the first time, employed to calculate the demagnetising factors for two-dimensional bonded magnet models and the results are comparable with those obtained using the basic energy method. Procedures for calculating demagnetising curves (J vs H) for

  12. The Creation of a Strong Magnetic Field by Means of Large Magnetic Blocks from NdFeB Magnets in Opposing Linear Halbach Arrays

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2016-01-01

    Roč. 21, č. 3 (2016), 364-373 ISSN 1226-1750 Institutional support: RVO:67985891 Keywords : magnetic field * permanent magnets * NdFeB magnets * Halbach Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.713, year: 2016 http://komag.org/journal/

  13. Effects of Dy and Nb on the magnetic properties and corrosion resistance of sintered NdFeB

    International Nuclear Information System (INIS)

    Yu, L.Q.; Wen, Y.H.; Yan, M.

    2004-01-01

    Dy and Nb were added into the sintered NdFeB magnets with the aim of improving their magnetic properties and corrosion resistance. It was found that intrinsic coercivity of magnets is promoted whilst remanence is reduced as a result of Dy addition. Simultaneous addition of Dy and Nb not only gives rise to greatly improved coercivity, but also suppresses the undesirable effect of Dy on the remanence. The optimum magnetic properties were achieved when 1.0% Dy and 1.5% Nb were incorporated. Moreover, corrosion resistance of NdFeB magnets improves with the increase in the content of Dy and Nb

  14. 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.

  15. Barkhausen jumps and magnetic viscosity in NdFeB magnets

    International Nuclear Information System (INIS)

    LoBue, M.; Basso, V.; Beatrice, G.; Bertotti, C.; Durin, G.; Sasso, C.P.

    2005-01-01

    We present the analysis of Barkhausen noise measured on a Nd-Fe-B sintered sample during viscosity experiments at constant applied field H. The measured jump sizes give direct evidence that the dominant magnetization process is the reversal of a single or of a small group of grains. The Barkhausen noise average amplitude allows to evaluate the viscosity coefficient S and the related activation volume v a . We found v a 1/3 ∼ 6nm which is comparable to the domain wall width, in agreement with previous interpretations. The Barkhausen jump sizes show a power-law distribution independent of the time elapsed from the beginning of the relaxation. This fact validates the interpretation of the observed relaxations as due to thermal activation over a distribution of energy barriers

  16. Barkhausen jumps and magnetic viscosity in NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    LoBue, M. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy)]. E-mail: lobue@ien.it; Basso, V. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy); Beatrice, G. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy); Bertotti, C. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy); Durin, G. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy); Sasso, C.P. [Instituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino (Italy)

    2005-04-15

    We present the analysis of Barkhausen noise measured on a Nd-Fe-B sintered sample during viscosity experiments at constant applied field H. The measured jump sizes give direct evidence that the dominant magnetization process is the reversal of a single or of a small group of grains. The Barkhausen noise average amplitude allows to evaluate the viscosity coefficient S and the related activation volume v{sub a}. We found v{sub a}{sup 1/3} {approx} 6nm which is comparable to the domain wall width, in agreement with previous interpretations. The Barkhausen jump sizes show a power-law distribution independent of the time elapsed from the beginning of the relaxation. This fact validates the interpretation of the observed relaxations as due to thermal activation over a distribution of energy barriers.

  17. 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.

  18. 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.

  19. Effect of molybdate on phosphating of Nd-Fe-B magnets for corrosion protection

    Directory of Open Access Journals (Sweden)

    Adonis Marcelo Saliba-Silva

    2005-06-01

    Full Text Available Nd-Fe-B magnets are highly susceptible to corrosion and need protection against environment attack. The use of organic coatings is one of the main methods of corrosion protection of these materials. Data related to the effect of conversion coatings, such as phosphating, on corrosion performance of these magnets is still scarce. Studies about the effect of phosphating on the corrosion resistance of a commercial Nd-Fe-B sintered magnet indicated that it increases the corrosion resistance of these magnets, compared to non-phosphated magnets. In this study, the solution chemistry of a phosphating bath was altered with the addition of molybdate and its effect on the corrosion resistance of magnets investigated. Sintered magnet specimens were phosphated in solutions of 10 g/L NaH2PO4 (pH 3.8, either with or without molybdate [10-3 M MoO4(2-], to improve their corrosion resistance. The effect of phosphating time was also evaluated, and specimens were phosphated for 4 and 18 hours. To evaluate the corrosion performance of phosphated and unphosphated specimens, a corrosion test based on monitoring hydrogen evolution on the surface of the magnets was used. This technique revealed that the addition of molybdate to the phosphating solution improved the corrosion resistance of the magnets phosphated by immersion for short periods but had no beneficial effect if phosphated by immersion for longer periods.

  20. Interaction domains in die-upset NdFeB magnets in dependence on the degree of deformation

    International Nuclear Information System (INIS)

    Khlopkov, K.; Gutfleisch, O.; Schaefer, R.; Hinz, D.; Mueller, K.-H.; Schultz, L.

    2004-01-01

    The magnetic domain structure of NdFeB magnets has been studied using high resolution, digitally enhanced Kerr-microscopy. Melt-spun NdFeB powder (MQU-F TM ) was hot pressed into fully dense samples and then hot deformed to axially textured magnets. Various degrees of deformation (height reduction) up to 76% have been realized. Pronounced interaction domains have been observed only in magnets, which were deformed to a degree of deformation of at least 52%. With increasing alignment of the grains the interaction domains become more and more visible and their size increases

  1. 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.

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

    International Nuclear Information System (INIS)

    Deng, Xiangxing; Liu, Zhongwu; Yu, Hongya; Xiao, Zhiyu; Zhang, Guoqing

    2015-01-01

    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) max increased from 65 to 120 kJ/m 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

  3. Angular dependence of coercivity in isotropically aligned Nd-Fe-B sintered magnets

    Science.gov (United States)

    Matsuura, Yutaka; Nakamura, Tetsuya; Sumitani, Kazushi; Kajiwara, Kentaro; Tamura, Ryuji; Osamura, Kozo

    2018-05-01

    In order to understand the coercivity mechanism in Nd-Fe-B sintered magnets, the angular dependence of the coercivity of an isotropically aligned Nd15Co1.0B6Febal. sintered magnet was investigated through magnetization measurements using a vibrating sample magnetometer. These results are compared with the angular dependence calculated under the assumption that the magnetization reversal of each grain follows the Kondorskii law or, in other words, the 1/cos θ law for isotropic alignment distributions. The calculated angular dependence of the coercivity agrees very well with the experiment for magnetic fields applied between angles of 0 and 60°, and it is expected that the magnetization reversal occurs in each grain individually followed the 1/cos θ law. In contrast, this agreement between calculation and experiment is not found for anisotropic Nd-Fe-B samples. This implies that the coercivity of the aligned magnets depends upon the de-pinning of the domain walls from pinning sites. When the de-pinning occurs, it is expected that the domain walls are displaced through several grains at once.

  4. Effects of proton irradiation on electronic structure of NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: lzhen@hit.edu.cn; Xu, C.Y.; Sun, X.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2009-09-15

    Effects of proton irradiation on electronic structure and atomic local structure of N35EH-type NdFeB permanent magnet were investigated by soft X-ray absorption spectrometry and Moessbauer spectrometry. The local coordination environment of Fe atoms changes after proton irradiation, and the average hyperfine field H{sub in} of the magnets decreases from 288.4 to 286.9 kOe. The effects of irradiation on Fe atoms local environment at different lattice sites are different. The near edge structure of Fe L{sub 3} edge is changed, indicating the density of unoccupied state of Fe 3d electrons increases after proton irradiation.

  5. Hydrogen Decrepitation Press-Less Process recycling of NdFeB sintered magnets

    Science.gov (United States)

    Xia, Manlong; Abrahamsen, Asger B.; Bahl, Christian R. H.; Veluri, Badrinath; Søegaard, Allan I.; Bøjsøe, Poul

    2017-11-01

    A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered in a graphite mold. Coercivities up to 534 kA/m were obtained in porous samples based on powder size d 100 μm. The coercivity reached Hci = 957 kA/m being 86% of the original N48M material without addition of rare earth elements.

  6. Coercivity enhancement in Nd-Fe-B sintered permanent magnet by Dy nanoparticles doping

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q., E-mail: liuweiqiang77@hotmail.co [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Sun, H. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yi, X.F. [Anhui Earth-panda Advance Magnetic Material Co., Ltd., Anhui 231500 (China); Liu, X.C.; Zhang, D.T. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yue, M., E-mail: yueming@bjut.edu.c [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Zhang, J.X. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

    2010-07-02

    Nd-Fe-B permanent magnets with a small amount of Dysprosium (Dy) nanoparticles doping were prepared by conventional sintered method, and the microstructure and magnetic properties of the magnets were studied. Investigation shows that the coercivity rises gradually, while the remanence decreases simultaneously with increased Dy doping amount. As a result, the magnet with 1.5 wt.% Dy exhibits optimal magnetic properties. Further investigation presumed that Dy is enriched as (Nd, Dy){sub 2}Fe{sub 14}B phase in the surface region of the Nd{sub 2}Fe{sub 14}B matrix grains indicated by the enhancement of the magneto-crystalline anisotropy field of the Nd{sub 2}Fe{sub 14}B phase. As a result, the magnet doped with a small amount of Dy nanoparticles possesses remarkably enhanced coercivity without sacrificing its magnetization noticeably.

  7. Effect of composition polymeric PVB binder on physical, magnetic properties and microstructure of bonded magnet NdFeB

    Science.gov (United States)

    Sardjono, P.; Muljadi; Suprapedi; Sinuaji, P.; Ramlan; Gulo, F.

    2017-04-01

    The bonded magnet NdFeB has been made by using the hot press method and using Poly Vinyl Butiral (PVB) as a binder. The composition of polymeric binder was varied: 0, 2, 4, 6 and 7 % of weight. Both raw materials are weighed and mixed according to the composition of PVB, then formed by hot press with a pressure 30 MPa, a temperature of 160 ° C and holding time for 30 minutes. The bulk density was measured by using Archimedes method. SEM observation was done to determine the microstructure of bonded magnet NdFeB. The flux magnetic value was measured by using a Gauss meter and the measurement of hysteresis curves was done to know value of remanence Br, coercivity Hc and energy product BHmax by using VSM. According to the characterization results show that the best composition of PVB is 2 of weight. The properties of bonded magnet NdFeB of those compositions are the bulk density around 5.66 g/cm3. Flux Magnetic value: 1862 Gauss, Br value: 5000 kGauss, Hc value: 8.49 kOe and BHmax value : 5.10 MGOe. According of SEM observation results show that the polymer matrix of PVB appears to have covered on all surface grain and filled grain boundary.

  8. Al–Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jingjing; Xu, Bajin; Ling, Guoping, E-mail: linggp@zju.edu.cn

    2014-06-01

    Al–Mn coatings were electrodeposited on sintered NdFeB permanent magnet in MnCl{sub 2}–AlCl{sub 3}–1-ethyl-3-methylim-idazolium chloride (MnCl{sub 2}–AlCl{sub 3}–EMIC) ionic liquid at room temperature. The coatings were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adhesion strength of the coating on NdFeB substrate was evaluated by thermal shock and scratch test. The hardness and corrosion behavior of Al–Mn coating were measured by a Knoop microhardness tester, immersion test and neutral salt spray test respectively. The results showed that the amorphous structure of the deposits was obtained at the current density of 6 mA/cm{sup 2}, while higher current densities resulted in a mixed structure of amorphous and crystalline. The Al–Mn coating showed excellent adhesion strength on NdFeB substrate with the thermal shock test over 30 cycles and L{sub c} > 80 N. The hardness of Al–Mn coating was up to 5.4 GPa. The amorphous Al–Mn coating showed an anodic sacrificial protection with a low corrosion rate for NdFeB. Meanwhile, the magnetic properties measured by an AMT-4 magnetic measurement device showed that Al–Mn coating did not deteriorate the magnetic property of NdFeB.

  9. Al–Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance

    International Nuclear Information System (INIS)

    Ding, Jingjing; Xu, Bajin; Ling, Guoping

    2014-01-01

    Al–Mn coatings were electrodeposited on sintered NdFeB permanent magnet in MnCl 2 –AlCl 3 –1-ethyl-3-methylim-idazolium chloride (MnCl 2 –AlCl 3 –EMIC) ionic liquid at room temperature. The coatings were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adhesion strength of the coating on NdFeB substrate was evaluated by thermal shock and scratch test. The hardness and corrosion behavior of Al–Mn coating were measured by a Knoop microhardness tester, immersion test and neutral salt spray test respectively. The results showed that the amorphous structure of the deposits was obtained at the current density of 6 mA/cm 2 , while higher current densities resulted in a mixed structure of amorphous and crystalline. The Al–Mn coating showed excellent adhesion strength on NdFeB substrate with the thermal shock test over 30 cycles and L c > 80 N. The hardness of Al–Mn coating was up to 5.4 GPa. The amorphous Al–Mn coating showed an anodic sacrificial protection with a low corrosion rate for NdFeB. Meanwhile, the magnetic properties measured by an AMT-4 magnetic measurement device showed that Al–Mn coating did not deteriorate the magnetic property of NdFeB.

  10. Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

    Science.gov (United States)

    Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

    2018-03-01

    In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

  11. 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.

  12. Effect of washing process on the magnetic properties of Nd-Fe-B nanoparticles prepared by reduction-diffusion method

    Science.gov (United States)

    Wang, Y.; Ahn, J.; Kim, D.; Ren, W. J.; Liu, W.; Zhang, Z. D.; Choi, C. J.

    2017-10-01

    Nd-Fe-B nanoparticles with a particle size below 50 nm and excellent magnetic properties were obtained via a novel route which makes use of both spray drying and reduction-diffusion processes. Uniform Nd-Fe-B particles were formed by the optimization of Ca amount as a reducing agent and additional washing by milling in ethanol media. Especially, we implemented a two-step washing process which contributed to the excellent magnetic properties with high remanence and coercivity. After the removal of CaO by novel washing process, the maximum energy product (BH)max of the particles showed 22.1 MGOe. This value is superior to those reported in reduction-diffusion process. We used Henkel plot to assume the mechanism of magnetic interactions of the Nd-Fe-B nanoparticles.

  13. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Popov, A.G. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Str. S. Kovalevskoy, 18, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences and Mathematics, Ural Federal University, Av. Mira, 19, 620002 Ekaterinburg (Russian Federation); Golovnia, O.A., E-mail: golovnya@imp.uran.ru [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Str. S. Kovalevskoy, 18, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences and Mathematics, Ural Federal University, Av. Mira, 19, 620002 Ekaterinburg (Russian Federation); Protasov, A.V. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Str. S. Kovalevskoy, 18, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences and Mathematics, Ural Federal University, Av. Mira, 19, 620002 Ekaterinburg (Russian Federation)

    2017-04-15

    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 – 3.2×10{sup 3} kg/m{sup 3}. 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 3.2×10{sup 3} kg/m{sup 3}, 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 B{sub r} ≥1.34 T, H{sub c} ≥950 kA/m, (BH){sub max} ≥340 kJ/m{sup 3}, and the degree of alignment exceeding 96% were produced. - Highlights: • The pressless process (PLP) in magnet production is studied. • A new method of the loading of powder in an applied DC magnetic field is suggested. • The method allows achieving higher degree of alignment in moderate magnetic field. • Density of sintered magnets is studied experimentally and via DEM simulation. • Low density is caused by the formation of magnetostatic chains of powder particles.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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 – 3.2×10 3 kg/m 3 . 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 3.2×10 3 kg/m 3 , 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 B r ≥1.34 T, H c ≥950 kA/m, (BH) max ≥340 kJ/m 3 , and the degree of alignment exceeding 96% were produced. - Highlights: • The pressless process (PLP) in magnet production is studied. • A new method of the loading of powder in an applied DC magnetic field is suggested. • The method allows achieving higher degree of alignment in moderate magnetic field. • Density of sintered magnets is studied experimentally and via DEM simulation. • Low density is caused by the formation of magnetostatic chains of powder particles.

  16. Effects of buffer layer temperature on the magnetic properties of NdFeB thin film magnets

    International Nuclear Information System (INIS)

    Kim, Y.B.; Cho, S.H.; Kim, H.T.; Ryu, K.S.; Lee, S.H.; Lee, K.H.; Kapustin, G.A.

    2004-01-01

    Effects of the buffer layer temperature (T b ) on the magnetic properties and microstructure of [Mo/NdFeB/Mo]-type thin films have been investigated. The Mo-buffer layer with low T b is composed of fine grains while that with high T b has coarse grains. The subsequent NdFeB layer also grows with fine or coarse grains following the buffer layer structure. The NdFeB layer grown on a low T b buffer shows high coercivity and strong perpendicular anisotropy. The best magnetic properties of i H c =1.01 MA/m (12.7 kOe), B r =1.31 T (13.1 kG) and BH max =329 kJ/m 3 (41.4 MGOe) were obtained from the film with T b =400 deg. C

  17. An environmentally friendly electro-oxidative approach to recover valuable elements from NdFeB magnet waste

    NARCIS (Netherlands)

    Venkatesan, P.; Sun, Z.; Sietsma, J.; Yang, Y.

    2018-01-01

    In this manuscript, we demonstrate a room temperature electrochemical process for efficiently recycling NdFeB magnet waste. First, the magnet waste was completely leached with HCl and then, in-situ electrochemical oxidation was performed to selectively oxidize Fe(II) in the leachate to Fe(III).

  18. Micro-structuring of thick NdFeB films using high-power plasma etching for magnetic MEMS application

    International Nuclear Information System (INIS)

    Jiang, Yonggang; Fujita, Takayuki; Higuchi, Kohei; Maenaka, Kazusuke; Masaoka, Shingo; Uehara, Minoru

    2011-01-01

    This paper describes the micro-patterning of thick NdFeB magnetic films using a high-power plasma etching method. The effects of RF bias power and gas composition on the selectivity and etching rate are experimentally studied. A maximum etching rate of 60 nm min −1 is achieved with an inductively coupled plasma power of 500 W and a RF bias power of 200 W. A maximum selectivity of 0.26 between hard baked AZP4903 photoresist and NdFeB magnetic films is achieved when volumetric Cl 2 concentration is 2.5%. NdFeB micro-magnets as thick as 4.2 µm are achieved by using AZP4903 photoresist. Magnetic film as thick as 10 µm can be patterned by using SU-8 photoresist with a thickness of 100 µm as the mask. The magnetic property of patterned microstructures is characterized using a vibrating sample magnetometer and the magnetic field distribution is measured using a Hall effect sensor IC. The characterization results indicate that the patterned magnetic microstructures have a high magnetic remanance of 1.0 T, which is comparable to that of the non-patterned NdFeB films.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nlebedim, I.C. [Ames Laboratory, Ames, IA 50011 (United States); Ucar, Huseyin; Hatter, Christine B. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); McCallum, R.W. [Ames Laboratory, Ames, IA 50011 (United States); McCall, Scott K. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Kramer, M.J. [Ames Laboratory, Ames, IA 50011 (United States); Paranthaman, M. Parans [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2017-01-15

    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. - Highlights: • Optimum alignment of anisotropic magnet powders can enable high performance bonded magnets. • The viscoelastic state of polymer binders determines the dominating coercivity mechanism. • The minimum deviation in coercivity and remanence, with magnetic field, can occur at different temperatures. • Melting characteristics of polymer binders and the change in magnetization during alignment can be correlated.

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Optimum alignment of anisotropic magnet powders can enable high performance bonded magnets. • The viscoelastic state of polymer binders determines the dominating coercivity mechanism. • The minimum deviation in coercivity and remanence, with magnetic field, can occur at different temperatures. • Melting characteristics of polymer binders and the change in magnetization during alignment can be correlated.

  1. Nd composition dependence of microstructure and magnetic properties for gradient sputtered NdFeB films

    International Nuclear Information System (INIS)

    Li Shandong; Wang Dawei; Fang Jianglin; Duh, J.-G.; Wang Yinying; Wu Yizhi; Huang Junheng; Zheng Hongjun

    2008-01-01

    NdFeB films with Nd compositions varied from 13.34 to 24.30 at% were deposited by DC gradient sputtering using targets Nd 12.5 Fe 71.5 B 16 and Nd. The hard magnetic properties, grain growth direction and magnetic domain structures were dramatically influenced by Nd composition. The samples with intermediate Nd concentrations exhibited optimal magnetic properties and microstructures, such as large squareness ratio over 0.9, large energy product up to 174 kJ/m 3 , and vertical domain structure. However, the samples with higher and lower Nd compositions showed almost isotropic loops. (0 0 l) as main X-ray diffraction peaks in the optimal Nd composition region indicated most of Nd 2 Fe 14 B grains with c-axis perpendicular to the film plane, while NdFeB grains in other region are almost random growth. The good magnetic properties can be attributed to the vertical growth of Nd 2 Fe 14 B grains

  2. Nd composition dependence of microstructure and magnetic properties for gradient sputtered NdFeB films

    Energy Technology Data Exchange (ETDEWEB)

    Li Shandong [Department of Physics, Fujian Normal University, Fuzhou 350007 (China)], E-mail: dylsd007@yahoo.com.cn; Wang Dawei [Department of Physics, Fujian Normal University, Fuzhou 350007 (China); Fang Jianglin [Center for Materials Analysis, Nanjing University, Nanjing 210093 (China); Duh, J.-G. [Department of Materials Science and Engineering, National TsingHua Universtiy, Hsinchu, Taiwan (China); Wang Yinying; Wu Yizhi; Huang Junheng; Zheng Hongjun [Department of Physics, Fujian Normal University, Fuzhou 350007 (China)

    2008-08-15

    NdFeB films with Nd compositions varied from 13.34 to 24.30 at% were deposited by DC gradient sputtering using targets Nd{sub 12.5}Fe{sub 71.5}B{sub 16} and Nd. The hard magnetic properties, grain growth direction and magnetic domain structures were dramatically influenced by Nd composition. The samples with intermediate Nd concentrations exhibited optimal magnetic properties and microstructures, such as large squareness ratio over 0.9, large energy product up to 174 kJ/m{sup 3}, and vertical domain structure. However, the samples with higher and lower Nd compositions showed almost isotropic loops. (0 0 l) as main X-ray diffraction peaks in the optimal Nd composition region indicated most of Nd{sub 2}Fe{sub 14}B grains with c-axis perpendicular to the film plane, while NdFeB grains in other region are almost random growth. The good magnetic properties can be attributed to the vertical growth of Nd{sub 2}Fe{sub 14}B grains.

  3. Influence of annealing temperature on the Dy diffusion process in NdFeB magnets

    Science.gov (United States)

    Hu, Sheng-qing; Peng, Kun; Chen, Hong

    2017-03-01

    Sintered NdFeB magnets were coated with a layer of Dy metal using electron beam evaporation method and then annealed at various temperatures to investigate the temperature dependence of Dy diffusion process in NdFeB magnets. A Dy-rich phase was observed along the grain boundaries after the grain boundary diffusion process, the diffusion coefficients of various temperatures were obtained, the diffusion coefficients of Dy along the grain boundaries at 800 °C and 900 °C were determined to be 9.8×10-8 cm2 s-1 and 2.4×10-7 cm2 s-1, respectively. The diffusion length depended on the annealing temperature and the maximum diffusion length of approximately 1.8 mm and 3.0 mm can be obtained after annealing at 800 °C and 900 °C for 8 h. Higher diffusion temperature results in the diffusion not only along the grain boundaries but also into grains and then decrease in magnetic properties. The optimum annealing conditions can be determined as 900 °C for 8 h. The coercivity was improved from 1040 kA/m to 1450 kA/m and its magnetization has no significant reduction after the grain boundary diffusion process at the optimum annealing conditions.

  4. Magnetic and structural properties of NdFeB thin film prepared by step annealing

    International Nuclear Information System (INIS)

    Serrona, Leo K.E.B.; Sugimura, A.; Fujisaki, R.; Okuda, T.; Adachi, N.; Ohsato, H.; Sakamoto, I.; Nakanishi, A.; Motokawa, M.

    2003-01-01

    The crystallization of the amorphous phase into the tetragonal Nd 2 Fe 14 B (PHI) phase and the corresponding changes in magnetic properties have been examined by step annealing experiment using a 2 μm thick NdFeB film sample. Microstructural and magnetic analysis indicate that the film was magnetically soft as deposited with the coercivity H ciperp -1 and the remnant magnetization 4πM rperp -1 was developed and diffraction analysis showed evidence of PHI phase 002l peaks being aligned perpendicular to the film plane. At an optimum annealing temperature of 575 deg. C, the remnant magnetization of this anisotropic thin film is around 0.60 T with intrinsic coercivity of ∼1340 kA m -1 . Annealing the film sample at 200 deg. C≤T ann ≤750 deg. C showed variations in magnetic properties that were mostly due to the change in the perpendicular anisotropy. Based on 4πM sperpendicular values plotted against T ann , a dip in 4πM sperpendicular values was observed as T ann increased in the soft-to-hard magnetic characteristics transition region and rose as the hard crystalline phase started to form. The results show that the magnetic properties of the NdFeB film were slightly influenced by the presence of NdO, film surface roughening and the small increase in crystal size as a consequence of repeated heat treatment. At T ann ∼300 deg. C, the nominal saturation magnetization indicated a certain degree of weak perpendicular magnetic anisotropy in the film sample considered to be essential in the enhancement of coercivity in crystallized films

  5. Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

    International Nuclear Information System (INIS)

    Ono, K.; Inami, N.; Saito, K.; Takeichi, Y.; Kawana, D.; Yokoo, T.; Itoh, S.; Yano, M.; Shoji, T.; Manabe, A.; Kato, A.; Kaneko, Y.

    2014-01-01

    The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant D sw (100.0 ± 4.9 meV.Å 2 ) and the exchange stiffness constant A (6.6 ± 0.3 pJ/m)

  6. 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.

  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

    2016-10-31

    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 H ci  = 688.4 kA/m, remanence B r  = 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.

  8. Rare Earth Extraction from NdFeB Magnet Using a Closed-Loop Acid Process.

    Science.gov (United States)

    Kitagawa, Jiro; Uemura, Ryohei

    2017-08-14

    There is considerable interest in extraction of rare earth elements from NdFeB magnets to enable recycling of these elements. In practical extraction methods using wet processes, the acid waste solution discharge is a problem that must be resolved to reduce the environmental impact of the process. Here, we present an encouraging demonstration of rare earth element extraction from a NdFeB magnet using a closed-loop hydrochloric acid (HCl)-based process. The extraction method is based on corrosion of the magnet in a pretreatment stage and a subsequent ionic liquid technique for Fe extraction from the HCl solution. The rare earth elements are then precipitated using oxalic acid. Triple extraction has been conducted and the recovery ratio of the rare earth elements from the solution is approximately 50% for each extraction process, as compared to almost 100% recovery when using a one-shot extraction process without the ionic liquid but with sufficient oxalic acid. Despite its reduced extraction efficiency, the proposed method with its small number of procedures at almost room temperature is still highly advantageous in terms of both cost and environmental friendliness. This study represents an initial step towards realization of a closed-loop acid process for recycling of rare earth elements.

  9. Recovery of rare earths from spent NdFeB magnets of wind turbine: Leaching and kinetic aspects.

    Science.gov (United States)

    Kumari, Aarti; Sinha, Manish Kumar; Pramanik, Swati; Sahu, Sushanta Kumar

    2018-05-01

    Increasing demands of rare earth (RE) metals for advanced technological applications coupled with the scarcity of primary resources have led to the development of processes to treat secondary resources like scraps or end of life products that are often rich in such metals. Spent NdFeB magnet may serve as a potential source of rare earths containing around ∼30% of neodymium and other rare earths. In the present investigation, a pyro-hydrometallurgical process has been developed to recover rare earth elements (Nd, Pr and Dy) from the spent wind turbine magnet. The spent magnet is demagnetized and roasted at 1123 K to convert rare earths and iron to their respective oxides. Roasting of the magnet not only provides selectivity, but enhances the leaching efficiency also. The leaching of the roasted sample with 0.5 M hydrochloric acid at 368 K, 100 g/L pulp density and 500 rpm for 300 min selectively recovers the rare earth elements almost quantitatively leaving iron oxide in the residue. Leaching of rare earth elements with hydrochloric acid follows the mixed controlled kinetic model with activation energy (E a ) of 30.1 kJ/mol in the temperature range 348-368 K. The leaching mechanism is further established by characterizing the leach residues obtained at different time intervals by scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Individual rare earth elements from the leach solution containing 16.8 g/L of Nd, 3.8 g/L Pr, 0.28 g/L of Dy and other minor impurity elements could be separated by solvent extraction. However, mixed rare earth oxide of 99% purity was produced by oxalate precipitation followed by roasting. The leach residue comprising of pure hematite has a potential to be used as pigment or can find other applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Magnetic hysteresis properties of melt-spun Nd-Fe-B alloys prepared by centrifugal method

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Pushkarsky, V.I.; Markin, P.E.; Zaikov, N.K.; Tarasov, E.N.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching onto the internal surface of an iron spinning wheel at tangential speeds in the range 5-20 m/s are reported. The alloy composition was Nd-36% wt, B-1.2% wt. and Fe-remainder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in applied range (18 kOe at 5 m/s and 22 kOe at 20 m/s), whereas the grain size of the basic phase (2-14-1) ste[ily decreases when the speed rises, starting from 2-3 μm for 5 m/s alloy down to the 200-300 nm for 20 m/s alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for tr[itionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbon in a vibration mill causes the coercivity drop to 7 kOe after 120 min of treatment. However, this operation increases the powder alignment ability and, as a result, the energy product for a fully dense magnet from anisotropic powder prepared from some ribbons rises to 20-23 MGOe. (orig.)

  11. Magnetic properties of centrifugally prepared melt-spun Nd-Fe-B alloys and their powders

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Kozlov, A.I.; Markin, P.E.; Pushkarskiy, V.I.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching on to the internal surface of an iron spinning wheel at the tangential speeds in the range 5-20 m/sec are reported. The alloy composition was Nd-36% wt. B-1.2% wt. and Fe-reminder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in the applied range (1430 kA/m at 5 m/sec and 1750 kA/m at 20 m/sec), whereas the grain size of the basic phase (2-14-1) steadily decreases when the speed rises, starting from 2-3 μm for 5 m sec alloy down to the 200-300 nm for 20 m/sec alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for traditionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbons subjected to hydrogen and annealing treatments causes the coercivity drop. However, this operations increase the powder alignment ability and, as a result, the energy product for fully dense magnet from such powder rises to 160-180 kJ/m 3 . (orig.)

  12. Micromagnetic simulation of anisotropic grain boundary diffusion for sintered Nd-Fe-B magnets

    Science.gov (United States)

    Li, W.; Zhou, Q.; Zhao, L. Z.; Wang, Q. X.; Zhong, X. C.; Liu, Z. W.

    2018-04-01

    A systematic investigation on the anisotropic grain boundary diffusion in sintered Nd-Fe-B magnets is carried out by micromagnetic simulation. The results indicate that the critical reason for the anisotropic diffusion effect is not the difference in the amount of Dy diffused along different directions but the macroscopic demagnetizing field. The diffusion parallel to the easy axis from both pole surfaces of the magnet can increase the nucleation fields in the two major regions with large macroscopic demagnetizing fields, where the reverse domains can nucleate easily. As a consequence, the grain boundary diffusion along the directions parallel to the easy axis from two pole surfaces is more effective to improve the coercivity of the magnets than that along other directions. It is also found that, to enhance the coercivity, only a limited diffusion depth is required. The present result is in good agreement with the recent experimental findings.

  13. 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.

  14. New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

    Science.gov (United States)

    Sun, Ruixue; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Jipeng; Deng, Zigang

    2018-01-01

    In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

  15. On the cooling rate of strip cast ingots for sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.Q. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yan, M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mse_yanmi@dial.zju.edu.cn; Wu, J.M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Luo, W. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Cui, X.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Ying, H.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2007-04-30

    Effects of the cooling rate of strip cast ingots on magnetic properties of sintered NdFeB magnets were studied. It is found that the magnetic properties greatly depend on wheel speed due to different alloy microstructures, which affect readily the particle size distribution of powders obtained after the subsequent jet milling. At higher cooling rate, interlamellar spacing between Nd-rich platelets of the alloy was small, resulting in a lower saturated magnetization due to increased amounts of small particles after jet milling. With further decreasing cooling rate, the resultant larger interlamellar spacing led to too large particle sizes as well as a more irregular shape; thus deteriorated the magnetic properties of the final magnet. A model was developed to disclose the effects of particle sizes on the magnetic alignment process. In the current investigation, optimum magnetic properties of the final magnets were obtained with a cooling rate of 2.6 m/s for preparing the strip. The magnets made by conventionally cast ingot technique exhibited the lowest magnetic properties because of the slowest cooling rate.

  16. 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

    for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of 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...

  17. The preparation of sintered NdFeB magnet with high-coercivity and high temperature-stability

    Energy Technology Data Exchange (ETDEWEB)

    Yan, G H; Chen, R J; Ding, Y; Guo, S; Lee, Don; Yan, A R, E-mail: yangh@nimte.ac.cn [Zhejiang province Key Laboratory of Magnetic Materials and Application Technology, Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 (China)

    2011-01-01

    The NdFeB magnets with high intrinsic coercivity have been produced by using the conventional powder metallurgy method (including SC, HD and JM) of sintered NdFeB magnets. The effects of grain boundary phases on the microstructure and magnetic properties of as-sintered and annealed magnets have been tried to investigate. Also the Curie temperature of the magnets was studied. By adopting suitable component ratio of some heavy rare-earth atoms and some micro-quantity additives, we have prepared high-coercivity sintered NdFeB magnets with magnetic properties of {sub j}H{sub c}=36.3kOe, B{sub r}=11.7kGs and (BH){sub max}=34.0MGOe. The temperature coefficient of residual magnetic flux of the magnets (between 20 and 200 deg. C) is -0.113%/deg. C, while the temperature coefficient of intrinsic coercivity -0.355%/deg. C. The Curie temperature of the magnets is about 342 deg. C.

  18. The preparation of sintered NdFeB magnet with high-coercivity and high temperature-stability

    International Nuclear Information System (INIS)

    Yan, G H; Chen, R J; Ding, Y; Guo, S; Lee, Don; Yan, A R

    2011-01-01

    The NdFeB magnets with high intrinsic coercivity have been produced by using the conventional powder metallurgy method (including SC, HD and JM) of sintered NdFeB magnets. The effects of grain boundary phases on the microstructure and magnetic properties of as-sintered and annealed magnets have been tried to investigate. Also the Curie temperature of the magnets was studied. By adopting suitable component ratio of some heavy rare-earth atoms and some micro-quantity additives, we have prepared high-coercivity sintered NdFeB magnets with magnetic properties of j H c =36.3kOe, B r =11.7kGs and (BH) max =34.0MGOe. The temperature coefficient of residual magnetic flux of the magnets (between 20 and 200 deg. C) is -0.113%/deg. C, while the temperature coefficient of intrinsic coercivity -0.355%/deg. C. The Curie temperature of the magnets is about 342 deg. C.

  19. 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.

  20. Electrodeposition of amorphous Ni-P coatings onto Nd-Fe-B permanent magnet substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ma, C.B [Department of Chemistry, Yuquan campus, Zhejiang University, Hangzhou 310027 (China); Cao, F.H [Department of Chemistry, Yuquan campus, Zhejiang University, Hangzhou 310027 (China); Zhang, Z. [Department of Chemistry, Yuquan campus, Zhejiang University, Hangzhou 310027 (China)]. E-mail: eaglezzy@zjuem.zju.edu.cn; Zhang, J.Q [Department of Chemistry, Yuquan campus, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory for Corrosion and Protection of Metals, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016 (China)

    2006-12-15

    Decorative and protective Ni-P amorphous coatings were electroplated onto NdFeB permanent magnet from an ortho-phosphorous acid contained bath. The influences of the main electroplating technological parameters including current density, bath pH, bath temperature and H{sub 3}PO{sub 3} on the structure and chemical composition of Ni-P coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in conjunction with X-ray diffraction (XRD), scanning transmission electron microscopy (SEM) and X-ray energy-dispersive spectrometry (EDX). The optimized amorphous Ni-P coated NdFeB can stand for ca. 180 h against neutral 3.0 wt.% NaCl salt spray without any pitting corrosion. Meanwhile, the results also showed that large phosphorous content is the precondition for Ni-P coatings to possess the amorphous structure, but too much high phosphorous content can damage the amorphous structure due to the separation of superfluous P from Ni{sub 2}P/Ni{sub 3}P and the resultant formation of multi-phase coatings (such as Ni{sub 2}P-P)

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: zhlcai2000@163.com; Wang Suyu; Wang Jiasu; Zheng Jun [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    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.

  2. Influence of annealing temperature on the Dy diffusion process in NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Sheng-qing, E-mail: joy_hsq@126.com [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Peng, Kun, E-mail: kpeng@hnu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Hong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2017-03-15

    Sintered NdFeB magnets were coated with a layer of Dy metal using electron beam evaporation method and then annealed at various temperatures to investigate the temperature dependence of Dy diffusion process in NdFeB magnets. A Dy-rich phase was observed along the grain boundaries after the grain boundary diffusion process, the diffusion coefficients of various temperatures were obtained, the diffusion coefficients of Dy along the grain boundaries at 800 °C and 900 °C were determined to be 9.8×10{sup −8} cm{sup 2} s{sup −1} and 2.4×10{sup −7} cm{sup 2} s{sup −1}, respectively. The diffusion length depended on the annealing temperature and the maximum diffusion length of approximately 1.8 mm and 3.0 mm can be obtained after annealing at 800 °C and 900 °C for 8 h. Higher diffusion temperature results in the diffusion not only along the grain boundaries but also into grains and then decrease in magnetic properties. The optimum annealing conditions can be determined as 900 °C for 8 h. The coercivity was improved from 1040 kA/m to 1450 kA/m and its magnetization has no significant reduction after the grain boundary diffusion process at the optimum annealing conditions. - Highlights: • The optimum annealing conditions can be determined as 900 °C for 8 h. • The diffusion coefficient of Dy at 900 °Care determined to be 2.4×10{sup −7} cm{sup 2} s{sup −1}. • A maximum diffusion length of about 3 mm can be obtained.

  3. Measurement of NdFeB permanent magnets demagnetization induced by high energy electron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Temnykh, Alexander B. [Wilson Lab, Cornell University, LEPP, Ithaca, NY 14850 (United States)], E-mail: abt6@cornell.edu

    2008-03-11

    Demagnetization of NdFeB permanent magnets has been measured as function of radiation dose induced by high energy electrons. The magnet samples were of different intrinsic coercive forces, {approx_equal}12 and {approx_equal}20KOe, dimensions and direction of magnetization. 5 GeV electron beam from 12 GeV Cornell Synchrotron was used as a radiation source. A calorimetric technique was employed for radiation dose measurement. Results indicated that depending on the sample intrinsic coercive force, shape and direction of magnetization the radiation dose causing 1% of demagnetization of the sample varies from 0.0765{+-}0.005Mrad to 11.3{+-}3.0Mrad, i.e., by more than a factor of 100. Experimental data analysis revealed that demagnetization of the given sample induced by radiation is strongly correlated with the sample demagnetizing temperature. This correlation was approximated by an exponential function with two parameters obtained from the data fitting. The function can be used to predict the critical radiation dose for permanent magnet assemblies like undulator magnets based on its demagnetizing temperature. The latter (demagnetization temperature) can be determined at the design stage from 3-D magnetic modeling and permanent magnet material properties.

  4. 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.

  5. Effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, R.S. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: zhenl@hit.edu.cn; Li, G.A. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2006-07-15

    The effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets has been investigated. The magnetic flux loss of two kinds of magnets before and after irradiation was measured. Results show that the effect of {gamma}-ray irradiation on the magnetic properties of sintered NdFeB is not so obvious as that on Fe-Cr-Co magnet. Irradiation-induced damage from {gamma}-ray for the Fe-Cr-Co magnets was characterized for the first time. The decline of permanent magnetic properties of Fe-Cr-Co magnet induced by {gamma}-ray irradiation is reversible except for the maximum energy product (BH){sub max}. The difference of coercivity mechanism between these two kinds of permanent magnets is responsible for the different dependence of magnetic properties loss induced by {gamma}-ray irradiation.

  6. Micro-patterning of resin-bonded NdFeB magnet for a fully integrated electromagnetic actuator

    Science.gov (United States)

    Tao, Kai; Wu, Jin; Kottapalli, Ajay Giri Prakash; Chen, Di; Yang, Zhuoqing; Ding, Guifu; Lye, Sun Woh; Miao, Jianmin

    2017-12-01

    This paper reports a fully-integrated, batch-fabricated electromagnetic actuator which features micro-patterned NdFeB magnets. The entire actuator is fabricated through MEMS-compatible laminated surface micromachining technology, eliminating the requirement for further component assembly processes. The fabrication strategy allowed the entire volume of the actuator to be reduced to a small size of 2.5 × 2.5 × 2 mm3, which is one of the smallest NdFeB-based electromagnetic actuators demonstrated to date. The magnetic properties of NdFeB thin films are further investigated and optimized using different types of lithographically-defined micromolds. By altering the direction of the input current, actuating displacements of approximately ±10 μm are achieved during both the attraction and the repulsion operations. This work demonstrates the viability and compatibility of using polymer-bonded magnets for magnetic MEMS applications.

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

    Directory of Open Access Journals (Sweden)

    Jun Fujisaki

    2016-05-01

    Full Text Available 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. Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

    Science.gov (United States)

    Fujiwara, Ryogen; Devillers, Thibaut; Givord, Dominique; Dempsey, Nora M.

    2018-05-01

    Hard magnetic films used in magnetic micro-systems may be exposed to elevated temperatures during film and system fabrication and also during use of the micro-system. In this work, we studied the influence of temperature on the magnetic properties of 10 μm thick out-of-plane textured NdFeB films fabricated by high rate triode sputtering. Out-of-plane hysteresis loops were measured in the range 300K - 650K to establish the temperature dependence of coercivity, magnetization at 7 T and remanent magnetization. Thermal demagnetization was measured and magnetization losses were recorded from 350K in films heated under zero or low (-0.1 T) external field and from 325 K for films heated under an external field of -0.5 T. The effect of thermal cycling under zero field on the remanent magnetization was also studied and it was found that cycling between room temperature and 323 K did not lead to any significant loss in remanence at room temperature, while a 4% drop is recorded when the sample is cycled between RT and 343K. Measurement of hysteresis loops at room temperature following exposure to elevated temperatures reveals that while remanent magnetisation is practically recovered in all cases, irreversible losses in coercivity occur (6.7 % following heating to 650K, and 1.3 % following heating to 343K). The relevance of these results is discussed in terms of system fabrication and use.

  9. Investigation of coercivity mechanism in hot deformed Nd-Fe-B permanent magnets by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Yano, M.; Manabe, A.; Shoji, T.; Kato, A.; Ono, K.; Harada, M.; Kohlbrecher, J.

    2014-01-01

    The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd 2 Fe 14 B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains

  10. 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.

  11. 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.

  12. A preparation method and effects of Al–Cr coating on NdFeB sintered magnets

    International Nuclear Information System (INIS)

    Zheng, Jingwu; Lin, Min; Xia, Qingping

    2012-01-01

    A 50 μm Al–Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 °C. The morphology and composition of the Al–Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al–Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al–Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al–Cr coating moves positively from −0.67 to −0.48 V, which is in accordance with Nyquist and Bode plots. The Al–Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: ► The Al–Cr coating can be prepared by dipping in solution, shaking dry and heating. ► The coating morphology shows to be an intense overlapping structure. ► The barrier effect combines with passivation and cathodic protection. ► The anticorrosion abilities improve while magnetic properties change little. ► Compared with other surface treatments, this method is convenient and low cost.

  13. A preparation method and effects of Al-Cr coating on NdFeB sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jingwu [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Lin, Min, E-mail: linm@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, 519 Road Zhuangshi, District Zhenghai, Ningbo 315201, People' s Republic of China (China); Xia, Qingping [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

    2012-11-15

    A 50 {mu}m Al-Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 Degree-Sign C. The morphology and composition of the Al-Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al-Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al-Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al-Cr coating moves positively from -0.67 to -0.48 V, which is in accordance with Nyquist and Bode plots. The Al-Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: Black-Right-Pointing-Pointer The Al-Cr coating can be prepared by dipping in solution, shaking dry and heating. Black-Right-Pointing-Pointer The coating morphology shows to be an intense overlapping structure. Black-Right-Pointing-Pointer The barrier effect combines with passivation and cathodic protection. Black-Right-Pointing-Pointer The anticorrosion abilities improve while magnetic properties change little. Black-Right-Pointing-Pointer Compared with other surface treatments, this method is convenient and low cost.

  14. Effect of forming process by using external magnetic field of bonded magnet made from NdFeB flakes to microstructure and magnetic properties

    Science.gov (United States)

    Suprapedi; Sardjono, P.; Muljadi; Djauhari, N. R.; Ramlan

    2018-03-01

    Research of fabricated bonded magnets NdFeB made from NdFeB flakes with variation of external magnetic field has been done. The materials preparation process begins with milling NdFeB flakes using High Energy Milling (HEM) for 60 minutes and mixing it with 5 wt % celuna binder and performing compaction to form pellet with a pressure of 40 Kgf/cm2 and then applying external magnetic field (0, 2000, 5000, 8000 and 11000 Gauss). The pellet samples were then dried using vacuum dryer with temperature of 100 °C for 1 hour. Characterization includes bulk density, measurement of magnetic properties with gauss meter, and Vibrating Sample Magnetometer (VSM). From the characterization results the best value was obtained on the external magnetic field orientation of 8000 to 11000 Gauss with a density value of 5.38 g/cm3, flux magnetic value of 465.9 – 467.1 Gauss, remanence value of 2.63–2.776 kGauss, and coercivity value of 1.905–1.925 kOe.

  15. Magnetic properties and magnetization reversal mechanism of Nd-Fe-B nanoparticles synthesized by a sol-gel method

    Science.gov (United States)

    Rahimi, Hamed; Ghasemi, Ali; Mozaffarinia, Reza; Tavoosi, Majid

    2017-12-01

    Nd-Fe-B oxide powders with various pH were prepared using chloride and nitrate precursors including NdCl3·6H2O, FeCl3·6H2O, H3BO3, Nd2O3, Fe(NO3)3·9H2O, HNO3, citric acid (CA), ethylene glycol (EG) by Pechini type sol-gel method. The pH of chloride and nitrate base sols were 0 and 2.2, respectively. Mixed oxide powders were obtained by calcination and annealing the gels. These oxides by using a reduction-diffusion process under high vacuum and employing CaH2 as reducing agent at 800 °C were hated to prepare Nd2Fe14B nanoparticles. The role of pH on phase, morphologies, microstructure, and magnetic properties of the powders were investigated. The results show that with a decrease in pH, the average particle size and coercivity of Nd-Fe-B oxide powders were decreased and increased, respectively. Nd2Fe14B nanoparticles were formed successfully after reduction process. The average particle size of reduction treated products were 30 and 65 nm for powders which made of chloride and nitrate base metal salts, respectively. Final powders which made of chloride and nitrate base metal salts had a saturation magnetization of 127.7 emu/g and 122.8 emu/g while the coercivity of samples were 3.32 kOe and 1.82 kOe, respectively. The experimental results in the angular dependence of coercivity indicated that the normalized coercivity of the permanent magnets Hc(θ)/Hc(0) obeys the 1/cosθ law and intermediate between the 1/cosθ law and Stoner-Wohlfarth formula for different Nd2Fe14B magnets which made of nitrate and chloride base metal salts, respectively. Also, the results show that different Nd2Fe14B magnets which made of nitrate and chloride base metal salts had the maximum energy product of 5 and 16 MGOe, respectively. The Henkel plot showed that magnetic phases in synthesized NdFeB magnets which made of chloride and nitrate base metal salts were coupled by exchange and dipolar interactions, respectively. Different average particle size, morphology and microstructure were

  16. Hydrocyclone Separation of Hydrogen Decrepitated NdFeB

    Directory of Open Access Journals (Sweden)

    Muhammad Awais

    2017-11-01

    Full Text Available Hydrogen decrepitation (HD is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB magnets. During the HD process, the NdFeB breaks down into a matrix phase (Nd2Fe14BHx and RE-rich grain boundary phase. The grain boundary phase in the HD powder is <2 μm in size. Recycled NdFeB material has a higher oxygen content compared to the primary source material. This additional oxygen mainly occurs at the Rare Earth (RE rich grain boundary phase (GBP, because rare earth elements oxidise rapidly when exposed to air. This higher oxygen level in the material results in a drop in density, coercivity, and remanence of sintered NdFeB magnets. The particle size of the GBP is too small to separate by sieving or conventional screening technology. In this work, an attempt has been made to separate the GBP from the matrix phase using a hydrocyclone, and to optimise the separation process. HD powder, obtained from hard disk drive (HDD scrap NdFeB sintered magnets, was used as a starting material and passed through a hydrocyclone a total number of six times. The X-ray fluorescence (XRF analysis and sieve analysis of overflows showed the matrix phase had been directed to the underflow while the GBP was directed to the overflow. The optimum separation was achieved with three passes. Underflow and overflow samples were further analysed using an optical microscope and MagScan and matrix phase particles were found to be magnetic.

  17. Leaching kinetics of cobalt from the scraps of spent aerospace magnetic materials.

    Science.gov (United States)

    Zhou, Xuejiao; Chen, Yongli; Yin, Jianguo; Xia, Wentang; Yuan, Xiaoli; Xiang, Xiaoyan

    2018-06-01

    Based on physicochemical properties of the scraps of spent aerospace magnetic materials, a roasting - magnetic separation followed by sulfuric acid leaching process was proposed to extract cobalt. Roasting was performed at 500 °C to remove organic impurity. Non-magnetic impurities were reduced by magnetic separation and then the raw material was sieved into desired particle sizes. Acid leaching was carried out to extract cobalt from the scraps and experimental parameters included agitation speed, particle size, initial concentration of sulfuric acid and temperature. Agitation speed higher than 300 r/min had a relatively small impact on the cobalt extraction. As the particle size reduced, the content of cobalt in the raw material decreases and the extraction of cobalt by acid leaching increased at first and decreased afterwards. Raising the initial concentration of sulfuric acid and temperature contributed to improve the cobalt extraction and the influence of temperature was more remarkable. SEM image revealed that the spent aerospace magnetic materials mainly existed in the sliced strip flake with a loose surface and porous structure. Under the experimental condition, the leaching rate of cobalt from the scraps in sulfuric acid solution could be expressed as ln(-ln(1 - α)) = lnk + nlnt. The apparent activation energy was found to be 38.33 kJ/mol and it was mainly controlled by the surface chemical reaction. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. 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.

  19. Removing metal debris from thermosetting EMC powders by Nd-Fe-B permanent magnets

    Directory of Open Access Journals (Sweden)

    Liaw Yowching

    2017-01-01

    Full Text Available During the preparation of thermosetting encapsulation molding compounds (EMCs for semiconductor packaging, metal debris are always present in the EMC powders due to the hard silica fillers in the compound. These metal debris in the EMC powders will cause circuit shortage and therefore have to be removed before molding. In this study, Nd-Fe-B permanent magnets are used to remove these debris. The results show that the metal debris can be removed effectively as the rate of accumulation of the metal debris increases as time proceeds in the removing operation. The removal effectiveness of the debris is affected by both the magnetic flux density and the flow around the magnet. The wake flow behind the magnet is a relatively low speed recirculation region which facilities the attraction of metal debris in the powders. Thus, the largest amount of the accumulated EMC powders occurs downstream of the magnet. Hence, this low speed recirculation region should be better utilized to enhance the removal efficiency of the metal debris.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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 (MNP cell ) appeared to be magnetic field- and concentration-dependent. In H-field, MNP cell 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 MNP cell , suggesting that magnetic force-induced uptake may be primarily contributed to enhanced MNP sedimentation. Although MNP distribution was much inhomogeneous in L-field, averaged MNP cell 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 MNP cell 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. - Graphical abstract: Averaged MNP uptake by glioma cells in the low and non-uniformed magnetic field reached as high as 80% of that in uniformed magnetic field, which is probably due to both heterogeneous distributions of MNPs in the non-uniformed magnetic field and high capacity of the MNP uptake by these cells. - Highlights: • Enhanced sedimentation

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

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yi-Ching; Chang, Fan-Yu [Department of Physiology and Pharmacology & Healthy Aging Research Center, Guishan, Taoyuan City 33302, Taiwan, ROC (China); Tu, Shu-Ju [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Guishan, Taoyuan City 33302, Taiwan, ROC (China); Chen, Jyh-Ping [Department of Chemical and Materials Engineering, Chang Gung University, Guishan, Taoyuan City 33302, Taiwan, ROC (China); Ma, Yunn-Hwa, E-mail: yhma@mail.cgu.edu.tw [Department of Physiology and Pharmacology & Healthy Aging Research Center, Guishan, Taoyuan City 33302, Taiwan, ROC (China); Department of Neurology, Chang Gung Memorial Hospital, Guishan, Taoyuan City 33305, Taiwan, ROC (China)

    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 (MNP{sub cell}) appeared to be magnetic field- and concentration-dependent. In H-field, MNP{sub cell} 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 MNP{sub cell}, suggesting that magnetic force-induced uptake may be primarily contributed to enhanced MNP sedimentation. Although MNP distribution was much inhomogeneous in L-field, averaged MNP{sub cell} 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 MNP{sub cell} 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. - Graphical abstract: Averaged MNP uptake by glioma cells in the low and non-uniformed magnetic field reached as high as 80% of that in uniformed magnetic field, which is probably due to both heterogeneous distributions of MNPs in the non-uniformed magnetic field and high capacity of the MNP uptake by these cells. - Highlights:

  2. Effect of crystal alignment on the remanence of sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Kawai, T.; Ma, B.M.; Sankar, S.G.; Wallace, W.E.

    1990-01-01

    Nd 15.4 Fe 77.8 B 6.8 magnets of various degrees of crystal alignment have been prepared by the conventional powder metallurgy technique. The alignment of these magnets have been determined by x-ray diffraction and fitting the standard deviation of a Gaussian distribution for the relative intensity versus the angle between the normals of (hkl) and the tetragonal c axis. The standard deviation is a good indicator for crystal alignment. An aligning field of 8 kOe is found to be essential to obtain a well-aligned NdFeB magnet. The remanence of sintered magnets is directly affected by the crystal alignment. Furthermore, the effect of crystal alignment on the remanence follows the theoretical prediction of the Stoner--Wohlfarth model. Below the spin reorientation temperature, the effect of crystal alignment on the shape of hysteresis loop becomes more significant. The remanences extrapolated from first and second quadrant of the hysteresis loops have been found to be consistent with the prediction of Stoner--Wohlfarth model

  3. The temperature dependence of magnetic anisotropy of Nd-Fe-B thin films

    Science.gov (United States)

    Sato, Takuya; Hashimoto, Ryuji; Tanaka, Yoshitomo; Suzuki, Kenichi; Enokido, Yasushi; Choi, Kyung-Ku; Suzuki, Takao

    2018-05-01

    The magnetic properties of Nd-Fe-B thin films with the three different compositions (#1: Nd12.6Fe81.5B5.9, #2: Nd14.6Fe78.1B7.4 and #3: Nd22.6Fe66.2B11.2) are discussed. With increasing Nd content, the c-axis orientation along the film normal is enhanced. It is found that sample #2 possesses the saturation magnetization Ms very close to that for Nd2Fe14B over a temperature range from 100 to about 300K. The magnetic anisotropy constant Ku2 for sample #2 is the highest among those samples, but smaller by about 20%, as compared to that for Nd2Fe14B. It is of interest to note that the temperature TR at which Ku1 changes its sign is lower by about 30K as compared to that previously reported for Nd2Fe14B. The reason for this discrepancy is not clear, but could be due to the presence of the minority phases of Nd-rich compounds and also a possible contribution of the magneto-elastic effect to the net magnetic anisotropy.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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/cm 3 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. (paper)

  5. 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.

  6. 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.

  7. 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.

  8. High performance hard magnetic NdFeB thick films for integration into micro-electro-mechanical systems

    International Nuclear Information System (INIS)

    Dempsey, N. M.; Walther, A.; May, F.; Givord, D.; Khlopkov, K.; Gutfleisch, O.

    2007-01-01

    5 μm thick NdFeB films have been sputtered onto 100 mm Si substrates using high rate sputtering (18 μm/h). Films were deposited at ≤500 deg. C and then annealed at 750 deg. C for 10 min. While films deposited at temperatures up to 450 deg. C have equiaxed grains, the size of which decreases with increasing deposition temperature, the films deposited at 500 deg. C have columnar grains. The out-of-plane remanent magnetization increases with deposition temperature, reaching a maximum value of 1.4 T, while the coercivity remains constant at about 1.6 T. The maximum energy product achieved (400 kJ/m 3 ) is comparable to that of high-quality NdFeB sintered magnets

  9. 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.

  10. 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.

  11. Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

    International Nuclear Information System (INIS)

    Xiaoya, Liu; Yuping, Li; Lianxi, Hu

    2013-01-01

    The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd 16 Fe 76 B 8 (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd 2 Fe 14 B phase decomposed into an intimate mixture of nano-structured NdH 2.7 , Fe 2 B and α-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd 2 Fe 14 B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 °C×30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m 3 , respectively. - Highlights: ► Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. ► Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. ► Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. ► Magnetic properties significantly improved by relative density enhancement and nanocrystallization of Nd 2 Fe 14 B phase. ► The effects of sintering parameters on magnetic properties and the underlying

  12. Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoya, Liu; Yuping, Li [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Lianxi, Hu, E-mail: hulx@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2013-03-15

    The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd{sub 16}Fe{sub 76}B{sub 8} (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd{sub 2}Fe{sub 14}B phase decomposed into an intimate mixture of nano-structured NdH{sub 2.7}, Fe{sub 2}B and {alpha}-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd{sub 2}Fe{sub 14}B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 Degree-Sign C Multiplication-Sign 30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m{sup 3}, respectively. - Highlights: Black-Right-Pointing-Pointer Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. Black-Right-Pointing-Pointer Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. Black-Right-Pointing-Pointer Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. Black-Right-Pointing-Pointer Magnetic properties significantly

  13. Structural and magnetic properties of NdFeB and NdFeB/Fe films with Mo addition

    Energy Technology Data Exchange (ETDEWEB)

    Urse, M; Grigoras, M; Lupu, N; Chiriac, H, E-mail: urse@phys-iasi.ro [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)

    2011-07-06

    The influence of the Mo addition on the microstructure and magnetic properties of Nd-Fe-B and Nd-Fe-B/Fe films was studied. The coercivity is a key parameter in the control of technical performances of Nd-Fe-B films. A small amount of about 1 at.% Mo can enhance the coercivity of Nd-Fe-B film by controlling the growth of soft and hard magnetic grains. A coercivity of 22.1 kOe, a remanence ratio, M{sub r}/M{sub s}, of 0.83 and a maximum energy product of 8 MGOe were obtained for Ta/[NdFeBMo(1at.%)(540nm)/Ta films annealed at 650{sup 0}C for 20 minutes due to Mo precipitates formed at the Nd{sub 2}Fe{sub 14}B phase boundaries which prevent the nucleation and expansion of the magnetic domains. Simultaneous use of Mo as addition and the stratification of Nd-Fe-B-Mo films using Fe as spacer layer are important tools for the improvement of the hard magnetic properties of Nd-Fe-B films. The Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta multilayer film annealed at 620{sup 0}C exhibits an increase in the coercivity from 12.1 kOe to 22.8 kOe, in the remanence ratio from 0.77 to 0.80, and in the maximum energy product from 4.5 to 7.1 MGOe in comparison with Ta/Nd-Fe-B/Ta film. As compared to Ta/Nd-Fe-B/Ta film, the Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta film presents a decrease in the crystallization temperature of about 30{sup 0}C.

  14. Magnetic circuit with large blocks from NdFeB magnets for suspended magnetic separators

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav

    2010-01-01

    Roč. 7, č. 2 (2010), s. 227-235 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic circuits * magnetic separation * permanent magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.452, year: 2010 www.irsm.cas.cz/?Lang=CZE&Menu=25,0,0,0

  15. Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

    Science.gov (United States)

    Zhao, L. Z.; Deng, X. X.; Yu, H. Y.; Guan, H. J.; Li, X. Q.; Xiao, Z. Y.; Liu, Z. W.; Greneche, J. M.

    2017-12-01

    High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC + HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

  16. Magnetization reversal mechanism and coercivity enhancement in three-dimensional granular Nd-Fe-B magnets studied by micromagnetic simulations

    Science.gov (United States)

    Lee, Jae-Hyeok; Choe, Jinhyeok; Hwang, Shinwon; Kim, Sang-Koog

    2017-08-01

    We studied the mechanism of magnetization reversals and coercivity enhancements in three-dimensional (3D) granular Nd-Fe-B permanent magnets using finite-element micromagnetic simulations. The magnetization reversals in the hard magnets consisting of hard-phase grains separated by relatively soft-phase grain boundaries were analyzed with reference to the simulation results for the magnetic field-dependent distributions of the local magnetizations. The saturation magnetization of the grain-boundary phase plays a crucial role in the transition between nucleation- and domain-wall-propagation-controlled reversal processes. The smaller the saturation magnetization of the grain-boundary phase is, the more preferable is the nucleation-controlled process, which results in a larger coercivity. The exchange stiffness of the grain-boundary phase determines the preferred paths of domain-wall propagations, whether inward into grains or along the grain boundaries for relatively small and large exchange stiffness, respectively. However, the exchange stiffness of the grain-boundary phase alone does not significantly contribute to coercivity enhancement in cases where the size of hard-phase grains is much greater than the exchange length. This work paves the way for the design of high-performance hard magnets of large coercivity and maximum-energy-product values.

  17. Effects of rare earth oxide addition on NdFeB magnets

    International Nuclear Information System (INIS)

    Ohashi, K.; Yokoyama, T.; Tawara, Y.

    1988-01-01

    The effects of addition of rare-earth oxides on the magnetic properties of Nd-Fe-B sintered magnets are studied. The addition of Dy 2 O 3 and Tb 4 O 7 leads to an increase in intrinsic coercivity. For addition of Dy 2 O 3 , the optimum conditions for powder mixing and the optimum Dy 2 O 3 particle size were determined. A mixing time of more than 10 minutes, and a Dy 2 O 3 particle size of less than 3 μm, are required to obtain a high intrinsic coercivity. EPMA measurements of NdFeBAl magnets with Dy 2 O 3 added reveal an inhomogeneous distribution of Dy in the Nd 2 Fe 14 B matrix: the material is Dy-rich near grain boundaries, but Dy-poor within the matrix. The appearance of such an inhomogeneous distribution of Dy is attributed to the reduction of Dy 2 O 3 in the Nd-rich phases, followed by diffusion of the resulting Dy atoms into the matrix

  18. Irradiation of Nd-Fe-B permanent magnets with APS bending magnet x-rays and 60Co γ-rays

    International Nuclear Information System (INIS)

    Alderman, J.; Job, P. K.; Puhl, J.

    2000-01-01

    The Advanced Photon Source (APS), as well as other third-generation synchrotron light sources, uses permanent magnets in the insertion devices to produce x-rays for scientific research. When placed in a high-energy storage ring, these permanent magnets are subjected to irradiation from synchrotron radiation, high-energy bremsstrahlung, and bremsstrahlung-produced photoneutrons. Previous investigations have exhibited varying degrees of degradation in the intensity of magnetization of these magnets due to irradiation from electron beams, 60 Co γrays, and high-energy neutrons. The APS specifically uses Nd-Fe-B permanent magnets in their insertion devices. Although no detectable radiation-induced demagnetization has been observed in the APS insertion devices so far, partial demagnetization has been observed in at least one insertion device at the European Synchrotron Radiation Facility (ESRF), where Nd-Fe-B permanent magnets are also used

  19. Changes of microstructure and magnetic properties of Nd-Fe-B sintered magnets by doping Al-Cu

    International Nuclear Information System (INIS)

    Ni Junjie; Ma Tianyu; Yan Mi

    2011-01-01

    The microstructural and magnetic properties of Al 100-x Cu x (15at%≤x≤45 at%) doped Nd-Fe-B magnets were studied. The distribution and alloying effects of Cu or Al on the intergranular microstructure were investigated by thermodynamic analysis, differential scanning calorimetery and microscopy techniques. It was observed that when the Cu content of Al 100x Cu x exceeds to 25 at%, the (Pr, Nd)Cu and CuAl 2 phases form in these magnets. The formation of (Pr, Nd)Cu phase depends on the negative formation enthalpy of (Pr, Nd)Cu and the exclusive distribution of Cu in the intergranular regions. The eutectic reaction between (Pr, Nd)Cu phase and (Pr, Nd) occurs at 480 deg. C, which forms the liquid phase that dissolves the (Pr, Nd) 2 Fe 14 B surface irregularities and thus increases the quantities of (Pr, Nd)-rich phase at the grain boundaries. These changes benefit the grain boundary microstructure, especially the distribution of (Pr, Nd)-rich phase, which effectively improves the intrinsic coercivity i H c due to the decreases of exchange coupling between the (Pr, Nd) 2 Fe 14 B grains. - Highlights: → Cu/Al effects on Nd-Fe-B structure depend on their distribution/alloying behaviors. → Cu exclusively distributes in grain boundaries different from Al and has negative mixing heat with Nd. → (Pr,Nd)Cu phase besides CuAl 2 forms in grain boundaries with Cu content increase. → (Pr,Nd)Cu phases optimize microstructure and increase magnetic properties.

  20. 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.

  1. Effects of powder flowability on the alignment degree and magnetic properties for NdFeB sintermagnets

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y. [School of Physics and Microelectronics, Shandong University, 250100 (China); Gao, R.W. [School of Physics and Microelectronics, Shandong University, 250100 (China)]. E-mail: gaorwbox@sdu.edu.cn; Han, G.B. [School of Physics and Microelectronics, Shandong University, 250100 (China); Bai, G. [School of Physics and Microelectronics, Shandong University, 250100 (China); Liu, T. [School of Physics and Microelectronics, Shandong University, 250100 (China); Wang, B. [School of Physics and Microelectronics, Shandong University, 250100 (China); Yantai Shougang Magnetic Material CO, LTD, 265500 (China)

    2006-04-15

    The magnetic powders for sintered NdFeB magnets have been prepared by using the strip casting (SC), hydrogen decrepitation (HD) and jet milling (JM) techniques. The effects of powder flowability and addition of a lubricant on the alignment degree and the hard magnetic properties of sintered magnets have been studied. The results show that the main factor affecting powder flowability is the aggregation of magnetic particles for powders in a loose state, but it is the friction between the powder particles for powders that are in a compact state. The addition of a lubricant with suitable dose can slightly prevent the congregating of powders, obviously decrease the friction between the powder particles, improve the powder flowability, and increase the alignment degree, remanence and energy product density of sintered magnets. Mixing a suitable dose of lubricant and adopting rubber isostatic pressing (RIP) with a pulse magnetic field, we have succeeded in producing the sintered NdFeB magnet with high hard magnetic properties of B {sub r}=14.57 KG, {sub j}H {sub c}=14.43 KOe (BH){sub max}=51.3 MGOe.

  2. Evaluation of effect of surface treatment on corrosion resistance of Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Martins, Emerson Alves

    2009-01-01

    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 (ψ). Treatment with silane, cerium, sam, Cr 6 + , tricationic phosphate followed by bath of chromium trioxide and in NaH 2 PO 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 2 PO 4 solution for 24 hours pH=3.8 was the

  3. Application of permanent magnet BaFe12O19 and NdFeB on small scale low speed permanent magnet generator

    International Nuclear Information System (INIS)

    Pudji Irasari; Novrita Idayanti

    2009-01-01

    Designing and manufacturing of low speed permanent magnet generator (PMG) for small scale electric power plant have been conducted. In this paper, the characteristics of generator using permanent magnet of barium ferrite (BaFe 12 O 19 ) and neodymium iron boron (NdFeB) were compared. Surface mounted type is selected as the rotor structure as all flux faces to stator winding and take a role in energy conversion. The experiment result demonstrates that at nominal speed, generator with BaFe 12 O 19 magnet can only generate power of 8.87 W while generator with NdFeB magnet can generate power of 1,988.93 W. (author)

  4. From NdFeB magnets towards the rare-earth oxides: a recycling process consuming only oxalic acid

    OpenAIRE

    Vander Hoogerstraete, Tom; Blanpain, Bart; Van Gerven, Tom; Binnemans, Koen

    2014-01-01

    A chemical process which consumes a minimum amount of chemicals to recover rare-earth metals from NdFeB magnets was developed. The recovery of rare-earth elements from end-of-life consumer products has gained increasing interest during the last few years. Examples of valuable rare earths are neodymium and dysprosium because they are important constituents of strong permanent magnets used in several large or growing application fields (e.g. hard disk drives, wind turbines, electric vehicles, m...

  5. Efek Waktu Wet Milling dan Suhu Annealing Terhadap Sifat Fisis, Mikrostruktur dan Magnet dari Flakes NdFeB

    OpenAIRE

    Sipahutar, Wahyu Solafide

    2015-01-01

    Had made research manufacture NdFeB magnets of flakes of wet milling process using a ball mill to the physic properties, microstructure, and magnetic properties with variations milling time is 16 hours, 24 hours, 48 hours, 72 hours. Powder result of mechanical milling using a ball mill and then analyzed the resulting particle size by using PSA and XRD. Then do the manufacture of test samples in the form of pellets by compaction process through print isotropy. Having obtained a sample of pelle...

  6. Multi-phase EBSD mapping and local texture analysis in NdFeB sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Woodcock, T.G., E-mail: t.woodcock@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden (Germany); Gutfleisch, O. [IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden (Germany)

    2011-02-15

    A combination of electron backscatter diffraction and energy-dispersive X-ray spectroscopy has been used to identify the crystal structure and composition of all the phases present in commercially available NdFeB sintered magnets and to map their spatial distribution. The Nd{sub 2}Fe{sub 14}B and NdO grains were shown to have low defect densities. The fcc Nd-rich and Nd{sub 2}O{sub 3} grains had intra-grain misorientation angles of up to 14{sup o}, which was shown to be due to defects. Large numbers ({approx}100) of data points for each phase were used to study texture in the NdO, Nd{sub 2}O{sub 3} and Nd{sub 2}Fe{sub 14}B phases. The Nd{sub 2}Fe{sub 14}B grains exhibited a <0 0 1> fibre texture. The Nd oxide phases showed no strong texture, which implied that no strongly preferred orientation relationships between those phases and Nd{sub 2}Fe{sub 14}B exist. The result was shown to be valid for optimally annealed samples exhibiting high coercivity and as-sintered samples exhibiting low coercivity.

  7. Improvement of the magnetic property, thermal stability and corrosion resistance of the sintered Nd-Fe-B magnets with Dy{sub 80}Al{sub 20} addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Beibei; Li, Xiangbin; Liang, Xiaolin [School of Physics and Technology, Wuhan University, Wuhan, Hubei (China); Yan, Gaolin, E-mail: gaolinyan@whu.edu.cn [School of Physics and Technology, Wuhan University, Wuhan, Hubei (China); Chen, Kan; Yan, Aru [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)

    2017-05-01

    To improve the coercivity and thermal stability of the Nd-Fe-B sintered magnets simultaneously, the Dy{sub 80}Al{sub 20} (at%) powders with low melting point were introduced into the Nd-Fe-B magnets. Additionally, the magnetic properties, microstructure and thermal stability of the sintered magnets with different amounts of Dy{sub 80}Al{sub 20} were investigated. By adding a small amount of Dy{sub 80}Al{sub 20}, the coercivity was significantly increased from 12.72 to 21.75 kOe. As indicated by the microstructure analysis, a well-developed core-shell structure was formed in the magnets with the addition of Dy{sub 80}Al{sub 20}. The improvement of magnetic properties could be attributed to the refined and uniform matrix phase, continuous grain boundaries and a (Nd, Dy){sub 2}Fe{sub 14}B hardening shell surrounding the matrix phase grains. With the addition of 0–4 wt% Dy{sub 80}Al{sub 20} powder, the reversible temperature coefficients of remanence (α) and coercivity (β) of the magnets could be improved from −0.117 to −0.108%/°C and −0.74 to −0.66%/°C in the range of 20–100 °C, respectively. Additionally, the irreversible loss of magnetic flux (hirr) decreased sharply as Dy{sub 80}Al{sub 20} powder was added. The results of temperature-dependent magnetic properties suggest that, the thermal stability of the magnets was effectively improved with the intergranular addition of Dy{sub 80}Al{sub 20} alloy. Also, the corrosion resistance was found to be improved through small addition of Dy{sub 80}Al{sub 20} powders This was partly due to the stability enhancement of the (Pr, Nd)-rich intergranular phase by Dy{sub 80}Al{sub 20}. - Highlights: • We successfully introduced the Dy{sub 80}Al{sub 20} alloy into the Nd-Fe-B magnets. • The magnetic properties and thermal stability of the Nd-Fe-B magnets were improved. • The corrosion resistance of the Nd-Fe-B magnets were improved.

  8. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Yang, L.; Zhen, L.; Xu, C.Y.; Sun, X.Y.; Shao, W.Z.

    2011-01-01

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  9. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L., E-mail: lzhen@hit.edu.c [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y.; Sun, X.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-01-15

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  10. 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.

  11. Measurement of the radiation incident on ALS NdFeB permanent magnet insertion device structures and a determination of their lifetime

    International Nuclear Information System (INIS)

    Krebs, G.F.; Holmes, M.

    1997-05-01

    Measurements of the radiation incident on ALS insertion device NdFeB permanent magnet structures were carried out using thermoluminescence dosimeters. A plastic scintillator gamma telescope was utilized to unravel the various contributions to the integrated dose. Magnet lifetimes were calculated for various operational conditions

  12. Characterisation of the aqueous corrosion process in NdFeB melt spun ribbon and MQI bonded magnets

    Science.gov (United States)

    McCain, Stephen

    A major factor limiting the use and longevity of rare earth based magnetic materials is their susceptibility to aqueous corrosion and associated detrimental effects upon the magnetic properties of the material. This process was investigated through a combination of exposure to simulated environmental conditions and hydrogen absorption/desorption studies (HADS) in conjunction with magnetic characterisation. This study utilises NdFeB MQP-B melt-spun ribbon manufactured by Magnequench, in the form of MQI bonded magnets and also in its unbonded state as MQ powder. Specifically, it was concerned with how effective a variety of bonding media (epoxy resin,PTFE, zinc) and surface coatings (PTFE, Qsil, zinc LPPS, Dex-Cool) were at limiting the impact of aqueous corrosion in MQI bonded magnets. To characterise the effect of hydrogen absorption upon the magnetic properties of the MQP-B, hydrogen uptake was induced followed by a series of outgassing heat treatments with subsequent magnetic characterisation accompanied by HADS techniques performed after each outgas. This allowed comparisons to be made between the effects of aqueous corrosion process and hydrogen absorption upon the magnetic properties of the alloy.. This study has clearly demonstrated the link between the abundance of environmental moisture and rate of Hci losses in MQI bonded magnets. In addition to this the key mechanism responsible for the degradation of magnetic properties has been identified. These losses have been attributed to the absorption of hydrogen generated by the dissociation of water in the presence of NdFeB during the aqueous corrosion process. It has been shown that the use of a bonding media that is impermeable to water can limit the effects of aqueous corrosion by limiting water access to the Magnequench particles (MQP) and also the positive effects of the use of suitable surface coatings has been shown to be effective for the same reason..

  13. Structure and Properties of Nd-Fe-B Alloy Subjected to HDDR Process

    Directory of Open Access Journals (Sweden)

    Szymański M.

    2016-03-01

    Full Text Available In this paper the Hydrogenation, Disproportionation, Desorption and Recombination (HDDR route was tested, for the Nd-Fe-B master alloy, as a prospective procedure for recycling of sintered scrap neodymium magnets. The HDDR method is based on the hydrogen induced reversal phase transformation of Nd-Fe-B alloy: Nd2Fe14B + (2±x H2 = 2NdH2±x + Fe2B + 12Fe. Microstructural observations (SEM, phase constitution studies (XRD and measurement of magnetic properties (VSM were done to investigate the HDDR transformation progress. It was observed that disproportionation reaction starts at the grain boundaries, where the Nd-rich phase is located. Average grain size was reduced and coercive material was produced as a result of the HDDR process. Obtained results are similar to literature data.

  14. 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.

  15. The Role of Annealing Temperature on Structural and Magnetic Properties of NdFeB Thin Films

    Directory of Open Access Journals (Sweden)

    A. Khanjani

    2016-06-01

    Full Text Available In the present research NdFeB thin films coupled with buffer and capping layer of W were formed on Si/SiO2 substrate by means of RF magnetron sputtering. The system was annealed at vaccum at different temperatures of 450, 500, 550,. 600 and 650 °C Phase analysis was carried out by XRD and it was found that NdFeB was formed without the formation of any kind of secondary phase. The cross sectional and grain size of the thin films were measured by scanning electron microscopy. Morphological studies were performed by atomic force microscopy. Magnetic properties of thin films including coercivity, saturation of magnetization and hysteresis area were evcaluated by vibrating sample magnetometer. It was found that by annealing at 400 °C the amorphous layer was formed.The highest intensity of peaks was formed at 550 °C and with an increase in temperature the intensity was declined. The grain size was increased by temperature and had an impact on the coercivity. With an increase of temperature up to 600 °C, perpendicular coercivity was increased and then by further increase of temperatute, coercivity was reduced. Based on the obtained data the temperature of 600 °C was selected as the optimum annealing temperature for reaching enhanced structural and magnetic feature.

  16. 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

  17. 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.

  18. Magnetization reversal mechanisms in hybrid resin-bonded Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Plusa, D.; Dospial, M.; Slusarek, B.; Kotlarczyk, U.

    2006-01-01

    The magnetic properties of isotropic epoxy resin-bonded magnets prepared by mixing a hard magnetic powder made from melt quenched Nd-Fe-Co-B ribbons and a soft magnetic iron powder have been examined. The magnetization reversal processes and the magnetic parameters have been studied by the measurement of the virgin magnetization curves, the major and minor hysteresis loops and sets of recoil curves. From these recoil curves the field dependence of the reversible and irreversible magnetization components during the magnetization and demagnetization processes has been derived. The remanence relationship was used to study the nature of magnetic interaction between the grains. A study of interaction domains was conducted using optical microscopy. Groups of domains, each over several grains, were observed. It was found that the reversal process in the samples investigated involves the rotation of magnetization vectors in the iron powder grains and pinning of domain walls at the MQP-B grain boundaries

  19. 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.

  20. Growth, microstructure, and hard magnetic properties of Nd-Fe-B layers; Wachstum, Mikrostruktur und hartmagnetische Eigenschaften von Nd-Fe-B-Schichten

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, U.

    2004-07-01

    In this thesis with pulsed laser deposition Nd-Fe-B layers were deposited. The Nd-Fe-B layers were deposited both on chromium and on tantalum buffers. The layers, which were deposed on tantalum buffers, showed a strong dependence of the nicrostructure and the magnetic properties on the deposition temperature. On layers which were deposited at deposition temperatures around 630 C on the tantalum buffer, the epitactical growth of Nd{sub 2}Fe{sub 14}B could be observed. Summarizingly these layers can be described as micrometer-large and parallely oriented single crystals.

  1. A new method of assembling large magnetic blocks from permanent NdFeB magnets

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2007-01-01

    Roč. 4, č. 3 (2007), 75-83 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnet assembly * magnet ic circuits * magnet ic separation Subject RIV: BM - Solid Matter Physics ; Magnet ism www.irsm.cas.cz

  2. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

    2014-01-01

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

  3. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2014-01-15

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    Amorphous SiO 2 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 SiO 2 and a few amorphous Fe 2 O 3 and Nd 2 O 3 . The amorphous SiO 2 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. - Highlights: • Amorphous SiO 2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

  5. Preparation and characterization of amorphous SiO{sub 2} coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Xiao, Q.F.; Mei, D.D. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [The Institute for Rare Earth Magnetic Materials and Devices, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Tong, Y.X. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)

    2017-03-15

    Amorphous SiO{sub 2} 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 SiO{sub 2} and a few amorphous Fe{sub 2}O{sub 3} and Nd{sub 2}O{sub 3}. The amorphous SiO{sub 2} 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. - Highlights: • Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

  6. Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2005-01-01

    Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

  7. Magnetism in grain-boundary phase of a NdFeB sintered magnet studied by spin-polarized scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kohashi, Teruo, E-mail: teruo.kohashi.fc@hitachi.com; Motai, Kumi [Central Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama 350-0395 (Japan); Nishiuchi, Takeshi; Hirosawa, Satoshi [Magnetic Materials Research Laboratory, Hitachi Metals Ltd., Osaka 618-0013 (Japan)

    2014-06-09

    The magnetism in the grain-boundary phase of a NdFeB sintered magnet was measured by spin-polarized scanning electron microscopy (spin SEM). A sample magnet was fractured in the ultra-high-vacuum chamber to avoid oxidation, and its magnetizations in the exposed grain-boundary phase on the fracture surface were evaluated through the spin polarization of secondary electrons. Spin-SEM images were taken as the fracture surface was milled gradually by argon ions, and the magnetization in the grain-boundary phase was quantitatively obtained separately from that of the Nd{sub 2}Fe{sub 14}B phase. The obtained magnetization shows that the grain-boundary phase of this magnet has substantial magnetization, which was confirmed to be ferromagnetic.

  8. Relation between Nd2Fe14B grain alignment and coercive force decrease ratio in NdFeB sintered magnets

    International Nuclear Information System (INIS)

    Matsuura, Yutaka; Hoshijima, Jun; Ishii, Rintaro

    2013-01-01

    It was found that the coercive force of NdFeB sintered magnets decreases as the Nd 2 Fe 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

  9. 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.

  10. Direct observation of magnetization reversal of hot-deformed Nd-Fe-B magnet

    Science.gov (United States)

    Zhu, Xiaoyun; Tang, Xu; Pei, Ke; Tian, Yue; Liu, Jinjun; Xia, Weixing; Zhang, Jian; Liu, J. Ping; Chen, Renjie; Yan, Aru

    2018-01-01

    The dynamic magnetic domain structure in magnetization and demagnetization process of hot-deformed and NdCu-diffused Nd2Fe14B magnets were in-situ observed by Lorentz transmission electron microscopy (LTEM). The demagnetization process of hot-deformed sample is dominated by domain-wall pinning, while that of NdCu-diffused sample is mainly the magnetization reversal of single grains or grain aggregations. This firstly observed result gives an explicit evidence to understand the coercivity mechanism of magnetically segregated magnet. The effect of magnetic field of TEM on decrease in domain wall energy was theoretically analyzed, which helps to understand the in-situ observation process of magnetic materials.

  11. Direct observation of magnetization reversal of hot-deformed Nd-Fe-B magnet

    Directory of Open Access Journals (Sweden)

    Xiaoyun Zhu

    2018-01-01

    Full Text Available The dynamic magnetic domain structure in magnetization and demagnetization process of hot-deformed and NdCu-diffused Nd2Fe14B magnets were in-situ observed by Lorentz transmission electron microscopy (LTEM. The demagnetization process of hot-deformed sample is dominated by domain-wall pinning, while that of NdCu-diffused sample is mainly the magnetization reversal of single grains or grain aggregations. This firstly observed result gives an explicit evidence to understand the coercivity mechanism of magnetically segregated magnet. The effect of magnetic field of TEM on decrease in domain wall energy was theoretically analyzed, which helps to understand the in-situ observation process of magnetic materials.

  12. Prediction of flux loss in a Nd-Fe-B ring magnet considering magnetizing process

    International Nuclear Information System (INIS)

    Fukunaga, H; Koreeda, H; Yanai, T; Nakano, M; Yamashita, F

    2010-01-01

    We developed a technique to predict flux loss of a magnet with a complicated magnetization pattern using the finite element method. The developed method consists of four steps. At first, the distribution of magnetization under magnetizing field is analyzed (Step 1), and a demagnetization curve of each element is deduced from the result of the first step (Step 2). After removing the magnetizing field, the distributions of magnetization at room and elevated temperatures are analyzed by using demagnetization curves determined in Step 2 (Step 3). Based on a physical model, the distribution of flux loss due to exposure at the elevated temperature is predicted by using the result obtained in Step 3 (Step 4). We applied this technique to a ring magnet with 10 poles, and large flux loss values were predicted at the transition regions between magnetic poles.

  13. Micro-patterning of NdFeB and SmCo magnet films for integration into micro-electro-mechanical-systems

    International Nuclear Information System (INIS)

    Walther, A.; Marcoux, C.; Desloges, B.; Grechishkin, R.; Givord, D.; Dempsey, N.M.

    2009-01-01

    The integration of high-performance RE-TM (NdFeB and SmCo) hard magnetic films into micro-electro-mechanical-systems (MEMS) requires their patterning at the micron scale. In this paper we report on the applicability of standard micro-fabrication steps (film deposition onto topographically patterned substrates, wet etching and planarization) to the patterning of 5-8 μm thick RE-TM films. While NdFeB comprehensively fills micron-scaled trenches in patterned substrates, SmCo deposits are characterized by poor filling of the trench corners, which poses a problem for further processing by planarization. The magnetic hysteresis loops of both the NdFeB and SmCo patterned films are comparable to those of non-patterned films prepared under the same deposition/annealing conditions. A micron-scaled multipole magnetic field pattern is directly produced by the unidirectional magnetization of the patterned films. NdFeB and SmCo show similar behavior when wet etched in an amorphous state: etch rates of approximately 1.25 μm/min and vertical side walls which may be attributed to a large lateral over-etch of typically 20 μm. Chemical-mechanical-planarization (CMP) produced material removal rates of 0.5-3 μm/min for amorphous NdFeB. Ar ion etching of such films followed by the deposition of a Ta layer prior to film crystallization prevented degradation in magnetic properties compared to non-patterned films

  14. Micro-patterning of NdFeB and SmCo magnet films for integration into micro-electro-mechanical-systems

    Energy Technology Data Exchange (ETDEWEB)

    Walther, A. [CEA Leti-MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France); Marcoux, C.; Desloges, B. [CEA Leti-MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Grechishkin, R. [Laboratory of Magnetoelectronics, Tver State University, 170000 Tver (Russian Federation); Givord, D. [Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France); Dempsey, N.M. [Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France)], E-mail: nora.dempsey@grenoble.cnrs.fr

    2009-03-15

    The integration of high-performance RE-TM (NdFeB and SmCo) hard magnetic films into micro-electro-mechanical-systems (MEMS) requires their patterning at the micron scale. In this paper we report on the applicability of standard micro-fabrication steps (film deposition onto topographically patterned substrates, wet etching and planarization) to the patterning of 5-8 {mu}m thick RE-TM films. While NdFeB comprehensively fills micron-scaled trenches in patterned substrates, SmCo deposits are characterized by poor filling of the trench corners, which poses a problem for further processing by planarization. The magnetic hysteresis loops of both the NdFeB and SmCo patterned films are comparable to those of non-patterned films prepared under the same deposition/annealing conditions. A micron-scaled multipole magnetic field pattern is directly produced by the unidirectional magnetization of the patterned films. NdFeB and SmCo show similar behavior when wet etched in an amorphous state: etch rates of approximately 1.25 {mu}m/min and vertical side walls which may be attributed to a large lateral over-etch of typically 20 {mu}m. Chemical-mechanical-planarization (CMP) produced material removal rates of 0.5-3 {mu}m/min for amorphous NdFeB. Ar ion etching of such films followed by the deposition of a Ta layer prior to film crystallization prevented degradation in magnetic properties compared to non-patterned films.

  15. Perspective for using Nd-Fe-B magnets as a tool for the improvement of the production and transportation of Vietnamese crude oil with high paraffin content

    International Nuclear Information System (INIS)

    Tung, N.P.; Vinh, N.Q.; Phong, N.T.P.; Long, B.Q.K.; Hung, P.V.

    2003-01-01

    Controlling the paraffin deposition is one of the most serious and costly problems for high-paraffin crude-oil production and transportation. This holds especially for offshore, deep-water wells and pipelines, like in Vietnam. For finding solutions for these problems, a series of experiments has been performed in order to study the effects of a magnetic field on the rheology of two often produced crude oil samples, using the high and variable magnetic-flux density of a Nd-Fe-B magnet. The resulting changes in the essential characteristics of the magnetically treated (MT) crude oils, like form and size of the paraffin clusters as well as the rheology parameters, have definitely proved the possibility to use a Nd-Fe-B magnetic tool as an environmentally friendly and effective method to control the paraffin deposition in crude oils of Vietnam that have a high paraffin content

  16. Magnetic properties of melt-spun Nd-rich NdFeB alloys with Dy and Ga substitutions

    International Nuclear Information System (INIS)

    Harland, C.L.; Davies, H.A.

    1998-01-01

    The results of a systematic investigation of the effects of Dy and Ga additions on the magnetic properties of a Nd-rich NdFeB alloy are presented and discussed. Particular attention is given to the effect of increasing Dy substitutions on the coercivity of the Nd 18 Fe 76 B 6 alloy. Substitution of 30% of the Nd by Dy resulted in a coercivity increase from 1590 to 3290 kA m -1 . However, contrary to previous suggestions, substitution of 1% of the Fe by Ga was found to have only a small influence on the magnetic properties of all the alloys in the compositional series (Nd 100-x Dy x ) 18 Fe 76 B 6 (x=0-30). (orig.)

  17. Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

    International Nuclear Information System (INIS)

    Saito, Kotaro; Ono, Kanta; Ueno, Tetsuro; Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira; Harada, Masashi; Keiderling, Uwe

    2015-01-01

    The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd 2 Fe 14 B grains

  18. Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kotaro, E-mail: kotaro.saito@kek.jp; Ono, Kanta [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, 305-0803 Tsukuba (Japan); Ueno, Tetsuro [Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, 1-2-1 Sengen, 305-0047 Tsukuba (Japan); Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira [Toyota Motor Corporation, Toyota, Aichi 471-8571 (Japan); Harada, Masashi [Toyota Central R and D Labs, Inc., Aichi 480-1192 (Japan); Keiderling, Uwe [Helmholtz-Zentrum Berlin für Materialien and Energie, 14109 Berlin (Germany)

    2015-05-07

    The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd{sub 2}Fe{sub 14}B grains.

  19. Angular dependence of coercivity derived from alignment dependence of coercivity in Nd-Fe-B sintered magnets

    Directory of Open Access Journals (Sweden)

    Yutaka Matsuura

    2018-01-01

    Full Text Available Experimental results of the alignment dependence of the coercivity in Nd-Fe-B sintered magnets showed that the angle of magnetization reversal for anisotropically aligned magnets was bigger than that obtained from the theoretical results calculated using the postulation that every grain independently reverses its magnetization direction following the 1/cos θ law. The angles of reversed magnetization (θ1 for Nd13.48Co0.55B5.76Febal. with alignment α=0.95 and for Nd12.75Dy0.84B5.81Co0.55Febal. with α=0.96 were 30° and 36°, respectively, which were very similar to that of an ideal magnet with a Gaussian distribution (σ=31° and 44°, respectively of the grain alignment. In this model, we postulated that every grain independently reversed according to the 1/cos θ law. The calculation results for the angular dependence of the coercivity using the values θ1=ω1(0°=30°, σ=31° and θ1=ω1(0°=36°, σ=44° could qualitatively and convincingly explain the observed angular dependence of the coercivity of Nd14.2B6.2Co1.0Febal. and Nd14.2Dy0.3B6.2Co1.0Febal.. It is speculated that the magnetic domain wall is pinned at grains tilted away from the easy magnetization direction, and when the magnetic domain wall de-pins from the tilted grains, the magnetic domain wall jumps through several grains. We suggest that the coercive force of the aligned magnet behaves like a low-aligned magnet owing to the magnetization reversal of the crust of the grains induced by the pinning and subsequent jumping of the magnetic domain wall.

  20. Angular dependence of coercivity derived from alignment dependence of coercivity in Nd-Fe-B sintered magnets

    Science.gov (United States)

    Matsuura, Yutaka; Nakamura, Tetsuya; Sumitani, Kazushi; Kajiwara, Kentaro; Tamura, Ryuji; Osamura, Kozo

    2018-01-01

    Experimental results of the alignment dependence of the coercivity in Nd-Fe-B sintered magnets showed that the angle of magnetization reversal for anisotropically aligned magnets was bigger than that obtained from the theoretical results calculated using the postulation that every grain independently reverses its magnetization direction following the 1/cos θ law. The angles of reversed magnetization (θ1) for Nd13.48Co0.55B5.76Febal. with alignment α=0.95 and for Nd12.75Dy0.84B5.81Co0.55Febal. with α=0.96 were 30° and 36°, respectively, which were very similar to that of an ideal magnet with a Gaussian distribution (σ=31° and 44°, respectively) of the grain alignment. In this model, we postulated that every grain independently reversed according to the 1/cos θ law. The calculation results for the angular dependence of the coercivity using the values θ1=ω1(0°)=30°, σ=31° and θ1=ω1(0°)=36°, σ=44° could qualitatively and convincingly explain the observed angular dependence of the coercivity of Nd14.2B6.2Co1.0Febal. and Nd14.2Dy0.3B6.2Co1.0Febal.. It is speculated that the magnetic domain wall is pinned at grains tilted away from the easy magnetization direction, and when the magnetic domain wall de-pins from the tilted grains, the magnetic domain wall jumps through several grains. We suggest that the coercive force of the aligned magnet behaves like a low-aligned magnet owing to the magnetization reversal of the crust of the grains induced by the pinning and subsequent jumping of the magnetic domain wall.

  1. Influence of AC external magnetic field perturbation on the guidance force of HTS bulk over a NdFeB guideway

    International Nuclear Information System (INIS)

    Zhang Longcai; Wang Jiasu; Wang Suyu; He Qingyong

    2007-01-01

    Superconducting maglev vehicle system requires that the surface magnetic field of the guideway is uniform along the forward direction. But in practice the surface magnetic field of the NdFeB permanent magnet guideway is not always immutable. So the HTS bulks in this case are exposed to AC external magnetic field, which may induce the energy loss in the bulk and influence the guidance force between the HTS bulks and the NdFeB guideway. In this paper, we experimentally studied the influence of the AC external magnetic field perturbation on the guidance force of a HTS bulk over the NdFeB guideway. The experimental results showed that the guidance force was influenced by the application of the AC external magnetic. The guidance fore hysteresis became more evident with the amplitude of the AC field and was independent of the frequency in the range 90-400 Hz. We attributed the reason to magnetic hysteresis loss in the superconductor

  2. Progress of sintered NdFeB permanent magnets by the diffusion of non-rare earth elements and their alloy compounds

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available It has been found that the coercivity (HC and corrosivity of sintered NdFeB magnets are closely related to the components and microstructure of their intergranular phase.The traditional smelting NdFeB magnets with adding heavy rare earth elements can modify intergranular phase to improve the HC and corrosion resistance of magnets.However,it makes the additives be homogenously distributed on the main phase,and causes magnetic decrease and cost increase.With the addition of non-rare earth materials into grain boundary,the microstructure of intergranular phase as well as its electrochemical potential and wettability can be optimized.As a result,the amount of heavy rare earth elements and cost of magnets could be reduced whilst the HC and corrosion resistance of magnets can be improved.This paper summarized the research on regulating the components and the microstructure of intergranular phase in sintered NdFeB magnets by non-rare earth metals and compounds,and its influence on coercivity and corrosion resistance.

  3. Influence of AC external magnetic field perturbation on the guidance force of HTS bulk over a NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China)]. E-mail: zhlcai2000@163.com; Wang Jiasu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China); Wang Suyu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China); He Qingyong [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China)

    2007-08-01

    Superconducting maglev vehicle system requires that the surface magnetic field of the guideway is uniform along the forward direction. But in practice the surface magnetic field of the NdFeB permanent magnet guideway is not always immutable. So the HTS bulks in this case are exposed to AC external magnetic field, which may induce the energy loss in the bulk and influence the guidance force between the HTS bulks and the NdFeB guideway. In this paper, we experimentally studied the influence of the AC external magnetic field perturbation on the guidance force of a HTS bulk over the NdFeB guideway. The experimental results showed that the guidance force was influenced by the application of the AC external magnetic. The guidance fore hysteresis became more evident with the amplitude of the AC field and was independent of the frequency in the range 90-400 Hz. We attributed the reason to magnetic hysteresis loss in the superconductor.

  4. 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.

  5. Effect of grain alignment distribution on magnetic properties in (MM, Nd)-Fe-B sintered magnets

    Science.gov (United States)

    Yu, Xiaoqiang; Yue, Ming; Zhu, Minggang; Liu, Weiqiang; Li, Yuqing; Xi, Longlong; Li, Jiajie; Zhang, Jiuxing; Li, Wei

    2018-03-01

    H cj of (MM x Nd1-x )-Fe-B sintered magnets decreases distinctly with x increasing when misch metal (MM) content (x) ranges from 0.3 to 1. Practical application is taken into consideration so that the (MM0.6Nd0.4)-Fe-B components are chosen to analyze the changes in behavior of the magnetic properties. Both Magnet II and Magnet III belong to (MM0.6Nd0.4)-Fe-B sintered magnets, however, it should be noted that Magnet II is prepared by the single alloying method (SAM) and Magnet III is prepared by the double main phase alloy method (DMPAM). Core-shell structures of the magnets prepared by DMPAM can result in the higher H cj and lower knee-point coercivity (H k) compared with that by SAM. Furthermore, for Magnet II, the abnormal grain growth contributes to a better grain alignment and smaller distribution coefficient (σ) defined as the degree of grain alignment, which will enforce a higher tendency of the H cj decreasing and H k increasing. The expression of their normalized coercivity h(σ) is deduced by combining Gao’s starting field model with Kronmüller’s nucleation mechanism. Based on the overall h(σ) ~ σ curve, the best desirable h(σ) value is calculated when σ  =  0.09. Theoretically, for Magnet III, the resultant larger σ should be attributed to the more uniform grain alignment. In addition, the deviations of grain size distributions on the c-plane become more remarkable with more MM concentrates, which can be presented by SEM images. Meanwhile, by means of the pole figures, it is also verified that the grain alignment distribution becomes much more diverse with x increasing. Therefore, it can be predicted whether the grain alignment distribution is significant for H k and H cj of (MM x Nd1-x )-Fe-B sintered magnets (x  ≠  0.6) prepared by SAM/DMPAM or not.

  6. Computation of magnetic field in DC brushless linear motors built with NdFeB magnets

    International Nuclear Information System (INIS)

    Basak, A.; Shirkoohi, G.H.

    1990-01-01

    A software package based on finite element technique has been used to compute three-dimensional magnetic fields and static forces developed in brushless d.c. linear motors. As the field flux-source two different types of permanent magnets, one of them being the high energy neodymium- iron-boron type, has been used in computer models. Motors with the same specifications as the computer models were built and experimental results obtained from them are compared with the computed results

  7. Aplikasi Magnet Berpengikat (Bonded NdFeB untuk S-band Circulator pada Rentang Frekuensi 2,00-4,00 GHz

    Directory of Open Access Journals (Sweden)

    Tony Kristiantoro

    2016-06-01

    Full Text Available Circulator merupakan perangkat elektronik yang memiliki fungsi penting pada suatu sistem pemancar dan penerima gelombang frekuensi radio (RF, di mana magnet permanen dapat berfungsi sebagai pengarah gelombang (waveguide. Penelitian ini bertujuan untuk menggantikan magnet permanen barium ferit (BaFe12O19 yang umumnya digunakan pada circulator dengan magnet permanen berpengikat (bonded neodymium besi boron (NdFeB. Bahan baku yang digunakan adalah serbuk NdFeB crashed ribbon dengan menggunakan metode pengepresan green-compact yang divariasikan pada tekanan 25, 50, 75, dan 100 kg.cm-2 dan dilanjutkan proses pemanasan pada temperatur 200 C selama 60 menit. Karakterisasi sifat magnet dilakukan dengan Permagraph, diperoleh nilai intrinsik optimum dari sampel 100 kg.cm-2 , induksi remanen (Br = 5,37 kG, koersifitas (HcJ = 4,74 kOe, produk energi maksimum (BHmax = 2,39 MGOe, dan densitas (ρ = 4,89 gr.cm-3 . Hasil pengukuran kuat medan permukaan (B dengan Gauss-meter menunjukkan nilai 800 G. Magnet dengan karakteristik optimum diterapkan pada circulator kemudian dikarakterisasi dengan Vector Network Analyzer dan menghasilkan voltage standing wave ratio (VSWR = 1,354, isolasi = -17,165 dB dan kerugian penyisipan = -0,200 dB pada titik kerja 3,00 GHz, sehingga magnet berpengikat (bonded NdFeB ini dapat diterapkan pada S-band circulator yang bekerja pada rentang frekuensi 2,00-4,00 GHz.

  8. 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%.

  9. 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%.

  10. Microstructure and magnetic properties of highly textured Nd-Fe-B films grown on Ta (1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, A.R. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr.20, D-01069 Dresden (Germany)]. E-mail: a.kwon@ifw-dresden.de; Hannemann, U. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr.20, D-01069 Dresden (Germany); Neu, V. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr.20, D-01069 Dresden (Germany); Faehler, S. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr.20, D-01069 Dresden (Germany); Schultz, L. [IFW Dresden, Institute for Metallic Materials, Helmholtzstr.20, D-01069 Dresden (Germany)

    2005-04-15

    Hard magnetic Nd-Fe-B films were deposited by pulsed laser deposition on a combined Cr/Ta buffer layer on single crystalline MgO(1 0 0) substrates. At suitable temperatures this system of substrate and buffers allows epitaxial growth of the Nd{sub 2}Fe{sub 14}B phase with the c-axis pointing out-of-plane. The films exhibit coercivities up to 1.3 T. The in-plane to out-of-plane remanence ratio between 560 deg. C and 600 deg. C is as low as 0.1. Using this buffer system a moderate substrate temperature of 420 deg. C is sufficient to deposit films with an out-of-plane coercivity above 1 T.

  11. Microstructure and magnetic properties of highly textured Nd-Fe-B films grown on Ta (1 0 0)

    International Nuclear Information System (INIS)

    Kwon, A.R.; Hannemann, U.; Neu, V.; Faehler, S.; Schultz, L.

    2005-01-01

    Hard magnetic Nd-Fe-B films were deposited by pulsed laser deposition on a combined Cr/Ta buffer layer on single crystalline MgO(1 0 0) substrates. At suitable temperatures this system of substrate and buffers allows epitaxial growth of the Nd 2 Fe 14 B phase with the c-axis pointing out-of-plane. The films exhibit coercivities up to 1.3 T. The in-plane to out-of-plane remanence ratio between 560 deg. C and 600 deg. C is as low as 0.1. Using this buffer system a moderate substrate temperature of 420 deg. C is sufficient to deposit films with an out-of-plane coercivity above 1 T

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

    International Nuclear Information System (INIS)

    Liu, Lihua; Sepehri-Amin, H.; Ohkubo, T.; Yano, M.; Kato, A.; Shoji, T.; Hono, K.

    2016-01-01

    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 90 Al 10 exhibited the highest coercivity of 2.5 T at room temperature. However, the sample processed with Nd 70 Cu 30 exhibited the highest coercivity of 0.7 T at 200 ° C. Microstructural observations using scanning transmission electron microscope (STEM) showed that nonferromagnetic Nd-rich intergranular phase envelops the Nd 2 Fe 14 B grains after the diffusion process. Abnormal grain growth and the dissolution of Al into the Nd 2 Fe 14 B grains were observed in the sample processed with Nd 90 Al 10 , which explains its inferior thermal stability of coercivity compared to the sample processed with Nd 70 Cu 30 . The coercivity enhancement and poor thermal stability of the coercivity of the Nd 90 Al 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 90 Al 10 shows the highest coercivity of 2.5 T at room temperature. • At 200 °C, Nd 70 Cu 30 diffusion-processed sample possesses the highest coercivity of 0.7 T.

  13. 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.

  14. Magnetic properties of (misch metal, Nd-Fe-B melt-spun magnets

    Directory of Open Access Journals (Sweden)

    R. Li

    2017-05-01

    Full Text Available The effect of replacing Nd with misch metal (MM on magnetic properties and thermal stability has been investigated on melt-spun (Nd1-xMMx13.5Fe79.5B7 ribbons by varying x from 0 to 1. All of the alloys studied crystallize in the tetragonal 2:14:1 structure with single hard magnetic phase. Curie temperature (Tc, coercivity (Hcj, remanence magnetization (Br and maximum energy product ((BHmax all decrease with MM content. The melt-spun MM13.5Fe79.5B ribbons with high ratio of La and Ce exhibit high magnetic properties of Hcj = 8.2 kOe and (BHmax= 10.3 MGOe at room temperature. MM substitution also significantly strengthens the temperature stability of coercivity. The coercivities of the samples with x = 0.2 and even 0.4 exhibit large values close to that of Nd13.5Fe79.5B7 ribbons above 400 K.

  15. The influence of concentration of Nd-Fe-B powder in composite coating of optical fiber to the sensibility to external magnetic field

    Directory of Open Access Journals (Sweden)

    Radojević Vesna J.

    2005-01-01

    Full Text Available Multi-mode optical fiber with magnetic composite coating was investigated as an optical fiber sensor element (OFMSE for magnetic field sensing The composite coating was formed with dispersions of permanent magnet powder of Nd-Fe-B in poly (ethylene-co-vinyl acetate-EVA solutions in toluene. The influence of the applied external magnetic field on the change of intensity of the light signal propagate trough developed optical fibers sensor element was investigated. In this paper the influence of the content of magnetic powder in the composite coating on the optical propagation characteristics of optical fiber were particularly investigated.

  16. Towards understanding of magnetization reversal in Nd-Fe-B nanocomposites: analysis by high-throughput micromagnetic simulations

    Science.gov (United States)

    Erokhin, Sergey; Berkov, Dmitry; Ito, Masaaki; Kato, Akira; Yano, Masao; Michels, Andreas

    2018-03-01

    We demonstrate how micromagnetic simulations can be employed in order to characterize and analyze the magnetic microstructure of nanocomposites. For the example of nanocrystalline Nd-Fe-B, which is a potential material for future permanent-magnet applications, we have compared three different models for the micromagnetic analysis of this material class: (i) a description of the nanocomposite microstructure in terms of Stoner-Wohlfarth particles with and without the magnetodipolar interaction; (ii) a model based on the core-shell representation of the nanograins; (iii) the latter model including a contribution of superparamagnetic clusters. The relevant parameter spaces have been systematically scanned with the aim to establish which micromagnetic approach can most adequately describe experimental data for this material. According to our results, only the last, most sophisticated model is able to provide an excellent agreement with the measured hysteresis loop. The presented methodology is generally applicable to multiphase magnetic nanocomposites and it highligths the complex interrelationship between the microstructure, magnetic interactions, and the macroscopic magnetic properties.

  17. 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.

  18. Multi-layered electroless Ni-P coatings on powder-sintered Nd-Fe-B permanent magnet

    International Nuclear Information System (INIS)

    Chen Zhong; Ng, Alice; Yi Jianzhang; Chen Xingfu

    2006-01-01

    This paper has shown a successful protective coating scheme for powder-sintered Nd-Fe-B permanent magnet using multi-layered electroless nickel (EN) deposition. A low-phosphorus nickel layer is plated with an alkaline EN solution first, followed by a high-phosphorus nickel layer plated with an acidic solution. An additional topcoat by medium-phosphorus nickel on the high-phosphorus coating is also explored. It is shown that the high-phosphorus nickel layer coated in acidic solution provides the best corrosion protection because of its dense amorphous structure. The medium phosphorus topcoat is also dense and is able to provide reasonable corrosion resistance. The low-phosphorus layer itself does not have enough corrosion resistance; its main role is to provide an intermediate coating on the powder-sintered magnet. X-ray diffraction measurement shows that the low-phosphorus coating consists of nano-crystallines, and the high- and the medium-phosphorus coatings are dominated by amorphous structure. Microscopic observation and scratch test on these composite coatings demonstrate good adhesion between the magnet and the coatings. Remanence and coercivity of the plated magnet decrease with the applied coatings, but measured values are still very attractive for practical applications among known hard magnets

  19. Effect of Partial Substitution of Neodymium with Praseodymium on the Magnetic and Process Properties of Sintered Magnets of Type NdFeB

    Science.gov (United States)

    Dormidontov, N. A.; Dormidontov, A. G.; Lileev, A. S.; Kamynin, A. V.; Lukin, A. A.

    2017-01-01

    The effect of substitution of neodymium with praseodymium in sintered magnets of type NdFeB on their magnetic and process properties in the concentration range of [Pr] = 0 - 13 wt.% is studied. The special features of milling of the alloys, sintering processes and heat treatments in the production of magnets containing praseodymium are discussed. Hysteresis characteristics of B r ≥ 1.2 T, H cJ ≥ 1200 kA/m, H cb ≥ 880 kA/m, H k ≥ 960 kA/m, and BH max ≥ 280 kJ/m3 are obtained for magnets with composition (in wt.%) 33 Nd, 10 Pr, 1.5 (Ti + Al + Cu), 1.3 B, the remainder Fe.

  20. Microstructure and Magnetic Properties of NdFeB Sintered Magnets Diffusion-Treated with Cu/Al Mixed Dyco Alloy-Powder

    Directory of Open Access Journals (Sweden)

    Lee M.-W.

    2017-06-01

    Full Text Available We investigated the microstructural and magnetic property changes of DyCo, Cu + DyCo, and Al + DyCo diffusion-treated NdFeB sintered magnets. The coercivity of all diffusion treated magnet was increased at 880ºC of 1st post annealing(PA, by 6.1 kOe in Cu and 7.0 kOe in Al mixed DyCo coated magnets, whereas this increment was found to be relatively low (3.9 kOe in the magnet coated with DyCo only. The diffusivity and diffusion depth of Dy were increased in those magnets which were treated with Cu or Al mixed DyCo, mainly due to comparatively easy diffusion path provided by Cu and Al because of their solubility with Ndrich grain boundary phase. The formation of Cu/Al-rich grain boundary phase might have enhanced the diffusivity of Dy-atoms. Moreover, relatively a large number of Dy atoms reached into the magnet and mostly segregated at the interface of Nd2Fe14B and grain boundary phases covering Nd2Fe14B grains so that the core-shell type structures were developed. The formation of highly anisotropic (Nd, Dy2Fe14B phase layer, which acted as the shell in the core-shell type structure so as to prevent the reverse domain movement, was the cause of enhancing the coercivity of diffusion treated NdFeB magnets. Segregation of cobalt in Nd-rich TJP followed by the formation of Co-rich phase was beneficial for the coercivity enhancement, resulting in the stabilization of the metastable c-Nd2O3 phase.

  1. Analysis and testing of a double armature brushless dc linear motor with NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Filho, A.F.F.

    1998-01-01

    The use of high-energy product NdFeB permanent magnets benefits the design and features of a double armature brushless dc linear motor. As the linear motor is also slotless, its 5 mm airgap requires a source of high flux to overcome the reluctance and produce an adequate amount of force. The linear motor employs a topology that makes use of five permanent magnets to provide excitation flux. The permanent magnets are arranged in such a way that maximises the force the linear motor can deliver. The actuator produces a force up to 86.2 N at an armature current of 4.5 A. However, the topology makes the actuator prone to saturation. It affects the operation point of the permanent magnets, reduces the airgap flux density and the force, and increases flux leakage. To avoid saturation, a flux compensation scheme was conceived. The results are presented and assessed by means of finite element simulation and by experimental results that presented a good agreement. (orig.)

  2. Microstructural and electrochemical characterization of Ni/Ti/sub 2/N composite coating for sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

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

    2009-01-01

    Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti/sub 2/N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer. (author)

  3. 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.

  4. Microstructure characteristic and excellent corrosion protection properties of sealed Zn-TiO{sub 2} composite coating for sintered NdFeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Yang Xiaokui [School of Materials Science and Engineering, Southwest University, Chongqing 400715 (China); Li Qing, E-mail: liqingd@swu.edu.c [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang Shiyan; Liu Fang; Wang Shaoyin; Zhang Haixiao [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2010-04-09

    In this paper, a protective sealed Zn-TiO{sub 2} composite coating (SCC) was prepared on sintered NdFeB magnet by electrodeposition and sol-gel combined technique. For a comparison, unsealed Zn-TiO{sub 2} composite coating (UCC) was also studied. The surface morphologies of composite coating were studied using scanning electron microscope (SEM). The microstructure of composite coatings and structure of sealing layer were studied by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectrum, respectively. The anticorrosive properties of composite coatings in neutral 3.5 wt.% NaCl solutions were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) technique. The results of corrosion tests showed that due to the blocking effect of sealing layer, SCC could suppress the corrosion process by holding back the transfer or diffusion of corrosive medium, and therefore showed the excellent corrosion protection properties for sintered NdFeB magnet.

  5. The effect of CuAl addition on the magnetic property, thermal stability and corrosion resistance of the sintered NdFeB magnets

    Science.gov (United States)

    Liu, Y. L.; Liang, J.; He, Y. Ch.; Li, Y. F.; Wang, G. F.; Ma, Q.; Liu, F.; Zhang, Y.; Zhang, X. F.

    2018-05-01

    To improve the coercivity of the Nd-Fe-B sintered magnets, the Cu29.8Al70.2 (at.%) powders with low melting point were introduced into the Nd-Fe-B magnets. The magnetic properties, microstructure, thermal stability and corrosion behavior of the sintered magnets with different amount of Cu29.8Al70.2 (0,0.25,0.50,0.75,1.0 wt.%) were investigated. When the amount of doped Cu29.8Al70.2 was less than 0.75 wt.%, the coercivity was improved, especially that of the magnets with 0.25 wt.% Cu29.8Al70.2, markedly increased to 13.97 kOe from 12.67 kOe (without CuAl). The improvement of magnetic properties could be attributed to enhanced wettability between Nd2Fe14B phase and Nd-rich phase and decreased exchange coupling between grains, which depended on the optimization of grain boundary microstructure and their distribution by codoping Cu and Al. With the addition of 0-1.0 wt.% Cu29.8Al70.2 powders, the reversible temperature coefficients of remanence and coercivity of the magnets could be also improved. The corrosion resistances was also found to be improved through small addition of Cu29.8Al70.2 powder in 3.5 wt.% NaCl solution by electrochemical and immersion tests, which could be due to the enhancement of the Nd-rich intergranular phase by addition Cu29.8Al70.2.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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, H 2 SO 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 2 SO 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

  7. 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.

  8. The effect of phase constitution on the magnetic structure of nanophase NdFeB alloys observed by magnetic force microscopy

    Science.gov (United States)

    Al-Khafaji, M. A.; Rainforth, W. M.; Gibbs, M. R. J.; Davies, H. A.; Bishop, J. E. L.

    1998-09-01

    Magnetic force microscopy (MFM) has been employed to image the magnetic structure in nanocrystalline melt spun ribbon samples of NdFeB alloys of three markedly different and contrasting compositions: Low-Nd (Nd 9.5Fe 84.5B 6) containing Nd 2Fe 14B and α-Fe phases, stoichiometric (Nd 11.8Fe 82.3B 5.9), and high-Nd (Nd 18Fe 76B 6) containing Nd 2Fe 14B and Nd-rich phases. It was found that the magnetic domain length scale is significantly larger than the mean Nd 2Fe 14B grain size (˜35 nm) in each case, although small changes in force gradient occurred down to ˜20 nm. However, both the domain length scale and the tip-sample interaction `strength' were found to decrease with increasing Nd-content. An interpretation of these results in terms of the microstructure is given.

  9. Hard magnetic properties of rapidly annealed NdFeB thin films on Nb and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; Evans, J.; O'Shea, M.J.; Du Jianhua

    2001-01-01

    NdFeB thin films of the form A (20 nm)/NdFeB(d nm)/A(20 nm), where d ranges from 54 to 540 nm and the buffer layer A is Nb or V were prepared on a Si(1 0 0) substrate by magnetron sputtering. The hard Nd 2 Fe 14 B phase is formed by a 30 s rapid anneal or a 20 min anneal. Average crystallite size ranged from 20 to 35 nm with the rapidly annealed samples having the smaller crystallite size. These samples also exhibited a larger coercivity and energy product than those treated by a 20 min vacuum anneal. A maximum coercivity of 26.3 kOe at room temperature was obtained for a Nb/NdFeB (180 nm)/Nb film after a rapid anneal at 725 deg. C. Initial magnetization curves indicate magnetization rotation rather than nucleation of reverse domains is important in the magnetization process. A Brown's equation analysis of the coercivity as a function of temperature allowed us to compare the rapidly annealed and 20 min annealed samples. This analysis suggests that rapid annealing gives higher quality crystalline grains than the 20 min annealed sample leading to the observed large coercivity in the rapidly annealed samples

  10. The effect of additional elements on the magnetic properties of hot-rolled Nd-Fe-B alloys

    International Nuclear Information System (INIS)

    Chang, W.C.; Nakamura, H.; Paik, C.R.; Sugimoto, S.; Okada, M.; Homma, M.

    1992-01-01

    The magnetic properties of hot-rolled Nd 16 Fe bal. B 6 M 1.5 (M = Cu, Ga and Al) and Nd 16 Fe 76 B 5.5 Ga 1.5 Al 1 alloys were investigated, in order to study the role of additive elements in improving the magnetic properties in the Nd-Fe-B system. It is found that the original grain size of Cu, Ga or Ga-Al added alloys is much finer than that of the ternary and Al added alloys. But the grain size is almost identical for all the alloys after hot-rolling at 1000degC with 90% reduction in thickness. The coercivity of hot-rolled alloys with Cu, Ga or Ga-Al addition is not improved as was expected, because Nd-rich liquid phase in these alloys is very easily squeezed out during high-reduction-ratio rolling. Less quantity and nonuniform distribution of Nd-rich phase between distributed grains are believed to be the main reasons to depress the effect on the grain boundary smoothing. This effect is not the same as those observed in the Pr-Fe-B system. The highest magnetic properties achieved in this study are B r = 10 kG, i H c = 8.2 kOe, (BH) max = 18.5 MGOe for the Nd 16 Fe 76.5 B 6 Al 1.5 alloy. (orig.)

  11. Amorphous Al–Mn coating on NdFeB magnets: Electrodeposition from AlCl3–EMIC–MnCl2 ionic liquid and its corrosion behavior

    International Nuclear Information System (INIS)

    Chen Jing; Xu Bajin; Ling Guoping

    2012-01-01

    Amorphous Al–Mn coating was electrodeposited on NdFeB magnets from AlCl 3 –EMIC–MnCl 2 ionic liquid with the pretreatment of anodic electrolytic etching in AlCl 3 –EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl 3 –EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al–Mn alloy coating to the NdFeB substrate. The amorphous Al–Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: ► Amorphous Al–Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. ► To remove the surface oxides of NdFeB, anodic etching pretreatment is used. ► The deposited Al–Mn alloy coating shows high adhesion to the NdFeB substrate. ► Corrosion tests show that amorphous Al–Mn alloy coating is anodic coating for NdFeB magnet.

  12. Amorphous Al-Mn coating on NdFeB magnets: Electrodeposition from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid and its corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jing; Xu Bajin [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Ling Guoping, E-mail: linggp@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2012-06-15

    Amorphous Al-Mn coating was electrodeposited on NdFeB magnets from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid with the pretreatment of anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al-Mn alloy coating to the NdFeB substrate. The amorphous Al-Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: Black-Right-Pointing-Pointer Amorphous Al-Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. Black-Right-Pointing-Pointer To remove the surface oxides of NdFeB, anodic etching pretreatment is used. Black-Right-Pointing-Pointer The deposited Al-Mn alloy coating shows high adhesion to the NdFeB substrate. Black-Right-Pointing-Pointer Corrosion tests show that amorphous Al-Mn alloy coating is anodic coating for NdFeB magnet.

  13. Corrosion resistance of rigid bonded magnet MQP-0 (NdFeB compound) pre and post surface coating

    International Nuclear Information System (INIS)

    Purwanto, Setyo; Ihsan, M.; Mujamilah; Mashadi

    2002-01-01

    Rigid Bonded Magnet (RBM) MQP-0 (NdFeB magnetics material compound) has been created and done some treatment. It has been known that corrosion resistance of RBM with epoxy resin binder is higher than RBM with polyester binder (PE). Corrosion rate in variety solutions like water. Na CI, H 2 SO 4 , has proved the earlier statement. For corrosion testing of RBM in Na CI solution with concentrations 0.05 M and 0.10 M shows corrosion rate 0.18 milli inches/year (mpy) and 2.93 mpy for epoxy binder, and 4.10 mpy and 24.87 mpy for polyester binder. In order to enhance the corrosion resistance, coating of RBM with epoxy resin has been done. And it has been known that coating of RBM with epoxy resin decrease of corrosion rate almost 50%. Corrosion rate of RBM with epoxy coating in 0.15 M Na CI is 9.38 mpy, compared without coating 15.11 mpy

  14. Preparation and Properties of Anisotropic Nano-crystalline NdFeB Powders Made by Hydrogen Decrepitation of Die Upsetting Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yi, P P; Lee, D; Yan, A R, E-mail: ypp@nimte.ac.cn [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2011-01-01

    Anisotropic nanocrystalline NdFeB powders were prepared by hydrogen decrepitation (HD) of die upsetting magnets. The effects of varying temperatures of HD on the microstructure and magnetic properties of the anisotropic NdFeB particles were studied. It shows that the powders which obtained by HD process at higher temperature were larger than that at lower temperature, and the HD powders show a well anisotropy at 723 K, the remanence (B{sub r}) was more than 12.46 kG, the maximum energy product ((BH){sub max}) was 19.06 MGOe, and the coercivity (H{sub cj}) was 7.2 kOe. The microstructure of the anisotropic powders revealed that with a reasonable HD temperature, the platelet grains were not destroyed. They were nearly 150-300 nm long and 30-50 nm wide. The results indicate that HD process was an effective way to prepare the anisotropic NdFeB powders.

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

    International Nuclear Information System (INIS)

    Liu Minxian; Wang Yan

    2012-01-01

    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.

  16. Inhomogeneity of surface magnetic field over a NdFeB guideway and its influence on levitation force of the HTS bulk maglev system

    International Nuclear Information System (INIS)

    Zhang, Longcai; Wang Jiasu; He Qingyong; Zhang Jianghua; Wang Suyu

    2007-01-01

    Superconducting maglev vehicle system was one of the most promising applications of HTS bulks. The NdFeB guideway in this system was composed of many NdFeB permanent magnets and screws, so the air gaps (airgaps) between two permanent magnets and the screws would result in the inhomogeneity of the surface magnetic field. In this paper, we studied the magnetic inhomogeneity over the permanent magnet guideway (PMG) used in high-temperature superconducting (HTS) maglev vehicle system and its influence on the levitation force of the HTS bulk. Firstly, we measured the transverse magnetic field above the airgap, the screw and the place under where there was no airgap and screw. It was found that the magnetic field 10 mm above the guideway was roughly uniform. Secondly, we investigated the influence of the magnetic inhomogeneity of the PMG on levitation force of the bulk superconductor. From the experiment results, we found that the influence was very small, and would be ignored. Therefore, we could conclude that the PMG made by this method satisfied the requirements of the HTS maglev vehicle system in a quasi-static state

  17. 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.

  18. Inhomogeneity of surface magnetic field over a NdFeB guideway and its influence on levitation force of the HTS bulk maglev system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Longcai [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China)]. E-mail: zhlcai2000@163.com; Wang Jiasu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); He Qingyong [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); Zhang Jianghua [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); Wang Suyu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China)

    2007-08-01

    Superconducting maglev vehicle system was one of the most promising applications of HTS bulks. The NdFeB guideway in this system was composed of many NdFeB permanent magnets and screws, so the air gaps (airgaps) between two permanent magnets and the screws would result in the inhomogeneity of the surface magnetic field. In this paper, we studied the magnetic inhomogeneity over the permanent magnet guideway (PMG) used in high-temperature superconducting (HTS) maglev vehicle system and its influence on the levitation force of the HTS bulk. Firstly, we measured the transverse magnetic field above the airgap, the screw and the place under where there was no airgap and screw. It was found that the magnetic field 10 mm above the guideway was roughly uniform. Secondly, we investigated the influence of the magnetic inhomogeneity of the PMG on levitation force of the bulk superconductor. From the experiment results, we found that the influence was very small, and would be ignored. Therefore, we could conclude that the PMG made by this method satisfied the requirements of the HTS maglev vehicle system in a quasi-static state.

  19. Crystallographic orientation analysis in HDDR process of anisotropic Nd-Fe-B magnet powders

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Rina, E-mail: 3ES15002M@s.kyushu-u.ac.jp [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Science and Engineering, Kyushu University, 6-1 Kasugakoen, Kasuga 816-8580 (Japan); Itakura, Masaru [Department of Applied Science for Electronics and Materials, Faculty of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Katayama, Nobuhiro; Morimoto, Koichiro [R& D Division, Toda Kogyo Corp., 1-4 Meijishinkai, Otake, Hiroshima 739-0652 (Japan)

    2017-07-01

    Highlights: • Over 70% of the Nd{sub 2}Fe{sub 14}B grains after the HDDR process are aligned within 30°. • The c-axis alignment of Nd{sub 2}Fe{sub 14}B slightly deteriorates by the Nd-rich phase formation. • α-Fe grains possess a uniaxial and 〈1 1 3〉 oriented texture in the decomposed stage. • α-Fe is most likely to induce the texture development of recombined Nd{sub 2}Fe{sub 14}B. - Abstract: Microstructural changes and crystallographic orientation information in the hydrogenation-decomposition-desorption-recombination (HDDR) process of Nd-Fe-B alloy were investigated using electron backscatter diffraction (EBSD) and precession electron diffraction (PED) in order to understand the mechanism of anisotropy inducement in the HDDR process. Recombined Nd{sub 2}Fe{sub 14}B grains were found to nucleate at the interfaces between NdH{sub 2} and α-Fe grains and to have a [0 0 1]-oriented texture from the beginning of the recombination reaction. The Fe grains form with alignment of one of the 〈1 1 3〉 directions at decomposed stage. This suggests that α-Fe most likely induces texture development of recombined Nd{sub 2}Fe{sub 14}B.

  20. Improved HDDR processing route for production of anisotropic powder from sintered NdFeB type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Sheridan, R.S.; Williams, A.J.; Harris, I.R.; Walton, A., E-mail: a.walton@bham.ac.uk

    2014-01-15

    The hydrogenation disproportionation desorption recombination (HDDR) process has been investigated as a possible means of producing bonded magnets from used NdFeB-type sintered magnets with compositions, Nd{sub 13.4}Dy{sub 0.8}Al{sub 0.7}Nb{sub 0.3}Fe{sub 78.5}B{sub 6.3} and Nd{sub 12.5}Dy{sub 1.8}Al{sub 0.9}Nb{sub 0.6}Co{sub 5.0}Fe{sub 72.8}B{sub 6.4} (atomic%). It has been shown that by increasing the processing temperature, an increase in the equilibrium pressure for disproportionation and in the overall reaction time was observed. The magnetic properties of the lower Dy content magnet were affected significantly by the change in processing temperature with a peak in properties observed at 880 °C producing magnetic powder with a remanence of 1.08 (±0.02) T, a coercivity of 840 (±17) kA m{sup −1}, and a maximum energy product of 175 (±2.5) kJ m{sup −3}. Further work on magnets with a significantly higher Dy content has shown that simultaneous processing of sintered magnets with varying compositions can be achieved by increasing the hydrogen pressure, however a range of magnetic properties are produced depending on the initial compositions of the samples in the input feed. - Highlights: • Reduced oxidation during the HDDR processing in this work compared to the previous paper resulted in a powder with a higher coercivity. • Increasing the hydrogen pressure for disproportionation allowed for Dy, Co rich NdFeB compositions to be processed. • Mixed compositions (which will be typical from “real scrap”) can be processed simultaneously in the same equipment. • Mixed feeds produced lower magnetic properties due to overprocessing of the low Dy content compositions.

  1. A Combined Experimental and Finite Element Analysis Method for the Estimation of Eddy-Current Loss in NdFeB Magnets

    Directory of Open Access Journals (Sweden)

    Radu Fratila

    2014-05-01

    Full Text Available NdFeB permanent magnets (PMs are widely used in high performance electrical machines, but their relatively high conductivity subjects them to eddy current losses that can lead to magnetization loss. The Finite Element (FE method is generally used to quantify the eddy current loss of PMs, but it remains quite difficult to validate the accuracy of the results with complex devices. In this paper, an experimental test device is used in order to extract the eddy current losses that are then compared with those of a 3D FE model.

  2. A combined experimental and finite element analysis method for the estimation of eddy-current loss in NdFeB magnets.

    Science.gov (United States)

    Fratila, Radu; Benabou, Abdelkader; Tounzi, Abdelmounaïm; Mipo, Jean-Claude

    2014-05-14

    NdFeB permanent magnets (PMs) are widely used in high performance electrical machines, but their relatively high conductivity subjects them to eddy current losses that can lead to magnetization loss. The Finite Element (FE) method is generally used to quantify the eddy current loss of PMs, but it remains quite difficult to validate the accuracy of the results with complex devices. In this paper, an experimental test device is used in order to extract the eddy current losses that are then compared with those of a 3D FE model.

  3. Effect of deformation ratios on grain alignment and magnetic properties of hot pressing/hot deformation Nd-Fe-B magnets

    Science.gov (United States)

    Guo, Zhaohui; Li, Mengyu; Wang, Junming; Jing, Zheng; Yue, Ming; Zhu, Minggang; Li, Wei

    2018-05-01

    The magnetic properties, microstructure and orientation degrees of hot pressing magnet and hot deformation Nd-Fe-B magnets with different deformation ratios have been investigated in this paper. The remanence (Br) and maximum magnetic energy product ((BH)max) were enhanced gradually with the deformation ratio increasing from 0% to 70%, whereas the coercivity (HCj) decreased. The scanning electron microscopy (SEM) images of fractured surfaces parallel to the pressure direction during hot deformation show that the grains tend to extend perpendicularly to the c-axes of Nd2Fe14B grains under the pressure, and the aspect ratios of the grains increase with the increase of deformation ratio. Besides, the compression stress induces the long axis of grains to rotate and the angle (θ) between c-axis and pressure direction decreases. The X-ray diffraction (XRD) patterns reveal that orientation degree improves with the increase of deformation ratio, agreeing well with the SEM results. The hot deformation magnet with a deformation ratio of 70% has the best Br and (BH)max, and the magnetic properties are as followed: Br=1.40 T, HCj=10.73 kOe, (BH)max=42.30 MGOe.

  4. 烧结钕铁硼添加合金元素的研究进展%Progress of Sintered NdFeB Magnets with Addition Element

    Institute of Scientific and Technical Information of China (English)

    刘涛; 周磊; 程星华; 张昕; 喻晓军; 李波

    2011-01-01

    磁性能优越的烧结钕铁硼永磁材料已成为永磁产业的支柱.过去的二十多年里钕铁硼已经在硬盘驱动器的VCM、电动机、信号发生器、手机和MRI等多种器件中得到广泛应用.在未来,由于汽车和电子应用领域对节能电动机的需求,使得电动机市场有望进一步扩展.因此,研究团队致力于钕铁硼磁性能的提高,从而推进电动机市场的快速发展.本文对近些年来通过添加合金元素来改善钕铁硼磁性能的一些研究成果进行了综述,最后,对添加合金元素改善钕铁硼磁体性能进行了总结.%Sintered Nd-Fe-B magnets, which have excellent magnetic performance, were the key materials in permanent magnet industry. In the past two decades, Nd-Fe-B magnets have a wide application, such as, VCM [voice core motor] in hard disc drive, motors, generators, mobile phone, MRI, etc. Motor market is expected to expand in future because of strong energy saving requirements from the automobile and electric appliances markets. Therefore, many groups have spent much effort to improve magnetic property of Nd-Fe-B magnets, which are helping for the rapid growth of the motor market. The research results of the effect of addition alloy elements on the magnetic properties and microstructural features of sintered NdFeB have been introduced in this paper. Finally, an overview how to improve the performance with addition element was outlined.

  5. Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

    NARCIS (Netherlands)

    Venkatesan, P.; Vander Hoogerstraete, Tom; Hennebel, Tom; Binnemans, Koen; Sietsma, J.; Yang, Y.

    2018-01-01

    NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The

  6. Effect of laser beam parameters on magnetic properties of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Fukunaga, H.; Nakano, M.; Yanai, T.; Kamikawatoko, T.; Yamashita, F.

    2011-01-01

    The effects of varying the laser power and the spot diameter of a laser beam on the magnetic properties, morphology, and deposition rate of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition (PLD) were investigated. Reducing the laser fluence on the target reduces the remanence and increases the Nd content and consequently the coercivity of the prepared films. The spot size of the laser beam was found to affect the film surface morphology, the deposition rate, and the reproducibility of the magnetic properties of the prepared films. Reducing the spot size reduces the number of droplets and the reproducibility of the magnetic properties and increases the droplet size. Controlling the spot size of the laser beam enabled us to maximize the deposition rate. Consequently, a coercivity of 1210 kA/m and a remanence of 0.51 T were obtained at a deposition rate of 11.8 μm/(h·W). This deposition rate is 30% greater than the highest previously reported deposition rate by PLD.

  7. Microstructure and property evolution of isotropic and anisotropic NdFeB magnets fabricated from nanocrystalline ribbons by spark plasma sintering and hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z W; Huang, H Y; Yu, H Y; Zhong, X C; Zeng, D C [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, X X; Zhu, J, E-mail: zwliu@scut.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2011-01-19

    Isotropic and anisotropic NdFeB magnets were synthesized by spark plasma sintering (SPS) and SPS+HD (hot deformation), respectively, using melt-spun ribbons as the starting materials. Spark plasma sintered magnets sintered at low temperatures (<700 {sup 0}C) almost maintained the uniform fine grain structure inherited from rapid quenching. At higher temperatures, due to the local high-temperature field caused by the spark plasma discharge, the grain growth occurred at the initial particle surfaces and the coarse grain zones formed in the vicinity of the particle boundaries. Since the interior of the particles maintained the fine grain structure, a distinct two-zone structure was formed in the spark plasma sintered magnets. The SPS temperature and pressure have important effects on the widths of coarse and fine grain zones, as well as the grain sizes in two zones. The changes in grain structure led to variations in the magnetic properties. By employing low SPS temperature and high pressure, high-density magnets with negligible coarse grain zone and an excellent combination of magnetic properties can be obtained. An anisotropic magnet with a maximum energy product of {approx}30 MG Oe was produced by the SPS+HD process. HD at 750 {sup 0}C did not lead to obvious grain growth and the two-zone structure still existed in the hot deformed magnets. Intergranular exchange coupling was demonstrated in the spark plasma sintered magnets and was enhanced by the HD process, which reduced the coercivity. Good temperature stability was manifested by low temperature coefficients of remanence and coercivity. The results indicated that nanocrystalline NdFeB magnets without significant grain growth and with excellent properties could be obtained by SPS and HD processes.

  8. Field homogeneity improvement of maglev NdFeB magnetic rails from joints.

    Science.gov (United States)

    Li, Y J; Dai, Q; Deng, C Y; Sun, R X; Zheng, J; Chen, Z; Sun, Y; Wang, H; Yuan, Z D; Fang, C; Deng, Z G

    2016-01-01

    An ideal magnetic rail should provide a homogeneous magnetic field along the longitudinal direction to guarantee the reliable friction-free operation of high temperature superconducting (HTS) maglev vehicles. But in reality, magnetic field inhomogeneity may occur due to lots of reasons; the joint gap is the most direct one. Joint gaps inevitably exist between adjacent segments and influence the longitudinal magnetic field homogeneity above the rail since any magnetic rails are consisting of many permanent magnet segments. To improve the running performance of maglev systems, two new rail joints are proposed based on the normal rail joint, which are named as mitered rail joint and overlapped rail joint. It is found that the overlapped rail joint has a better effect to provide a competitive homogeneous magnetic field. And the further structure optimization has been done to ensure maglev vehicle operation as stable as possible when passing through those joint gaps. The results show that the overlapped rail joint with optimal parameters can significantly reduce the magnetic field inhomogeneity comparing with the other two rail joints. In addition, an appropriate gap was suggested when balancing the thermal expansion of magnets and homogenous magnetic field, which is considered valuable references for the future design of the magnetic rails.

  9. The corrosion mechanism of the sintered (Ce, Nd)-Fe-B magnets prepared by double main phase and single main phase approaches

    Science.gov (United States)

    Shi, Xiaoning; Zhu, Minggang; Zhou, Dong; Song, Liwei; Guo, Zhaohui; Li, Jia; Li, Wei

    2018-05-01

    The sintered (Ce, Nd)-Fe-B magnets were produced widely by Double Main Phase (DMP) method in China as the magnetic properties of the DMP magnets are superior to those of single main phase (SMP) magnets with the same nominal composition. In this work, the microstructure and corrosion mechanism of the sintered (Ce0.2Nd0.8)30FebalB (wt.%) magnets prepared by DMP and SMP method were studied in detail. Compared to SMP magnets, the DMP magnets have more positive corrosion potential, lower corrosion current density, larger electron transfer resistance, and lower mass loss of the free corrosion experiment in 0.5mol/l Na2SO4 aqueous solution. All of the results show that the DMP magnets have better corrosion resistance than SMP magnets. The back scattered electron images show that the crystalline grains of the DMP magnets are sphericity with a smooth surface while the SMP ones have plenty of edges and corners. Besides, the distribution of Ce/Nd is much more uneven in both magnetic phase and rare earth (Re)-rich phase of the DMP magnets than those of SMP magnets. After corrosion, DMP magnets show eroded magnetic phase and intact Re-rich phase, which indicate that galvanic corrosion of the Re-rich phase acting as the cathode appears.

  10. The production and characterization of Ptfe bonded Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Mokal, B.; Williams, A.J.; Hay, J.N.; Harris, I.R.

    1996-01-01

    A study of the processing and characteristics of PTFE bonded Nd Fe B magnets has been carried out. PTFE was used because of its low coefficient of friction, thus enabling its flow between the particles of Nd Fe B powder. PTFE also increases the resistance to corrosion of the magnet. In these investigations, the production of bonded magnets by cold compaction and by hot processing (HP) of MQ powders using PTFE as the binder was investigated . Magnetic, microstructural, and mechanical properties were investigated and are presented together with a correlation with the different processing techniques used. The corrosion behaviour of the hot pressed magnets was also investigated. These studies could lead to the development of simpler and more effective processing routes for the production of bonded magnets. (author)

  11. Baking effect for NdFeB magnets against demagnetization induced by high-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bizen, T. E-mail: bizen@spring8.or.jp; Asano, Y.; Hara, T.; Marechal, X.; Seike, T.; Tanaka, T.; Lee, H.S.; Kim, D.E.; Chung, C.W.; Kitamura, H

    2003-12-11

    The effect of thermal stabilization (pre-baking at 142 deg. C) on the sensitivity of neodymium-iron-boron (Nd{sub 2}Fe{sub 14}B) magnets to irradiation was studied. Thermally stabilized magnets showed higher resistance to irradiation with 2.0 GeV electrons: their demagnetization curves decrease linearly with respect to the number of electrons, and with a demagnetization rate remarkably smaller than that of the unbaked magnets.

  12. Recoil curve properties and coercive force decrease ratio in NdFeB sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Yutaka, E-mail: Yutaka_Matsuura@hitachi-metals.co.jp; Kitai, Nobuyuki; Ishii, Rintaro; Natsumeda, Toshimitsu; Hoshijima, Jun

    2013-11-15

    It is examined that whether a reverse domain and magnetic domain wall exist in a lower demagnetization area than the coercive force and whether the observed demagnetization ratio curve can be explained using the alignment distribution function or not. From measurements of the recoil curve in the low demagnetization field, it was confirmed that minor demagnetization occurred in every demagnetization field and magnets of every grade of coercive force. The alignment distribution of Nd{sub 2}Fe{sub 14}B grains was also measured by electron back-scattering diffraction (EBSD). The alignments and the coercive force decrease ratios were calculated using these alignment distributions. These data were compared against the results obtained from magnetization measurements. From EBSD data, it was found that the alignment distributions of magnets used in this experiment were close to a Gaussian distribution. It was also found that there was no difference in the alignment distribution between magnets with Dy and without Dy, even though the coercive force decrease ratios were Dy dependent. The calculated alignments using the alignment distribution functions were close to the values of magnetization measurements. However, it was found that the calculated coercive force decrease ratios were different from the results obtained from magnetization measurement. - Highlights: • Reverse magnetic domains already exist lower magnetic field than coercive force. • Demagnetization happens not only from surface but also from inside of magnets. • Calculated alignment agrees well with that of the magnetic properties measurement. • Coercive force decrease ratio could not explain from alignment distribution. • We could not find any difference with and without Dy magnets in alignment distribution.

  13. Photopatternable Magnetic Hollowbots by Nd-Fe-B Nanocomposite for Potential Targeted Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Hui Li

    2018-04-01

    Full Text Available In contrast to traditional drug administration, targeted drug delivery can prolong, localize, target and have a protected drug interaction with the diseased tissue. Drug delivery carriers, such as polymeric micelles, liposomes, dendrimers, nanotubes, and so on, are hard to scale-up, costly, and have short shelf life. Here we show the novel fabrication and characterization of photopatternable magnetic hollow microrobots that can potentially be utilized in microfluidics and drug delivery applications. These magnetic hollowbots can be fabricated using standard ultraviolet (UV lithography with low cost and easily accessible equipment, which results in them being easy to scale up, and inexpensive to fabricate. Contact-free actuation of freestanding magnetic hollowbots were demonstrated by using an applied 900 G external magnetic field to achieve the movement control in an aqueous environment. According to the movement clip, the average speed of the magnetic hollowbots was estimated to be 1.9 mm/s.

  14. 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

  15. 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.

  16. Micromagnetic simulation of the influence of grain boundary on cerium substituted Nd-Fe-B magnets

    Directory of Open Access Journals (Sweden)

    D. Liu

    2017-05-01

    Full Text Available A three-dimensional finite element model was performed to study the magnetization reversal of (CexNd1-x2Fe14B nanocomposite permanent magnets. The influences of volume fraction, width and performance parameters of the grain boundary (GB composition on the coercivity were analyzed by the method of micromagnetic simulation. The calculation results indicate that the structure and chemistry of GB phase play important roles in Nd2Fe14B-based magnets. An abnormal increase in the value of coercivity is found to be connected with the GB phase, approximately when the percentage of doped cerium is between 20% and 30%. While the coercivity decreases directly with the increase in cerium content instead of being abnormal when there is no GB phase in magnets at all or the value of magnetocrystalline anisotropy or exchange integral is too large.

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

    NARCIS (Netherlands)

    Li, L; Tirado, A.; Nlebedim, I.C.; Rios, O.; Post, B.; Kunc, V.; Lowden, R.R.; Lara-Curzio, E.; Fredette, R.; Ormerod, J.; Lograsso, T.A.; Paranthaman, M.P.

    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

  18. Structure and phases of low-neodymium NdFeB permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Žák, Tomáš; Talijan, N.; Ćosović, V.; Grujić, A.

    2006-01-01

    Roč. 56, Suppl. E (2006), E45-E50 ISSN 0011-4626. [Mossbauer Spectroscopy in Materials Science. Kočovce, 11.06.2006-15.06.2006] R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : nanocomposite permanent magnets * Mossbauer spectroscopy * X-ray diffraction * thermomagnetic curve Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.568, year: 2006

  19. 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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A novel tubular linear motor equipped with radially anisotropic NdFeB ring magnets

    International Nuclear Information System (INIS)

    Hor, P.J.

    1998-01-01

    The paper describes the design synthesis and optimisation of a novel tubular linear motor employing radially magnetised anisotropic ring magnets. Design issues, related to optimising the dimensions for maximum acceleration capability, minimum cogging force and low harmonic distortion in the emf waveform, are discussed. The influence of inhomogeneities in the magnets on the performance of a prototype motor is discussed, and its dynamic performance is validated experimentally against a typical target specification for automated high-speed manufacturing applications. (orig.)

  1. Corrosion resistance and mechanical properties of pulse electrodeposited Ni-TiO{sub 2} composite coating for sintered NdFeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Li Qing, E-mail: liqingd@swu.edu.c [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yang Xiaokui [School of Materials Science and Engineering, Southwest University, Chongqing 400715 (China); Zhang Liang; Wang Juping; Chen Bo [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2009-08-12

    Ni-TiO{sub 2} composite coating which was prepared under pulse current conditions was successfully performed on sintered NdFeB magnet. As a comparison, pure nickel coating was also prepared. The phase structure, the surface morphology, the chemical composition, the anti-corrosion performance of the coatings for magnets, the microhardness and the wearing resistance performance of the coatings were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), electrochemical technique, Vickers hardness tester and ball-on-disc tribometer, respectively. The results revealed that Ni-TiO{sub 2} composite coating provided excellent anti-corrosion performance for the magnets, and showed higher microhardness and better anti-wear performance.

  2. 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.

  3. Improvement of the corrosion resistance on Nd-Fe-B magnet with nickel plating

    International Nuclear Information System (INIS)

    Minowa, T.; Yoshikawa, M.; Honshima, M.

    1989-01-01

    The authors describe the corrosion-resistant test humidity test (80 0 C, 90%R.H.) autoclave test (120 0 C, 2atm, saturated with water vapor), salt spray test (35 0 C, 5% NaCl) performed on the sintered Nd magnet treated with nickel plating. Al ion-plating and without coating were also exposed to the corrosion test. After the specified periods of corrosion test, the permanent flux loss of the re-magnetized sample was measured. The changes in the appearance were also observed

  4. An analysis of radiation effects on NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Kurth, Michael; Cao, Lei R., E-mail: cao.152@osu.edu

    2015-01-01

    Radiation-induced demagnetization of permanent magnets may present a serious problem in a number of applications including robots conducting rescue and sampling missions in radiation-intense environments, NASA applications, and particle accelerators. Therefore, developing a good understanding of the underlying mechanisms of this phenomenon is crucial. In this study, hysteresis loops pre- and post-irradiation are examined via the Jiles–Atherton (JA) model, Molecular Dynamics (MD) simulations are conducted to establish length and time scales of the thermal spike process, and Density Functional Theory (DFT) calculations are performed to better characterize the effects of microstructure damage on the magnetization. It is found that the interaction between the domains of the magnet increases and that the pinning energy is also increased in the irradiated sample. Furthermore, the MD simulation allowed us to determine that the thermal spike process occurs on time scales of tens to hundreds of femtoseconds and on length scales of a few nanometers. Finally, the DFT simulations clearly depicted the effects of lattice structure defects on the magnetization. These observations showed qualitative agreement with previous studies. The results of this study will be used in a future Monte Carlo simulation that will attempt to take all these effects into account to model the process of radiation-induced demagnetization.

  5. Boundary structure modification and magnetic properties of Nd-Fe-B sintered magnets by co-doping with Dy{sub 2}O{sub 3}/S powders

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fang [Institute for Advanced Materials& Technology, University of Science and Technology Beijing, Beijing 100083 (China); Guo, Leichen [School of Engineering Technology, Purdue University, West Lafayette, Indiana 47907 (United States); Li, Ping [Institute for Advanced Materials& Technology, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Xuzhe [School of Engineering Technology, Purdue University, West Lafayette, Indiana 47907 (United States); Sui, Yanli [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Guo, Zhimeng, E-mail: guozhimengustb@163.com [Institute for Advanced Materials& Technology, University of Science and Technology Beijing, Beijing 100083 (China); Gao, Xuexu [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-05-01

    In this paper, the effect of Dy{sub 2}O{sub 3}/S co-doping on the magnetic properties and microstructure was studied in Nd-Fe-B sintered magnets. With S co-doping, the coercivity increased due to grain boundary modification and Dy selective introduction. Continuous grain boundary phases were formed in the co-doped magnets with smaller grain size. The average grain size after a doping of 0.2 wt% S is 7.25 µm, which is approximately 2.37 µm smaller than that of the S-free sintered magnets(9.62 µm). The coercivity of the Dy{sub 2}O{sub 3}/0.2 wt% S co-doped magnets could be increased from 20.9 to 22.8 kOe with changing the remanence and the maximum magnetic energy product slightly. S precipitates in the Nd-rich phases were hexagonal Nd{sub 2}O{sub 2}S phase. Dy avoided the Nd{sub 2}O{sub 2}S phase in the triple junction region, resulting in more available Dy atoms diffusing into the Nd{sub 2}Fe{sub 14}B phase grains to enhance the anisotropy field. Dy-saving was achieved by forming Nd{sub 2}O{sub 2}S phase in the Dy{sub 2}O{sub 3}/S co-doped magnets. - Highlights: • The average grain size of Dy{sub 2}O{sub 3}/S co-doped magnets is 2.37 μm smaller than that of Dy{sub 2}O{sub 3} doped magnets. • The Dy atoms avoid the Nd{sub 2}O{sub 2}S phases and more of them become available to diffuse into the Nd{sub 2}Fe{sub 14}B phases. • The coercivity reaches maximum when S content is 0.2 wt%, 9% higher than the 20.9 kOe coercivity of the S-free magnets.

  6. 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.

  7. Effects of surface modification of Nd-Fe-B powders using parylene C by CVDP method on the properties of anisotropic bonded Nd–Fe–B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Bin; Sun, Aizhi, E-mail: sunaizhi@126.com; Lu, Zhenwen; Cheng, Chuan; Xu, Chen

    2016-10-15

    This paper presents effects of surface modification of Nd–Fe–B powders using parylene C by means of chemical vapor deposition polymerization (CVDP) on the properties of anisotropic bonded Nd–Fe–B magnets. It can be well verified from SEM images and EDS analysis that the surface of Nd–Fe–B powder is coated with thin parylene C films. The maximum energy product ((BH)max), degree of alignment (DOA), actual density and corrosion resistance of parylene Nd–Fe–B magnets prepared at room temperature are much higher than that of non-parylene Nd–Fe–B magnets. (BH)max, DOA and actual density of parylene Nd–Fe–B magnets (70 kJ/m{sup 3}, 0.342, 5.82 g/cm{sup 3}) prepared at room temperature under 578 MPa are improved by 18.6%, 4.6%, 2.1% and 27.3%, 29.1%, 7.8% compared with non-parylene Nd‐Fe‐B magnets prepared at 140 °C (59 kJ/m{sup 3}, 0327, 5.70 g/cm{sup 3}) and room temperature (55 kJ/m{sup 3}, 0.265, 5.40 g/cm{sup 3}), respectively. Additional, the improvement of actual density and the room temperature process also solve problems such as powders’ sticking wall, non-uniform powder filling, non-uniform magnetic properties, seriously mould damage, short life cycle of mould and so on, which exists during warm compaction process. Parylene Nd–Fe–B magnets have better corrosion resistance and worse mechanical properties than that of non-parylene Nd–Fe–B magnets. The reason for the improvement of magnetic properties and actual density is the low friction cofficient of parylene C films, which results in lower frictional resistance and better lubricating property of parylene Nd–Fe–B powders. - Highlights: • Parylene Nd–Fe–B magnets prepared at room temperature show higher (BH)max and DOA. • Actual density of parylene Nd–Fe–B magnet is improved greatly. • Problems such as powders’ sticking wall, mould damage and so on are solved. • Parylene NdFeB magnets have better corrosion resistance. • Low friction cofficient of

  8. The suspended magnetic separator with large blocks from NdFeB magnets and its long term technological tests

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2011-01-01

    Roč. 8, č. 1 (2011), s. 89-97 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic separation * magnetic separators * magnetic circuits Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/abstracts/AGG/01_11/8_Zezulka.pdf

  9. The thermal expansion of hard magnetic materials of the Nd-Fe-B system

    Science.gov (United States)

    Savchenko, Igor; Kozlovskii, Yurii; Samoshkin, Dmitriy; Yatsuk, Oleg

    2017-10-01

    The results of dilatometric measurement of the thermal expansion of hard magnetic materials brands N35M, N35H and N35SH containing as a main component the crystalline phase of Nd2Fe14B type are presented. The temperature range from 200 to 750 K has been investigated by the method of dilatometry with an error of 1.5-2×10-7 K-1. The approximation dependences of the linear thermal expansion coefficient have been obtained. The character of changes of the thermal coefficient of linear expansion in the region of the Curie point has been specified, its critical indices and critical amplitudes have been defined.

  10. The thermal expansion of hard magnetic materials of the Nd-Fe-B system

    Directory of Open Access Journals (Sweden)

    Savchenko Igor

    2017-01-01

    Full Text Available The results of dilatometric measurement of the thermal expansion of hard magnetic materials brands N35M, N35H and N35SH containing as a main component the crystalline phase of Nd2Fe14B type are presented. The temperature range from 200 to 750 K has been investigated by the method of dilatometry with an error of 1.5-2×10-7 K-1. The approximation dependences of the linear thermal expansion coefficient have been obtained. The character of changes of the thermal coefficient of linear expansion in the region of the Curie point has been specified, its critical indices and critical amplitudes have been defined.

  11. 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.

  12. A Combined TEM/STEM and Micromagnetic Study of the Anisotropic Nature of Grain Boundaries and Coercivity in Nd-Fe-B Magnets

    Directory of Open Access Journals (Sweden)

    Gregor A. Zickler

    2017-01-01

    Full Text Available The nanoanalytical high resolution TEM/STEM investigation of the intergranular grain boundary phase of anisotropic sintered and rapidly quenched heavy rare earth-free Nd-Fe-B magnet materials revealed a difference in composition for grain boundaries parallel (large Fe-content and perpendicular (low Fe content to the alignment direction. This behaviour vanishes in magnets with a high degree of misorientation. The numerical finite element micromagnetic simulations are based on the anisotropic compositional behaviour of GBs and show a decrease of the coercive field with an increasing thickness of the grain boundary layer. The magnetization reversal and expansion of reversed magnetic domains primarily start as Bloch domain wall at grain boundaries parallel to the c-axis and secondly as Néel domain wall perpendicular to the c-axis into the adjacent hard magnetic grains. The increasing misalignment of grains leads to the loss of the anisotropic compositional behaviour and therefore to an averaged value of the grain boundary composition. In this case the simulations show an increase of the coercive field compared to the anisotropic magnet. The calculated coercive field values of the investigated magnet samples are in the order of μ0HcJ=1.8 T–2.1 T for a mean grain boundary thickness of 4 nm, which agrees perfectly with the experimental data.

  13. High-coercivity Nd-Fe-B magnets obtained with the electrophoretic deposition of submicron TbF3 followed by the grain-boundary diffusion process

    International Nuclear Information System (INIS)

    Soderžnik, Marko; Korent, Matic; Žagar Soderžnik, Kristina; Katter, Matthias; Üstüner, Kaan; Kobe, Spomenka

    2016-01-01

    Using a grain-boundary diffusion process (GBDP) involving the electrophoretic deposition (EPD) of submicron TbF 3 powder, we substantially increased the coercivity of sintered Nd-Fe-B permanent magnets. The experiments used magnets with low heavy-rare-earth (HRE) content (HRE = 1.2 wt%) and a coercivity of 790 kA/m (at 75 °C). After experiencing optimized conditions at 875 °C for 10 h and subsequent annealing at 500 °C for 1 h, the coercivity was increased to 1536 kA/m (at 75 °C). This value is 1.94 times higher than that for a sintered magnet, without post-sintering heat treatment. Furthermore, a vibration test revealed satisfactory adhesion of the TbF 3 powder to the surface of the magnet with no detected reduction in coercivity. Using field emission gun scanning electron microscopy (FEG-SEM) with an energy dispersive spectroscope (EDS), we confirmed the formation of various secondary intergranular phases and the core-shell-type microstructure, which increases the coercivity. The Tb content in the magnet, exposed to the EPD-based GBDP, was controlled by inductively coupled plasma optical electron spectroscopy (ICP-OES). The additional Tb detected in the magnet due to the described technology was only 0.12 wt%.

  14. MAGNETIC SEPARATORS AND THEIR PLACE IN MODEM FOUNDRY. REFINEMENT OF WASTE (ALUMINIUM SCRAP WITH THE PURPOSE O F FURTHER USING IN OWN PRODUCTION ON BASIS OF PRUP “MINSK MOTOR PLANT”

    Directory of Open Access Journals (Sweden)

    V. V. Ovchinnikov

    2007-01-01

    Full Text Available The types of magnetic separators used in casting are given. The technology of preparation of aluminium chip scrap for further using in domestic manufacture is developed and implemented at Minsk Motor Works.

  15. Numerical evaluation of guidance force decay of HTS bulk exposed to AC magnetic field over a NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [P.O. Box 152, Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: zhlcai2000@163.com; Wang Jiasu; Wang Suyu; Zheng Jun; He Qingyong [P.O. Box 152, Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2007-12-01

    The guidance force of the YBCO bulk over a NdFeB guideway used in the high-temperature superconducting maglev vehicle system was decayed by the application of the AC external magnetic field. In our previous work, we explained that the decay was due to the temperature rise of the HTS bulk caused by AC losses. In this paper, we adopted an analytic model to evaluate the decay of the critical current density of the bulk. And based on the analytic results and the Bean critical-state model, we calculated the guidance force as a function of times. Compared with the experimental results, the calculation results have almost the same trend and can qualitatively reveal the characteristics of guidance force of HTS bulk in this situation. Therefore, the guidance force decay of HTS bulk in the maglev vehicle system can be evaluated simply by this numerical method.

  16. Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We numerically demonstrated the magnetization reversal process inside a hot-deformed nanocrystalline permanent magnet. We performed large-scale micromagnetics simulation based on the Landau–Lifshitz–Gilbert equation with 0.1 billion calculation cells. The simulation model for the hot-deformed nanocrystalline permanent magnet consists of 2622 tabular grains that interact with each other by inter-grain exchange and dipole interactions. When the strength of the external field approached a coercive force, nucleation cores were created at the grain surface. The magnetization reversal was propagated by the inter-grain and dipole interactions. When the grains had overlapping regions parallel to the external field, the magnetization reversal propagated quickly between the grains due to the dipole interaction. In contrast, the motion of the magnetic domain wall was inhibited at interfaces between the grains perpendicular to the external field. Reversal magnetic domains had a pillar-shaped structure that is parallel to the external field. In the perpendicular direction, the reversal magnetic domain expanded gradually because of the inhibition of the domain wall motion.

  17. Effect of hydrogenation disproportionation conditions on magnetic anisotropy in Nd-Fe-B powder prepared by dynamic hydrogenation disproportionation desorption recombination

    Directory of Open Access Journals (Sweden)

    Masao Yamazaki

    2017-05-01

    Full Text Available Various anisotropic Nd-Fe-B magnetic powders were prepared by the dynamic hydrogenation disproportionation desorption recombination (d-HDDR treatment with different hydrogenation disproportionation (HD times (tHD. The resulting magnetic properties and microstructural changes were investigated. The magnetic anisotropy was decreased with increasing tHD. In the d-HDDR powders with higher magnetic anisotropy, fine (200–600 nm and coarse (600–1200 nm Nd2Fe14B grains were observed. The coarse Nd2Fe14B grains showed highly crystallographic alignment of the c-axis than fine Nd2Fe14B grains. In the highly anisotropic Nd2Fe14B d-HDDR powder, a large area fraction of lamellar-like structures consisting of NdH2 and α-Fe were observed after HD treatment. Furthermore, the mean diameter of the lamellar-like regions, where lamellar-like structures orientate to the same direction in the HD-treated alloys was close to that of coarse Nd2Fe14B grains after d-HDDR treatment. Thus, the lamellar-like regions were converted into the crystallographically aligned coarse Nd2Fe14B grains during desorption recombination treatment, and magnetic anisotropy is closely related to the volume fraction of lamellar-like regions observed after HD treatment.

  18. Effects of excessive grain growth on the magnetic and mechanical properties of hot-deformed NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, M., E-mail: linm@nimte.ac.c [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, Ningbo 315201 (China); Wang, H.J. [Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081 (China); Yi, P.P.; Yan, A.R. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, Ningbo 315201 (China)

    2010-08-15

    The magnetic and mechanical properties of rare-earth magnets hot-deformed at temperature range 750-950 deg. C have been investigated. The grains tended to grow excessively from dozens of nanometers to several microns at the temperatures above 850 deg. C. The alignment of grains was disrupted by the hot deformation at the high temperatures. The Nd-rich phase was extruded at the temperatures which are higher than 850 deg. C. The Nd-rich phase extrusion resulted in the reduction of density by 1% and the reduction of remanence from 1.42 to 0.72 T. The reduction of grain boundaries caused by flat platelet-shaped grains changing to spherical grains and the weak binding strength among large grains of Nd{sub 2}Fe{sub 14}B phase may be the main reasons for the low mechanical strength of hot-deformed magnets.

  19. 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.

  20. Normal and abnormal grain growth in fine-grained Nd-Fe-B sintered magnets prepared from He jet milled powders

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, F., E-mail: f.bittner@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden (Germany); Technische Universität Dresden, Institute of Materials Science, 01062 Dresden (Germany); Woodcock, T.G. [IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden (Germany); Schultz, L. [IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden (Germany); Technische Universität Dresden, Institute of Materials Science, 01062 Dresden (Germany); Schwöbel, C. [Technische Universität Darmstadt, Materialwissenschaft, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany); Gutfleisch, O. [Technische Universität Darmstadt, Materialwissenschaft, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany); Fraunhofer ISC, Projektgruppe für Werkstoffkreisläufe und Ressourcenstrategie IWKS, Rodenbacher Chaussee 4, 63457 Hanau (Germany); Zickler, G.A.; Fidler, J. [Technische Universität Wien, Institute of Solid State Physics, Wiedner Hauptstr. 8-10, 1040 Wien (Austria); Üstüner, K.; Katter, M. [Vacuumschmelze GmbH & Co. KG, 63412 Hanau (Germany)

    2017-03-15

    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. - Highlights: • He Jet milling to reduce Nd-Fe-B grain size and to enhance coercivity. • Normal and abnormal grain growth observed for low temperature sintering. • Well oriented abnormal grown grains explained by size dependent field alignment. • Poor rectangularity is caused by low nucleation field of

  1. Normal and abnormal grain growth in fine-grained Nd-Fe-B sintered magnets prepared from He jet milled powders

    International Nuclear Information System (INIS)

    Bittner, F.; Woodcock, T.G.; Schultz, L.; Schwöbel, C.; Gutfleisch, O.; Zickler, G.A.; Fidler, J.; Üstüner, K.; Katter, M.

    2017-01-01

    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. - Highlights: • He Jet milling to reduce Nd-Fe-B grain size and to enhance coercivity. • Normal and abnormal grain growth observed for low temperature sintering. • Well oriented abnormal grown grains explained by size dependent field alignment. • Poor rectangularity is caused by low nucleation field of

  2. High electrical resistivity Nd-Fe-B die-upset magnet doped with eutectic DyF3–LiF salt mixture

    Directory of Open Access Journals (Sweden)

    K. M. Kim

    2017-05-01

    Full Text Available Nd-Fe-B-type die-upset magnet with high electrical resistivity was prepared by doping of eutectic DyF3–LiF salt mixture. Mixture of melt-spun Nd-Fe-B flakes (MQU-F: Nd13.6Fe73.6Co6.6Ga0.6B5.6 and eutectic binary (DyF3–LiF salt (25 mol% DyF3 – 75 mol% LiF was hot-pressed and then die-upset. By adding the eutectic salt mixture (> 4 wt%, electrical resistivity of the die-upset magnet was enhanced to over 400 μΩ.cm compared to 190 μΩ.cm of the un-doped magnet. Remarkable enhancement of the electrical resistivity was attributed to homogeneous and continuous coverage of the interface between flakes by the easily melted eutectic salt dielectric mixture. It was revealed that active substitution of the Nd atoms in neighboring flakes by the Dy atoms from the added (DyF3–LiF salt mixture had occurred during such a quick thermal processing of hot-pressing and die-upsetting. This Dy substitution led to coercivity enhancement in the die-upset magnet doped with the eutectic (DyF3–LiF salt mixture. Coercivity and remanence of the die-upset magnet doped with (DyF3–LiF salt mixture was as good as those of the DyF3-doped magnet.

  3. The practical limits for enhancing magnetic property combinations for bulk nanocrystalline NdFeB alloys through Pr, Co and Dy substitutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.W. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (Singapore)]. E-mail: phylz@nus.edu.sg; Davies, H.A. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (Singapore)

    2007-06-15

    Pr, Co and Dy additions have been employed to improve the combinations of magnetic properties for nanocrystalline Nd {sub x} Fe{sub 94-} {sub x} B{sub 6} melt spun alloys. The dependences of the magnetic properties on the solute element concentrations have been extensively investigated and the relationships between the measured remanence, maximum energy product (BH){sub max} and intrinsic coercivity for several compositional series are discussed. The composition ranges for these elemental substitutions which can be used to achieve the highest values of (BH){sub max} are identified. It is found that, when we employ individual or combined substitutions of Pr and Dy for Nd and Co for Fe in NdFeB alloys with various RE:Fe ratios, the practical limit of (BH){sub max} lies in the range {approx}160-180 kJ/m{sup 3}, combined with a coercivity in the range {approx}400-800 kA/m.

  4. 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.

  5. 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.

  6. First report on soapnut extract-mediated synthesis of sulphur-substituted nanoscale NdFeB permanent magnets and their characterization

    Science.gov (United States)

    Jayapala Rao, G. V. S.; Prasad, T. N. V. K. V.; Shameer, Syed; Arun, T.; Purnachandra Rao, M.

    2017-10-01

    Biosynthesis of nanoscale materials has its own advantages over other physical and chemical methods. Using soapnut extract as reducing and stabilizing agent for the synthesis of inorganic nanoscale materials is novel and has not been exploited to its potential so far. Herein, we report for the first time on the effects of sulphur substitution on soapnut extract-mediated synthesis of nanoscale NdFeB (S-NdFeB) permanent magnetic powders (Nd 15%, Fe 77.5%, B 7.5% and S with molar ratios: 0.1, 0.2, 0.3, 0.4, and 0.5). To synthesize, a 10 ml of 10% soapnut extract was added to 90 ml of respective chemical composition and heated to 60 °C for 30 min and aged for 24 h. The dried powder was sintered at 500 °C for 1 h. The characterization of the as-prepared nanoscale S-NdFeB magnetic materials was done using the techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS for size and zeta potential measurements) and vibrating sample magnetometer (VSM)-hysteresis loop studies. The results revealed that particles were highly stable (with a negative zeta potential of 25.7 mV) with irregular and spherical shape (with measured hydrodynamic diameter 6.7 and 63.5 nm). The tetragonal structures of the formed powders were revealed by XRD micrographs. Hysteresis loop studies clearly indicate the effect of S concentration on the enhanced magnetization of the materials.

  7. The analysis of adhesion failure between Ni-coating and sintered NdFeB substrate

    Energy Technology Data Exchange (ETDEWEB)

    Hengxiu, Y; Yong, D; Zhenlun, S, E-mail: yanghengxiu@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201 (China)

    2011-01-01

    Ni-coating was widely used to protect the sintered NdFeB magnet from corrosion by Watt electro-deposition solution. However, the protection failure always occurs due to poor adhesion strength between Ni-coating and NdFeB substrate. In present work, the adhesion strength of the Ni-coating on NdFeB substrate was measured by vertical tensile method to strip Ni-coating from NdFeB substrate. The results revealed that the adhesion failure was occurred in the side of the NdFeB substrate due to a weak zone sometimes shown cracks located inside of NdFeB substrate, rather than in the interface between Ni-coating and NdFeB substrate. Comparing with cross section morphology of NdFeB magnet after pretreatment, it is concluded that the crack could be formed during the electro-deposition process. The effect of the pH value of bath on adhesion strength indicated that the crack could be induced due to electrochemical hydrogenation of NdFeB substrate during electro-deposition.

  8. Powder alignment system for anisotropic bonded NdFeB Halbach cylinders \\ud

    OpenAIRE

    Zhu, Z.Q.; Xia, Z.P.; Atallah, K.; Jewell, G.W.; Howe, D.

    2000-01-01

    A Halbach cylinder, fabricated from pre-magnetized sintered NdFeB magnet segments, is proposed for the powder aligning system during the compression or injection moulding of anisotropic bonded Halbach oriented NdFeB ring magnets. The influence of leading design parameters of the powder aligning system, viz. the number of magnet segments per pole, their axial length and radial thickness, and their clearance from the mould, is investigated by finite element analysis, and validated experimentally

  9. High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

    International Nuclear Information System (INIS)

    Bizen, Teruhiko; Asano, Yoshihiro; Marechal, Xavier-Marie; Seike, Takamitsu; Aoki, Tsuyoshi; Fukami, Kenji; Hosoda, Naoyasu; Yonehara, Hiroto; Takagi, Tetsuya; Hara, Toru; Tanaka, Takashi; Kitamura, Hideo

    2007-01-01

    High-energy electron-beam bombardment of Nd 2 Fe 14 B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small

  10. High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

    Energy Technology Data Exchange (ETDEWEB)

    Bizen, Teruhiko [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)]. E-mail: bizen@spring8.or.jp; Asano, Yoshihiro [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Marechal, Xavier-Marie [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Seike, Takamitsu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Aoki, Tsuyoshi [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Fukami, Kenji [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoda, Naoyasu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yonehara, Hiroto [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takagi, Tetsuya [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Toru [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Tanaka, Takashi [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kitamura, Hideo [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2007-05-11

    High-energy electron-beam bombardment of Nd{sub 2}Fe{sub 14}B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small.

  11. Hot deformed anisotropic nanocrystalline NdFeB based magnets prepared from spark plasma sintered melt spun powders

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Y.H.; Huang, Y.L. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Z.W., E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zeng, D.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2013-09-01

    Highlights: • Microstructure evolution and its influence on the magnetic properties were investigated. • The increase of stray field and weakening of domain-wall pinning effects were the main reasons of the decrease of the coercivity with increasing the compression ratio. • The influences of non-uniform plastic deformation on the microstructure and magnetic properties were investigated. • Magnetic properties and temperature coefficient of coercivity are indeed very promising without heavy rare earth elements. -- Abstract: Anisotropic magnets were prepared by spark plasma sintering (SPS) followed by hot deformation (HD) using melt-spun powders as the starting material. Good magnetic properties with the remanence J{sub r} > 1.32 T and maximum of energy product (BH){sub max} > 303 kJ/m{sup 3} have been obtained. The microstructure evolution during HD and its influence on the magnetic properties were investigated. The fine grain zone and coarse grain zone formed in the SPS showed different deformation behaviors. The microstructure also had an important effect on the temperature coefficients of coercivity. A strong domain-wall pinning model was valid to interpret the coercivity mechanism of the HDed magnets. The increase of stray field and weakening of domain-wall pinning effects were the main reasons of the decrease of the coercivity with increasing the compression ratio. The influences of non-uniform plastic deformation on the microstructure and magnetic properties were investigated. The polarization characteristics of HDed magnets were demonstrated. It was found out that the HDed magnets had better corrosion resistance than the counterpart sintered magnet.

  12. 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.

  13. Phase composition, structure and magnetic behaviour of low neodymium rapid-quenched Nd-Fe-B alloys

    Czech Academy of Sciences Publication Activity Database

    Ćosović, V.; Žák, Tomáš; Talijan, N.; Grujić, A.; Stajić-Trošić, J.

    2008-01-01

    Roč. 456, 1-2 (2008), s. 251-256 ISSN 0925-8388 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : multiphase Nd(Pr)-Fe-B alloys * rapid solidification * magnetic measurements * Mossbauer spectroscopy * X-ray diffraction * Nanocrystalline composite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.510, year: 2008

  14. Coercivity enhancement of NdFeB sintered magnets by low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy modification

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Zhang, Pei; Jin, Jiaying; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2014-04-15

    To improve coercivity without sacrificing other magnetic performance of NdFeB sintered magnets, a low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced as an intergranular additive. Magnetic properties and microstructure of the magnets with different Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} contents were studied. At the optimum addition of 3 wt%, coercivity H{sub cj} was enhanced from 12.7 to 15.2 kOe, the maximum magnetic energy product (BH){sub max} was simultaneously increased from 46.6 to 47.8 MG Oe, accompanied by a slight reduction in remanence B{sub r}. Further investigation on microstructure and grain boundary composition indicated that the enhanced H{sub cj} and (BH){sub max} could be attributed to the refined and uniform 2:14:1 phase grains, continuous grain boundaries and a (Nd,Dy){sub 2}Fe{sub 14}B hardening shell surrounding the 2:14:1 phase grains. - Highlights: • Low melting-point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced to NdFeB magnets. • The doped magnet exhibits enhanced coercivity and maximum energy product. • (Nd,Dy){sub 2}Fe{sub 14}B shell was expected to form in the surface of Nd{sub 2}Fe{sub 14}B grains. • The continuous grain boundary layer formed between neighboring Nd{sub 2}Fe{sub 14}B grains.

  15. Large-scale micromagnetic simulation of Nd-Fe-B sintered magnets with Dy-rich shell structures

    Directory of Open Access Journals (Sweden)

    T. Oikawa

    2016-05-01

    Full Text Available Large-scale micromagnetic simulations have been performed using the energy minimization method on a model with structural features similar to those of Dy grain boundary diffusion (GBD-processed sintered magnets. Coercivity increases as a linear function of the anisotropy field of the Dy-rich shell, which is independent of Dy composition in the core as long as the shell thickness is greater than about 15 nm. This result shows that the Dy contained in the initial sintered magnets prior to the GBD process is not essential for enhancing coercivity. Magnetization reversal patterns indicate that coercivity is strongly influenced by domain wall pinning at the grain boundary. This observation is found to be consistent with the one-dimensional pinning theory.

  16. Extrapolated surface dose measurements using a NdFeB magnetic deflector for 6 MV x-ray beams.

    Science.gov (United States)

    Damrongkijudom, N; Butson, M; Rosenfeld, A

    2007-03-01

    Extrapolated surface dose measurements have been performed using radiographic film to measure 2-Dimensional maps of skin and surface dose with and without a magnetic deflector device aimed at reducing surface dose. Experiments are also performed using an Attix parallel plate ionisation chamber for comparison to radiographic film extrapolation surface dose analysis. Extrapolated percentage surface dose assessments from radiographic film at the central axis of a 6 MV x-ray beam with magnetic deflector for field size 10 x 10 cm2, 15 x 15 cm2 and 20 x 20 cm2 are 9 +/- 3%, 13 +/- 3% and 16 +/- 3%, these compared to 14 +/- 3%, 19 +/- 3%, and 27 +/- 3% for open fields, respectively. Results from Attix chamber for the same field size are 12 +/- 1%, 15 +/- 1% and 18 +/- 1%, these compared to 16 +/- 1%, 21 +/- 1% and 27 +/- 1% for open fields, respectively. Results are also shown for profiles measured in-plane and cross-plane to the magnetic deflector and compared to open field data. Results have shown that the surface dose is reduced at all sites within the treatment field with larger reductions seen on one side of the field due to the sweeping nature of the designed magnetic field. Radiographic film extrapolation provides an advanced surface dose assessment and has matched well with Attix chamber results. Film measurement allows for easy 2 dimensional dose assessments.

  17. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li Jinlong; Mao Shoudong; Sun Kefei [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Li Xiaomin [Shanghai Institute of Ceramics Chinese Academy of Sciences, Shanghai 200050 (China); Song Zhenlun [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)], E-mail: songzhenlun@nimte.ac.cn

    2009-11-15

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  18. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Li Jinlong; Mao Shoudong; Sun Kefei; Li Xiaomin; Song Zhenlun

    2009-01-01

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  19. Influence of the spin reorientation transition on the hysteresis characteristics of Nd-Fe-B film and bulk magnets

    International Nuclear Information System (INIS)

    Lileev, A.S.; Parilov, A.A.; Reissner, M.; Steiner, W.

    2004-01-01

    A comparison was made of the hysteresis characteristics of hard magnetic films with those of bulk samples based on Nd 2 Fe 14 B in the temperature range between 4.2 and 293 K. In both types of specimens characteristic 'dips' appear below 135 K in the demagnetisation curves which are caused by both the spin reorientation from easy axis to easy cone and the deviation from a perfect texture of the sample

  20. Coercivity enhancement of sintered Nd-Fe-B magnets by chemical bath deposition of TbCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shuai, E-mail: gshuai@nimte.ac.cn; Zhang, Xiaofeng; Ding, Guangfei; Chen, Renjie; Yan, Aru [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Lee, Don [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); University of Dayton, Dayton, Ohio 45469 (United States)

    2014-05-07

    The chemical bath deposition (CBD) and the grain boundary diffusion method were combined to diffuse the heavy rare earth for obtain the thick magnets with high coercivity and low heavy rare earth. The jet mill powders were soaked into the alcohol solution of 0.2 wt. % TbCl{sub 3}. A thin layer of TbCl{sub 3} was wrapped to the surface of (PrNd){sub 2}Fe{sub 14}B powder particles. The coercivity of magnet is increased from 11.89 kOe to 14.72 kOe without significant reduction of remanence after grain boundary diffusion in the sintering and the annealing processes. The temperature coefficients of the remanence and the coercivity are improved by the substitution of PrNd by Tb in the surface of grains. The highly accelerated temperature/humidity stress test (HAST) results indicate that the CBD magnet has poor corrosion resistance, attributing to the present of Cl atoms in the grain boundaries.

  1. Thin films of NdFeB deposited by PLD technique

    International Nuclear Information System (INIS)

    Constantinescu, C.; Scarisoreanu, N.; Moldovan, A.; Dinescu, M.; Petrescu, L.; Epureanu, G.

    2007-01-01

    Neodymium-iron-boron (NdFeB) is a material with important magnetic properties, mostly used in permanent magnet fabrication. Thin layers of NdFeB are needed for miniaturization in electrical engineering, electronics and for high-tech devices. In this paper we applied pulsed lased deposition (PLD) in vacuum for obtaining thin films of NdFeB from stoichiometric targets. The influence of different buffer layers and of the laser parameters (wavelength and fluence) on the NdFeB structures, composition and magnetic properties have been investigated. The obtained structures were characterized by atomic force microscopy (AFM) and optical microscopy. Vibrating sample magnetometry (VSM) has been performed for specific magnetic characterization

  2. Thin films of NdFeB deposited by PLD technique

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, C. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Scarisoreanu, N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Moldovan, A. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO-077125 Magurele, Bucharest (Romania)]. E-mail: dinescum@ifin.nipne.ro; Petrescu, L. [Department of Electrical Engineering, ' Politehnica' University of Bucharest, 313 Spl. Independentei, 060042 Bucharest (Romania); Epureanu, G. [Department of Electrical Engineering, ' Politehnica' University of Bucharest, 313 Spl. Independentei, 060042 Bucharest (Romania)

    2007-07-31

    Neodymium-iron-boron (NdFeB) is a material with important magnetic properties, mostly used in permanent magnet fabrication. Thin layers of NdFeB are needed for miniaturization in electrical engineering, electronics and for high-tech devices. In this paper we applied pulsed lased deposition (PLD) in vacuum for obtaining thin films of NdFeB from stoichiometric targets. The influence of different buffer layers and of the laser parameters (wavelength and fluence) on the NdFeB structures, composition and magnetic properties have been investigated. The obtained structures were characterized by atomic force microscopy (AFM) and optical microscopy. Vibrating sample magnetometry (VSM) has been performed for specific magnetic characterization.

  3. 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, Nd 2 Fe 14 B. 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 Nd 2 Fe 14 B 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.

  4. 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.

  5. Coercivity enhancement of HDDR-processed Nd-Fe-B permanent magnet with the rapid hot-press consolidation process

    Energy Technology Data Exchange (ETDEWEB)

    Nozawa, N. [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan); Sepehri-Amin, H. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Ohkubo, T. [Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Hono, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Nishiuchi, T. [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan); Hirosawa, S., E-mail: Satoshi_Hirosawa@hitachi-metals.co.j [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan)

    2011-01-15

    High coercivity, fully dense anisotropic permanent magnets of submicron grain sizes were produced by rapid hot-press consolidation of hydrogenation-disproportionation-desorption-recombination (HDDR) processed Nd-Fe-Co-B powders. In the hot-press process, the coercivity of the consolidated material showed a sharp minimum prior to full densification. Thereafter, it reached a value 25% higher than that of the initial powder. Scanning electron microscopy and transmission electron microscopy observations revealed that the variation in H{sub cJ} was caused by a redistribution of Nd along the grain boundaries during hot pressing and that the high coercivity was attributable to the formation of thin, continuous Nd-rich phase along the grain boundaries.

  6. NdFeB thick films prepared by tape casting

    International Nuclear Information System (INIS)

    Pawlowski, B.; Schwarzer, S.; Rahmig, A.; Toepfer, J.

    2003-01-01

    NdFeB films of thickness between 100 and 800 μm were prepared by tape casting of a slurry containing 84-95 wt% of commercial NdFeB powder (MQP-B, -Q and -S). After curing the flexible green tapes at 120 deg. C non-porous magnetic films are obtained. The remanence of the films is in the range of 350-450 mT and the coercivity is between 300 and 800 kA/m depending on the type of MQP powder used. The magnetic properties of the films are discussed in relation to film composition and type of magnetic material. For MEMS applications the thick films are magnetized with a multi-pole stripe pattern with 1 mm pole pitch. The induction at the surface of the films was measured with a Hall probe and compared to theoretical calculations. The results indicate that the films are completely magnetized regardless of the film thickness. Tape-casted NdFeB thick films are promising candidates for applications in micro-systems or actuators. Miniaturization of the magnet components is one of the key issues in the development of electromagnetic micro-systems, thus creating a need for replacement of small sintered magnets by magnetic thick film components. Other applications include encoders

  7. Study of Magnetic Properties on the Corrosion Behavior and Influence of Temperature in Permanent Magnet (Nd-Fe-B) Used in PMSM

    OpenAIRE

    N. Yogal; C. Lehrmann

    2014-01-01

    The use of permanent magnets (PM) is increasing in permanent magnet synchronous machines (PMSM) to fulfill the requirements of high efficiency machines in modern industry. PMSM are widely used in industrial applications, wind power plants and the automotive industry. Since PMSM are used in different environmental conditions, the long-term effect of NdFeB-based magnets at high temperatures and their corrosion behavior have to be studied due to the irreversible loss of magn...

  8. Progress in sintered NdFeB magnets with Dy/Tb grain boundary diffusion%晶界扩散Dy/Tb烧结NdFeB研究进展

    Institute of Scientific and Technical Information of China (English)

    刘涛; 周磊; 张昕; 程星华; 林德; 喻晓军; 李波

    2011-01-01

    由于汽车和电子应用领域对节能电动机的需求,在VCM、电动机、信号发生器、手机和MRI等领域中得到广泛应用的烧结钕铁硼在电动机市场应用会进一步扩展.剩磁和矫顽力等磁性能的提高有利于烧结磁体在电动机市场快速增长.通常,烧结磁体一些性能的改善总是以牺牲其他性能为代价.而晶界扩散Dy/Tb烧结磁体与传统的同类磁体相比较,其矫顽力和剩磁可同时得以改善,本文对晶界扩散Dy/Tb钕铁硼的一些研究成果进行了综述和总结.晶界扩散Dy/Tb过程中烧结磁体晶界的成份和微观组织的变化对烧结磁体磁性能改善至为重要.%Many new applications of Nd-Fe-B magnets, such as voice coil motor (VCM) in hard disc drive, motors, generators, mobile phone, MRI, etc, are expected to expand in future because of strong energy saving requirements from the automobile and electric appliances markets. Magnetic property improvement in residual (Br) and coercive force (Hcj) helps the rapid growth of the motor market. In many instances, an improvement of some characteristics of sintered magnet is achieved but only at the expense of other characteristics. It has been found that Dy/Tb grain boundary diffusion processed Nd-Fe-B sintered magnets have improvement in both the highest remanence and cocercivity among conventional rare-earth permanent mgnets, which have been introduced in this paper. The influence of Dy/Tb grain boundary diffusion on composition and microstructure of grain boundaries phase is a key point for magnetic property improvement of sintered magnet.

  9. 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

  10. 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)

    1991-12-31

    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

  11. Electrodeposition and Properties of Copper Layer on NdFeB Device

    Directory of Open Access Journals (Sweden)

    LI Yue

    2017-06-01

    Full Text Available To decrease the impact of the regular Ni/Cu/Ni coating on the magnetic performance of sintered NdFeB device, alkaline system of HEDP complexing agent was applied to directly electro-deposit copper layer on NdFeB matrix, then nickel layer was electrodeposited on the copper layer and Cu/Ni coating was finally obtained to replace the regular Ni/Cu/Ni coating. The influence of concentration of HEDP complexing agent on deposition course was tested by electrochemical testing; morphology of copper layer was characterized by SEM, XRD and TEM; the binding force of copper layer and the thermal reduction of magnetic of NdFeB caused by electrodeposited coating were respectively explored through the thermal cycle test and thermal demagnetization test. The results show that the concentration of HEDP has great impact on the deposition overpotential of copper. In the initial electrodepositing stage, copper particles precipitate at the grain boundaries of NdFeB magnets with a preferred (111 orientation. The copper layer is compact and has enough binding force with the NdFeB matrix to meet the requirements in SJ 1282-1977. Furthermore, the thermal demagnetization loss rate of the sintered NdFeB with the protection of Cu/Ni coating is significantly less than that with the protection of Ni/Cu/Ni coating.

  12. Methods of characterization of multiphase Nd-Fe-B melt-spun alloys

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2007-01-01

    Full Text Available Nanocomposite permanent magnetic materials based on Nd-Fe-B alloys with a low Nd content are a new type of permanent magnetic material. The microstructure of these nanocomposite permanent magnets is composed of a mixture of magnetically soft and hard phases providing the so called exchange coupling effect. Beside the optimization process parameters, methods of characterization have a very important role in the design of an optimal magnetic matrix of multiphase melt-spun Nd-Fe-B alloys. Different methods and techniques of characterization were used for observation and study of the microstructure evolution during crystallization. A summary results of measurements using different methods of characterization are presented to enable a better insight into relations between the microstructure and magnetic properties of the investigated melt-spun Nd-Fe-B alloys. .

  13. Relations microstructure - magnetic properties - squareness factor of PrFeB and NdFeB sintered magnets prepared with hydrogen

    International Nuclear Information System (INIS)

    Perigo, Elio Alberto

    2009-01-01

    In this work, it has firstly been evaluated the preparation of Pr 16 Fe 76 B 8 sintered permanent magnets (% at.) by means of high-energy milling using a planetary ball mill. The influence of both milling speed and time has been verified. The best magnetic properties [J R = (1.02 ± 0.02) T, μ 0J H c = (1.42 ± 0.03) T and (BH) max = (200 ± 4) kJm -3 ] have been found for a permanent magnet prepared with the magnetic alloy milled during 75 minutes using a rotational milling speed of 200 rpm. In order to improve the remanence, the hydrogen decrepitation process time has been reduced from 60 minutes to 2 minutes. In this case, it has been obtained a sintered magnet with J R = (1.14 ± 0.02) T, μ 0J H c = (1.44 ± 0.03) T and (BH) max = (250 ± 5) kJm -3 due to the improvement of crystallographic alignment of the hard magnetic phase. During such investigation, a new methodology to quantify the parameter has been developed. Subsequently, for the first time, a quantitative correlation between the microstructure and the squareness factor in anisotropic sintered RE 16 Fe 76 B 8 (RE = Nd or Pr) magnets has been proposed. The presented expression utilizes the mean size, the mean elongation and the mean roundness of the hard magnetic grains as well as their respective standard deviations. The squareness factor can be improved with a microstructure with rounder grains and with a sharp grain size distribution. The grain size homogeneity is more important to enhance the squareness factor compared to grain shape homogeneity. Furthermore, it has also been verified that the annealing after sintering improves the grain shape homogeneity and the milling enhances the grain size homogeneity. Moreover, the effect of the temperature on the squareness factor of anisotropic sintered magnets has also been evaluated. Such parameter is mainly controlled by the sample's microstructure, in agreement with the proposed expression. Furthermore, a quantitative correlation between the maximum

  14. Structure and magnetic properties of NdFeB thin films with Cr, Mo, Nb, Ta, Ti, and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; O'Shea, M.J.

    2000-01-01

    Layers of NdFeB of the form A(20 nm)/NdFeB(d nm)/A(20 nm) where A represents Cr, Mo, Nb, Ta, Ti, V were prepared on a silicon substrate by magnetron sputtering. The purpose is to determine how (i) the chosen buffer layer and (ii) NdFeB layer thickness d (especially d 2 Fe 14 B with no preferred crystalline orientation. Our highest coercivities occur for buffer layer elements from row five of the periodic table, 20 kOe (1600 kA/m) in a Nb buffered sample with d of 180 nm and 17 kOe (1350 kA/m) in a Mo buffered sample with d of 180 nm. Buffer layers from row four (Ti, V, and Cr) and row six (Ta) all give lower coercivities. Our largest energy product, 10.3 MG-Oe (82 kJ/m 3 ), is obtained for the Mo buffered sample. Average Nd 2 Fe 14 B crystallite size for this sample is 27 nm. Only the Cr and Ti buffered films show a large coercivity (≥2 kOe) for d of 54 nm with the Cr films showing the highest coercivity, 2.7 kOe (215 kA/m). In films subjected to a rapid thermal anneal (anneal time 30 s) we find that both the coercivity and energy product are larger than in samples subjected to a 20 min anneal. In our Nb buffered systems we obtain coercivities as high as 26.3 kOe (2090 kA/m) after a rapid thermal anneal

  15. Motion stability of the magnetic levitation and suspension with YBa2Cu3O7-x high-Tc superconducting bulks and NdFeB magnets

    Science.gov (United States)

    Li, Jipeng; Zheng, Jun; Huang, Huan; Li, Yanxing; Li, Haitao; Deng, Zigang

    2017-10-01

    The flux pinning effect of YBa2Cu3O7-x high temperature superconducting (HTS) bulk can achieve self-stable levitation over a permanent magnet or magnet array. Devices based on this phenomenon have been widely developed. However, the self-stable flux pinning effect is not unconditional, under disturbances, for example. To disclose the roots of this amazing self-stable levitation phenomenon in theory, mathematical and mechanical calculations using Lyapunov's stability theorem and the Hurwitz criterion were performed under the conditions of magnetic levitation and suspension of HTS bulk near permanent magnets in Halbach array. It is found that the whole dynamical system, in the case of levitation, has only one equilibrium solution, and the singular point is a stable focus. In the general case of suspension, the system has two singular points: one is a stable focus, and the other is an unstable saddle. With the variation of suspension force, the two first-order singular points mentioned earlier will get closer and closer, and finally degenerate to a high-order singular point, which means the stable region gets smaller and smaller, and finally vanishes. According to the center manifold theorem, the high-order singular point is unstable. With the interaction force varying, the HTS suspension dynamical system undergoes a saddle-node bifurcation. Moreover, a deficient damping can also decrease the stable region. These findings, together with existing experiments, could enlighten the improvement of HTS devices with strong anti-interference ability.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yiqin [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Min; Tao, Lei; Wang, Wei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Bai, Peiwen [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)

    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. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

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

    International Nuclear Information System (INIS)

    Yamamuro, S; Okano, M; Tanaka, T; Sumiyama, K; Nozawa, N; Nishiuchi, T; Hirosawa, S; Ohkubo, T

    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/α-Fe nanocomposite permanent magnets.

  19. High performance permanent magnet materials

    International Nuclear Information System (INIS)

    Sankar, S.G.; Herbst, J.F.; Koon, N.C.

    1987-01-01

    This book contains 25 selections. Some of the titles are: Initial magnetization behavior of rapidly quenched neodymium-iron-boron magnets; Optimization of liquid dynamic compaction for Fe-Nd-B magnet alloys; Misch-metal and/or aluminum substitutions in Nd-Fe-B permanent magnets; and NdFeB magnets with improved temperature characteristics

  20. Contaminated nickel scrap processing

    International Nuclear Information System (INIS)

    Compere, A.L.; Griffith, W.L.; Hayden, H.W.; Johnson, J.S. Jr.; Wilson, D.F.

    1994-12-01

    The DOE will soon choose between treating contaminated nickel scrap as a legacy waste and developing high-volume nickel decontamination processes. In addition to reducing the volume of legacy wastes, a decontamination process could make 200,000 tons of this strategic metal available for domestic use. Contaminants in DOE nickel scrap include 234 Th, 234 Pa, 137 Cs, 239 Pu (trace), 60 Co, U, 99 Tc, and 237 Np (trace). This report reviews several industrial-scale processes -- electrorefining, electrowinning, vapormetallurgy, and leaching -- used for the purification of nickel. Conventional nickel electrolysis processes are particularly attractive because they use side-stream purification of process solutions to improve the purity of nickel metal. Additionally, nickel purification by electrolysis is effective in a variety of electrolyte systems, including sulfate, chloride, and nitrate. Conventional electrorefining processes typically use a mixed electrolyte which includes sulfate, chloride, and borate. The use of an electrorefining or electrowinning system for scrap nickel recovery could be combined effectively with a variety of processes, including cementation, solvent extraction, ion exchange, complex-formation, and surface sorption, developed for uranium and transuranic purification. Selected processes were reviewed and evaluated for use in nickel side-stream purification. 80 refs

  1. The steel scrap age.

    Science.gov (United States)

    Pauliuk, Stefan; Milford, Rachel L; Müller, Daniel B; Allwood, Julian M

    2013-04-02

    Steel production accounts for 25% of industrial carbon emissions. Long-term forecasts of steel demand and scrap supply are needed to develop strategies for how the steel industry could respond to industrialization and urbanization in the developing world while simultaneously reducing its environmental impact, and in particular, its carbon footprint. We developed a dynamic stock model to estimate future final demand for steel and the available scrap for 10 world regions. Based on evidence from developed countries, we assumed that per capita in-use stocks will saturate eventually. We determined the response of the entire steel cycle to stock saturation, in particular the future split between primary and secondary steel production. During the 21st century, steel demand may peak in the developed world, China, the Middle East, Latin America, and India. As China completes its industrialization, global primary steel production may peak between 2020 and 2030 and decline thereafter. We developed a capacity model to show how extensive trade of finished steel could prolong the lifetime of the Chinese steelmaking assets. Secondary steel production will more than double by 2050, and it may surpass primary production between 2050 and 2060: the late 21st century can become the steel scrap age.

  2. Contaminated nickel scrap processing

    Energy Technology Data Exchange (ETDEWEB)

    Compere, A.L.; Griffith, W.L.; Hayden, H.W.; Johnson, J.S. Jr.; Wilson, D.F.

    1994-12-01

    The DOE will soon choose between treating contaminated nickel scrap as a legacy waste and developing high-volume nickel decontamination processes. In addition to reducing the volume of legacy wastes, a decontamination process could make 200,000 tons of this strategic metal available for domestic use. Contaminants in DOE nickel scrap include {sup 234}Th, {sup 234}Pa, {sup 137}Cs, {sup 239}Pu (trace), {sup 60}Co, U, {sup 99}Tc, and {sup 237}Np (trace). This report reviews several industrial-scale processes -- electrorefining, electrowinning, vapormetallurgy, and leaching -- used for the purification of nickel. Conventional nickel electrolysis processes are particularly attractive because they use side-stream purification of process solutions to improve the purity of nickel metal. Additionally, nickel purification by electrolysis is effective in a variety of electrolyte systems, including sulfate, chloride, and nitrate. Conventional electrorefining processes typically use a mixed electrolyte which includes sulfate, chloride, and borate. The use of an electrorefining or electrowinning system for scrap nickel recovery could be combined effectively with a variety of processes, including cementation, solvent extraction, ion exchange, complex-formation, and surface sorption, developed for uranium and transuranic purification. Selected processes were reviewed and evaluated for use in nickel side-stream purification. 80 refs.

  3. Issues in recycling galvanized scrap

    Energy Technology Data Exchange (ETDEWEB)

    Koros, P.J. [LTV Steel Co., Inc., Cleveland, OH (United States); Hellickson, D.A. [General Motors Corp., Detroit, MI (United States); Dudek, F.J. [Argonne National Lab., IL (United States)

    1995-02-10

    The quality of the steel used for most galvanizing (and tinplate) applications makes scrap derived from their production and use a premier solid charge material for steelmaking. In 1989 the AISI created a Task Force to define the issues and to recommend technologically and economically sound approaches to assure continued, unhindered recyclability of the growing volume of galvanized scrap. The AISI program addressed the treatment of full-sized industrial bales of scrap. The current, on-going MRI (US)--Argonne National Laboratory program is focused on ``loose`` scrap from industrial and post-consumer sources. Results from these programs, issues of scrap management from source to steel melting, the choices for handling zinc in iron and steelmaking and the benefits/costs for removal of zinc (and lead) from scrap prior to melting in BOF and foundry operations are reviewed in this paper.

  4. High anisotropic NdFeB submicro/nanoflakes prepared by surfactant-assisted ball milling at low temperature

    Science.gov (United States)

    An, Xiaoxin; Jin, Kunpeng; Abbas, Nadeem; Fang, Qiuli; Wang, Fang; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

    2017-11-01

    Hard magnetic NdFeB submicro/nanoflakes were successfully prepared by surfactant-assisted ball milling at low temperature (SABMLT) by specially using 2-methyl pentane and trioctylamine (TOA) as solvent and surfactant, respectively. Influences of the amount of TOA and milling temperature on the crystal structure, morphology and magnetic performances of the as-prepared NdFeB powders were investigated systematically. There is significant difference on morphology between the NdFeB powders milled at room and low temperature. The NdFeB powders with flaky morphology could be obtained even with a small amount of TOA by SABMLT, which could not be achieved by surfactant-assisted ball milling at room temperature (SABMRT). The better crystallinity, better grain alignment, higher coercivity, larger saturation magnetization and remanence ratio were achieved in the samples prepared by SABMLT. Furthermore, the final NdFeB powders prepared by SABMLT possessed a lower amount of residual TOA than those prepared by SABMRT. It was demonstrated that SABMLT is a promising way to fabricate rare-earth-transition metal nanoflakes with high anisotropy for permanent magnetic materials. The effective method of preparing NdFeB flakes by lowering temperature will be also useful to fabricate flakes of other functional materials.

  5. Global use structures of the magnetic materials neodymium and dysprosium. A scenario-based analysis of the effect of the diffusion of electromobility on the demand for rare earths

    International Nuclear Information System (INIS)

    Gloeser-Chahoud, Simon; Kuehn, Andre; Tercero Espinoza, Luis

    2016-01-01

    Neodymium-iron-boron magnets (NdFeB) have experienced a significant demand as the most powerful permanent magnet in recent years, especially for the manufacture of compact electric servomotors with high efficiency and high power density, especially for mobile applications in hybrid traction motors and electric vehicles or for electric bikes. However, NdFeB magnets are also increasingly being used in general mechanical engineering (conveying and pumping systems, tools, air conditioning systems, lift motors, etc.), in the small electric motors of conventional passenger cars or in the generators of large wind power plants with permanent magnetic direct drive. Nevertheless, there is still high uncertainty in the use structures of NdFeB magnets and the contained rare earth elements neodymium and dysprosium. An effective instrument for increasing the market transparency and the understanding of complex anthropogenic material cycles is the dynamic material flow modeling. In the present work paper, this instrument is used for an in-depth analysis of the use structures of NdFeB magnets and the contained rare earths on a global scale. The dynamic modeling of product usage cycles reveals today's usage structures and quantifies future magnetic quantities in obsolete product flows. It could be shown that the magnets in today's scrap volume are mainly contained in obsolete electronics applications such as hard disks (HDD), CD and DVD drives, which makes the recycling hardly seem to be economical due to the small magnets and the high material spread, but in the foreseeable future with larger magnetic quantities from synchronous servomotors and generators can be expected, which significantly increases the recycling potential. In a further step, the effect of the diffusion of alternative drives in the automotive market on the dysprosium requirement is analyzed using a system dynamics model and possible adaptation mechanisms in the form of different substitution effects in the

  6. The influence of inhomogeneous magnetic field over a NdFeB guideway on levitation force of the HTS bulk maglev system

    Science.gov (United States)

    Zhao, Lifeng; Deng, Jiangtao; Li, Linbo; Feng, Ning; Wei, Pu; Lei, Wei; Jiang, Jing; Wang, Xiqin; Zhang, Yong; Zhao, Yong

    2018-04-01

    Dynamic responses of high temperature superconducting bulk to inhomogeneous magnetic field distribution of permanent magnet guideway, as well as enlarged amplitude of magnetic field obtained by partially covering the permanent magnet guideway (PMG) with iron sheets in different thickness, are investigated. Experiments show that the instantaneous levitation force increases with the increase of the variation rate of magnetic field (dB/dt). Meanwhile, inhomogeneous magnetic field from PMG causes the decay of levitation force. The decay of levitation force almost increases linearly with the increase of alternating magnetic field amplitude. It should be very important for the application of high-speed maglev system.

  7. 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.

  8. Scrap is no crap

    DEFF Research Database (Denmark)

    Wenzel, Henrik

    2009-01-01

    Scrap is good business for the environment. When we recycle metal - meaning to collect, sort and melt it down - we emit much less CO2 than when we extract metal from the ground. The environmental benefit applies to all metals and is gained every time we recycle them. That is a positive message in...... in a world where we search for methods to reduce our CO2 emission. And the environmental potential is big: There are no upper limits for how many times we can recycle metals, which makes recycling an important part of the fight against global warming....

  9. Interaction domains in high performance NdFeB thick films

    Energy Technology Data Exchange (ETDEWEB)

    Woodcock, Tom; Khlopkov, Kirill; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, IMW, Dresden (Germany); Walther, Arno [Insitut Neel, CNRS-UJF, Grenoble (France); CEA Leti - MINATEC, Grenoble (France); Dempsey, Nora; Givord, Dominique [Insitut Neel, CNRS-UJF, Grenoble (France)

    2009-07-01

    Thick sputtered films (5-300 micron) of NdFeB have excellent hard magnetic properties which make them attractive for applications in micro-electro-mechanical systems (MEMS). A two step process consisting of triode sputtering and high temperature annealing produced films with energy densities approaching those of sintered NdFeB magnets. Magnetic force microscopy (MFM) using hard magnetic tips showed that the films deposited without substrate heating and at 300 C exhibited magnetic domains typical of low anisotropy materials. These films were amorphous in the as-deposited state. The film deposited at 500 C was crystalline and displaid hard magnetic properties. This was reflected in the magnetic microstructure which showed interaction domains typical of highly textured and high magnetic anisotropy materials with a grain size below or equal to the critical single-domain particle limit. With increasing substrate temperature, the domain patterns of the annealed films became coarser, indicating higher degrees of texture.

  10. Methods of assembling large magnetic blocks from NdFeB magnets with a high value of (BH)max and their influence on the magnetic induction reached in an air gap of magnetic circuit

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2008-01-01

    Roč. 44, č. 4 (2008), s. 485-491 ISSN 0018-9464 Institutional research plan: CEZ:AV0Z30460519 Keywords : assembly * demagnetization * magnet ic circuits Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 1.129, year: 2008

  11. ORO scrap metal decontamination program

    International Nuclear Information System (INIS)

    Jugan, M.

    1987-01-01

    The Oak Ridge Operations Office (ORO) of the US Department of Energy (DOE) has approximately 80,000 tons of contaminated scrap metal at the Oak Ridge Gaseous Diffusion Plant in Oak Ridge, Tennessee; Paducah Gaseous Diffusion Plant in Paducah, Kentucky; Portsmouth Gaseous Diffusion Plant in Piketon, Ohio; and the Feed Materials Production Center in Fernald, Ohio. After unsuccessful in-house attempts to eliminate/recycle the contaminated metal, DOE is allowing private enterprise the opportunity to participate in this program. DOE is making this opportunity available under a two-phase approach, which is being supported by two separate and corresponding Request for Proposals. Phase I, which is nearing completion, is a demonstration phase to establish a group of companies that the DOE will consider qualified to eliminate the scrap at one or more sites. In Phase I, the companies decontaminated 25-50 tons of scrap to demonstrate capabilities to DOE and to gain the knowledge required to plan/bid on elimination of the scrap at one or more sites. Phase II will request proposals for elimination of the total scrap at one or more of the above noted sites. Multiple awards for Phase II are also anticipated. Companies participating in Phase II will be required to take title to the contaminated scrap and decontaminate/process the scrap for beneficial reuse. Radioactive wastes and metal that cannot be successfully decontaminated/processed will be returned to DOE

  12. Fast neutron Damage Studies on NdFeB Materials

    OpenAIRE

    Anderson, S.; Spencer, J.; Wolf, Z.; Boussoufi, M.; Baldwin, A.; Pellett, D.; Volk, J.

    2005-01-01

    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. 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 the P...

  13. Scrapping of student bursaries confirmed.

    Science.gov (United States)

    Longhurst, Chris

    2016-07-27

    Student bursaries for nurses will be scrapped from next year, the government has confirmed. Undergraduate nursing and midwifery students in England will now face tuition fees and student loans from August 2017.

  14. The development of microstructure during hydrogenation–disproportionation–desorption–recombination treatment of sintered neodymium-iron-boron-type magnets

    International Nuclear Information System (INIS)

    Sheridan, R.S.; Harris, I.R.; Walton, A.

    2016-01-01

    The hydrogen absorption and desorption characteristics of the hydrogenation disproportionation desorption and recombination (HDDR) process on scrap sintered neodymium-iron-boron (NdFeB) type magnets have been investigated. At each stage of the process, the microstructural changes have been studied using high resolution scanning electron microscopy. It was found that the disproportionation reaction initiates at grain boundaries and triple points and then propagates towards the centre of the matrix grains. This process was accelerated at particle surfaces and at free surfaces produced by any cracks in the powder particles. However, the recombination reaction appeared to initiate randomly throughout the particles with no apparent preference for particle surfaces or internal cracks. During the hydrogenation of the grain boundaries and triple junctions, the disproportionation reaction was, however, affected by the much higher oxygen content of the sintered NdFeB compared with that of the as-cast NdFeB alloys. Throughout the entire HDDR reaction the oxidised triple junctions (from the sintered structure) remained unreacted and hence, remained in their original form in the fine recombined microstructure. This resulted in a very significant reduction in the proportion of cavitation in the final microstructure and this could lend to improved consolidation in the recycled magnets. - Highlights: • Disproportionation reaction initiates at grain boundaries and triple points. • Disproportionation then propagates towards the centre of the matrix grains. • Disproportionation was affected by the high oxygen content of sintered NdFeB. • Oxidised triple points remain unreacted in original form in final HDDR structure. • Significant reduction in the proportion of cavitation in the final microstructure.

  15. The development of microstructure during hydrogenation–disproportionation–desorption–recombination treatment of sintered neodymium-iron-boron-type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Sheridan, R.S.; Harris, I.R.; Walton, A., E-mail: a.walton@bham.ac.uk

    2016-03-01

    The hydrogen absorption and desorption characteristics of the hydrogenation disproportionation desorption and recombination (HDDR) process on scrap sintered neodymium-iron-boron (NdFeB) type magnets have been investigated. At each stage of the process, the microstructural changes have been studied using high resolution scanning electron microscopy. It was found that the disproportionation reaction initiates at grain boundaries and triple points and then propagates towards the centre of the matrix grains. This process was accelerated at particle surfaces and at free surfaces produced by any cracks in the powder particles. However, the recombination reaction appeared to initiate randomly throughout the particles with no apparent preference for particle surfaces or internal cracks. During the hydrogenation of the grain boundaries and triple junctions, the disproportionation reaction was, however, affected by the much higher oxygen content of the sintered NdFeB compared with that of the as-cast NdFeB alloys. Throughout the entire HDDR reaction the oxidised triple junctions (from the sintered structure) remained unreacted and hence, remained in their original form in the fine recombined microstructure. This resulted in a very significant reduction in the proportion of cavitation in the final microstructure and this could lend to improved consolidation in the recycled magnets. - Highlights: • Disproportionation reaction initiates at grain boundaries and triple points. • Disproportionation then propagates towards the centre of the matrix grains. • Disproportionation was affected by the high oxygen content of sintered NdFeB. • Oxidised triple points remain unreacted in original form in final HDDR structure. • Significant reduction in the proportion of cavitation in the final microstructure.

  16. 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%).

  17. 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.

  18. MFM study of NdFeB and NdFeB/Fe/NdFeB thin films

    International Nuclear Information System (INIS)

    Gouteff, P.C.; Folks, L.; Street, R.

    1998-01-01

    Domain structures of NdFeB thin films, ranging in thickness between 1500 and 29 nm, have been studied qualitatively by magnetic force microscopy (MFM). Samples were prepared using a range of sputtering conditions resulting in differences in properties such as texture, coercivity and magnetic saturation. MFM images of all the films showed extensive interaction domain structures, similar to those observed in nanocrystalline bulk NdFeB. An exchange-coupled NdFeB/Fe/NdFeB trilayer with layer thicknesses 18 nm/15 nm/18 nm, respectively, was also examined using MFM. (orig.)

  19. The fluctuation field and anomalous magnetic viscosity in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Collocott, S.J. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)], E-mail: stephen.collocott@csiro.au; Dunlop, J.B. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)

    2008-08-15

    The fluctuation field, H{sub f}, is a useful parameter for characterising any ferromagnetic material that displays hysteresis, as it is a measure of the thermally activated rate processes that govern magnetisation reversals. Anomalous magnetic viscosity, i.e. nonmonotonic behaviour of the time dependent magnetisation, where the magnetisation is seen to increase, reach a peak, and then decrease, has been observed on both the upper and lower branches of minor loops or recoil curves in some ferromagnetic materials. Parameters relevant to the Preisach model are discussed as to their usefulness in predicting anomalous magnetic viscosity in ferromagnetic materials. This is done with reference to measurements of H{sub f} and the time dependent magnetisation in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}.

  20. Interaction domains in high-performance NdFeB thick films

    Energy Technology Data Exchange (ETDEWEB)

    Woodcock, T.G. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)], E-mail: t.woodcock@ifw-dresden.de; Khlopkov, K. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Walther, A. [Insitut Neel, CNRS-UJF, 25 avenue de Martyrs, 38042 Grenoble (France); CEA Leti - MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Dempsey, N.M.; Givord, D. [Insitut Neel, CNRS-UJF, 25 avenue de Martyrs, 38042 Grenoble (France); Schultz, L.; Gutfleisch, O. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

    2009-05-15

    The magnetic domain structure in sputtered NdFeB thick films has been imaged by magnetic force microscopy. The local texture of the films was investigated by electron backscatter diffraction. The average misorientation of the grains was shown to decrease with increasing substrate temperature during deposition. Interaction domains were observed and are discussed with reference (i) to the sample grain size compared to the single domain particle size and (ii) to sample texture.

  1. Performance enhancement of NdFeB nanoflakes prepared by surfactant-assisted ball milling at low temperature by using different surfactants

    Science.gov (United States)

    An, Xiaoxin; Jin, Kunpeng; Wang, Fang; Fang, Qiuli; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

    2017-02-01

    Hard magnetic NdFeB submicron and nanoflakes were successfully prepared by surfactant-assisted ball milling at room temperature (SABMRT) and low temperature (SABMLT) by using oleic acid (OA), oleylamine (OLA) and trioctylamine (TOA) as surfactant, respectively. Among the surfactants used, OA and OLA have similar effects on the morphology of the NdFeB nanoflakes milled at both room and low temperature. In the case of TOA, irregular micron-sized particles and submirco/nanoflakes were obtained for the NdFeB powders prepared by SABMRT and SABMLT, respectively. Samples prepared by SABMLT show better crystallinity and better degree of grain alignment than that prepared by SABMRT with the same surfactant. Comparing with the samples milled at RT, higher coercivity and larger remanence ratio were achieved in the NdFeB samples prepared at LT. The amounts of residual surfactants in final NdFeB powders were also calculated, which reveals that the final NdFeB powders milled at LT possess lower amount of residual surfactants than those milled at RT. It was found that lowering milling temperature of SABM would be a promising way for fabricating permanent magnetic materials with better hard magnetic properties.

  2. 7 CFR 29.3526 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling...

  3. 7 CFR 29.3034 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  4. 7 CFR 29.6022 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...

  5. 7 CFR 29.2277 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  6. High Value Scrap Tire Recycle

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B. D.

    2003-02-01

    The objectives of this project were to further develop and scale-up a novel technology for reuse of scrap tire rubber, to identify and develop end uses for the technology (products), and to characterize the technology's energy savings and environmental impact.

  7. Relations microstructure - magnetic properties - squareness factor of PrFeB and NdFeB sintered magnets prepared with hydrogen; Estudo das correlacoes entre microestrutura, propriedades magneticas e fator de quadratura em imas sinterizados de PrFeB e NdFeB processados com hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Perigo, Elio Alberto

    2009-07-01

    In this work, it has firstly been evaluated the preparation of Pr{sub 16}Fe{sub 76}B{sub 8} sintered permanent magnets (% at.) by means of high-energy milling using a planetary ball mill. The influence of both milling speed and time has been verified. The best magnetic properties [J{sub R} = (1.02 {+-} 0.02) T, {mu}{sub 0J}H{sub c} = (1.42 {+-} 0.03) T and (BH){sub max} = (200 {+-} 4) kJm{sup -3}] have been found for a permanent magnet prepared with the magnetic alloy milled during 75 minutes using a rotational milling speed of 200 rpm. In order to improve the remanence, the hydrogen decrepitation process time has been reduced from 60 minutes to 2 minutes. In this case, it has been obtained a sintered magnet with J{sub R} = (1.14 {+-} 0.02) T, {mu}{sub 0J}H{sub c} = (1.44 {+-} 0.03) T and (BH){sub max} = (250 {+-} 5) kJm{sup -3} due to the improvement of crystallographic alignment of the hard magnetic phase. During such investigation, a new methodology to quantify the parameter has been developed. Subsequently, for the first time, a quantitative correlation between the microstructure and the squareness factor in anisotropic sintered RE{sub 16}Fe{sub 76}B{sub 8} (RE = Nd or Pr) magnets has been proposed. The presented expression utilizes the mean size, the mean elongation and the mean roundness of the hard magnetic grains as well as their respective standard deviations. The squareness factor can be improved with a microstructure with rounder grains and with a sharp grain size distribution. The grain size homogeneity is more important to enhance the squareness factor compared to grain shape homogeneity. Furthermore, it has also been verified that the annealing after sintering improves the grain shape homogeneity and the milling enhances the grain size homogeneity. Moreover, the effect of the temperature on the squareness factor of anisotropic sintered magnets has also been evaluated. Such parameter is mainly controlled by the sample

  8. The development of technology for recycling of electronic scrap

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hyo-Shin; Kim, Won-Baek; Sohn, Yong-Uhn [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Electronic devices, especially computer becomes an essential tools for home and industries entering the information era. The number of computers exceed over 100 million, hence, the amount of end of life(EOL) computer and electronic scrap is increasing. These wastes and scraps include products rejected from manufacturing processes and obstacle computers. Owing to a short life cycle of electronic products and rapid growth of electronic industries, the number of domestic EOL computers goes beyond a million and its disposal causes an environmental problems. Therefore, this recycling is considered to play an important role from the viewpoint of environmental preservation as well as reusable resources. The process development for the recovery of valuable materials and minimization of waste from electronic scrap has been carried out. In the first year of three year project, physical separation such as shredding, crushing, and magnetic separation is established to reclaim valuable materials effectively. Then, hydro- and pyrometallurgical processes are employed to recover valuable metals from electronic scrap. First, metallic and nonmetallic portion are separated from PCBs by a newly designed shredder to prevent hazardous organic materials from further chemical treatment. The optimum conditions for each unit process were found in terms of separation ratio, energy consumption, recovery rate, etc. (author). 92 refs., 24 tabs., 39 figs.

  9. Single step preparation of NdFeB alloy by magnesiothermic reduction-diffusion process

    International Nuclear Information System (INIS)

    Singha, Vinay Kant; Surendranathana, A.O.; John Berchmans, L.

    2014-01-01

    Magnesiothermic reduction is a new approach to produce the NdFeB alloy on a commercial scale. Similar studies were conducted for the preparation of LaNi 5 and SmCo 5 using magnesium as the reductant. In the present investigation NdFeB Hard magnetic bulk materials were synthesized by metallothermic 'Reduction – Diffusion (R-D) Process' using Magnesium as a reductant. For this process oxide precursors of Nd, Fe and B were blended with flux (LiCl/CaCl 2 ) and Mg chips were sandwiched in alternate layers. Thermal analysis (TGA/DTA) was carried out to find the dissociation and decomposition temperature of the reactants. The phase analysis, structure, and elemental composition were assessed by X-ray diffraction (XRD) and electron dispersive spectrometry (EDS). The infrared (IR) spectra were recorded by Fourier transform infrared spectrometer (FTIR). The morphological features and particle size was assessed by scanning electron microscope (SEM). The magnetic behaviour of the alloy was assessed using electron paramagnetic resonance (EPR) and vibratory sample magnetometer (VSM). From these studies it has been concluded that the NdFeB magnetic particles can be prepared using magnesium as the reductant. The process is faster and consumes very less amount of energy for the completion as compared to conventional calciothermic reduction process. Traces of MgO were detected in the alloy which increases the perpendicular anisotropy, thus increasing the coercivity of the material

  10. 32 CFR 644.522 - Clearance of military scrap.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Clearance of military scrap. 644.522 Section 644... Excess Land and Improvements § 644.522 Clearance of military scrap. Military scrap can contain or be... destruction, by using command, of all military scrap and scrap metal from lands suitable for cultivation or...

  11. 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...

  12. 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.

  13. Developments in radioactive scrap monitoring

    International Nuclear Information System (INIS)

    Bellian, J.G.

    1997-01-01

    Over the past ten years there have been major developments in radiation monitoring systems used for detecting shielded radioactive sources in scrap metal. The extent of the problem and industry's awareness of the problem have both grown significantly during that time. The multimillion dollar expenses associated with decontamination after a source passes into the melt and the potential health hazard to employees and the public have added further impetus to the development of monitoring systems. Early attempts at scrap monitoring could detect some radiation, but testing with real life situations showed them to be virtually incapable of detecting shielded sources of radioactivity in incoming vehicles. More sophisticated detector technology and the development of advanced software made useful by more powerful microprocessors led to successive generations of monitoring systems with order-of-magnitude improvement in detection capability. The next generation includes larger detectors and more complex algorithms offering further improvement in truck and rail car monitoring. Complete solutions require monitoring at additional locations within the site, such as the charge bucket and conveyor lines, and at the scrap processor's site

  14. Fernald scrap metal recycling and beneficial reuse

    International Nuclear Information System (INIS)

    Motl, G.P.; Burns, D.D.

    1993-10-01

    The Fernald site, formerly the Feed Materials Production Facility, produced uranium metal products to meet defense production requirements for the Department of Energy from 1953 to 1989. In this report is is described how the Fernald scrap metal project has demonstrated that contractor capabilities can be used successfully to recycle large quantities of Department of Energy scrap metal. The project has proven that the open-quotes beneficial reuseclose quotes concept makes excellent economic sense when a market for recycled products can be identified. Topics covered in this report include the scrap metal pile history, the procurement strategy, scrap metal processing, and a discussion of lessons learned

  15. Analysis of NdFeB thin films prepared by facing target sputtering

    International Nuclear Information System (INIS)

    Shivalingappa, L.; Mohan, S.; Ghantasala, M.K.; Sood, D.K.

    1999-01-01

    In this paper, we present the details of our work on the deposition and characterization of NdFeB thin films. These films were prepared using facing target sputtering technique. The silicon(100) substrates were maintained at a substrate temperature of 400 to 600 deg C during deposition. Film structure, composition and magnetic properties are analyzed using Rutherford Backscattering Spectroscopy (RBS) and X-ray Diffraction (XRD) techniques. Films deposited below 400 deg C were x-ray amorphous, while the onset of crystallinity was observed with the films deposited at 500 deg C. Typical film composition was Nd:Fe:B = 2.2:12.5:2. Film composition appear to be a function of deposition conditions. Oxygen has been found to be the main impurity in the films. Oxygen content in the film reduced as the substrate temperature is increased

  16. Introduction to permanent magnets

    International Nuclear Information System (INIS)

    Zijlstra, H.

    1985-01-01

    Some general considerations concerning the application of permanent magnets are developed. The relevant magnet properties are discussed, with particular reference to Nd-Fe-B alloy. The author comes to the following conclusions; the air gap field B should be high, for high electrical efficiency; the magnet should face the air gap, for efficient use of the magnet material; the magnet material should therefore have a high remanence; and the new Nd-Fe-B magnet fits in nicely, having (potentially) the highest remanence ever reported in permanent magnets, combined with sufficient coercivity to sustain it

  17. 7 CFR 29.2529 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  18. Influence of shape and thickness on the levitation force of YBaCuO bulk HTS over a NdFeB guideway

    International Nuclear Information System (INIS)

    Ren Zhongyou; Wang Jiasu; Wang Suyu; Jiang He; Zhu Min; Wang Xiaorong; Song Honghai

    2003-01-01

    Levitation forces of YBaCuO bulk high temperature superconductors (HTS) with different shape and size over a NdFeB guideway were studied. Here, the concentrating magnetic field of the NdFeB guideway was 1.2 T, and the YBaCuO bulk HTSs include three cylindrical samples with different diameter and thickness and one hexagonal sample. The maximum levitation force is as high as 85.3 N at a gap of 5 mm between the bottom surface of YBaCuO bulk HTS and the top surface of the NdFeB guideway, where the applied magnetic field is about 0.8 T. The results show that the shape and the size have large influences on the levitation force of YBaCuO bulk HTSs

  19. Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

    International Nuclear Information System (INIS)

    Constantinescu, C.; Patroi, E.; Codescu, M.; Dinescu, M.

    2013-01-01

    Highlights: ► NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. ► Nitrogen inclusion in thin film structures is related to improved coercitivity. ► Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3ω and 4ω) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 °C), nitrogen gas pressure, and radiofrequency power (75–150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

  20. Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, C., E-mail: catalin.constantinescu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania); Patroi, E.; Codescu, M. [National Institute for Research and Development in Electrical Engineering - Advanced Research, 313 Spl. Unirii, Sector 3, RO-030138, Bucharest (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania)

    2013-03-01

    Highlights: Black-Right-Pointing-Pointer NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. Black-Right-Pointing-Pointer Nitrogen inclusion in thin film structures is related to improved coercitivity. Black-Right-Pointing-Pointer Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3{omega} and 4{omega}) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 Degree-Sign C), nitrogen gas pressure, and radiofrequency power (75-150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

  1. Collision-Free Structure Using Thin-Film Magnet For Electrostatic Energy Harvester

    International Nuclear Information System (INIS)

    Yoshii, S; Yamaguchi, K; Fujita, T; Kanda, K; Maenaka, K

    2016-01-01

    This paper proposes collision-free structure using NdFeB thin-film magnet for vibration energy harvesters. By using stripe shaped NdFeB magnet array on the Si MEMS structure, we finally obtained 3 mN of magnetic repulsive force on 8 × 8 mm 2 specimen with 40 μm air-gap. (paper)

  2. Collision-Free Structure Using Thin-Film Magnet For Electrostatic Energy Harvester

    Science.gov (United States)

    Yoshii, S.; Yamaguchi, K.; Fujita, T.; Kanda, K.; Maenaka, K.

    2016-11-01

    This paper proposes collision-free structure using NdFeB thin-film magnet for vibration energy harvesters. By using stripe shaped NdFeB magnet array on the Si MEMS structure, we finally obtained 3 mN of magnetic repulsive force on 8 × 8 mm2 specimen with 40 μm air-gap.

  3. AIR EMISSIONS FROM SCRAP TIRE COMBUSTION

    Science.gov (United States)

    The report discusses air emissions from two types of scrap tire combustion: uncontrolled and controlled. Uncontrolled sources are open tire fires, which produce many unhealthful products of incomplete combustion and release them directly into the atmosphere. Controlled combustion...

  4. Radiation protection aspects in importing metallic scraps

    International Nuclear Information System (INIS)

    Risica, S.; Di Ciaccio, P.

    1996-09-01

    The meeting deals with radiation protection problems caused by the possibility that radioactive metal scraps or radioactive sources hidden in the scraps, may arrive in a foundry. The importance of this issue and of rational and systematic solutions is showed by several accidents, happened in the past in numerous countries, by many signals in Italy and by some papers published in international scientific journals or reports issued by authorities and institutions in different countries

  5. Management options for recycling radioactive scrap metals

    Energy Technology Data Exchange (ETDEWEB)

    Dehmel, J.C.; MacKinney, J.; Bartlett, J.

    1997-02-01

    The feasibility and advantages of recycling radioactive scrap metals (RSM) have yet to be assessed, given the unique technical, regulatory, safety, and cost-benefit issues that have already been raised by a concerned recycling industry. As is known, this industry has been repeatedly involved with the accidental recycling of radioactive sources and, in some cases, with costly consequences. If recycling were deemed to be a viable option, it might have to be implemented with regulatory monitoring and controls. Its implementation may have to consider various and complex issues and address the requirements and concerns of distinctly different industries. There are three basic options for the recycling of such scraps. They are: (1) recycling through the existing network of metal-scrap dealers and brokers, (2) recycling directly and only with specific steelmills, or (3) recycling through regional processing centers. Under the first option, scrap dealers and brokers would receive material from RSM generators and determine at which steelmills such scraps would be recycled. For the second option, RSM generators would deal directly with selected steelmills under specific agreements. For the third option, generators would ship scraps only to regional centers for processing and shipment to participating steelmills. This paper addresses the potential advantages of each option, identifies the types of arrangements that would need to be secured among all parties, and attempts to assess the receptivity of the recycling industry to each option.

  6. Detection of radioactivity in scrap in Germany

    International Nuclear Information System (INIS)

    Kugeler, E.; Thierfeldt, S.; Sefzig, R.; Weimer, G.

    1999-01-01

    Although Germany's scrap export exceeds the import, the imports of scrap amount to more than one million Mg per year. Radioactivity has been found mainly in imported scrap in Germany. This radioactivity can consist of surface contamination in scrap e.g. from the oil and gas industry, nuclear and other technical applications or of radiation sources, e.g. from medical or technical irradiation devices where the source has not been removed prior to scrapping. Fortunately really large sources have been involved in only very few occasions. More serious incidents have, however, been reported from other countries. Today, measurement facilities have been installed at the entrances to virtually all German foundries and larger scrap yards. These measurement facilities allow the swift measurement of whole lorry or freight car loads. The lower limit of detection is for some devices as low as ca. 5 nSv/h (dose rate increase above background at the detector) which is achieved by very advanced hardware and software. Additionally, simplified dose rate measurements are performed by German customs officials at the eastern borders for scrap loads to be imported into Germany. When activity is detected in a load, several options exist, like e.g.: (i) sending the scrap back to the sender; (ii) allowing the whole load to be melted down; (iii) careful unloading and separating the load with the aim of localizing and removing the contamination. This paper analyses these various options after detection, discusses the role of the competent authorities and evaluates the possible radiological consequences. Realistic dose calculations show that it is possible that a person may receive doses of several mSv or even 10 mSv if precautionary measures are neglected or if a larger source is not detected at all. This paper further addresses which types and amounts of radioactivity may be detected and which conclusions can be drawn from the dose rate at the detector. The continuous increase in the number

  7. Testing of wet scrap recovery equipment for mixed oxide scrap reprocessing

    International Nuclear Information System (INIS)

    Demiter, J.A.; Klem, M.J.; Owen, T.J.

    1984-08-01

    The Wet Scrap Recovery (WSR) program was initiated at the Hanford Engineering Development Laboratory (HEDL) by Westinghouse Hanford Company in Richland, Washington to demonstrate fuel fabrication scrap recovery and reconversion to fuel grade oxide powder using the continuous coprecipitation-calcination (COPRECAL) conversion process. Advancements in process control equipment and instrumentation were also developed and demonstrated

  8. Leachability of heavy metals from scrap dirt sampled at two scrap iron and metal recycling facilities

    DEFF Research Database (Denmark)

    Jensen, Dorthe Lærke; Holm, Peter Engelund; Christensen, Thomas Højlund

    2000-01-01

    Column and batch leaching experiments were performed to quantify leaching of heavy metals (Pb, Cu, Cd and Zn) from scrap dirt representing different activities at two iron scrap and metal recycling facilities. The scrap dirt is often found directly upon the bare unprotected soil at recycling...... battery salvage locations was different, showing lower pH and signi®cant leaching of lead (up to 8000 mg Pb l±1), cadmium (up to 40 mg Cd l±1), and zinc (up to 2000 mg Zn l±1). The column and batch leaching experiments gave comparable results at the order of magnitude level, and both approaches are......, at that level, useful for evaluation of leaching potentials from scrap dirt. The experiments showed that scrap dirt at recycling facilities constitutes only a modest leaching problem, but a long-term soil pollution problem from a land-use perspective. Leaching experiments with compost solution indicated...

  9. Rare earth permanent magnets

    International Nuclear Information System (INIS)

    Higuchi, Akira

    1992-01-01

    This paper is a review of the new technologies for Nd-Fe-B magnets, their markets and future perspectives. This type of magnet is a product approaching the ideal magnet, and is based upon the development history of two previous generations of Sm-Co alloy systems and the recent progress on physical and metallurgical research. (orig.)

  10. The new MAW scrap processing facility

    International Nuclear Information System (INIS)

    Kueppers, L.

    1994-01-01

    The shielded bunker for heat-generating waste attached to the MAW scrap processing cell will be modified and extended to comprise several MAW scrap processing cells of enhanced throughput capacity, and a new building to serve as an airlock and port for acceptance of large shipping casks (shipping cask airlock, TBS). The new facility is to process scrap from decommissioned nuclear installations, and in addition radwaste accrued at operating plants of utilities. This will allow efficient and steady use of the new MAW scrap processing facility. The planning activities for modification and extension are based on close coordination between KfK and the GNS mbH, in order to put structural dimensioning and capacity planning on a realistic basis in line with expected amounts of radwaste from operating nuclear installations of utilities. The paper indicates the currently available waste amount assessments covering solid radwaste (MAW) from the decommissioning of the WAK, MZFR, and KNK II, and existing waste amounts consisting of core internals of German nuclear power plant. The figures show that the MAW scrap processing facility will have to process an overall bulk of about 1100 Mg of solid waste over the next ten years to come. (orig./HP) [de

  11. Corrosion properties of aluminium coatings deposited on sintered NdFeB by ion-beam-assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mao Shoudong; Yang Hengxiu; Li Jinlong; Huang Feng [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Ningbo 315201 (China); Song Zhenlun, E-mail: songzhenlun@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Ningbo 315201 (China)

    2011-04-15

    Pure Al coatings were deposited by direct current (DC) magnetron sputtering to protect sintered NdFeB magnets. The effects of Ar{sup +} ion-beam-assisted deposition (IBAD) on the structure and the corrosion behaviour of Al coatings were investigated. The Al coating prepared by DC magnetron sputtering with IBAD (IBAD-Al-coating) had fewer voids than the coating without IBAD (Al-coating). The corrosion behaviour of the Al-coated NdFeB specimens was investigated by potentiodynamic polarisation, a neutral salt spray (NSS) test, and electrochemical impedance spectroscopy (EIS). The pitting corrosion of the Al coatings always began at the voids of the grain boundaries. Bombardment by the Ar{sup +} ion-beams effectively improved the corrosion resistance of the IBAD-Al-coating.

  12. Characterisation of NdFeB thin films prepared on (100)Si substrates with SiO2 barrier layers

    International Nuclear Information System (INIS)

    Sood, D.K.; Muralidhar, G.K.

    1998-01-01

    This work presents a systematic study of the deposition and characterization of NdFeB films on substrates of Si(100) and of SiO2 layer thermally grown on Si(100) held at RT, 360 deg C or 440 deg C. The post-deposition annealing is performed at 600 or 800 deg C in vacuum. The films are characterised using the analytical techniques of RBS, SIMS, XRD, OM and SEM. Results indicate that SiO2 is, in deed, an excellent diffusion barrier layer till 600 deg C but becomes relatively less effective at 800 deg C. Without this barrier layer, interdiffusion at the Si-NdFeB film interface leads to formation of iron silicides, α-Fe and B exclusion from the diffusion zone, in competition with the formation of the magnetic NdFeB phase. (authors)

  13. Progress of HDDR NdFeB powders modulated by the diffusion of low melting point elements and their alloys

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available The hydrogenation-disproportionation-desorption-recombination (HDDR process is the main technique for the fabrication of anisotropic NdFeB magnetic powder.But the intrinsic coercivity (HC of HDDR magnetic powder is low.The addition of heavy rare earth element Dy could improve its HC.It was found that the added Dy is mainly distributed in the grain boundary of HDDR magnets,which regulates grain boundary phase and increases the thickness of grain boundary to improve the anisotropy field (HA and HC of the magnets.However,Dy becomes scarcer and more expensive,which limits the practical application of HDDR magnets.To reduce the dependence on heavy rare earth elements and cost,researchers replaced the heavy rare earth element Dy by low melting point elements and their alloys through grain boundary diffusion technique.During diffusion process low melting point metal exists as liquid phase that increases the diffusion coefficient of diffusion medium as well as its contact area with grain boundary phases of HDDR magnets,and benefits its diffusion along grain boundaries and regulation of grain boundary phase.The modified grain boundary in magnets improve HC.This review paper focuses on the research progress in improving HC of HDDR NdFeB magnets by low melting point elements and their alloys.

  14. Soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB ferromagnetic materials and their characterization

    Science.gov (United States)

    Rao, G. V. S. Jayapala; Prasad, T. N. V. K. V.; Shameer, Syed; Rao, M. Purnachandra

    2018-04-01

    Neodymium iron boron (NdFeB) permanent magnets have high energy product with suitable magnetic and physical properties for an array of applications including power generation and motors. However, synthetic routes of NdFeB permanent magnets involve critical procedures with high energy and needs scientific skills. Herein, we report on soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB (Co-NdFeB) permanent magnetic powders (Nd: 15%, Fe: 77.5%, B: 7.5% and Co with molar ratios: 0.5, 1, 1.5 and 2). A 10 ml of 10% soapnut extract was added to 90 ml of respective chemical composition and heated to 60 °C for 30 min and aged for 24 h. The dried powder was sintered at 500 °C for 1 h. The characterization of the prepared nanoscale Co-NdFeB magnetic powders was done using the techniques such as Dynamic Light Scattering (DLS for size and zeta potential measurements), X-ray diffraction (XRD) for structural determination, Scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS) for surface morphological and elemental analysis, Fourier transform infrared spectroscopy (FT-IR) for the identification of functional groups associated and hysteresis loop studies to quantify the magnetization. The results revealed that particles were in irregular and tubular shaped and highly stable (Zeta potential: -44.4 mV) with measured size <100 nm. XRD micrographs revealed a tetragonal crystal structure and FTIR showed predominant N-H and O-H stretching indicates the involvement of these functional groups in the reduction and stabilization process of Co-NdFeB magnetic powders. Hysteresis studies signify the effect of an increase in Co concentration.

  15. 7 CFR 29.1169 - Scrap (S Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Scrap (S Group). 29.1169 Section 29.1169 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Grades § 29.1169 Scrap (S Group). A byproduct of stemmed and unstemmed tobacco. Scrap...

  16. 7 CFR 29.2441 - Scrap (S Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Scrap (S Group). 29.2441 Section 29.2441 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Grades § 29.2441 Scrap (S Group). A byproduct of unstemmed and stemmed tobacco. Scrap...

  17. Vitrification for stability of scrap and residue

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W. [Oak Ridge National Lab., TN (United States)

    1996-05-01

    A conference breakout discussion was held on the subject of vitrification for stabilization of plutonium scrap and residue. This was one of four such sessions held within the vitrification workshop for participants to discuss specific subjects in further detail. The questions and issues were defined by the participants.

  18. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Griffin, T.P.; Johnston, J.E.

    1994-01-01

    The contract was conceived to establish the commercial capability of Catalytic Extraction Processing (CEP) to treat contaminated scrap metal in the DOE inventory. In so doing, Molten Metal Technology, Inc. (MMT), pursued the following objectives: demonstration of the recycling of ferrous and non-ferrous metals--to establish that radioactively contaminated scrap metal can be converted to high-grade, ferrous and non-ferrous alloys which can be reused by DOE or reintroduced into commerce; immobilize radionuclides--that CEP will concentrate the radionuclides in a dense vitreous phase, minimize secondary waste generation and stabilize and reduce waste volume; destroy hazardous organics--that CEP will convert hazardous organics to valuable industrial gases, which can be used as feed gases for chemical synthesis or as an energy source; recovery volatile heavy metals--that CEP's off-gas treatment system will capture volatile heavy metals, such as mercury and lead; and establish that CEP is economical for processing contaminated scrap metal in the DOE inventory--that CEP is a more cost-effective and, complete treatment and recycling technology than competing technologies for processing contaminated scrap. The process and its performance are described

  19. A study of liberation and separation process of metals from printed circuit boards (PCBs) scrap

    International Nuclear Information System (INIS)

    Noorliyana, H.A.; Zaheruddin, K.; Mohd Fazlul Bari; M. Sri Asliza; Nurhidayah, A.Z.; Kamarudin, H.

    2009-01-01

    Since the metallic elements are covered with or encapsulated by various plastic or ceramic materials on printed circuit boards, a mechanical pre-treatment process allowing their liberation and separation is first needed in order to facilitate their efficient extraction with hydrometallurgy route. Even though many studies have been performed on the mechanical pre-treatment processing for the liberation and separation of the metallic components of printed circuit boards scrap, further studies are required to pave the way for efficient recycling of waste printed circuit boards through a combination of mechanical pre-treatment and hydrometallurgical technology. In this work, a fundamental study has been carried out on the mechanical pre-treatment that is necessary to recover metallic concentrates from printed circuit boards scraps. The most important problem is to separate or release particles from the associated gangue minerals at the possible liberation particle size. The distribution of metallic elements has been also investigated in relation to the particle size of the milled printed circuit boards. The samples of printed circuit boards were separated into the magnetic and non-magnetic fractions by Rare-earth Roll Magnetic separator. Thereafter, the magnetic and non-magnetic fractions were separated to heavy fraction (metallic elements) and light fraction (plastic) by Mozley Laboratory Table Separator. The recovery ratios and the evaluation of the metallic concentrates recovered by each separation process were also investigated. This study is expected to provide useful data for the efficient mechanical separation of metallic components from printed circuit boards scraps. (author)

  20. Harvinaisten maametallien talteenotto NdFeB -magneeteista

    OpenAIRE

    Kangas, Sanna

    2017-01-01

    Tutkielman kirjallisessa osassa käsitellään yleisesti harvinaisia maametalleja, niiden ominaisuuksia, valmistusta, käyttökohteita ja kierrätystä lopputuotteista. Harvinaisten maametallien käyttökohteista keskitytään neodyymi-rauta-boori -magneetteihin (NdFeB -magneetit) ja niiden kierrätykseen. Tutkielmassa käydään läpi erilaiset harvinaisten maametallien hydrometallurgiset ja pyrometallurgiset talteenottomenetelmät. Tutkimusprojektissa pyrittiin kehittämään NdFeB -magneettien kierrätysme...

  1. Studies on the Production of NdFeB Alloy by Calciothermic Reduction of Neodymium Oxide

    International Nuclear Information System (INIS)

    Charoensri, Apisara

    2003-06-01

    Neodymium-Iron-Boron (NdFeB) is a class of permanent magnets having the highest energy product (BH max ). It has been used in various electronic devices of small size and light weight. This research is to study the preparation of Neodymium-Iron-Boron alloy by calciothermic reduction of neodymium oxide mixed with iron and iron-boron. The reduction process essentially involves the compaction of the charge mixture with calcium metal and then heating at 900-1200οC in argon atmosphere. The results show that charge blend compaction, temperature and time of reaction are important parameters of the process. It is found that at proper conditions, magnetic phase structure of Neodymium-Iron-Boron alloy can be prepared satisfactory although the alloy produced from the reduction contains higher impurities of oxygen and calcium than the alloy produced from the conventional method using Nd metal

  2. Potential interference of small neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators.

    Science.gov (United States)

    Wolber, Thomas; Ryf, Salome; Binggeli, Christian; Holzmeister, Johannes; Brunckhorst, Corinna; Luechinger, Roger; Duru, Firat

    2007-01-01

    Magnetic fields may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets, which are small in size but produce strong magnetic fields, have become widely available in recent years. Therefore, NdFeB magnets may be associated with an emerging risk of device interference. We conducted a clinical study to evaluate the potential of small NdFeB magnets to interfere with cardiac pacemakers and ICDs. The effect of four NdFeB magnets (two spherical magnets 8 and 10 mm in diameter, a necklace made of 45 spherical magnets, and a magnetic name tag) was tested in forty-one ambulatory patients with a pacemaker and 29 patients with an ICD. The maximum distance at which the magnetic switch of a device was influenced was observed. Magnetic interference was observed in all patients. The maximum distance resulting in device interference was 3 cm. No significant differences were found with respect to device manufacturer and device types. Small NdFeB magnets may cause interference with cardiac pacemakers and ICDs. Patients should be cautioned about the interference risk associated with NdFeB magnets during daily life.

  3. Orientation and magnetic properties of the thick multilayered [NdFeBxTby]n films

    International Nuclear Information System (INIS)

    Liu, Weifang; Suzuki, Shunji; Machida, Kenichi

    2007-01-01

    Multilayered [NdFeB x /Tb y ] n films were prepared by a three-demensional sputtering system. From the thickness of NdFeB layer dependence on the orientation and magnetic properties of multilayered [NdFeB (xμm)/Tb (50nm)] n films with 7.2μm as a total thickness of NdFeB layers, it was found that the orientation of NdFeB grains was maintained. However, the coercivity was enhanced with decreasing the thickness of each NdFeB thin layer. The (BH) max value of 240kJ/m 3 was obtained on the layered [NdFeB (1.2μm)/Tb (50 nm)] 6 film as an optimal value. For the multilayered [NdFeB (1.2μm)/Tb (50 nm)] n films with various multiple layer sets (n), the coercivity value increased with the film thickness without any deterioration of the c-axis texture and consequently, multilayered NdFeB/Tb film magnets with total thickness values around 70μm showed the superior magnetic properties (H cj approx. = 1360kA/m, I r approx.= 1.05T, and (BH) max approx.= 202kJ/m 3 ). (author)

  4. Coercivity enhancement and thermal-stability improvement in the melt-spun NdFeB ribbons by grain boundary diffusion

    Science.gov (United States)

    Xie, Jiajun; Yuan, Chao; Luo, Yang; Yang, Yuanfei; Hu, Bin; Yu, Dunbo; Yan, Wenlong

    2018-01-01

    Rapidly quenched NdFeB ribbons with high coercivity were obtained by Nd70Cu30 diffusion process. Samples with a high coercivity of 22.02 kOe at room temperature were obtained after grain boundary diffusion with 20 wt% Nd70Cu30 alloys. The NdCu diffusion process promoted grain growth in the ribbons, and grain boundary phases were formed with Cu segregation among NdFeB grains. Coercivity above 10 kOe at 150 °C was achieved in the bonded magnets with NdCu content over 10 wt%. The flux loss of bonded magnets was reduced by ∼32% at 120 °C after diffusion treatment with only a small amount (2 wt%) of NdCu.

  5. Evaluation of radioactive scrap metal recycling

    International Nuclear Information System (INIS)

    Nieves, L.A.; Chen, S.Y.; Kohout, E.J.; Nabelssi, B.; Tilbrook, R.W.; Wilson, S.E.

    1995-12-01

    This report evaluates the human health risks and environmental and socio-political impacts of options for recycling radioactive scrap metal (RSM) or disposing of and replacing it. Argonne National Laboratory (ANL) is assisting the US Department of Energy (DOE), Office of Environmental Restoration and Waste Management, Oak Ridge Programs Division, in assessing the implications of RSM management alternatives. This study is intended to support the DOE contribution to a study of metal recycling being conducted by the Task Group on Recycling and Reuse of the Organization for Economic Cooperation and Development. The focus is on evaluating the justification for the practice of recycling RSM, and the case of iron and steel scrap is used as an example in assessing the impacts. To conduct the evaluation, a considerable set of data was compiled and developed. Much of this information is included in this document to provide a source book of information

  6. Evaluation of radioactive scrap metal recycling

    Energy Technology Data Exchange (ETDEWEB)

    Nieves, L.A.; Chen, S.Y.; Kohout, E.J.; Nabelssi, B.; Tilbrook, R.W.; Wilson, S.E.

    1995-12-01

    This report evaluates the human health risks and environmental and socio-political impacts of options for recycling radioactive scrap metal (RSM) or disposing of and replacing it. Argonne National Laboratory (ANL) is assisting the US Department of Energy (DOE), Office of Environmental Restoration and Waste Management, Oak Ridge Programs Division, in assessing the implications of RSM management alternatives. This study is intended to support the DOE contribution to a study of metal recycling being conducted by the Task Group on Recycling and Reuse of the Organization for Economic Cooperation and Development. The focus is on evaluating the justification for the practice of recycling RSM, and the case of iron and steel scrap is used as an example in assessing the impacts. To conduct the evaluation, a considerable set of data was compiled and developed. Much of this information is included in this document to provide a source book of information.

  7. Developing methods for detecting radioactive scrap

    International Nuclear Information System (INIS)

    Bellian, J.G.; Johnston, J.G.

    1995-01-01

    During the last 10 years, there have been major developments in radiation detection systems used for catching shielded radioactive sources in scrap metal. The original testing required to determine the extent of the problem and the preliminary designs of the first instruments will be discussed. Present systems available today will be described listing their advantages and disadvantages. In conclusion, the newest developments and state of the art equipment will also be included describing the limits and most appropriate locations for the systems

  8. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  9. Import of metal scrap - risks associated with radioactivity

    International Nuclear Information System (INIS)

    Elert, M.

    1992-11-01

    There is a growing concern in Sweden for the possibility that imported metal scrap is radioactive. The recent political and economical changes in eastern Europe and the increased cooperation with the CEC has affected Swedens import. In the last years, the import of metal scrap from the former USSR has increased considerably. In view of recent incidents, when radioactive materials have been found, the Swedish Radiation Protection Institute has detected a need for identifying the potential risk sources and evaluating the magnitude of the risk associated with the import of metal scrap. The purpose of this report is to provide some background material concerning import statistics, use of metal scrap in Sweden and to identify potential sources of radioactive metal scrap. In addition, the radionuclides of most concern has been identified and the possibility of detecting them in metal scrap shipments is analyzed

  10. 49 CFR 173.218 - Fish meal or fish scrap.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized for...

  11. Life Cycle Assessment of Neodymium-Iron-Boron Magnet-to-Magnet Recycling for Electric Vehicle Motors.

    Science.gov (United States)

    Jin, Hongyue; Afiuny, Peter; Dove, Stephen; Furlan, Gojmir; Zakotnik, Miha; Yih, Yuehwern; Sutherland, John W

    2018-03-20

    Neodymium-iron-boron (NdFeB) magnets offer the strongest magnetic field per unit volume, and thus, are widely used in clean energy applications such as electric vehicle motors. However, rare earth elements (REEs), which are the key materials for creating NdFeB magnets, have been subject to significant supply uncertainty in the past decade. NdFeB magnet-to-magnet recycling has recently emerged as a promising strategy to mitigate this supply risk. This paper assesses the environmental footprint of NdFeB magnet-to-magnet recycling by directly measuring the environmental inputs and outputs from relevant industries and compares the results with production from "virgin" materials, using life cycle assessments. It was found that magnet-to-magnet recycling lowers environmental impacts by 64-96%, depending on the specific impact categories under investigation. With magnet-to-magnet recycling, key processes that contribute 77-95% of the total impacts were identified to be (1) hydrogen mixing and milling (13-52%), (2) sintering and annealing (6-24%), and (3) electroplating (6-75%). The inputs from industrial sphere that play key roles in creating these impacts were electricity (24-93% of the total impact) and nickel (5-75%) for coating. Therefore, alternative energy sources such as wind and hydroelectric power are suggested to further reduce the overall environmental footprint of NdFeB magnet-to-magnet recycling.

  12. Reduction of crystallization temperature of the Nd-Fe-B thin films by Cu addition

    International Nuclear Information System (INIS)

    Ma Yungui; Yang Zheng; Matsumoto, M.; Morisako, A.; Takei, S.

    2004-01-01

    Nonmagnetic Cu element has been doped into the sputtered Nd-Fe-B thin films. It is found that the introduction of suitable amount of copper atoms could reduce the crystallization temperature of the 2:14:1 phase by near 100 deg. C, compared with that without Cu. For the 15 nm Nd 16 Fe 70.2 Cu 1.8 B 12 film deposited at 340 deg. C, perpendicular coercivity and remanent magnetization ratio of 350 kA/m and 0.96 have been successfully obtained. Cu addition would lead to the grain growth, but the average grain size in the films could be greatly decreased through lowering the deposition temperature. These results are compared with those found in the fabrication of FePtCu films

  13. High energy permanent magnets - Solutions to high performance devices

    International Nuclear Information System (INIS)

    Ma, B.M.; Willman, C.J.

    1986-01-01

    Neodymium iron boron magnets are a special class of magnets providing the highest level of performance with the least amount of material. Crucible Research Center produced the highest energy product magnet of 45 MGOe - a world record. Commercialization of this development has already taken place. Crucible Magnetics Division, located in Elizabethtown, Kentucky, is currently manufacturing and marketing six different grades of NdFeB magnets. Permanent magnets find application in motors, speakers, electron beam focusing devices for military and Star Wars. The new NdFeB magnets are of considerable interest for a wide range of applications

  14. Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

    Science.gov (United States)

    Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

    2016-02-01

    Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

  15. High coercivity, anisotropic, heavy rare earth-free Nd-Fe-B by Flash Spark Plasma Sintering.

    Science.gov (United States)

    Castle, Elinor; Sheridan, Richard; Zhou, Wei; Grasso, Salvatore; Walton, Allan; Reece, Michael J

    2017-09-11

    In the drive to reduce the critical Heavy Rare Earth (HRE) content of magnets for green technologies, HRE-free Nd-Fe-B has become an attractive option. HRE is added to Nd-Fe-B to enhance the high temperature performance of the magnets. To produce similar high temperature properties without HRE, a crystallographically textured nanoscale grain structure is ideal; and this conventionally requires expensive "die upset" processing routes. Here, a Flash Spark Plasma Sintering (FSPS) process has been applied to a Dy-free Nd 30.0 Fe 61.8 Co 5.8 Ga 0.6 Al 0.1 B 0.9 melt spun powder (MQU-F, neo Magnequench). Rapid sinter-forging of a green compact to near theoretical density was achieved during the 10 s process, and therefore represents a quick and efficient means of producing die-upset Nd-Fe-B material. The microstructure of the FSPS samples was investigated by SEM and TEM imaging, and the observations were used to guide the optimisation of the process. The most optimal sample is compared directly to commercially die-upset forged (MQIII-F) material made from the same MQU-F powder. It is shown that the grain size of the FSPS material is halved in comparison to the MQIII-F material, leading to a 14% increase in coercivity (1438 kA m -1 ) and matched remanence (1.16 T) giving a BH max of 230 kJ m -3 .

  16. A comparative thermomagnetic study of melt-spun Nd-Fe-B alloys with different Nd content

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2009-01-01

    Full Text Available Changes in the phase composition and magnetic properties of three types of commercial Nd-Fe-B alloys with different Nd content - low (10-12 wt%, near stoichiometric (21-25 wt% and rich (26-29 wt% caused by thermomagnetic analysis (TM were observed in regard to optimal magnetic state. Phase compositions of investigated alloys before and after TM measurement up to 800°C were compared using 57Fe Mössbauer spectroscopy and X-Ray analysis. The TM measurements decompose all three materials and the main products of decomposition process α-Fe and Fe2B phase. Observed changes in structure and phase composition had direct influence on magnetic properties. Loss of magnetic properties induced by thermal decomposition is clearly illustrated on corresponding SQUID hysteresis loops.

  17. Technical Review of the Characteristics of Spent Nuclear Fuel Scrap

    International Nuclear Information System (INIS)

    Kuhn, William L.; Abrefah, John; Pitner, Allen L.; Damschen, Dennis W.

    2000-01-01

    Spent Nuclear Fuel scrap generated while washing the SNF in Hanford's K-Basins to prepare it for cold vacuum drying differed significantly from that envisioned during project design. Therefore, a technical review panel evaluated the new information about the physical characteristics of scrap generated during processing by characterizing it based on measured weights and digital photographic images. They examined images of the scrap and from them estimated the volume and hence the masses of inert material and of large fragments of spent fuel. The panel estimated the area of these particles directly from images and by fitting a lognormal distribution to the relative number particles in four size ranges and then obtaining the area-to-volume ratio from the distribution. The estimated area is 0.3 m2 for the mass of scrap that could be loaded into a container for drying, which compares to a value of 4.5 m2 assumed for safe operation of the baseline process. The small quantity of scrap genera ted is encouraging. However, the size and mass of the scrap depend both on processes degrading the fuel while in the basin and on processes catching the scrap during washing, the latter including essentially unintentional filtration as debris accumulates. Therefore, the panel concluded that the estimated surface area meets the criterion for loading scrap into an MCO for drying, but because it did not attempt to evaluate the criterion itself, it is not in a position to actually recommend loading the scrap. Further, this is not a sufficiently strong technical position from which to extrapolate the results from the examined scrap to all future scrap generated by the existing process

  18. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  19. A comparative study of magnetoresistance and magnetic structure in recycled vs. virgin NdFeB-type sintered magnets

    Science.gov (United States)

    Shen, Shida; Tsoi, Maxim; Prosperi, Davide; Tudor, Catalina O.; Dove, Stephen K.; Bevan, Alex I.; Furlan, Gojmir; Zakotnik, Miha

    2017-11-01

    Recycled NdFeB magnets are emerging as a viable alternative to virgin NdFeB, because of lower production costs and environmental impacts. Recycled NdFeB magnets produced via the recently reported magnet-to-magnet (m2 m™) recycling process display unanticipated enhancements of magnetic and physical properties that may arise because of their unique microstructure. In the present study, we compare electrical transport and magnetic properties of these recycled magnets (Grade: N42SH, Br = 1289 mT, Hcj = 1876 kA/m, BHmax = 323.4 kJ/m3, Dy content = 4.0 wt%) with an equivalent grade of commercial NdFeB magnet produced from virgin material by conventional techniques (Grade: N42SH, Br = 1215 mT, Hcj = 1943 kA/m, BHmax = 285.0 kJ/m3, with Dy content = 4.6 wt%). Atomic force microscopy (AFM) and magnetic force microscopy (MFM) analyses revealed very similar surface morphology and magnetic structure for the virgin and recycled samples. However, bulk electrical transport measurements demonstrated a 27% enhancement in the resistivity of the recycled magnets. This suggests that the electrical properties of NdFeB alloys are enhanced during Grain Boundary Engineering™ (GBE™). Moreover, point-contact measurements, used to probe the electrical transport properties on the microscopic scale, found similar results to those of the bulk measurements.

  20. Incident involving radioactive material in steel scrap

    International Nuclear Information System (INIS)

    Drabova, D.; Matzner, J.; Prouza, Z.

    1998-01-01

    In early March of 1996, a wagon with steel scrap heading from the Czech Republic to Italy was returned as a strongly contaminated material. Based on the integral dose (dose rate 650 mGy/h in front of the wagon) and spectrometric measurement and evaluation, it was concluded that an unshielded cobalt-60 source (1.6 TBq) was present. The history of the event (notification, assessment, intervention planning, intervention) is highlighted and the lesson learned from the incident is discussed. (P.A.)

  1. Economic feasibility of radioactive scrap steel recycling

    International Nuclear Information System (INIS)

    Balhiser, R.; Rosholt, D.; Nichols, F.

    1995-01-01

    The goal of MSE's Radioactive Scrap Steel (RSS) Recycle Program is to develop practical methods for recycling RSS into useful product. This paper provides interim information about ongoing feasibility investigations that are scheduled for completion by September 1995. The project approach, major issues, and cost projections are outlined. Current information indicates that a cost effective RSS Recycling Facility can be designed, built, and in operation by 1999. The RSS team believes that high quality steel plate can be made from RSS at a conversion cost of $1500 per ton or less

  2. Cryogenic Permanent Magnet Undulators

    International Nuclear Information System (INIS)

    Chavanne, J.; Lebec, G.; Penel, C.; Revol, F.; Kitegi, C.

    2010-01-01

    For an in-vacuum undulator operated at small gaps the permanent magnet material needs to be highly resistant to possible electron beam exposure. At room temperature, one generally uses Sm 2 Co 17 or high coercivity NdFeB magnets at the expense of a limited field performance. In a cryogenic permanent magnet undulator (CPMU), at a temperature of around 150 K, any NdFeB grade reveals a coercivity large enough to be radiation resistant. In particular, very high remanence NdFeB material can be used to build undulators with enhanced field and X-ray brilliance at high photon energy provided that the pre-baking of the undulator above 100 deg. C can be eliminated. The ESRF has developed a full scale 2 m long CPMU with a period of 18 mm. This prototype has been in operation on the ID6 test beamline since January 2008. A significant effort was put into the characterization of NdFeB material at low temperature, the development of dedicated magnetic measurement systems and cooling methods. The measured heat budget with beam is found to be larger than expected without compromising the smooth operation of the device. Leading on from this first experience, new CPMUs are currently being considered for the upgrade of the ESRF.

  3. Scrap of gloveboxes No. 801-W and No. 802-W

    CERN Document Server

    Ohuchi, S; Kurosawa, M; Okane, S; Usui, T

    2002-01-01

    Both gloveboxes No. 801-W for measuring samples of uranium or plutonium and No. 802-W for analyzing the quantity of uranium or plutonium are established at twenty five years ago in the analyzing room No. 108 of Plutonium Fuel Research Facility. It was planned to scrap the gloveboxes and to establish new gloveboxes. This report describes the technical view of the scrapping works.

  4. 46 CFR Sec. 12 - Disposition of removed equipment and scrap.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Disposition of removed equipment and scrap. Sec. 12... CONTRACT-NSA-LUMPSUMREP Sec. 12 Disposition of removed equipment and scrap. (a) Article 8 of the NSA-LUMPSUMREP Contract provides that any ship equipment, fuel, lube oil, supplies, stores, furniture, fixtures...

  5. Hydrogen isotope storage in zircaloy scrap

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. S.; Kuk, I. H.; Chung, H.; Paek, S. W.; Kang, H. S

    1999-08-01

    8 MCi of tritium a year will be produced after wolsong TRF is in operation. The metal hydride form is one of useful tritium storage. The metals in use for metal hydride are uranium, titanium, etc., however uranium is limited to use by regulation, and titanium is relatively costly. Both metals are not produced in country but whole amount is imported. On the other hand 2,000kg of zircaloy scrap is produced by CANDU nuclear fuel fabrication process, which is also useful for hydrogen storage. The purpose of this study is to evaluation of hydrogen absorption capacity for zircaloy scrap that is produced as waste by CANDU nuclear fuel fabrication process. The sample evacuated for an hour at 1000 deg C. The strip showed higher capacity : 0.7 at 25 deg C, 2.0 at 200 deg C, 2.0 at 200 deg C, 2.0 at 400 deg C, respectively. The H/M values for commercial zircaloy sponge were 2.0 at 25 deg C and 2.0 at 400 deg C.

  6. Hydrogen isotope storage in zircaloy scrap

    International Nuclear Information System (INIS)

    Lee, H. S.; Kuk, I. H.; Chung, H.; Paek, S. W.; Kang, H. S.

    1999-08-01

    8 MCi of tritium a year will be produced after wolsong TRF is in operation. The metal hydride form is one of useful tritium storage. The metals in use for metal hydride are uranium, titanium, etc., however uranium is limited to use by regulation, and titanium is relatively costly. Both metals are not produced in country but whole amount is imported. On the other hand 2,000kg of zircaloy scrap is produced by CANDU nuclear fuel fabrication process, which is also useful for hydrogen storage. The purpose of this study is to evaluation of hydrogen absorption capacity for zircaloy scrap that is produced as waste by CANDU nuclear fuel fabrication process. The sample evacuated for an hour at 1000 deg C. The strip showed higher capacity : 0.7 at 25 deg C, 2.0 at 200 deg C, 2.0 at 200 deg C, 2.0 at 400 deg C, respectively. The H/M values for commercial zircaloy sponge were 2.0 at 25 deg C and 2.0 at 400 deg C

  7. Sulfur dioxide leaching of spent zinc-carbon-battery scrap

    Energy Technology Data Exchange (ETDEWEB)

    Avraamides, J.; Senanayake, G.; Clegg, R. [A.J. Parker Cooperative Research Centre for Hydrometallurgy, Murdoch University, Perth, WA 6150 (Australia)

    2006-09-22

    Zinc-carbon batteries, which contain around 20% zinc, 35% manganese oxides and 10% steel, are currently disposed after use as land fill or reprocessed to recover metals or oxides. Crushed material is subjected to magnetic separation followed by hydrometallurgical treatment of the non-magnetic material to recover zinc metal and manganese oxides. The leaching with 2M sulfuric acid in the presence of hydrogen peroxide recovers 93% Zn and 82% Mn at 25{sup o}C. Alkaline leaching with 6M NaOH recovers 80% zinc. The present study shows that over 90% zinc and manganese can be leached in 20-30min at 30{sup o}C using 0.1-1.0M sulfuric acid in the presence of sulfur dioxide. The iron extraction is sensitive to both acid concentration and sulfur dioxide flow rate. The effect of reagent concentration and particle size on the extraction of zinc, manganese and iron are reported. It is shown that the iron and manganese leaching follow a shrinking core kinetic model due to the formation of insoluble metal salts/oxides on the solid surface. This is supported by (i) the decrease in iron and manganese extraction from synthetic Fe(III)-Mn(IV)-Zn(II) oxide mixtures with increase in acid concentration from 1M to 2M, and (ii) the low iron dissolution and re-precipitation of dissolved manganese and zinc during prolonged leaching of battery scrap with low sulfur dioxide. (author)

  8. Global use structures of the magnetic materials neodymium and dysprosium. A scenario-based analysis of the effect of the diffusion of electromobility on the demand for rare earths; Globale Verwendungsstrukturen der Magnetwerkstoffe Neodym und Dysprosium. Eine szenariobasierte Analyse der Auswirkung der Diffusion der Elektromobilitaet auf den Bedarf an Seltenen Erden

    Energy Technology Data Exchange (ETDEWEB)

    Gloeser-Chahoud, Simon; Kuehn, Andre; Tercero Espinoza, Luis

    2016-06-15

    Neodymium-iron-boron magnets (NdFeB) have experienced a significant demand as the most powerful permanent magnet in recent years, especially for the manufacture of compact electric servomotors with high efficiency and high power density, especially for mobile applications in hybrid traction motors and electric vehicles or for electric bikes. However, NdFeB magnets are also increasingly being used in general mechanical engineering (conveying and pumping systems, tools, air conditioning systems, lift motors, etc.), in the small electric motors of conventional passenger cars or in the generators of large wind power plants with permanent magnetic direct drive. Nevertheless, there is still high uncertainty in the use structures of NdFeB magnets and the contained rare earth elements neodymium and dysprosium. An effective instrument for increasing the market transparency and the understanding of complex anthropogenic material cycles is the dynamic material flow modeling. In the present work paper, this instrument is used for an in-depth analysis of the use structures of NdFeB magnets and the contained rare earths on a global scale. The dynamic modeling of product usage cycles reveals today's usage structures and quantifies future magnetic quantities in obsolete product flows. It could be shown that the magnets in today's scrap volume are mainly contained in obsolete electronics applications such as hard disks (HDD), CD and DVD drives, which makes the recycling hardly seem to be economical due to the small magnets and the high material spread, but in the foreseeable future with larger magnetic quantities from synchronous servomotors and generators can be expected, which significantly increases the recycling potential. In a further step, the effect of the diffusion of alternative drives in the automotive market on the dysprosium requirement is analyzed using a system dynamics model and possible adaptation mechanisms in the form of different substitution effects in

  9. Feasibility of re-melting NORM-contaminated scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Winters, S. J.; Smith, K. P.

    1999-10-26

    Naturally occurring radioactive materials (NORM) sometimes accumulate inside pieces of equipment associated with oil and gas production and processing activities. Typically, the NORM accumulates when radium that is present in solution in produced water precipitates out in scale and sludge deposits. Scrap equipment containing residual quantities of these NORM-bearing scales and sludges can present a waste management problem if the radium concentrations exceed regulatory limits or activate the alarms on radiation screening devices installed at most scrap metal recycling facilities. Although NORM-contaminated scrap metal currently is not disposed of by re-melting, this form of recycling could present a viable disposition option for this waste stream. Studies indicate that re-melting NORM-contaminated scrap metal is a viable recycling option from a risk-based perspective. However, a myriad of economic, regulatory, and policy issues have caused the recyclers to turn away virtually all radioactive scrap metal. Until these issues can be resolved, re-melting of the petroleum industry's NORM-impacted scrap metal is unlikely to be a widespread practice. This paper summarizes the issues associated with re-melting radioactive scrap so that the petroleum industry and its regulators will understand the obstacles. This paper was prepared as part of a report being prepared by the Interstate Oil and Gas Compact Commission's NORM Subcommittee.

  10. Release of Radioactive Scrap Metal/Scrap Metal (RSM/SM) at Nevada Test Site (NTS)

    International Nuclear Information System (INIS)

    1993-01-01

    Reynolds Electrical and Engineering Company, Inc. (REECo) is the prime contractor to the US Department of Energy (DOE) in providing service and support for NTS operations. Mercury Base Camp is the main control point for the many forward areas at NTS, which covers 1,350 square miles. The forward areas are where above-ground and underground nuclear tests have been performed over the last 41 years. No metal (or other material) is returned to Mercury without first being tested for radioactivity. No radioactive metals are allowed to reenter Mercury from the forward areas, other than testing equipment. RAMATROL is the monitor check point. They check material in various ways, including swipe tests, and have a large assortment of equipment for testing. Scrap metal is also checked to address Resource Conservation and Recovery Act concerns. After addressing these issues, the scrap metals are categorized. Federal Property Management Regulations (FPMR) are followed by REECo. The nonradioactive scrap material is sold through the GSA on a scheduled basis. Radioactive scrap metal are presently held in forward areas where they were used. REECo has gained approval of their Nevada Test Site Defense Waste Acceptance Criteria, Certification, and Transfer Requirements, NVO-325 application, which will allow disposal on site, when RSM is declared a waste. The guideline that REECo uses for release limits is DOE Order 5480.11, Radiation Protection for Occupational Works, Attachment 2, Surface Radioactivity Guides, of this order, give release limits for radioactive materials. However, the removal of radioactive materials from NTS require approval by DOE Nevada Operations Office (DOE/NV) on a case-by-case basis. Requirements to consider before removal are found in DOE Order 5820.2A, Radioactive Waste Management

  11. 40 CFR 63.10885 - What are my management practices for metallic scrap and mercury switches?

    Science.gov (United States)

    2010-07-01

    ... minimize the presence of mercury in scrap from end-of-life vehicles. (3) Option for specialty metal scrap... metallic scrap and mercury switches? 63.10885 Section 63.10885 Protection of Environment ENVIRONMENTAL... Affected Sources § 63.10885 What are my management practices for metallic scrap and mercury switches? (a...

  12. The Design of a Device for the Generation of a Strong Magnetic Field in an Air Gap Using Permanent Magnets

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2017-01-01

    Roč. 22, č. 2 (2017), s. 250-256 ISSN 1226-1750 Institutional support: RVO:67985891 Keywords : magnet ic field * permanent magnet s * NdFeB magnet s * Halbach arrays Subject RIV: BM - Solid Matter Physics ; Magnet ism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.713, year: 2016

  13. Economic feasibility of radioactive scrap steel recycling

    International Nuclear Information System (INIS)

    Nichols, F.; Balhiser, R.; Rosholt, D.

    1995-01-01

    In the past, government and commercial nuclear operators treated radioactive scrap steel (RSS) as a liability and disposed of it by burial; this was an accepted and economical solution at that time. Today, environmental concerns about burial are changing the waste disposal picture by (a) causing burial costs to soar rapidly, (b) creating pressure to close existing burial sites, and (c) making it difficult and expensive to open and operate burial facilities. To exacerbate the problem, planned dismantling of nuclear facilities will substantially increase volumes of RSS open-quotes wasteclose quotes over the next 30 yr. This report describes a project with the intention of integrating the current commercial mini-mill approach of recycling uncontaminated steel with radiological controls to design a system that can process contaminated metals at prices significantly below the current processors or burial costs

  14. Radioactive scrap metal decontamination technology assessment report

    International Nuclear Information System (INIS)

    Buckentin, J.M.; Damkroger, B.K.; Schlienger, M.E.

    1996-04-01

    Within the DOE complex there exists a tremendous quantity of radioactive scrap metal. As an example, it is estimated that within the gaseous diffusion plants there exists in excess of 700,000 tons of contaminated stainless steel. At present, valuable material is being disposed of when it could be converted into a high quality product. Liquid metal processing represents a true recycling opportunity for this material. By applying the primary production processes towards the material's decontamination and re-use, the value of the strategic resource is maintained while drastically reducing the volume of material in need of burial. Potential processes for the liquid metal decontamination of radioactively contaminated metal are discussed and contrasted. Opportunities and technology development issues are identified and discussed. The processes compared are: surface decontamination; size reduction, packaging and burial; melting technologies; electric arc melting; plasma arc centrifugal treatment; air induction melting; vacuum induction melting; and vacuum induction melting and electroslag remelting

  15. Update on Recovering Lead From Scrap Batteries

    Science.gov (United States)

    Cole, E. R.; Lee, A. Y.; Paulson, D. L.

    1985-02-01

    Previous work at the Bureau of Mines Rolla Research Center, U.S. Department of the Interior, resulted in successful development of a bench-scale, combination electrorefining-electrowinning method for recycling lead from scrap batteries by using waste fluosilicic acid (H2SiF6) as electrolyte.1,2 This paper describes larger scale experiments. Prior attempts to electrowin lead failed because large quantities of insoluble lead dioxide were deposited on the anodes at the expense of lead deposition on the cathodes. A major breakthrough was achieved with the discovery that lead dioxide formation at the anodes is prevented by adding a small amount of phosphorus to the electrolyte. The amount of PbO2 formed on the anodes during lead electrowinning was less than 1% of the total lead deposited on the cathodes. This work recently won the prestigious IR·100 award as one of the 100 most significant technological advances of 1984.

  16. Scrap uranium recycling via electron beam melting

    International Nuclear Information System (INIS)

    McKoon, R.

    1993-11-01

    A program is underway at the Lawrence Livermore National Laboratory (LLNL) to recycle scrap uranium metal. Currently, much of the material from forging and machining processes is considered radioactive waste and is disposed of by oxidation and encapsulation at significant cost. In the recycling process, uranium and uranium alloys in various forms will be processed by electron beam melting and continuously cast into ingots meeting applicable specifications for virgin material. Existing vacuum processing facilities at LLNL are in compliance with all current federal and state environmental, safety and health regulations for the electron beam melting and vaporization of uranium metal. One of these facilities has been retrofitted with an auxiliary electron beam gun system, water-cooled hearth, crucible and ingot puller to create an electron beam melt furnace. In this furnace, basic process R ampersand D on uranium recycling will be performed with the goal of eventual transfer of this technology to a production facility

  17. Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

    Science.gov (United States)

    Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

    2017-04-01

    This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.

  18. Contaminated scrap metal management on the Oak Ridge Reservation

    International Nuclear Information System (INIS)

    Hayden, H.W.; Stephenson, M.J.; Bailey, J.K.; Weir, J.R.; Gilbert, W.C.

    1993-01-01

    Large quantities of scrap metal are accumulating at the various Department of Energy (DOE) installations across the country as a result of ongoing DOE programs and missions in concert with present day waste management practices. DOE Oak Ridge alone is presently storing around 500,000 tons of scrap metal. The local generation rate, currently estimated at 1,400 tons/yr, is expected to increase sharply over the next couple of years as numerous environmental restoration and decommissioning programs gain momentum. Projections show that 775,000 tons of scrap metal could be generated at the K-25 Site over the next ten years. The Y-12 Plant and Oak Ridge National Laboratory (ORNL) have similar potentials. The history of scrap metal management at Oak Ridge and future challenges and opportunities are discussed

  19. Cost-assessment Analysis of Local Vehicle Scrapping Facility

    Science.gov (United States)

    Grabowski, Lukasz; Gliniak, Maciej; Polek, Daria; Gruca, Maria

    2017-12-01

    The purpose of the paper was to analyse the costs of recycling vehicles at local vehicle scrapping facility. The article contains regulations concerning vehicle decommissioning, describes the types of recovery, vehicles recycling networks, analyses the structure of a disassembly station, as well as the financial and institutional system in charge of dealing with the recycling of vehicles in Poland. The authors present the number of scrapped vehicles at local recycling company and the level of achieved recovery and recycling. The research presented in the article shows financial situation of the vehicle scrapping industry. In addition, it has been observed that the number of subsidies are directly proportional to the number of scrapped vehicles, and achieved levels of recycling and recovery depends on the percentage of incomplete vehicles.

  20. The Scrap Tire Problem: A Preliminary Economic Analysis (1985)

    Science.gov (United States)

    The purpose of the study was to conduct a preliminary economic analysis of the social benefits of EPA action to require more appropriate disposal of scrap tires versus the social costs of such an action.

  1. Analysis of disposition alternatives for radioactively contaminated scrap metal

    International Nuclear Information System (INIS)

    Nieves, L.A.; Chen, S.Y.; Kohout, E.J.; Nabelssi, B.; Tilbrook, R.W.; Wilson, S.E.

    1997-01-01

    Millions of tonnes of slightly radioactive, scrap iron and steel, stainless steel, and copper are likely to become available as nuclear and other facilities and equipment are withdrawn from service. Disposition of this material is an international policy issue under consideration currently. The major alternatives for managing this material are to either develop a regulatory process for decontamination and recycling that will safeguard human health or to dispose of the scrap and replace the metal stocks. To evaluate the alternatives, we estimate quantities of scrap arising from nuclear power plant decommissioning, evaluate potential price impacts of recycling on regional markets, and assess the health and environmental impacts of the management alternatives. We conclude that decontaminating and recycling the scrap is the superior alternative

  2. Visualization of magnetic dipolar interaction based on scanning transmission X-ray microscopy

    International Nuclear Information System (INIS)

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

    2014-01-01

    Using scanning transmission X-ray microscopy (STXM), in this report we visualized the magnetic dipolar interactions in nanocrystalline Nd-Fe-B magnets and imaged their magnetization distributions at various applied fields. We calculated the magnetic dipolar interaction by analyzing the interaction between the magnetization at each point and those at the other points on the STXM image.

  3. Radiation survey of aircraft and heavy machinery scrap

    International Nuclear Information System (INIS)

    Idriss, Hajo; Salih, Isam; Gumaa, Elsadig; Yassin, Abbas; Yousif, E.H.; Abdel Hamid, Saad Eldeen M.; Sam, A.K.

    2012-01-01

    This study was conducted primarily to survey aircraft and heavy machinery at 30 locations within Khartoum State using handheld radiation survey meters to detect and identify any radiation sources that might be present and to estimate radiation dose levels. The survey has resulted in detection of 16 sealed sources of 90 Sr and one of 226 Ra in aircraft scrap. Of course, 90 Sr sources are used in military aircraft as temperature sensors while 226 Ra is used for indicating fuel levels. These sources were found intact without spreading radioactivity contamination; however, none was detected in heavy machine scrap. The levels of radiation dose measured at 0.1 m from the source fall within the range of 25.1–40.2 μSv/h with an average value of 33.52±4.06 μSv/h. These orphan sources have been separated from the scrap, tested for possible leakage, conditioned and stored in waste management facility. The result of this study has revealed without doubt that the scrap constitute a serious source of public exposure and highlights the importance of legislation making radiation monitoring of scrap in the country mandatory before it is sold to metal industry for reprocessing. - Highlights: ► Sealed radioactive sources ( 90 Sr and 226 Ra) were detected in aircraft scrap. ► No source was detected in heavy machine scrap. ► Radiation dose measured at 0.1 m from the source can be used to estimate exposure to public. ► Monitoring of scrap was found to be useful for protection (from orphan sources).

  4. Economic comparison of management modes for contaminated metal scrap

    International Nuclear Information System (INIS)

    Janberg, K.

    1987-01-01

    This report presents an economic study of the three following management modes for contaminated metal scrap: - decontamination of scrap metal followed by release, - direct melting of scrap metal, followed by release or restricted reuse, - super-compaction followed by disposal as radioactive waste. The present study, which refers to conditions prevailing in Germany, includes reviews of the contaminated scrap arisings, of experience with scrap management and of the licensing conditions for metal recycling. The results obtained during the treatment of more than 140 t of contaminated scrap metal show that: - super-compaction is the best procedure for all mixed metallic wastes of small dimensions and complex geometries, as decontamination is very costly in such a case and the melting would lead to undefined metallurgical products; - decontamination is recommendable for simple geometries and activities higher than the regulatory upper limit for melting in an industrial foundry (74 Bq/g); - direct melting for lower activity levels is gaining in competitiveness and has a good chance to be the best solution, in particular when the free use levels will be reduced below the currently accepted levels in Germany

  5. Structure and magnetic properties of hot deformed Nd2Fe14B magnets doped with DyHx nanoparticles

    Science.gov (United States)

    Wang, C. G.; Yue, M.; Zhang, D. T.; Liu, W. Q.; Zhang, J. X.

    2016-04-01

    Commercial NdFeB powders mixed with DyHx nanoparticles are hot pressed and hot deformed into anisotropic magnets by Spark Plasma Sintering (SPS). The hot deformed magnet exhibits strong c-axis crystallographic texture. The coercivity of the magnet doped with 1.0 wt% DyHx is increased by 66.7%, compared with the magnet without DyHx, while the remanence decreases only by 3%. TEM observation shows that there exists a continuous (Nd,Dy)2Fe14B layer between Nd-rich phase and NdFeB main phase.

  6. Catalytic extraction processing of contaminated scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M. [Molten Metal Technology, Inc., Waltham, MA (United States)] [and others

    1995-10-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT`s proprietary elemental recycling technology, to DOE`s inventory of low level mixed waste. This includes DOE`s inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D&D) of DOE sites.

  7. Handling and disposal of radioactive scrap

    International Nuclear Information System (INIS)

    Witte, K.

    1975-01-01

    The 9th special course for journalists was in this year on the highly topical subject 'handling and disposal of radioactive scrap'. It was held on the 26th and 27th May 1975 at the Nuclear Research Centre at Karlsruhe. These courses have been held for several years by the Nuclear Research Association (GfK) in the School for Nuclear Engineering and are intended mainly to contribute to journalists of the daily papers, radio and television who are 'not previously technically trained' an introduction into the difficult subject matter of nuclear engineering with its ancillary areas. In view of the many discussions carried on in public the course is further intended to achieve that the problems discussed are treated by means of publicity which is free from emotion. In the journalists' course this year specially selected experts gave technical information prepared for general information as to how radioactive waste can be safely worked up and then finally stored without adverse effects on the environment. Since the interesting collection of questions was put forward in a compressed form and at the same time clearly presented, the author reports on the different separate subjects on which lectures were given. (orig.) [de

  8. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.

    1995-01-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT's proprietary elemental recycling technology, to DOE's inventory of low level mixed waste. This includes DOE's inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D ampersand D) of DOE sites

  9. Feasibility analysis of recycling radioactive scrap steel

    International Nuclear Information System (INIS)

    Nichols, F.; Balhiser, B.; Cignetti, N.

    1995-09-01

    The purpose of this study is to: (1) establish a conceptual design that integrates commercial steel mill technology with radioactive scrap metal (RSM) processing to produce carbon and stainless steel sheet and plate at a grade suitable for fabricating into radioactive waste containers; (2) determine the economic feasibility of building a micro-mill in the Western US to process 30,000 tons of RSM per year from both DOE and the nuclear utilities; and (3) provide recommendations for implementation. For purposes of defining the project, it is divided into phases: economic feasibility and conceptual design; preliminary design; detail design; construction; and operation. This study comprises the bulk of Phase 1. It is divided into four sections. Section 1 provides the reader with a complete overview extracting pertinent data, recommendations and conclusions from the remainder of the report. Section 2 defines the variables that impact the design requirements. These data form the baseline to create a preliminary conceptual design that is technically sound, economically viable, and capitalizes on economies of scale. Priorities governing the design activities are: (1) minimizing worker exposure to radionuclide hazards, (2) maximizing worker safety, (3) minimizing environmental contamination, (4) minimizing secondary wastes, and (5) establishing engineering controls to insure that the plant will be granted a license in the state selected for operation. Section 3 provides details of the preliminary conceptual design that was selected. The cost of project construction is estimated and the personnel needed to support the steel-making operation and radiological and environmental control are identified. Section 4 identifies the operational costs and supports the economic feasibility analysis. A detailed discussion of the resulting conclusions and recommendations is included in this section

  10. Radiation survey of aircraft and heavy machinery scrap.

    Science.gov (United States)

    Idriss, Hajo; Salih, Isam; Gumaa, Elsadig; Yassin, Abbas; Yousif, E H; Abdel Hamid, Saad Eldeen M; Sam, A K

    2012-12-01

    This study was conducted primarily to survey aircraft and heavy machinery at 30 locations within Khartoum State using handheld radiation survey meters to detect and identify any radiation sources that might be present and to estimate radiation dose levels. The survey has resulted in detection of 16 sealed sources of (90)Sr and one of (226)Ra in aircraft scrap. Of course, (90)Sr sources are used in military aircraft as temperature sensors while (226)Ra is used for indicating fuel levels. These sources were found intact without spreading radioactivity contamination; however, none was detected in heavy machine scrap. The levels of radiation dose measured at 0.1m from the source fall within the range of 25.1-40.2 μSv/h with an average value of 33.52 ± 4.06 μSv/h. These orphan sources have been separated from the scrap, tested for possible leakage, conditioned and stored in waste management facility. The result of this study has revealed without doubt that the scrap constitute a serious source of public exposure and highlights the importance of legislation making radiation monitoring of scrap in the country mandatory before it is sold to metal industry for reprocessing. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Y-12 old salvage yard scrap metal characterization study

    International Nuclear Information System (INIS)

    Anderson, L.M.; Melton, S.G.; Shaw, S.S.

    1993-11-01

    The purpose of the Y-12 Old Salvage Yard scrap metal Characterization Study is to make conservative estimates of the quantities of total uranium and the wt % 235 U contained in scrap metal. The original project scope included estimates of thorium, but due to the insignificant quantities found in the yards, thorium was excluded from further analysis. Metal in three of the four Y-12 scrap metal yards were characterized. The scrap metal yard east of the PIDAS fence is managed by the Environmental Restoration Program and therefore was not included in this study. For all Y-12 Plant scrap metal shipments, Waste Transportation, Storage, and Disposal (WTSD) personnel must complete a Request for Authorization to Ship Nuclear Materials, UCN-16409, which requires the grams of total uranium, the wt % 235 U, and the grams of 235 U contained in the shipment. This information is necessary to ensure compliance with Department of Transportation regulations, as well as to ensure that the receiving facility is adhering to its operating license. This characterization study was designed to provide a technical basis for determining these necessary radioactive quantities

  12. Recovery of gold from electronic scrap by hydrometallurgical processes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Churl Kyoung; Rhee, Kang-In [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of); Sohn, Hun Joon [Seoul National University, Seoul (Korea, Republic of)

    1997-09-30

    A series of processes has been developed to recover the gold from electronic scrap containing about 200{approx}600 ppm Au. First, mechanical beneficiation including shredding, crushing and screening was employed. Results showed that 99 percent of gold component leaves in the fraction of under 1 mm of crushed scrap and its concentration was enriched to about 800 ppm without incineration. The crushed scrap was leached in 50% aqua regia solution and gold was completely dissolved at 60 deg. C within 2 hours. Other valuable metals such as silver, copper, nickel and iron were also dissolved. The resulting solution was boiled to remove nitrous compounds in the leachate. Finally, a newly designed electrolyzer was tested to recover the gold metal. More than 99% of gold and silver were recovered within an hour by electrowinning process. (author). 10 refs., 5 tabs., 6 figs.

  13. German experience in recycling of contaminated scrap by melting

    International Nuclear Information System (INIS)

    Quade, U.

    2003-01-01

    Recycling of radioactively contaminated scrap to products for further application in the nuclear cycle is Germany as an economic alternative. It has been shown that recycling within the nuclear industry reduces the collective dose as well as the number of individuals who receive doses. In the future when decommissioning of NPP will increase, a high amount of slightly radioactive steel scrap has to be managed safely. Recycling will play an important role to keep as much of these materials within the nuclear cycle as economically possible. Siempelkamp supplies a broad range of products made of recycled material from the nuclear industry. Containers made of nodular cast iron for transport and storage of radwaste as well as containers made of concrete with iron granules additive to increase the density up to 4 g/cm 3 , are offered. Interim and final disposal volume, having consequences on costs, can be reduced when recycling is applied for slightly contaminated metallic scrap

  14. Cold compaction behavior of nano-structured Nd-Fe-B alloy powders prepared by different processes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoya [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Hu, Lianxi, E-mail: hulx@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Erde [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2013-02-25

    Graphical abstract: Relative density enhancement and nanocrystallization of Nd{sub 2}Fe{sub 14}B phase are two major effective means to improve magnetic properties. Since the matrix Nd{sub 2}Fe{sub 14}B phase in the starting Nd-Fe-B alloy can be disproportionated into a nano-structured mixture of NdH{sub 2.7}, Fe{sub 2}B, and {alpha}-Fe phases during mechanical milling in hydrogen. It is thus important to study the densification behavior of nanocrystalline powders to evaluate and predict the cold compactibility of powders. By comparison with the as milled as well as melt-spun Nd{sub 16}Fe{sub 76}B{sub 8} alloy powders, we find that the as-disproportionated Nd{sub 16}Fe{sub 76}B{sub 8} alloy powder exhibits the best cold compactibility. As evident from the illustration presented below, compaction parameters (representing the powder compactibility) have been determined by fitting density-pressure data with double logarithm compaction equation. Densification mechanisms involved during cold compaction process are clarified in our work by referring to microstructure observation of samples prepared by various methods. As a result, highly densified green magnet compact can be obtained by cold pressing of as-disproportionated NdFeB alloy powders. Highlights: Black-Right-Pointing-Pointer Nano-structured disproportionated Nd-Fe-B alloy powders by mechanical milling in hydrogen. Black-Right-Pointing-Pointer Highly densified green magnet compact by cold pressing of as-disproportionated Nd-Fe-B alloy powders. Black-Right-Pointing-Pointer Density-pressure data fitted well by an empirical powder compaction model. Black-Right-Pointing-Pointer As-disproportionated powder showed better compactibility than as milled and melt-spun counterparts. Black-Right-Pointing-Pointer The effects of physical properties on powder compactibility and densification mechanisms are clarified. - Abstract: The compaction behavior of nano-structured Nd{sub 16}Fe{sub 76}B{sub 8} (atomic ratio) alloy

  15. Impact on Sensex of Scrapping Double Taxation of Dividends

    OpenAIRE

    Ragunathan V; Varma, Jayanth R.

    1997-01-01

    The taxation of dividends has generated an active debate in recent months in the media. While the industry representatives have been critical of the double taxation of dividends, the Government seems to be questioning the very premise that dividends are double taxed in India. The argument that scrapping the double taxation of dividends will give the Sensex a much needed boost seems to have tilted the scales. What will be the impact of scrapping of dividend tax on Sensex? One finds that the st...

  16. Advanced technologies for decontamination and conversion of scrap metal

    International Nuclear Information System (INIS)

    Muth, T.R.; Shasteen, K.E.; Liby, A.L.

    1995-01-01

    The Department of Energy (DOE) accumulated large quantities of radioactive scrap metal (RSM) through historic maintenance activities. The Decontamination and Decommissioning (D ampersand D) of major sites formerly engaged in production of nuclear materials and manufacture of nuclear weapons will generate additional quantities of RSM, as much as 3 million tons of such metal according to a recent study. The recycling of RSM is quickly becoming appreciated as a key strategy in DOE's cleanup of contaminated sites and facilities. The work described here has focused on recycle of the concentrated and high-value contaminated scrap metal resource that will arise from cleanup of DOE's gaseous diffusion plants

  17. The melting treatment of bulk scrap from decommissioning

    International Nuclear Information System (INIS)

    Deng Junxian; Deng Feng

    2014-01-01

    Large amount of radioactive scrap will come out from reactor decommissioning. The melting treatment can be used for the volume reduction, the recycle and reuse of the radioactive scrap to reduce the mass of the radioactive waste disposal and to reuse most of the metal. The melting treatment has the advantages in volume reduction, conditioning, radionuclide confinement, reduction of radioactivity concentration, easy monitoring of radioactivity; and the effective of decontamination for several radionuclide. Therefore to use the melting technology other decontamination technology should be performed ahead, the decontamination effect of the melting should be predicted, the utility of recycle and reuse should be defined, and the secondary waste should be controlled effectively. (authors)

  18. Advanced technologies for decontamination and conversion of scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Muth, T.R.; Shasteen, K.E.; Liby, A.L. [Manufacturing Sciences Corp., Oak Ridge, TN (United States)] [and others

    1995-10-01

    The Department of Energy (DOE) accumulated large quantities of radioactive scrap metal (RSM) through historic maintenance activities. The Decontamination and Decommissioning (D&D) of major sites formerly engaged in production of nuclear materials and manufacture of nuclear weapons will generate additional quantities of RSM, as much as 3 million tons of such metal according to a recent study. The recycling of RSM is quickly becoming appreciated as a key strategy in DOE`s cleanup of contaminated sites and facilities. The work described here has focused on recycle of the concentrated and high-value contaminated scrap metal resource that will arise from cleanup of DOE`s gaseous diffusion plants.

  19. 41 CFR 109-27.5107 - Recovery of silver from used hypo solution and scrap film.

    Science.gov (United States)

    2010-07-01

    ... used hypo solution and scrap film. 109-27.5107 Section 109-27.5107 Public Contracts and Property... § 109-27.5107 Recovery of silver from used hypo solution and scrap film. The requirements for the recovery of silver from used hypo solution and scrap film are contained in § 109-45.1003 of this chapter. ...

  20. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    International Nuclear Information System (INIS)

    Ma, Y.L.; Liu, X.B.; Nguyen, V.V.; Poudyal, N.; Yue, M.; Liu, J.P.

    2016-01-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd 2 Fe 14 B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH) max of 10 MGOe was obtained at NdFeB content of 50 wt%.

  1. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.L. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); College of Metallurgical and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Liu, X.B.; Nguyen, V.V.; Poudyal, N. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Yue, M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, J.P., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2016-08-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd{sub 2}Fe{sub 14}B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH){sub max} of 10 MGOe was obtained at NdFeB content of 50 wt%.

  2. Optimally segmented magnetic structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bahl, Christian; Bjørk, Rasmus

    We present a semi-analytical algorithm for magnet design problems, which calculates the optimal way to subdivide a given design region into uniformly magnetized segments.The availability of powerful rare-earth magnetic materials such as Nd-Fe-B has broadened the range of applications of permanent...... is not available.We will illustrate the results for magnet design problems from different areas, such as electric motors/generators (as the example in the picture), beam focusing for particle accelerators and magnetic refrigeration devices.......We present a semi-analytical algorithm for magnet design problems, which calculates the optimal way to subdivide a given design region into uniformly magnetized segments.The availability of powerful rare-earth magnetic materials such as Nd-Fe-B has broadened the range of applications of permanent...... magnets[1][2]. However, the powerful rare-earth magnets are generally expensive, so both the scientific and industrial communities have devoted a lot of effort into developing suitable design methods. Even so, many magnet optimization algorithms either are based on heuristic approaches[3...

  3. Magnetic properties and thermal stability of MnBi/NdFeB hybrid bonded magnets

    International Nuclear Information System (INIS)

    Cao, S.; Yue, M.; Yang, Y. X.; Zhang, D. T.; Liu, W. Q.; Zhang, J. X.; Guo, Z. H.; Li, W.

    2011-01-01

    Magnetic properties and thermal stability were investigated for the MnBi/NdFeB (MnBi = 0, 20, 40, 60, 80, and 100 wt.%) bonded hybrid magnets prepared by spark plasma sintering (SPS) technique. Effect of MnBi content on the magnetic properties of the hybrid magnets was studied. With increasing MnBi content, the coercivity of the MnBi/NdFeB hybrid magnets increases rapidly, while the remanence and maximum energy product drops simultaneously. Thermal stability measurement on MnBi magnet, NdFeB magnet, and the hybrid magnet with 20 wt.% MnBi indicates that both the NdFeB magnet and the MnBi/NdFeB hybrid magnet have a negative temperature coefficient of coercivity, while the MnBi magnet has a positive one. The (BH) max of the MnBi/NdFeB magnet (MnBi = 20 wt.%) is 5.71 MGOe at 423 K, which is much higher than 3.67 MGOe of the NdFeB magnet, indicating a remarkable improvement of thermal stability.

  4. Dysprosium-free melt-spun permanent magnets

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 Nd 2 Fe 14 B 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. (paper)

  5. 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.

  6. Mechanical design and fabrication of pure-permanent magnet undulator

    International Nuclear Information System (INIS)

    Chouksey, Sanjay; Vinit Kumar; Abhay Kumar; Krishnagopal, Srinivas

    2003-01-01

    A 50 mm period, 2.5 m long (50 periods), pure permanent magnet, variable gap undulator using NdFeB magnets is being built in two sections, each 1.25 m long. We present details of the mechanical design, fabrication experience, assembly and inspection of the undulator. (author)

  7. PRODUCTION OF ELECTROTECHNICAL WIRE OF SCRAP AND COPPER WASTES

    Directory of Open Access Journals (Sweden)

    I. P. Volchok

    2006-01-01

    Full Text Available Chemical composition, structure and properties of copper upon base steps of wire production technology (melting of anode copper with using of scrap and waste, electrolitical refining, producing of rod by continuous casting, manufacture of electrotechnical wire and fibres is described.

  8. Transboundary Movement of Radioactively Contaminated Scrap Metal - Lessons Learned

    Energy Technology Data Exchange (ETDEWEB)

    Nizamska, M., E-mail: m.nimzamska@bnra.bg [Emergency Planning and Preparedness Division, Bulgarian Nuclear Regulatory Agency, Sofia (Bulgaria)

    2011-07-15

    Starting in 1989, Bulgaria has undergone a comprehensive transformation of its economy and social conditions. Part of this process is related to the intensive privatization that started in 2001. This privatization included facilities, as well as sites that use radioactive material for different applications - industry, medicine, agriculture, science, etc. The rapid change of property ownership and, in some cases, the resulting bankruptcy, has caused difficulties in tracing and identifying radioactive sources and materials and a deterioration of the system of safety, physical protection, etc. of radioactive material. In some cases, radioactive sources were stolen because of the value of their protective containers and sold for scrap metal. This led to the occurrence of different types of radiation incidents, mainly related to the discovery of radioactive sources in scrap metal. The consequences of these incidents include the risk of radiation exposure of the workers at scrap metal yards or reprocessing facilities and of members of the public and, in addition, radioactive contamination of the environment. The Bulgarian Nuclear Regulatory Agency (BNRA) has been responding to these incidents and has carried out a series of measures to improve the control over materials (e.g. activated or surface contaminated materials) and radioactive sources and to strengthen the preventive, monitoring, emergency preparedness and mitigating measures at facility, national and transboundary levels. This paper presents an analysis of the lessons learned by the BNRA and of the control of the transboundary movement of radioactively contaminated scrap metal through the territory of Bulgaria. (author)

  9. Problems concerned with scrap metal monitoring at borders

    International Nuclear Information System (INIS)

    Duftschmid, K.E.

    1997-01-01

    Since the early 1980's numerous incidents have been reported in which radioactive material or empty labelled containers for radioactive sources have been found in scrap metal. Apart from the potential health hazard to employees and the general public resulting costs for decontamination, shutdown of production and waste of products already amounted to multi-million dollar figures. Since the opening of the ''iron border'' in Europe, incidents of illicit trafficking of radioactive sources across borders and contamination of scrap metal imported from the former ''Eastern Countries'' have considerably increased, as a result of the lack of a suitable radiation protection infrastructure in some of these countries. This initiated monitoring of scrap metal transports at the borders of several European countries, such as Austria, Finland, Germany and Italy. Up to now neither universally accepted clearance levels for scrap contamination, nor an agreed standardised procedure for its control exist, although the IAEA as well as the European Commission have proposed some recommendations. As a pragmatic solution for border monitoring it is suggested to apply, as practical clearance level, a dose rate on the outside of the vehicle in the order of 0,1 μSv/h, which is approximately equivalent to double natural environmental background. This dose rate would correspond to an activity concentration for 60 Co in the order of 1 kBq/kg and therefore be in a tolerable range, even in view of products coming in close contact with the public. (author)

  10. Primary Raw Materials for Steelmakers: Scrap and Pig Iron

    Directory of Open Access Journals (Sweden)

    Cristina Bumbac

    2011-10-01

    Full Text Available Most of the daily steel we so much need is obtained now in electric furnaces, for which the main raw material is scrap. The scrap market is a very sensitive one, depending very much on internal collect, exports and imports, the market of steel and freight. Commerce with scrap is one of the most intense among all the countries of the world and covers all the routes and regions. Every ten years or so importers become exporters and vice versa, due to the period of life of the metallic products. For example, China was for the last 10 years one of the biggest importers (after Turkey, which is number one in importers' hierarchy, but prognoses tell that in 2-3 years China might become self-sufficient due to the investments which began some 20 years ago. USA was one of the largest exporters, but some 3 years ago some analysts advanced the idea that it may become a net importer (it didn't happened, though. The scrap market is not only important, it is also very interesting, with twisted evolutions and volatile prices in some periods.

  11. Innovative technologies for recycling contaminated concrete and scrap metal

    International Nuclear Information System (INIS)

    Bossart, S.J.; Moore, J.

    1993-01-01

    Decontamination and decommissioning of US DOE's surplus facilities will generate enormous quantities of concrete and scrap metal. A solicitation was issued, seeking innovative technologies for recycling and reusing these materials. Eight proposals were selected for award. If successfully developed, these technologies will enable DOE to clean its facilities by 2019

  12. Assessment of recycling or disposal alternatives for radioactive scrap metal

    International Nuclear Information System (INIS)

    Murphie, W.E.; Lilly, M.J. III; Nieves, L.A.; Chen, S.Y.

    1993-01-01

    The US Department of Energy, Office of Environmental Restoration and Waste Management, Oak Ridge Programs Division, is participating with the Organization for Economic Cooperation and Development in providing analytical support for evaluation of management alternatives for radioactive scrap metals. For this purpose, Argonne National Laboratory is assessing environmental and societal implications of recycling and/or disposal process alternatives. This effort includes development of inventory estimates for contaminated metals; investigation of scrap metal market structure, processes, and trends; assessment of radiological and nonradiological effects of recycling; and investigation of social and political factors that are likely to either facilitate or constrain recycling opportunities. In addition, the option of scrap metal disposal is being assessed, especially with regard to the environmental and health impacts of replacing these metals if they are withdrawn from use. This paper focuses on the radiological risk assessment and dose estimate sensitivity analysis. A open-quotes tieredclose quotes concept for release categories, with and without use restrictions, is being developed. Within the tiers, different release limits may be indicated for specific groupings of radionuclides. Depending on the spectrum of radionuclides that are present and the level of residual activity after decontamination and/or smelting, the scrap may be released for unrestricted public use or for specified public uses, or it may be recycled within the nuclear industry. The conservatism of baseline dose estimates is examined, and both more realistic parameter values and protective measures for workers are suggested

  13. Feasibility study of a portable smelter for scrap metals

    International Nuclear Information System (INIS)

    Cavendish, J.H.

    1976-06-01

    The use of a portable smelter to process uranium-contaminated scrap metals was studied. Objectives were to convert scrap metal located at many diverse sites into a form which would be suitable for unlicensed sale and reduce the problems associated with storing the scrap. The Foundry Design Company study indicated the portable smelter concept was feasible from an equipment and transportation standpoint. Capital costs for a 5-ton/hour (steel) nominal capacity unit were estimated to be $2,349,000. Technical evaluation indicates that all the common metals considered, i.e., iron, nickel, copper, and aluminum, are amenable to uranium decontamination by smelting except aluminum. An economic evaluation of the processing of the 30,000 tons of steel scrap to be generated by the Cascade Improvement Program by a portable smelter was made based upon information supplied by Foundry Design Company, plus the assumption that the product metal could be sold for $120.00 per ton. This evaluation indicated a net return of $2,424,000 to the government could be realized. The Health and Safety study indicated no major problems of this nature would be encountered in operating a portable smelter. The legal review indicated the proposed operation fell within the authority of existing regulations. Consideration of possible conflicts with regard to competition with the private sector was suggested

  14. Effect of pretreating technologies on the adhesive strength and anticorrosion property of Zn coated NdFeB specimens

    International Nuclear Information System (INIS)

    Zhang, Pengjie; Xu, Guangqing; Liu, Jiaqin; Yi, Xiaofei; Wu, Yucheng; Chen, JingWu

    2016-01-01

    Graphical abstract: Zn coated NdFeB specimens pretreated with different technologies possess different adhesive strengths and anticorrosion properties. And the combined technology of sandblasting and pickling (5 s) achieves the best comprehensive performance. - Highlights: • Zn coated NdFeB specimens are achieved with different pretreating technologies. • Combined technology possesses the highest adhesive strength. • Combined technology possesses excellent anticorrosion property. - Abstract: Zinc coated NdFeB specimens were prepared with different pretreating technologies, such as polishing, pickling (50 s), sandblasting and combined technology of sandblasting and pickling (5 s). Morphologies of the NdFeB substrates pretreated with different technologies were observed with a scanning electron microscope equipped with an energy dispersive spectrometer and an atomic force microscope. The tensile test was performed to measure the adhesive strength between Zn coating and NdFeB substrate. The self-corrosion behavior of the NdFeB specimen was characterized by potentiodynamic polarization curve. The anticorrosion properties of Zn coated NdFeB specimens were characterized by neutral salt spray tests. The pretreating technologies possess obvious impact on the adhesive strength and anticorrosion property of Zn coated NdFeB specimens. Combined pretreating technology of sandblasting and pickling (5 s) achieves the highest adhesive strength (25.56 MPa) and excellent anticorrosion property (average corrosion current density of 21 μA/cm 2 ) in the four pretreating technologies. The impacting mechanisms of the pretreating technology on the adhesive strength and anticorrosion properties are deeply discussed.

  15. Results of chemical decontamination of DOE`s uranium-enrichment scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Levesque, R.G.

    1997-02-01

    The CORPEX{reg_sign} Nuclear Decontamination Processes were used to decontaminate representative scrap metal specimens obtained from the existing scrap metal piles located at the Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS), Piketon, Ohio. In September 1995, under contract to Lockheed Martin Energy Systems, MELE Associates, Inc. performed the on-site decontamination demonstration. The decontamination demonstration proved that significant amounts of the existing DOE scrap metal can be decontaminated to levels where the scrap metal could be economically released by DOE for beneficial reuse. This simple and environmentally friendly process can be used as an alternative, or in addition to, smelting radiologically contaminated scrap metal.

  16. Evaluation of workability and strength of green concrete using waste steel scrap

    Science.gov (United States)

    Neeraja, D.; Arshad, Shaik Mohammed; Nawaz Nadaf, Alisha K.; Reddy, Mani Kumar

    2017-11-01

    This project works on the study of workability and mechanical properties of concrete using waste steel scrap from the lathe industry. Lathe industries produce waste steel scrap from the lathe machines. In this study, an attempt is made to use this waste in concrete, as accumulation of waste steel scrap cause disposal problem. Tests like compressive test, split tensile test, NDT test (UPV test) were conducted to determine the impact of steel scrap in concrete. The percentages of steel scrap considered in the study were 0%, 0.5%, 1%, 1.5%, and 2% respectively by volume of concrete, 7 day, 28 days test were conducted to find out strength of steel scrap concrete. It is observed that split tensile strength of steel scrap concrete is increased slightly. Split tensile strength of Steel scrap concrete is found to be maximum with volume fraction of 2.0% steel scrap. The steel scrap gives good result in split tensile strength of concrete. From the study concluded that steel scrap can be used in concrete to reduce brittleness of concrete to some extent.

  17. The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)

    2011-05-15

    The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.

  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. © 2013.

  19. Influence of cooling rate on microstructure of NdFeB strip casting flakes

    Energy Technology Data Exchange (ETDEWEB)

    Binglin Guo; Bo Li; Dongling Wang; Xiaojun Yu [Central Iron and Steel Research Inst., Beijing, BJ (China); Jifan Hu [Shandong Univ., Jinan (China)

    2005-07-01

    In this paper, flakes of NdFeB cast alloys were prepared by using the strip casting technique. Microstructure and composition of phases in NdFeB SC flakes were studied by SEM and energy spectra. Especially, the influences of cooling rate on the microstructure of SC flakes were discussed, helping us to master strip casting technology. The results show that the cooling rate plays an important role in obtaining the perfect microstructure of SC flakes, which thickness is supposed not less than 0.32mm in these studies. (orig.)

  20. Magnetizing of permanent magnet using HTS bulk magnet

    International Nuclear Information System (INIS)

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

    2011-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole containing 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 magnetic plates inversely with various overlap distances between the tracks of the HTS 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. (author)