Top PDF Method of making bonded or sintered permanent magnets

Method of making bonded or sintered permanent magnets

Method of making bonded or sintered permanent magnets

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.
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Method of making bonded or sintered permanent magnets

Method of making bonded or sintered permanent magnets

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.
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Method of making permanent magnets

Method of making permanent magnets

A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties.
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Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets

Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets

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 dogbone 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.
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Micromagnetic Simulations of Magnetization Reversals in Nd Fe B Based Permanent Magnets

Micromagnetic Simulations of Magnetization Reversals in Nd Fe B Based Permanent Magnets

Considering the grain size range of Nd-Fe-B magnets, ~250 nm for HDDR processed magnets and hot-deformed magnets to ~5 µm for Nd-Fe-B sintered magnets, realistic mi- cromagnetic simulation of Nd-Fe-B magnets needs computa- tion of large scaled models. This is the current challenge for conventional micromagnetic simulations to simulate large grained materials. Hence, development of a new algorithm that can speed up the calculation time is necessary enabling us to simulate large scaled models. Recently, Exl et al. has introduced a steepest decent energy minimization method for micromagnetics to simulate quasistatic hysteresis loops 45) .
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Improvement of Corrosion Resistance and Magnetic Properties of NdFeB Sintered Magnets with Cu and Zr Co-Added

Improvement of Corrosion Resistance and Magnetic Properties of NdFeB Sintered Magnets with Cu and Zr Co-Added

crystals were much stronger as compared with that of the (410) crystal face (See Fig. 3 (a), (b) and (c)).It demonstrates that a strong (00l) texture is formed in the NdFeB sintered magnets. Similar results were also observed in the sintered magnets with other intergranular addition [15,16]. To illustrate the intensity of the (00l) texture of the Nd 2 Fe 14 B crystals in the NdFeB sintered magnets, the pole density

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Mechanical Properties Of Mullite-Bonded Silicon Carbide Sintered At Various Heating Temperature

Mechanical Properties Of Mullite-Bonded Silicon Carbide Sintered At Various Heating Temperature

3.2 3.3 Fabrication of mullite-bonded porous silicon carbide 3.2.1 Raw material aggregate 3.2.2 Dry milling 3.2.3 Powder preparation with binder 3.2.4 Green Compact Preparation 3.2.5 Sin[r]

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Mechanical Properties of Injection-Molded Nd-Fe-B Type Permanent Magnets

Mechanical Properties of Injection-Molded Nd-Fe-B Type Permanent Magnets

embedded in a Nylon matrix. The irregular plate shape Nd-Fe-B particles (Figure 2.4 (a)) were produced through the melt-spinning and grinding methods. This procedure creates thin plates of about 35 µm thickness. The size of the flakes varies significantly from as small as 10 µm to as large as 500 µm. The spherical particles (Figure 2.4 (b)) were produced with the atomization method. Their sizes vary as well, ranging from 5 µm to 50 µ m diameters. These two types of particles were injection molded at different volume percentages to create tensile and flexural specimens.
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A New Design of Permanent Magnets Reluctance Generator Andi Pawawoi, Syafii

A New Design of Permanent Magnets Reluctance Generator Andi Pawawoi, Syafii

Previous studies, associated with the permanent magnet, showed that the permanent magnet can be used as an energy source. The energy conversions from permanent magnets have been done [1], which made Parendev Permanent Magnet Motor (PPMM). Accordance with its name, this engine produces mechanical rotation energy derived from permanent magnet energy of motor that build it. Several other researchers also have made a permanent magnet motor with a different design from the motor Varendev.

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Optimization of the magnetic properties of nanostructured Y Co Fe alloys for permanent magnets

Optimization of the magnetic properties of nanostructured Y Co Fe alloys for permanent magnets

≤ 0.5 ) were investigated. The magnetization increases with Fe-doping up to the solid solubility limit, x = 0.3 without destroying the crystal structure or degrad- ing the coercivity. A special magnet array is designed using ring magnets for pressing the powders under magnetic field in order to achieve magnetic align- ment. A dramatic increase in magnetization is observed for magnetically aligned YCo 4.8 Fe 0.2 pressed ingots. C 2016 Author(s). All article content, except where

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Discussion About the Analytical Calculation of the Magnetic Field Created by Permanent Magnets

Discussion About the Analytical Calculation of the Magnetic Field Created by Permanent Magnets

speaking, these two configurations are different when we look at their magnetic components. We can see that by comparing their magnetic components with the help of the component switch theorem (even if this theorem cannot be used). For this purpose, we represent in Figs. 6 and 7, the radial component of the magnetic field created by a ring axially magnetized and the axial component of the magnetic field created by a ring permanent magnet radially magnetized. We see that these two components seem to verify the component switch theorem. However we will see that it is not strictly the case. We can also compare the axial component created by a ring permanent magnet axially magnetized and the radial component of the magnetic field created by a ring permanent magnet radially magnetized. These two components are represented in Figs. 8 and 9.
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Permanent Rare Earth Magnets—The Need to Protect Them against Corrosion

Permanent Rare Earth Magnets—The Need to Protect Them against Corrosion

One of the main industrial applications of rare-earth metals (RE) is the perma- nent magnets production. Nowadays, permanent magnets are used in wind power, electronics, electric vehicles and other fields. China is the world’s largest supplier of RE products and the international market leader. China has always strictly controlled exports of RE and, in 2012, had imposed a restriction of RE How to cite this paper: dos Santos, C.A.L.

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Performance Evaluation of a Permanent Magnet-Assisted Synchronous Reluctance Machine with Hybrid Magnets of Ferrite Magnets and Rare-earth PMs

Performance Evaluation of a Permanent Magnet-Assisted Synchronous Reluctance Machine with Hybrid Magnets of Ferrite Magnets and Rare-earth PMs

Some parameters including torque density, power density, PM material costs and the maximum efficiency are compared for PMASynRM with different magnet ratio, as shown in Table 2. It should be worth mentioning that all PMASynRMs have the same structure and excitations, and the only difference is magnet ratio. The proposed PMASynRM with rare-earth PMs has the highest torque density, power density and total cost, which is 1.46, 1.65, and 301 times of ferrite magnets, respectively. It indicated that potentially offer some desirable cost-performance trade-off. Therefore, if there is no limit to the machine volume, the total cost of PMASynRM can be reduced for obtaining the same output torque by using low-cost ferrite magnets. In addition, the high torque density can be obtained in the proposed PMASynRM when the multi-layer structure of rotor is adopted by using hybrid magnets. The proposed PMASynRM can be applied in aerospace, vehicle traction, industrial application, and energy power generation.
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Improving the Efficiency of Electrical High-rpm

 Generators with Permanent Magnets and Tooth Winding

Improving the Efficiency of Electrical High-rpm Generators with Permanent Magnets and Tooth Winding

In our work, we resolve the issue of minimization of the losses in the HSEMPM magnetic stator circuit by using amorphous iron, and develop two HSEMPM projects: an electric power generator of 100 kW and a rotor speed of 60,000 rpm and an electric power generator of 200 kW with a rotor speed of 45,000 rpm for use in distributed power generation plants. The HSEMPM stator magnetic circuit in both projects is made of amorphous iron according to our proposed technology, which allows making electrical machines with a power of more than 100 kW. This result is new and is not presented in publications. One of the main requirements to the electric machines that we create is the minimum axial length. To fulfill this requirement, the electrical machines are made with tooth winding. But the number of slots per pole and phase is not fractional, which allows, in contrast to the known works on HSEMPMs with tooth winding, to minimize the spatial MMF harmonics and, accordingly, the eddy current losses in permanent magnets due to these harmonics. The article provides the results of calculations of two HSEMPMs using FEMM methods. The HSEMPM parameters obtained are compared with the HSEMPM prototype with a distributed winding and the magnetic circuit of electrical steel made by us earlier. Upon the results of these comparisons, we conclude on the appropriateness of the solutions proposed for HSEMPM. The rotor of HSEMPM studied is made from a single cylindrical SmCo magnet. According to the research, we have created a prototype of the stator magnetic circuit of amorphous iron and experimentally measured the losses in it.
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Magnetic Domain Structure Analysis of Nd Fe B Sintered Magnets Using XMCD PEEM Technique

Magnetic Domain Structure Analysis of Nd Fe B Sintered Magnets Using XMCD PEEM Technique

common interpretation is based on the nucleation of reverse domains. According to this theory, the morphologies of the complementary phases and magnetic domain structures are important, because such phases become the nucleation sites of reverse domains or inhibiters of domain-wall propagation. The details of such behaviours and functions, therefore, should be understood more clearly to achieve a breakthrough in developing higher-coercivity magnets. In particular, if the relationship between those microstructures and domain structures is clarified, the guiding principle of microstructure control for higher-coercivity magnets will be suggested. Magnetic domain observation is one of the effective approaches to reveal such mechanisms of magnetic reversal in the submicron scale. In fact, there have been a variety of domain observations and analyses reported for Nd-Fe-B magnets. 21) For instance, an optical microscope utilizing the Kerr effect is the most prevalent method, 22–25) and is still
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Carbide/nitride grain refined rare earth iron boron permanent magnet and method of making

Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.
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Magnets for Sarcasm: Making Sarcasm Detection Timely, Contextual and Very Personal

Magnets for Sarcasm: Making Sarcasm Detection Timely, Contextual and Very Personal

We model the speaker at the time of utterance production using mood indicators de- rived from the most recent prior tweets, and model context using features derived from the proximate ca[r]

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Characteristics of an ECR Sheet-Shaped Plasma Formed by a Combination of Permanent Magnets and Field Coils

Characteristics of an ECR Sheet-Shaped Plasma Formed by a Combination of Permanent Magnets and Field Coils

the discharge chamber and injected a 2.45 GHz microwave power through a quartz glass window. Large current to maintain the magnetic field for long operations is not ideal. Morishita et al. [9] employed a set of permanent magnets to produce cusp field near the cathode. While a uniform sheet plasma in the length of 20 cm is produced, the field profile is limited by the fix flux density created by the per- manent magnets. Noguera and Ramos [10], and Ramos, et al. [11] employed a sheet plasma device with the magnetic field structure similar to the original Uramoto-type sheet to form TiN films for hard coatings. Impurity emissions from the plasma cathode often restrict usage of this type of device for any plasma process that forbids introduction of trace impurities.
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Mathematical Model of High-frequency Electromechanical Energy Transducer with High-coercitive Permanent Magnets

Mathematical Model of High-frequency Electromechanical Energy Transducer with High-coercitive Permanent Magnets

Abstract — A mathematical model of a high-frequency electromechanical energy transducer with high-coercitive permanent magnets in cylindrical coordinates is represented in the paper. It allows analyzing magnetic field in the electromechanical energy transducer air gap taking into account temperature fields and mechanical parameters which influence it. The investigations of the mathematical model are conducted and comparisons are found, and inconsistent of the field task solution in the cylindrical and rectangular coordinates is determined.
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RARE-EARTH PERMANENT MAGNETS VACODYM VACOMAX ADVANCED MATERIALS THE KEY TO PROGRESS

RARE-EARTH PERMANENT MAGNETS VACODYM VACOMAX ADVANCED MATERIALS THE KEY TO PROGRESS

No phase transitions occur between –40°C and the melting point of 232°C. The deposition process is optimized by VAC for RE magnets especially to preclude hydrogen damage to the surface of the magnet during coating positively. Small parts can be coated economically in a barrel. Larger parts are galvanized in a rack. The decision on which method to use is governed by the weight of the part and/or the geo- metry (typical nominal values: <25 g barrel; >25 g rack). The special merits of tin coatings are their high resistance to environmental influences (e.g. 85°C/85 % relative humidity) as generally specified for electronic applications. Tin is high- ly ductile and is almost free of internal stresses over a wide coating thickness range, moreover the process is highly reli- able. There is no risk of cracking or flaking. Mechanical stress does not lead to chipping but merely to deformation of the tin coating so that the magnetic material is still protec- ted safely.
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