Top PDF 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

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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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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Production method for making rare earth compounds

Production method for making rare earth compounds

A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.
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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 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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Fuzzy PI Position Control Method for Permanent Magnet Synchronous

Fuzzy PI Position Control Method for Permanent Magnet Synchronous

The application of fuzzy PI λ control in permanent magnet synchronous motor servo system is studied. The disadvantages of traditional PID control and the disadvantages of variable parameters, non -linearity, time delay and time variation of servo system are overcome by using the characteristics of fuzzy control such as non-linearity, variable structure, self-adaptation, self-tuning and strong robustness. Fuzzy parameter self-tuning fractional-order PI controller, simulation results show that the control effect is better than th e traditional PID control, and the desired system control effect can be obtained. After adding feed -forward compensation, the response speed is accelerated, the overshoot is small, and the parameters of the PID controller can be adjusted online and real-time according to the changes of the controlled object, which can reduce the system error; moreover, the system has strong robustness and is not susceptible to external interference and changes in system parameters. It can be seen that for AC servo system wi th non-linearity and time-varying parameters, the compound position control with fuzzy PI λ and feed-forward compensation can meet the requirements of system control and improve the dynamic and static characteristics of the system.
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A New Hunting Control Method for Permanent Magnet Hysteresis Motors

A New Hunting Control Method for Permanent Magnet Hysteresis Motors

Abstract: Hunting is a flutter associated with the synchronous speed that gives rise to the gyro drifting errors and may cause objectionable time-displacement errors in video head wheel drives and other precision scanning systems. In this paper, dynamic characteristics of permanent Magnet hysteresis motors are presented and hunting is explained. New damping techniques have been developed using optimized eigenvalues calculation. They are calculated from LQR optimization method. In this damping method, a distinct reduction in hunting has been archived. Furthermore field oriented control result of motor is presented that have good effect on Hunting. Nearest agreement between simulated and measurement results shows the accuracy of motor model. Comparison between this paper results and other measured damping methods result are shown its success.
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Toxicity evaluation of boron nitride nanospheres and water-soluble boron nitride in <em>Caenorhabditis elegans</em>

Toxicity evaluation of boron nitride nanospheres and water-soluble boron nitride in <em>Caenorhabditis elegans</em>

and SOD3) and MAPK-signaling genes (MEK1 and PMK1) required for oxidative stress responses in L4 larvae exposed to BNNSs or BN-800-2 (500 µ g ⋅ mL - 1 ).. Previous studies have.[r]

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NOVEL METHODS FOR PERMANENT MAGNET DEMAGNETIZATION DETECTION IN PERMANENT MAGNET SYNCHRONOUS MACHINES

NOVEL METHODS FOR PERMANENT MAGNET DEMAGNETIZATION DETECTION IN PERMANENT MAGNET SYNCHRONOUS MACHINES

This chapter proposes an online PM demagnetization fault detection method based on the analysis of PMSM output torque ripple. Firstly, a torque ripple based rotor flux linkage detection model considering electromagnetic noises is proposed using continuous wavelet transforms (CWT) approach. It can extract the torque ripple ridge value from the de-noised torque ripple measurements caused by the inherent vibrations of the PMSMs. This method can reveal the torque ripple variation and eliminate the effect of VSI error. Secondly, Grey System Theory (GST) is employed to facilitate the detection of demagnetization ratios and torque ripple energy pulsations caused by demagnetization. It can yield a feedback value to the current loop in the drive system. Thirdly, a current regulation strategy is proposed to minimize the torque ripples induced by PM demagnetization, which contributes to making the proposed approach feasible in interior PMSMs. The proposed approach is experimentally verified on a down-scaled laboratory interior PMSM rated at 4.25 kW designed for EV. The result shows that the proposed real-time demagnetization diagnosis approach can identify the demagnetization fault under different operating conditions. Moreover, the proposed current regulation is validated to be able to minimize the torque ripple under demagnetization.
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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

These phases in magnet microstructure have different corrosion potentials that lead a poor corrosion resistance [6]. It is possible to improve the corrosion resistance by adding alloying elements such as Co, Nb, V, Mo, Cu and Ga in the magnet [7] or applying coatings. The most common protective coatings are the metallic, conversion (phosphatized as a temporary protection) and organic (paint) layers [8].

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Boron nitride nanotubes: synthesis and applications

Boron nitride nanotubes: synthesis and applications

Boron nitride nanotube (BNNT) has similar tubular nanostructure as carbon nanotube (CNT) in which boron and nitrogen atoms arranged in a hexagonal network. Owing to the unique atomic structure, BNNT has numerous excellent intrinsic properties such as superior mechanical strength , high thermal conductivity, electrically insulating behavior, piezoelectric property, neutron shielding capability, and oxidation resistance. Since BNNT was first synthe- sized in 1995, developing efficient BNNT production route has been a significant issue due to low yield and poor qual- ity in comparison with CNT, thus limiting its practical uses. However, many great successes in BNNT synthesis have been achieved in recent years, enabling access to this material and paving the way for the development of promising applications. In this article, we discussed current progress in the production of boron nitride nanotube, focusing on the most common and effective methods that have been well established so far. In addition, we presented various applications of BNNT including polymer composite reinforcement, thermal management packages, piezo actuators, and neutron shielding nanomaterial.
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Preparations of rare earth iron alloys by thermite reduction

Preparations of rare earth iron alloys by thermite reduction

conditions, to a temperature suf?cient to react the rare An improved method for the preparation of high earth and iron ?uoride mixture with the calcium to form purity rare earth-iron all[r]

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Axial field permanent magnet DC motor with powder iron armature

Axial field permanent magnet DC motor with powder iron armature

Ideally, 3-D FEA is needed to analyze such a machine, but it tends to be very time consuming—requiring thousands of hours to simulate a few seconds [13]. In this paper, 2-D FEA was, therefore, used to analyze the motors described. The use of 2-D FEA to analyze the axial-gap machines is well established [7], [10], [12], [13]. An equivalent linear model of the machine with a pole pitch equal to that measured at the average radius is usually used. The depth of the model is taken to be the active length of the machine, which usually equals the radial length of the magnet. Figs. 13 and Figs. 14 show such models for the powder iron and the lamination machines, respectively.
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Novel Unified Control Method of Induction and Permanent Magnet Synchronous Motors

Novel Unified Control Method of Induction and Permanent Magnet Synchronous Motors

Many control schemes have been proposed for induction motor and permanent magnet synchronous motor control, which are almost highly complex and non-linear. Also, a simple and efficient method for unified control of the electric moto are rarely investigated. In this paper, a novel control method based on rotor flux orientation is proposed. The novelties of proposed method are elimination of q-axis current loop (one controller is omitted) and utilization of a new dynamic current rate limiter. Also, unlike the conventional methods, the proposed control method could be applied on both induction motor and permanent magnet synchronous motor with only minor modifications. In addition to mentioned advantages, the torque ripple and current harmonic is reduced, too. Theoretical survey and simulation results clearly show the capability of proposed method for high and low speed applications in steady and transient states.
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Permanent Magnet DC Motor

Permanent Magnet DC Motor

The stator is the fixed part of the motor in which the rotor turns. The stator consists of permanent magnets aligned so that poles of opposite polarities face each other. Therefore, lines of magnetic field pass from one permanent magnet to the other through the metallic armature. The rotor is the rotating part of the motor. It consists of a wire loop mounted on a rotary metallic armature. The ends of the wire loop are connected to terminals on the dc motor, via a commutator and a pair of brushes (usually made of carbon). The commutator has two segments isolated from one another. Each segment is connected to one terminal of the wire loop.
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Permanent Magnet Generator pdf

Permanent Magnet Generator pdf

Each magnet rotor is built on a steel disk, 6mm thick. See diagram 32. Do not use aluminium or stainless steel for this disk! The disks have to be made of magnetic material. The disk has holes to mount it to the hub - in this manual the hub has four holes, each 10mm diameter, on a circle at 4 inches (102mm) PCD. If a different hub is chosen, then all the jigs and moulds must match this hub.

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Implementation and Analysis of Direct Torque Control for Permanent Magnet Synchronous Motor Using Gallium Nitride based Inverter

Implementation and Analysis of Direct Torque Control for Permanent Magnet Synchronous Motor Using Gallium Nitride based Inverter

Permanent magnet synchronous machines (PMSMs) attract considerable attention in various industrial applications, such as electric and hybrid electric vehicles, due to their high efficiency and high-power density. In this thesis, the mathematical model of PMSM and two popular control strategies, field-oriented control (FOC) and direct torque control (DTC), are analyzed and compared. The results demonstrated that the DTC has better dynamic response in comparison to FOC. Moreover, DTC can eliminate the use of position sensor, which will save the cost of the PMSM drive system. Therefore, this thesis focuses on the design and implementation of high-performance DTC for PMSMs with a Gallium Nitride (GaN) based high switching frequency motor drive.
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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

Magnetized rare-earth magnets of VACODYM and VACOMAX exhibit high field and exert strong, attractive forces on iron and other magnetic parts in their vicinity. Consequently, they must be handled with care to avoid damage. Owing to their strong magnetic forces there is a risk of injury when hand- ling larger magnets. They should always be manipulated individually or with the aid of jigs. We recommend protective gloves be worn as well as for handling of uncoated VACO- MAX and Ni-coated parts, especially for people with allergies to metals.

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Finite Element Model and Size Dependent Stability Analysis of Boron Nitride and Silicon Carbide Nanowires/Nanotubes

Finite Element Model and Size Dependent Stability Analysis of Boron Nitride and Silicon Carbide Nanowires/Nanotubes

The stability analysis of silicon carbide and boron nitride nanotubes and nanowires resting on an elastic substrate was carried out in the present study. To model the nanostructures, Euler-Bernoulli beam theory was employed. Since the analysis was done on a nano scale, dierent small-scale eective theories were used to take small-scale eect into consideration. Nonlo- cal elasticity theory, surface elasticity theory and its combination with the former theory, modied strain gradient theory, and modied couple stress theories were used and compared to investigate their inuence on the buckling results. In addition, nite element analysis was applied to nanostructures both by the con- tinuum model and computer software products. In g- ures, nonlocal elasticity theory is represented as NET, surface elasticity theory as SET, the combination of nonlocal elasticity theory and surface elasticity theory as NSET, modied strain gradient theory as MSGT, and modied couple stress theory as MCST. To obtain dimensionless analysis results, Winkler and Pasternak foundation parameters are used in the dimensionless form as K w = k w EI L 4 and K p = k p L
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Recycling of Rare Earth Magnet Waste by Removing Rare Earth Oxide with Molten Fluoride

Recycling of Rare Earth Magnet Waste by Removing Rare Earth Oxide with Molten Fluoride

fi ne, and neither suspension of alloy in the fl ux nor suspension of fl ux in the alloy was observed. Oxygen concentration of alloy decreased from 5000 to 160 mass-ppm by charging fl ux of 1.5 times of equivalent amount for complete dissolution of oxide. Substitution of neodymium in the alloy and dysprosium in the fl ux was observed. The investigated process should be utilized for mildly contaminated waste such as a used (end- of-life) magnet because of simple process, energy saving and unlimited location. [doi:10.2320 / matertrans.M-M2013836]

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