scholarly journals Magnetism and ε-τ Phase Transformation in MnAl-Based Nanocomposite Magnets

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 896
Author(s):  
Alina Daniela Crisan ◽  
Aurel Leca ◽  
Cristina Bartha ◽  
Ioan Dan ◽  
Ovidiu Crisan
Keyword(s):  
Phase Transformation ◽  
Permanent Magnets ◽  
Diffusion Processes ◽  
Magnetic Measurements ◽  
Low Cost ◽  
Antiphase Boundary ◽  
Rapid Quenching ◽  
Annealed Sample ◽  
Scanning Calorimetry ◽  
Ε Phase

Melt spun ribbons of Mn53Al45C2 and Mn52Al46C2 have been synthesized by rapid quenching of the melt with the purpose of monitoring the ε-τ phase transformation to show technologically feasible ways to increase magnetic parameters and to illustrate the viability of these alloys as the next generation of rare earth (RE)-free magnets. By differential scanning calorimetry (DSC), activation energies and temperatures of onset of the ε-τ phase transformation were obtained. Structural analysis was performed using X-ray diffraction (XRD) and the resulting XRD patterns were quantitatively assessed using full profile Rietveld-type analysis. Appropriate annealing was performed in order to enable the ε-τ phase transformation. While hcp ε-phase was found to be predominant in the as-cast samples, after appropriate annealing, the tetragonal τ-phase, the one that furnishes the relevant magnetic response, was found to be predominant with an abundance of about 90%. The data suggested a mechanism of hcp ε-phase decomposition controlled by the segregation towards the interfacial regions, having the rate of transformation governed by antiphase boundary diffusion processes. Magnetic measurements of annealed sample Mn53Al45C2, consisting of predominant tetragonal τ-phase, showed high values of magnetization and increased coercivity, consistent with an energy product of about 10 MGOe, similar with previously reported magnetization measurements, providing further insight into the realization of future class of RE-free low-cost permanent magnets.

scholarly journals Role of Disordered Precursor in L10 Phase Formation in FePt-Based Nanocomposite Magnet

2021 ◽  
Vol 7 (11) ◽  
pp. 149
Author(s):  
Alina Daniela Crisan ◽  
Ioan Dan ◽  
Ovidiu Crisan
Keyword(s):  
Permanent Magnets ◽  
Magnetic Measurements ◽  
Phase Evolution ◽  
Annealed Sample ◽  
X Ray Diffraction ◽  
Soft Magnetic ◽  
Spectra Analysis ◽  
Annealing Temperatures ◽  
Wide Range

In order to prove the usefulness of having a structurally disordered precursor to the formation of FePt L10 phase and to facilitate the co-existence of exchange coupled hard and soft magnetic phases with optimized magnetic properties in various conditions of annealing, a Fe-Pt-Zr-B melt spun alloy has been synthesized and detailed structural and magnetic investigations have been undertaken to probe its phase evolution during annealing. The dynamics of formation of the hard magnetic L10 phase during the gradual disorder–order phase transformation has been monitored by using a complex combination of X-ray diffraction methods and 57Fe Mössbauer spectroscopy methods, over a wide range of annealing temperatures. Multiple phases co-existing in the annealed sample microstructures, observed in XRD, have been reconfirmed by the Mössbauer spectra analysis and, moreover, accurate quantitative data have been acquired in what concerns the relative abundance of each of the observed crystalline phases in every stage of annealing. It is shown that the formation of the hard magnetic phase, emerging from the chemically disordered precursor, is gradual and occurs via complex mechanisms, involving the presence of a disordered Fe-Zr-B-rich intergranular region which contributes to an increase in the abundance of the L10 phase for higher annealing temperatures. Magnetic measurements have confirmed the good performances of these alloys in terms of coercivity and remanence. These results contribute to the development of these alloys as the next generation of rare earth, free permanent magnets.

Study and design of dual stator permanent magnet machine with spoke-type configurations using phase-group concentrated-coil windings

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1381-1389
Author(s):  
Dezhi Chen ◽  
Chengwu Diao ◽  
Zhiyu Feng ◽  
Shichong Zhang ◽  
Wenliang Zhao
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Low Cost ◽  
Dynamic Performance ◽  
Torque Ripple ◽  
Permanent Magnet Machine ◽  
Torque Density ◽  
Phase Group ◽  
High Torque ◽  
Simulation Results

In this paper, a novel dual-stator permanent magnet machine (DsPmSynM) with low cost and high torque density is designed. The winding part of the DsPmSynM adopts phase-group concentrated-coil windings, and the permanent magnets are arranged by spoke-type. Firstly, the winding structure reduces the amount of copper at the end of the winding. Secondly, the electromagnetic torque ripple of DsPmSynM is suppressed by reducing the cogging torque. Furthermore, the dynamic performance of DsPmSynM is studied. Finally, the experimental results are compared with the simulation results.

Characterization of a Polymeric Membrane for the Separation of Hydrogen in a Mixture with CO2

2016 ◽  
Vol 9 (1) ◽  
pp. 126-136 ◽  
Author(s):  
Dionisio H. Malagón-Romero ◽  
Alexander Ladino ◽  
Nataly Ortiz ◽  
Liliana P. Green
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Production ◽  
Test Performance ◽  
Low Cost ◽  
Time Lag ◽  
Polymeric Membrane ◽  
Biological Processes ◽  
Scanning Calorimetry ◽  
Environmentally Sustainable ◽  
Production Of Hydrogen

Hydrogen is expected to play an important role as a clean, reliable and renewable energy source. A key challenge is the production of hydrogen in an economically and environmentally sustainable way on an industrial scale. One promising method of hydrogen production is via biological processes using agricultural resources, where the hydrogen is found to be mixed with other gases, such as carbon dioxide. Thus, to separate hydrogen from the mixture, it is challenging to implement and evaluate a simple, low cost, reliable and efficient separation process. So, the aim of this work was to develop a polymeric membrane for hydrogen separation. The developed membranes were made of polysulfone via phase inversion by a controlled evaporation method with 5 wt % and 10 wt % of polysulfone resulting in thicknesses of 132 and 239 micrometers, respectively. Membrane characterization was performed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and ASTM D882 tensile test. Performance was characterized using a 23 factorial experiment using the time lag method, comparing the results with those from gas chromatography (GC). As a result, developed membranes exhibited dense microstructures, low values of RMS roughness, and glass transition temperatures of approximately 191.75 °C and 190.43 °C for the 5 wt % and 10 wt % membranes, respectively. Performance results for the given membranes showed a hydrogen selectivity of 8.20 for an evaluated gas mixture 54% hydrogen and 46% carbon dioxide. According to selectivity achieved, H2 separation from carbon dioxide is feasible with possibilities of scalability. These results are important for consolidating hydrogen production from biological processes.

scholarly journals The Effect of Crystallization and Phase Transformation on the Mechanical and Electrochemical Corrosion Properties of Ni-P Coatings

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 447
Author(s):  
Martin Buchtík ◽  
Leoš Doskočil ◽  
Roman Brescher ◽  
Pavel Doležal ◽  
Jiří Másilko ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Crystallite Size ◽  
Electrochemical Corrosion ◽  
Az91 Magnesium Alloy ◽  
Scanning Calorimetry ◽  
Corrosion Properties ◽  
High Phosphorus ◽  
P Content ◽  
Az91 Magnesium ◽  
Increasing Temperature

This paper deals with the study of the crystallization and phase transformation of Ni-P coatings deposited on AZ91 magnesium alloy. Prepared samples were characterized in terms of surface morphology and elemental composition by means of scanning electron microscopy with energy-dispersive spectroscopy analysis. The results of X-ray diffraction analysis and differential scanning calorimetry suggested that increasing the phosphorus content caused Ni-P coatings to develop an amorphous character. The crystallization of Ni was observed at 150, 250, and 300 °C for low-, medium- and high-phosphorus coatings, respectively. The Ni crystallite size increased with increasing temperature and decreasing P content. Conversely, the presence of the Ni3P phase was observed at a maximum peak of 320 °C for the high-phosphorus coating, whereas the crystallization of the Ni3P phase shifted to higher temperatures with decreasing P content. The Ni3P crystallite size increased with increasing temperature and increasing P content. An increase in microhardness due to the arrangement of Ni atoms and Ni3P precipitation was observed. The deposition of as-deposited Ni-P coatings led to an improvement in the corrosion resistance of AZ91. However, the heat treatment of coatings resulted in a deterioration in corrosion properties due to the formation of microcracks.

Calculations of Phase Transformations in Welding Simulations

2014 ◽  
Vol 611 ◽  
pp. 46-53 ◽  
Author(s):  
Ladislav Novotný ◽  
Vladimír Ivančo
Keyword(s):  
Heat Flux ◽  
Phase Transformation ◽  
Boundary Conditions ◽  
Phase Transformations ◽  
Diffusion Processes ◽  
Transient Solution ◽  
Welding Simulation

In the paper the principle of welding simulation is presented and the methods of solution of phase transformation are described. The first part characterizes elementary equations of heat transient solution, boundary conditions during welding simulation (prescribing moving heat flux, convection, radiation). The methods of phase transformations’ solution are described for diffusion processes as well as diffusionless processes.

Faraday’s Law Low-Cost Experiment Without Permanent Magnets

2021 ◽  
Vol 59 (5) ◽  
pp. 345-347
Author(s):  
Daniel T. M. Fontes ◽  
André Machado Rodrigues
Keyword(s):  
Permanent Magnets ◽  
Low Cost ◽  
Faraday’S Law

Structure, Magnetic Properties and Hyperfine Parameters of Nd-Substituted Ni-Fe-Ga Heusler Alloys

MRS Advances ◽  
2017 ◽  
Vol 2 (25) ◽  
pp. 1341-1346
Author(s):  
Monica Sorescu ◽  
Felicia Tolea ◽  
Mihaela Valeanu ◽  
Mihaela Sofronie
Keyword(s):  
Melt Spinning ◽  
Magnetic Measurements ◽  
Heusler Alloys ◽  
Hyperfine Magnetic Field ◽  
Rapid Quenching ◽  
Linear Least Squares ◽  
X Ray Diffraction ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Field Distributions

ABSTRACTSamples of Ni57-xNdxFe18Ga25 with x=2 and 4 were prepared in ribbon form by rapid quenching via melt spinning route. The samples were analyzed by X-ray diffraction (XRD), magnetic measurements and Mössbauer spectroscopy, both in the as-quenched form and after thermal annealing at 900 oC for 2 min and 400 °C for 2 hours. For x=2 the Nd atoms are completely dissolved in the Ni-Fe-Ga matrix, while for x=4 the additional occurrence of the secondary 2:17 phase could be resolved. These findings were supported by the analysis of hyperfine magnetic field distributions obtained from the non-linear least-squares fitting of the Mössbauer spectra.

scholarly journals 3D Printing of Functional Assemblies with Integrated Polymer-Bonded Magnets Demonstrated with a Prototype of a Rotary Blood Pump

2018 ◽  
Vol 8 (8) ◽  
pp. 1275 ◽  
Author(s):  
Kai von Petersdorff-Campen ◽  
Yannick Hauswirth ◽  
Julia Carpenter ◽  
Andreas Hagmann ◽  
Stefan Boës ◽  
...  
Keyword(s):  
Fused Deposition Modeling ◽  
Permanent Magnets ◽  
Low Cost ◽  
Magnetic Bearing ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Pump Impeller ◽  
Fused Deposition ◽  
Magnetic Components ◽  
Deposition Modeling

Conventional magnet manufacturing is a significant bottleneck in the development processes of products that use magnets, because every design adaption requires production steps with long lead times. Additive manufacturing of magnetic components delivers the opportunity to shift to agile and test-driven development in early prototyping stages, as well as new possibilities for complex designs. In an effort to simplify integration of magnetic components, the current work presents a method to directly print polymer-bonded hard magnets of arbitrary shape into thermoplastic parts by fused deposition modeling. This method was applied to an early prototype design of a rotary blood pump with magnetic bearing and magnetic drive coupling. Thermoplastics were compounded with 56 vol.% isotropic NdFeB powder to manufacture printable filament. With a powder loading of 56 vol.%, remanences of 350 mT and adequate mechanical flexibility for robust processability were achieved. This compound allowed us to print a prototype of a turbodynamic pump with integrated magnets in the impeller and housing in one piece on a low-cost, end-user 3D printer. Then, the magnetic components in the printed pump were fully magnetized in a pulsed Bitter coil. The pump impeller is driven by magnetic coupling to non-printed permanent magnets rotated by a brushless DC motor, resulting in a flow rate of 3 L/min at 1000 rpm. For the first time, an application of combined multi-material and magnet printing by fused deposition modeling was shown. The presented process significantly simplifies the prototyping of products that use magnets, such as rotary blood pumps, and opens the door for more complex and innovative designs. It will also help postpone the shift to conventional manufacturing methods to later phases of the development process.

scholarly journals Effect of Pristine Palygorskite Powders on Explosion Characteristics of Methane-Air Premixed Gas

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2496 ◽  
Author(s):  
Yimin Zhang ◽  
Yan Wang ◽  
Ligang Zheng ◽  
Tao Yang ◽  
Jianliang Gao ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Low Cost ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Flame Propagation Velocity ◽  
Explosion Pressure ◽  
Pyrolysis Characteristics ◽  
Explosion Suppression ◽  
Adsorption Desorption ◽  
Methane Explosion

In this study, pristine palygorskite powders were used as the inhibition materials to suppress the explosion of methane-air premixed gas for the first time. The composition, porosity and pyrolysis characteristics of the powders were tested by X-ray diffraction (XRD), energy dispersive spectrometry (EDS), N2 adsorption-desorption and Thermogravimetry-differential scanning calorimetry (TG-DSC) techniques. The effects of pristine palygorskite powders concentration on the explosion pressure and the average velocity of flame propagation of the 9.5% methane-air premixed gas were tested by a 20 L spherical explosion system and a 5 L pipeline explosion system. The results indicated the pristine palygorskite powders possess a considerable suppression property on methane explosion. When the mass concentration of pristine palygorskite powders was 0.20 g·L−1, the max-pressure of methane explosion was decreased by 23.9%. The methane explosion flame propagation velocity was inhibited obviously. Owing to the excellent inhibitory performance and the advantage of low-cost and environmental harmlessness, pristine palygorskite powders are potential new materials for the application on gas explosion suppression.

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