scholarly journals Influence of electromagnetic effect parameters on ferromagnetic powders fluidity

2018 ◽  
Vol 226 ◽  
pp. 03002
Ivan N. Egorov ◽  
Nikolay Ya. Egorov

The paper presents result of experimental studies of ferromagnetic powders fluidity management by effecting on particulate medium with constant and alternating gradient magnetic fields. Induction lines of constant magnetic field are perpendicular to symmetry axis of powder hopper. Alternating field is created by electromagnet with one tapering pole and has higher induction gradient values near hopper outlet. These fields form magneto fluidized bed from powder in hopper allowing powders of barium and strontium hexaferrite to flow through the hopper outlet. Dependencies of efflux speed from parameters of electromagnetic fields are presented for barium hexaferrite powder with average particle size 1 μm and strontium hexaferrite powders with average particle sizes 1 and 9 μm.

2020 ◽  
Vol 989 ◽  
pp. 199-203
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Viktor P. Kryzhanovsky

The paper presents the results of experimental studies of strontium hexa-ferrite average particle size and structural characteristics changes during milling process. Coarse strontium hexaferrite was milled in beater mill, without and with electromagnetic effect. Electromagnetic effect was produced by constant and alternating gradient magnetic fields with mutually perpendicular induction lines. Particle sizes were measured by microscopic methods, and structural characteristics were calculated by processing of X-ray diffractograms. Diffraction studies showed that during milling process, both with and without electromagnetic effect, the most intensive changes of coherent scattering region (CSR) sizes, dislocation densities and relative deformation of particulate material occur at earlier stage of milling. At this stage the speed of average particle size decrease is maximal. At later stage both average particle size and structural characteristic changes correlate and have asymptotic character.

2018 ◽  
Vol 284 ◽  
pp. 158-162
I.N. Yegorov ◽  
Nikolay Ya. Egorov

The paper experimentally substantiates effectiveness of method of milling particulate ferromagnetic materials in magneto fluidized bed. Comparative results of particle size distributions and structural parameters of strontium hexaferrite SrFe12O19 powder obtained by milling coarse material in beater mill without electromagnetic effect and in same mill with formation of magneto fluidized bed from mill material are presented. The magneto fluidized bed is formed by constant and alternating gradient magnetic fields with induction lines that are mutually perpendicular and parallel to the plane of rotating beaters. It is shown that application of electromagnetic effect to milling coarse material in beater mill allowed to greatly intensify that process, significantly increase powder quality: increase particle size distribution uniformity and decrease average particle size from 1558.50 μm to 0.56 μm after 120 minutes of processing in the mill. X-ray diffraction analysis showed that milling in beater mill in magneto fluidized bed leads to reduction of coherent-scattering region size, increase of lattice microstrain and dislocation density, making powder more active during sintering process.

2020 ◽  
Vol 299 ◽  
pp. 392-396
I.N. Egorov ◽  
Nikolay Ya. Egorov

The paper experimentally proves the efficiency of electromagnetic effect on stimulated fluidity of magneto-hard powders. Fine Nd-Fe-B powder doesn’t have natural fluidity. To make it flow through hopper outlet we effected on the powder by constant and alternating gradient magnetic fields. Induction lines of constant magnetic field were horizontal, and alternating field lines were vertical. In order to form stimulated powder fluidity, higher induction gradient was situated below the powder receiver chamber. We experimentally found optimal magnetic fields parameters that form steady magneto fluidized bed from Nd-Fe-B powder, with an average particle size 1 μm. The study results of influence of magneto fluidized bed electromagnetic parameters on Ne-Fe-B powder efflux speed through outlets with diameters 1 and 2 mm are presented. Gradient field topology and parameters of electromagnetic effect providing minimal efflux time of 1000 mg of powder are defined.

2016 ◽  
Vol 690 ◽  
pp. 236-239
Oratai Jongprateep ◽  
Rachata Puranasamriddhi

High photocatalytic activity of nanoparticulate titanium dioxide has attracted worldwide attention. Synthesis techniques of the nanoparticles, however, often require high energy supply or costly initial reagents. Solution combustion technique is an energy-effective technique capable of synthesizing nanosized titanium powders. This research aimed at utilizing a less expensive initial reagent in synthesis of nanoparticulate titanium dioxide by the solution combustion technique. The research also examined effects of dissolving agents on chemical composition and particle sizes of the synthesized powders. A low-cost initial reagent, titanium dioxide with average particle size of 154 nanometers, was dissolved in sulfuric acid or dispersed in nitric acid prior to the combustion. Experimental results revealed that the pure anatase phase titanium dioxide was successfully obtained in powders prepared from both sulfuric acid and nitric acid. The average particle size of the powder prepared from sulfuric acid was 77 nanometers, while that of the powder prepared from nitric acid was 117 nanometers. The difference in particle sizes was attributed to solubility of the initial reagent in the acid. Complete solution of initial reagent in sulfuric acid was the main factor attributed to finer particle size.

2008 ◽  
Vol 8 (2) ◽  
pp. 650-654 ◽  
Svetoslav Kolev ◽  
Tatyana Koutzarova ◽  
Andrey Yanev ◽  
Chavdar Ghelev ◽  
Ivan Nedkov

We investigated the microwave absorbing properties of composite bulk samples with nanostructured and micron-sized fillers. As magnetic fillers we used magnetite powder (Fe3O4 with low magnetocrystalline anisotropy) and strontium hexaferrite (SrFe12O19 with high magnetocrystalline anisotropy). The dielectric matrix consisted of silicone rubber. The average particle size was 30 nm for the magnetite powder and 6 μm for the strontium hexaferrite powder. The micron-sized SrFe12O19 powder was prepared using a solid-state reaction. We investigated the influence of the filler concentration and the filler ratio (Fe3O4/SrFe12O19) in the polymer matrix on the microwave absorption in a large frequency range (1 ÷ 18 GHz). The results obtained showed that the highly anisotropic particles become centers of clusterification and the small magnetite particles form magnetic balls with different diameter depending on the concentration. The effect of adding micron-sized SrFe12O19 to the nanosized Fe3O4 filler in composites absorbing structures has to do with the ferromagnetic resonance (FMR) shifting to the higher frequencies due to the changes in the ferrite filler's properties induced by the presence of a magnetic material with high magnetocrystalline anisotropy. The two-component filler possesses new values of the saturation magnetization and of the anisotropy constant, differing from those of both SrFe12O19 and Fe3O4, which leads to a rise in the effective anisotropy field. The results demonstrate the possibility to vary the composite's absorption characteristics in a controlled manner by way of introducing a second magnetic material.

1999 ◽  
Vol 14 (9) ◽  
pp. 3647-3652 ◽  
Hanns P. Steier ◽  
Joaquin Requena ◽  
José S. Moya

The formation of barium hexaferrite from stoichiometric mixtures of BaCO3 and Fe2O3 has been investigated by means of differential thermal analysis and thermogravimetry, x-ray diffraction, and transmission electron microscopy–energy dispersive spectrometry. The first step, which implies decarbonatation and monoferrite formation, includes the formation of various intermediate compounds, which are formed at contact points between BaCO3 and Fe2O3 grains, and implies diffusion of both species. In the second step, barium hexaferrite is formed at interfaces between monoferrite and iron oxide mainly by diffusion of barium through the BF6 lattice into the hematite lattice. This exothermic reaction process leads to nonagglomerated pseudohexagonal platelets with an average particle size very close to the one of the starting powder mixture (∼1 μm).

Ahmed Nassef ◽  
Waleed El-Garaihy ◽  
Medhat Elhadek

Iron powders having average particle sizes of ~40µm are mechanically mixed thoroughly with aluminum powders ranging from 1 to 10 in wt.% with an average particle size of ~10µm. Two different powder metallurgical techniques cold and hot pressing are used to study the effect of the additive element powder on the mechanical properties, wear properties and the microstructure of the iron based alloys. The hot pressing technique was performed at a temperature up to 500°C at 445.6 MPa. The cold pressing technique was performed at 909 MPa in room temperature. By increasing the Al content to 10 wt. % in the base Fe-based matrix, the hardness was decreased from 780 to 690 MPa and the radial strength was decreased from 380 to 202 MPa with reductions of 11.5% and 40%, respectively. Improvement of the wear resistance with the increase addition of the Al powder to the Fe matrix up to 5 times was achieved compared to the alloy without Al addition for different wear parameters namely; wear time and sliding speed.

Hakan Gokmese

Abstract: A large area cross section of the production of spherical metal powders by gas atomization in the manufacturing method. Powder metal characteristic improves with small powder size. This aim was realized by vertical gas atomization unit, a new a closely-matched nozzle system and manufacture. In the experimental studies, pure aluminium powders which has an important place in the automotive, air and defence industries were produced. In the studies carried out with the Vertical Gas Atomization unit, aluminium was superheated up to 900°C and atomized at different gas pressures (20-30 bar). Scanning electron microscope (SEM) and particle size measuring device were used for the characterization and size measurements of the produced powders, respectively. The average particle size of the finest powder produced with increasing atomization pressure was determined as d50=19.50µm. Aluminium powder shape and morphology was used as spherical and very little satellization was seen. Keywords: Powder Metallurgy, Atomisation, Nozzle, Al powder, Characterisation

2020 ◽  
Vol 989 ◽  
pp. 801-805
Evgeniy V. Ageev ◽  
O.G. Loktionova ◽  
A.Y. Altukhov

The main requirement for powders for additive machines is the spherical shape of the particles. Such particles most compactly fit into a certain volume and provide the “fluidity” of the powder composition in the material supply systems with minimal resistance. Based on the peculiarities of the methods of obtaining spherical powders in order to obtain spherical granules of a regulated grain size, the technology of electroerosive dispersion, which is distinguished by relatively low energy costs and ecological cleanliness of the process, is proposed. The main advantage of the proposed technology is the use of waste as raw materials, which is much cheaper than the pure components used in traditional technologies. In addition, this technology is powder, which allows to obtain powder-alloys. The widespread use of the method of EED for the processing of metal waste into powders for the purpose of their reuse and application in additive technologies is hampered by the lack of complete information in the scientific and technical literature on the influence of the original composition, modes and media on the properties of powders and technologies of practical application. Therefore, the development of technologies for the reuse of EED powders and the evaluation of the effectiveness of their use requires the conduct of comprehensive theoretical and experimental studies. The purpose of this work was to obtain and study additive products from electroerosive cobalt-chromium powders of a specific particle size distribution and to study their microstructure. The granulometry of the obtained powders was determined on a laser analyzer of particle sizes “Analysette 22 NanoTec”. The microstructure of additive samples from cobalt-chromium powders (by transverse polishing) was investigated by optical microscopy on an inverted optical microscope OLYMPUS GX51. On the basis of completed studies, aimed at obtaining and studying additive products from electroerosive cobalt-chrome powders of a specific particle size distribution, and studying their microstructure, it was found that additive samples, obtained from a cobalt-chrome powder with an average particle size of 35,68 microns, have practically no pores.

2021 ◽  
pp. 309-312
E.V. Ageev ◽  
A.S. Pereverzev

The results of experimental studies of the structure and properties of electroerosive materials from lead bronze waste BrS30 obtained in oxygen- and carbon-containing media are presented. The influence of the chemical composition of liquids and technological parameters of dispersion on the properties of the resulting electroerosive materials is shown. In particular, a part of oxygen is present on the surface of particles obtained in distilled water, and part of carbon is present in lighting kerosene. The average particle size obtained in lighting kerosene is 1.2 times higher than the average particle size obtained in distilled water. The particles of the BrS30 alloy dispersed by electroerosion have a regular spherical, elliptical shape and agglomerates.

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