Study of Electromagnetic Effect Parameters Influence on Fluidity of Fine Nd-Fe-B Powder

2020 ◽  
Vol 299 ◽  
pp. 392-396
Author(s):  
I.N. Egorov ◽  
Nikolay Ya. Egorov
Keyword(s):  
Magnetic Fields ◽  
Fluidized Bed ◽  
Average Particle Size ◽  
Gradient Field ◽  
Average Particle ◽  
Electromagnetic Effect ◽  
Study Results ◽  
Flow Through ◽  
Field Lines ◽  
Efflux Time

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.

The Influence of Milling Regimes in Beater Mill on Particle Size Distribution and Structural Characteristics of Strontium Hexaferrite Powder

2018 ◽  
Vol 284 ◽  
pp. 158-162
Author(s):  
I.N. Yegorov ◽  
Nikolay Ya. Egorov
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Structural Parameters ◽  
Average Particle Size ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Electromagnetic Effect ◽  
Coarse Material

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.

scholarly journals Influence of electromagnetic effect parameters on ferromagnetic powders fluidity

2018 ◽  
Vol 226 ◽  
pp. 03002
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov
Keyword(s):  
Symmetry Axis ◽  
Average Particle Size ◽  
Experimental Studies ◽  
Barium Hexaferrite ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Particle Sizes ◽  
Electromagnetic Effect ◽  
Flow Through ◽  
Particulate Medium

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.

Kinetics of Structural Changes in Strontium Hexa-Ferrite Powder during Milling in Beater Mill

2020 ◽  
Vol 989 ◽  
pp. 199-203
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Viktor P. Kryzhanovsky
Keyword(s):  
Particle Size ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Experimental Studies ◽  
Milling Process ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Relative Deformation ◽  
Ferrite Powder ◽  
Electromagnetic Effect

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.

scholarly journals FORMULATION AND EVALUATION OF EXTENDED RELEASE PELLETS OF PIOGLITAZONE HYDROCHLORIDE USING NATURAL AND SYNTHETIC POLYMERS BY FLUIDIZED BED COATING TECHNIQUE

2019 ◽  
pp. 438-446
Author(s):  
GOWTHAMI B ◽  
NIHITHA S ◽  
SANTHI PRIYA NAGAM ◽  
RAMA RAO NADENDLA
Keyword(s):  
Fluidized Bed ◽  
Average Particle Size ◽  
Entrapment Efficiency ◽  
Synthetic Polymers ◽  
Lag Phase ◽  
Average Particle ◽  
Simulated Intestinal Fluid ◽  
Coating Technique ◽  
Fluidized Bed Coating

Objective: The objective of the current work was to develop Pioglitazone hydrochloride (HCl) pellets coated with natural polymer extracted from peas gum and also to compare the drug release profile with coatings containing semi-synthetic and synthetic polymers. Methods: Fluidized bed coating technique was used to develop pellets. A 22 factorial design was employed to study the effect of independent variables (inlet air temperature and spray rate), on dependent variables (percentage entrapment efficiency, percentage friability, and average particle size). Optimization was done by fitting experimental data to the software program. Obtained pellets were subjected to different evaluation parameters which are critical in the development of the dosage form. An in vitro lag phase study was carried out for all batches in simulated gastric fluid (0.1N HCl) for 5 h and in vitro drug release study was carried out for optimized batch (E-2 and P-3) in simulated intestinal fluid (pH 7.4 phosphate buffer). Results: The optimized batches E-2 and P-3 showed satisfactory percentage entrapment efficiency of 92.66±1.52, percentage friability of 0.57±0.03, and average particle size of 1424±16 μm. All batches maintained lag phase for 5 h in 0.1N HCl. An optimized batch of two different sizes exhibited a burst release within 30 min in a simulated intestinal fluid with no significant difference in release rate constant (*p>0.05) and followed first-order kinetics. Conclusion: Thus, Pioglitazone HCl pulsatile pellets were successfully developed for treating diabetes mellitus by fluidized bed coating technique employing factorial design.

Milling Duration Influence on Strontium Hexaferrite Technological Characteristics

2021 ◽  
Vol 410 ◽  
pp. 730-734
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Svetlana I. Egorova
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Bulk Density ◽  
Fluidized Bed ◽  
Average Particle Size ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Actual Problem ◽  
Technological Characteristics ◽  
Milling Duration

Fine powders of strontium hexaferrite are widely used in powder metallurgy for the production of permanent magnets resistant to atmospheric oxygen and high working temperatures. Obtaining powders with predefined technological characteristics in minimal time and with minimal energy consumption is an actual problem of powder metallurgy. The paper provides the results of experimental studies of technological characteristics of strontium hexaferrite powder (SrFe12O19) during milling in a beater mill. Mechanical milling of coarse strontium hexaferrite was carried out in the mill with the system of rotating beaters for 120 minutes without and with the creation of a pseudo fluidized bed. The fluidization was formed by a perpendicular constant and alternating magnetic field with induction gradients of 150 and 210 mT/m. Average particle size and powder bulk density dependencies from milling time were studied. Experimental data show that milling with the formation of a magneto fluidized bed allows intensifying the process. Beginning from 70 minutes, the dependencies of average particle size and bulk density come to almost asymptotic behavior making further milling rather ineffective. Carried out research allows choosing optimal milling duration for obtaining the required average particle size.

Diagnostic of Structural Changes in Ferromagnetic Powders during Milling in Beater Mill

2021 ◽  
Vol 316 ◽  
pp. 187-192
Author(s):  
I.N. Egorov ◽  
S.I. Egorova ◽  
G.F. Lemeshko
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Coherent Scattering ◽  
Milling Process ◽  
Average Particle ◽  
Ferrite Powder ◽  
Great Decrease

Problem of obtaining fine powders of strontium hexa-ferrite is actual because of its wide applications. The paper provides the results of studies of particle size distribution and structural characteristic changes of strontium hexa-ferrite powder (SrFe12O19) during milling in impact mill and after its consequent annealing. Mechanical processing of coarse particulate system was carried out in the mill for 120 minutes without electromagnetic effect and with creation of magneto fluidized bed, formed by perpendicular constant and alternating magnetic field with induction gradient of 210 mT/m, providing reciprocating motion of particles and aggregates with sizes of 3 – 4 mm. It was shown that milling of coarse strontium hexa-ferrite with average particle size 1558.5 μm and the most possible size 1500 μm in magneto fluidized bed allowed to intensify milling process and to provide a significant increase of powder particle sizes uniformity. It was found out, that milling in magneto fluidized bed leads to a great decrease of coherent scattering regions sizes and an increase of lattice micro-deformations and relative dislocation density. Consequent annealing of the powder for 2 hours at 850°C refined structural characteristics significantly. The carried out research allows to choose the optimal milling duration for solution of practical problems of powder metallurgy.

scholarly journals Fluidized-Bed Granulation of Probiotics-Encapsulated Spray-Dried Skim Milk Powder: Effects of a Fluidizing Aid, Moisture-Activation and Dehydration

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1600
Author(s):  
Dong-Hyun Lim ◽  
Andres Letona ◽  
Minjeong Lee ◽  
Dayoung Lim ◽  
Nam-Soo Han ◽  
...  
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Average Particle Size ◽  
Milk Powder ◽  
Lactobacillus Rhamnosus ◽  
Skim Milk ◽  
Fold Increase ◽  
Skim Milk Powder ◽  
Average Particle ◽  
Spray Dried

A probiotic powder of poor flowability with high dust content, prepared by spray drying reconstituted skim milk fermented with Lactobacillus rhamnosus GG (LGG), was granulated by fluidized-bed granulation (FBG). The effects of the addition of skim milk powder (SMP) as a fluidizing aid, and of simple moisture-activation with or without dehydration, were investigated with respect to the performance of the FBG process. A fine, poorly fluidizable LGG powder (Geldart Group C) could be fluidized and granulated, with a 4- to 5-fold increase in particle size (d4,3 = 96–141 μm), by mixing with SMP (30–50%), which has larger, fluidizable particles belonging to Geldart Group A. Moisture-activation after the mixing, followed by fluidized-bed dehydration with hot air to remove excess moisture, further improved the FBG; the yield of the granules increased from 42% to 61% and the particle size distribution became much narrower, although the average particle size remained almost the same (d4,3 = 142 μm). These granules showed a popcorn-type structure in scanning electron microscopy images and encapsulated a sufficient level of viable LGG cells (1.6 × 108 CFU g−1). These granules also exhibited much better flowability and dispersibility than the spray-dried LGG powder.

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

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