scholarly journals MAGNESIOCHROMITE (MgCr2O4) SYNTHESIS: EFFECT OF MECHANICAL AND MICROWAVE PRETREATMENT

2020 ◽  
Vol 63 (8) ◽  
pp. 96-102 ◽  
Author(s):  
Nadezhda F. Kosenko ◽  
Natalya V. Filatova ◽  
Anastasia A. Egorova
Keyword(s):  
Mechanical Treatment ◽  
Plane Surface ◽  
Microwave Treatment ◽  
Effective Rate ◽  
Planetary Mill ◽  
Spinel Formation ◽  
Defective Layer ◽  
Approximation Coefficients ◽  
Positive Effect ◽  
Preliminary Mechanical Activation

Magnesiochromite spinel synthesis based on oxides, hydroxides and nitrates of magnesium and chromium was investigated. The precursors reactivity was compared by means of effective rate constants calculated by Ginstling-Brounshtein equation. The possibility of use of this equation was confirmed by the dependences linearity with high linear approximation coefficients. The reactivity of MgO various forms (soft-burned, or caustic magnesite, and dead-burned, or periclase) in the spinel formation was compared. Oxide precursors (especially with the periclase participation) reacted with the substantially less rate in comparison with hydroxides and salts. The influence of a preliminary mechanical activation by impact-and-attrition (planetary mill) and attrition (ball-ring mill) action as well as a microwave treatment (2.45 GHz) was analyzed. The most positive effect of a mechanical treatment in a planetary mill that was associated with an activation of Mg and Cr compounds became apparent in the field of relatively low temperatures (700-1100 °С). For example, MgCr2O4 yield at 1000 °С and the joint impact treatment of oxides was twice as much than under the simple mixing. The subsequent temperature rising lead to some decrease of a pretreatment effect so long as diffusion coefficients in these conditions grew, so the reaction run rapidly even without a preliminary mechanical treatment. It was noticed that an appreciable reduction of MgO reactivity in the spinel formation after a certain attrition in a ball-ring mill linked to the plane sliding in cubic crystals and resulted in the removing of the most disordered and defective layer from grains and the plane surface uncovering. The combined method consisting of a mechanical treatment of magnesium and chromium nitrates mixture in a planetary mill and the subsequent burning in a thermal kiln (1000 °С) was considered as the most effective as it resulted in practically single product. The microwave treatment took up an intermediate position by the effectiveness.

scholarly journals Effect of the Mechanical and Thermal Prehistory of Precursors on the Zinc Spinel Synthesis

2020 ◽  
pp. 53-64
Author(s):  
Nadezhda F. Kosenko ◽  
Natalya V. Filatova ◽  
Viktoriia I. Rodionova
Keyword(s):  
Mechanical Activation ◽  
Mechanical Treatment ◽  
Microwave Treatment ◽  
Planetary Mill ◽  
Combined Method ◽  
Single Product ◽  
Preliminary Mechanical Activation ◽  
Thermal Prehistory

Thezinc spinel (gahnite) formation by a treatment of reaction mixtures of Zn and Al oxides, hydroxides, and salts was investigated. The influence of a preliminary mechanical activation by impact (planetary mill) and attrition (ball-ring mill) action as well as a microwave treatment was analyzed. The combined method consisting of a mechanical treatment of nitrates mixture in a planetary mill and the subsequent burning in a thermal kiln was considered as the most effective as it resulted in practically single product

About Determing the Microhardness of Composite Coatings

2021 ◽  
Vol 1037 ◽  
pp. 486-493
Author(s):  
Sergey Y. Zhachkin ◽  
Anatoly I. Zavrazhnov ◽  
Nikita A. Penkov ◽  
George V. Kudryavtsev ◽  
Paul V. Tsisarenko
Keyword(s):  
Composite Coating ◽  
Mechanical Treatment ◽  
Composite Coatings ◽  
Operational Parameters ◽  
Deposition Parameters ◽  
Cylinder Liners ◽  
High Degree ◽  
Applied Coating ◽  
Positive Effect ◽  
Selection Of

One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.

scholarly journals Study on indium leaching from mechanically activated hard zinc residue

2011 ◽  
Vol 47 (1) ◽  
pp. 63-72 ◽  
Author(s):  
J.H. Yao ◽  
X.H. Li ◽  
Y.W. Li
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Planetary Mill ◽  
Leaching Rate ◽  
Obvious Effect ◽  
Diffusion Controlled ◽  
Leaching Reaction ◽  
Kinetics Of ◽  
Positive Effect ◽  
Solution Kinetics

In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x)1/3]2=kt and (1-2x/3)-(1-x)2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled) and 11.65 kJ/mol (activated) within the temperature range of 30?C to 90?C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

scholarly journals The Influence of Ultrasound Cavitation on the Process of Degradation of Organic Substances in Wastewater of Pharmaceutical Production

2020 ◽  
Vol 69 (11-12) ◽  
pp. 631-638
Author(s):  
Uliana Vashkurak ◽  
Lilia Shevchuk ◽  
Ivan Aftanaziv ◽  
Anna Romaniv
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Impurity Content ◽  
Effective Rate ◽  
Matter Content ◽  
Air Supply ◽  
Pharmaceutical Plant ◽  
Approximation Coefficients ◽  
Pharmaceutical Production ◽  
Common Action

The influence of ultrasound cavitation in the atmosphere of different gases, namely oxygen, air, and nitrogen, on the destruction of impurities of butanol and ethanol found in wastewater from the pharmaceutical plant “Galichpharm” was investigated. The effect of the corresponding gases (oxygen, nitrogen, and air) without ultrasound cavitation on the destruction of ethanol and butanol impurities in wastewater was comparatively investigated. The degree of oxidation of organic matter, effective rate constants, and approximation coefficients were calculated. It was found that the air supply is the least effective for both ethanol and butanol impurities. Degradation of ethanol by air contributed to the reduction in the organic matter content by 14.6 %, while oxidation of butanol was not observed. Ultrasound cavitation enhanced the effect of air and in common action with air the ethanol impurity content reduced by 32.58 %, and butanol impurity by 4.05 %. Nitrogen bubbling produced mediocre results for the destruction of ethanol and butanol impurities giving a decrease by 17.04 % and 0.67 %, respectively. The highest results were obtained with oxygen. Ethanol impurities decreased by 22.47 % and butanol impurities by 1.75 %. With the common action of oxygen and ultrasound, much higher results were obtained, 44.32 % for ethanol impurities and 7.43 % for butanol impurities.

scholarly journals Method for the improvement of mechanical properties of biodegradable polymeric scaffolds

2019 ◽  
Vol 5 (1) ◽  
pp. 485-487
Author(s):  
Kerstin Schümann ◽  
Daniela Arbeiter ◽  
Niels Grabow ◽  
Klaus-Peter Schmitz
Keyword(s):  
Mechanical Properties ◽  
Mechanical Treatment ◽  
Material Characteristics ◽  
Polymeric Scaffolds ◽  
Thermo Mechanical Treatment ◽  
Positive Effect

AbstractAt present, a main focus in the field of stent technologies is on the development of biodegradable polymeric stents. Due to inferior material characteristics of polymers compared to permanent metals stents require thicker stents struts to accomplish adequate mechanical properties. Therefore, a thermo-mechanical treatment of polymeric stents was tested, which showed a positive effect on mechanical stent characteristics.

scholarly journals RADIATION-THERMAL METHOD FOR LITHIUM-ZINC FERRITE CERAMICS MANUFACTURING

2018 ◽  
Vol 61 (6) ◽  
pp. 69
Author(s):  
Elena N. Lysenko ◽  
Anatoly P. Surzhikov ◽  
Andrey V. Malyshev ◽  
Vitaly A. Vlasov ◽  
Evgeniy V. Nikolaev
Keyword(s):  
Mechanical Activation ◽  
Zinc Ferrite ◽  
Sintering Temperature ◽  
High Energy ◽  
Planetary Mill ◽  
Thermal Method ◽  
X Ray ◽  
Crystallite Sizes ◽  
Diffraction Peaks ◽  
Preliminary Mechanical Activation

The structural and magnetic properties of lithium-zinc ferrite ceramics of Li0.4Fe2.4Zn0.2O4 composition, which was obtained under complex high-energy action based on the use of mechanical activation of Fe2O3-Li2CO3-ZnO initial reagents mixture in AGO-2C planetary mill and subsequent its heating to a sintering temperature of 1050 °C for 140 min by ELV-6 continuous electrons beam with an electron energy of 1.4 MeV, were investigated. X-ray phase analysis showed a broadening of diffraction peaks due to the decrease in the crystallite sizes and the increase in the values of microdeformation as a result of mechanical milling. It was established that preliminary mechanical activation of the initial reagents mixture in a planetary mill allows not only to accelerate the synthesis of ferrite materials, but also to combine the both technological stages of synthesis and sintering in one stage of radiation-thermal treatment, consisting in a heating of press-billets by a high-energy electron beam to a sintering temperature. Lithium-zinc ferrite ceramics, obtained by the radiation-thermal method, is characterized by high density and low porosity as well as high values of the specific magnetization and the Curie temperature.Forcitation:Lysenko E.N., Surzhikov A.P., Malyshev A.V., Vlasov V.A., Nikolaev E.V. Radiation-thermal method for lithium-zinc ferrite ceramics. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 69-75

Isotope Exchange between 18O2 Gas and Mechanoactivated Oxide NdMnO3+δ

2013 ◽  
Vol 333 ◽  
pp. 193-198 ◽  
Author(s):  
O.M. Fedorova ◽  
Anatoly Yakovlevich Fishman ◽  
Tatiana Eugenievna Kurennykh ◽  
Vladimir Borisovich Vykhodets ◽  
V.B. Vykhodets
Keyword(s):  
Mechanical Activation ◽  
Isotope Exchange ◽  
Mechanical Treatment ◽  
Isothermal Annealing ◽  
Planetary Mill ◽  
Ceramic Technology ◽  
Activation Time ◽  
Graaff Accelerator ◽  
Nuclear Microanalysis ◽  
Exchange Parameters

sotope exchange of oxygen 18О2 with oxides NdMnO3+δ was investigated. The oxide was obtained from oxides Nd2O3 and Mn2O3 using a ceramic technology with annealing in air at 1400°C for 90 hours followed by cooling in a furnace. A planetary mill AGO-2 with a centrifugal factor of g = 60 was used for mechanical treatment of oxides. The study of isotope exchange was carried out by nuclear microanalysis. The concentration of the isotopes 18O and 16O in oxides was determined using a Van de Graaff accelerator and 18O(p, α)15N and 16O(d, p)17O* reactions at the energies of incident beams 762 and 900 keV. Isothermal annealing of powders was carried out in oxygen, enriched to 80% by the isotope 18O. It was established that the concentration of the isotope 18O in mechanically activated powders was several times higher than in the initial micropowder under the same conditions of annealing. The effect increased with increasing of mechanical activation time (30 - 300 s). The isotope exchange parameters connected with the processes at the boundaries of the particles of mechano-activated powder and within their volume were analyzed.

scholarly journals Effect of dispersity of powder system Al-Mg-B on the phase composition of sintered ceramics AlMgB14

2018 ◽  
Vol 243 ◽  
pp. 00009 ◽  
Author(s):  
Pavel Nikitin ◽  
Ilya Zhukov ◽  
Alexander Vorozhtsov ◽  
Alexander Zhukov ◽  
Yana Dubkova
Keyword(s):  
Mechanical Treatment ◽  
Planetary Mill ◽  
Optimal Time ◽  
Mechanical Processing ◽  
Vacuum Sintering ◽  
Maximum Phase ◽  
Powder Mixtures ◽  
Powder System ◽  
Aluminium Powder ◽  
Maximum Content

In work studies of materials obtained from various powder mixtures Al-Mg-B after mechanical processing in a planetary mill and subsequent vacuum sintering were carry out. It was found that for each mixture exists optimal time of mechanical treatment in a planetary mill, at which the maximum content of AlMgB14-phase is reached. It was shown that for the samples synthesized from the Al-Mg-B powder mixture with the dispersion of the raw aluminium powder <d>~80 μm after 5 hours of mechanical activation and subsequent vacuum sintering at a temperature of 1130 °C, the maximum phase of AlMgB14 is ~ 85-90 wt.%.

scholarly journals Magnesium use in pre-sowing treatment of spring wheat seeds

2021 ◽  
Vol 36 ◽  
pp. 04003
Author(s):  
Venera Ramazanova
Keyword(s):  
Spring Wheat ◽  
Plant Development ◽  
Growth And Development ◽  
Effective Rate ◽  
Initial Growth ◽  
Sprout Length ◽  
Different Content ◽  
Magnesium Nanoparticles ◽  
Positive Effect ◽  
Wheat Seeds

Studies of different content of magnesium nanoparticles in combination with stabilizers polyvinylpyrrolidone (PVP) and collagen hydrolyzate (GC) on the effect on the growth processes of spring wheat plants were conducted. It was found that the most positive effect on germination was produced by magnesium preparations in the following concentrations Mg 10 mg + PVP with a rate of 5 ml/t, Mg 20 mg + PVP with a rate of 1 ml/t, Mg 10 mg + GC with a rate of 1 ml/t. The initial growth and development of the root was significantly affected by the variant No3 Mg 10 mg + Ag 1 ml + PVP at the rate of 1 ml/t, and the development of the sprout was affected by all magnesium nanosets at the rate of 1 ml/t. When analyzing the assessment of plant development on days 7, 10 and 15, it was found that magnesium preparations with collagen stabilizer (GC) had a positive effect. Treatment with magnesium preparations on vegetative parts of plants, namely daily sprouts determined the effective rate of the preparation of 5 ml and more. The high values were in the variants Mg 20 mg + PVP, Mg 10 mg + Ag 1 ml + GC, where the increase in sprout length was 2.7-2.9 cm, weight 1.0-1.3 g.

Influence of carbon fibers and composite technologies on the properties of PCM based on polytetrafluoroethylene

2020 ◽  
Vol 11 ◽  
pp. 59-68
Author(s):  
M. A. Markova ◽  
◽  
P. N. Petrova ◽  
Keyword(s):  
Mechanical Activation ◽  
Polymer Composites ◽  
Carbon Fibers ◽  
Polymer Matrix ◽  
Planetary Mill ◽  
Mass Ratio ◽  
Adhesive Interaction ◽  
The Given ◽  
Technological Methods ◽  
Positive Effect

The given paper presents the results of studies on the development of various technological methods for producing composites based on polytetrafluoroethylene (PTFE) and UVIS-AK-P carbon fibers. The methods consist in the physical and ultrasonic actions on the components of polymer composites. The dependence of the physical-mechanical and tribotechnical properties on the production technology of polymer composite materials (PCM) based on PTFE and carbon fibers of the UVIS-AK-P brand is investigated. Two technological methods were applied in the present work to improve the distribution of discrete carbon fibers in the polymer matrix: ultrasonic treatment of the powder composition in a dry medium and the technology of introducing the filler into the polymer matrix through a polymer concentrate with carbon fibers (CF). Herewith, the influence of the filler content in the concentrate on the properties of polymer composites is considered. To increase the adhesive interaction of the polymer with filler, the technology of joint activation of the components was used at the stage of obtaining the concentrate. Afterward, the resulting mixture was mixed with a portion of the polymer to the required concentration of the filler. The positive effect of the technology of joint mechanical activation of components on the properties of PCM based on PTFE and UVIS-AK-P carbon fibers has been established. It has been revealed that the composite with a carbon fiber content of 5 wt. % obtained using combined mechanical activation of a polymer with CF at a rotational speed of planetary mill drums of 400 rpm with a mass ratio of 50 % concentrate and 50 % PTFE has optimal properties. The deformation and strength characteristics of this composite at the level of the initial factor, the wear resistance is higher than in 2020, compared with PTFE and 5, compared with a composite obtained by a simple mixed concentration with a polymer.

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