Перегляд за Автор "Sakhnenko, N. D."
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Документ AFM surface analysis of Fe–Co–Mo electrolytic coatings(Інститут хімії поверхні ім. О. О. Чуйка НАН України, 2017) Yermolenko, I. Yu.; Ved, M. V.; Sakhnenko, N. D.; Zubanova, S. I.; Tychyna, O. N.The study aims at the investigation of the morphology and topography of the ternary Fe–Co–Mo electrolytic coatings. Compositions and morphology of the alloys are examined by scanning electron microscopy and X-ray analysis. Both topography and surface roughness are studied by an atomic force microscopy AFM using a NT–206 microscope. The Fe–Co–Mo coatings with an iron content of 47 at.%, cobalt 28 at.% and molybdenum 25 at.% are deposited on mild steel substrate by pulse electrolysis mode from citrate bath with the ratio of concentrations с(Fe³⁺):с(Co²⁺):с(MoO₄²⁻) = 2.5:3:1. Atomic force microscope analysis topography of the coatings Fe–Co–Mo at the scanning area 39.9×39.9 μm show that their surface is more developed compared with the substrate material. Moreover the AFM analysis of the coatings morphology and surface topography indicates the parts with a globular structure with an average conglomerates size of 0.2-0.5 μm and singly located sharp grains. Within the same scan area, sites with a developed surface are detected the topography of which is identical to the crystal structure of cobalt with the crystallite size in the range of 0.2-1.75 μm. The parameters Ra and Rq for parts with different morphology as well as average characteristics of coatings demonstrated the low roughness of the surface. Electrolytic deposits Fe–Co–Mo can be attributed to 8-9-th class of roughness. The study tested the magnetic behavior of Fe–Co–Mo coatings. The coercive force of 7-10 Oe confirms the soft magnetic properties of materials which in combination with high microhardness open prospects for usage of Fe–Co–Mo systems in the production of magnetic head elements for recording and reproducing information.Документ ANN simulation of nanocomposites Fe(Co)-W corrosion resistance(Харківський національний університет міського господарства імені О. М. Бекетова, 2019) Ved, M. V.; Sakhnenko, N. D.; Nenastina, T. A.; Volobuyev, M. N.; Yar-Muhamedova, G. H.Документ Catalytic properties of binary and ternary alloys based on silver(Науково-технологічний комплекс «Інститут монокристалів» Національної академії наук України, 2013) Ved, M. V.; Glushkova, M. A.; Sakhnenko, N. D.The correlation between the morphology, composition and catalytic properties of silver-cobalt alloys has been shown. The galvanic Ag-Co alloy is established as synergetic ones, and the values obtained for the exchange current density of the model hydrogen evolution reaction are similar to platinum. The catalytic activity testing results of binary (Ag-Co) and ternary (Ag-Co-Zr, Ag-Co-Bi) alloys in the carbon monoxide oxidation to carbon dioxide were analyzed.Документ Characterization and photocatalytic activity of Ti/TinOm∙ZrxOy coatings for azo-dye degradation(Institute for Single Crystals, 2014) Sakhnenko, N. D.; Ved, M. V.; Bykanova, V. V.Anodic oxidation of VT1-0 titanium and E-125 zirconium alloy in aqueous electrolyte solutions based on H₂SO₄ and K₄P₂O₇ was used to obtain oxide coatings composed of Zr/ZrOx Ti/TiOy, and mixed oxide systems Ti/TinOm ZrxOy. It was shown that, depending on the electrolyte pH, the films contain up 0.17 to 2.1 % wt. of zirconium. Catalytic activity of the synthesized coatings in the oxidation reaction of methyl orange azo dye under UV irradiation was established. The process rate constants and synergy factors for the mixed systems were calculated.Документ Cobalt based coatings as catalysts for methanol oxidation(Науково-технологічний комплекс "Інститут монокристалів", 2020) Nenastina, T. A.; Ved, M. V.; Sakhnenko, N. D.; Yermolenko, I. Yu.; Volobuyev, M.; Proskurina, V. O.The cobalt based coatings with refractory metals (Mo, W, Zr) were deposited from pyrophosphate-citrate electrolytes in a pulsed mode. It has been shown that, with increasing current density, Co-Mo-W and Co-W-ZrO2 alloys are enriched in tungsten, grain sizes decrease, but a network of cracks appears on the surface of the Co-Mo-W coating. In the Co-Mo-ZrO2 coating, with increasing current density, the zirconium content increases due to molybdenum, and the surface is the most fractured and small-globular. The surface roughness parameters for Co-Mo-ZrO2 are one order of magnitude higher than those for Co-Mo-W. Cyclic voltammograms show that the Co-Mo-ZrO2 deposits are characterized by the highest stability under anodic polarization due to the inclusion of molybdenum and zirconium(IV) oxide in their composition. The kinetics of the methanol anodic oxidation on electrodes coated with cobalt alloys was studied, and the participation of intermediate metal oxides in oxygen transport was revealed. A significant increase in the anode current peak indicates a higher electro-catalytic activity of the zirconium-containing coatings among the studied alloys.Документ Composition and Corrosion Behavior of Iron-Cobalt-Tungsten(Institute of Combustion Problems, Kazakhstan, 2018) Ved, M. V.; Sakhnenko, N. D.; Yermolenko, I. Yu.; Yar-Mukhamedova, G. Sh.; Atchibayev, R.Principles of three component Iron-Cobalt-Tungsten alloys electrodeposition from complex Fe (III) based citrate electrolytes are discussed. It is shown, that deposition of ternary alloys proceeds through competitive reduction of cobalt and tungsten with iron. With increasing ligand concentration coatings are enriched with a refractory component; however, increasing current density favors a reverse trend. The effect of both current density and pulse on/off time on the quality, content of alloying metals and surface topography of electrolytic coatings were determined. The application of pulsed electrolysis provides increasing tungsten content up to 13 at.%, at current efficiency of 70–75%. Globular relief of Fe-Co-W coatings is caused by refractory metals incorporation, and crystalline and amorphous parts of structure are visualized by X-ray spectroscopy, including inter-metallic phases Co₇W₆, Fe₇W₆ along with α-Fe and Fe₃C. The crystallite size of the amorphous part is near 7–8 nm. Corrosion resistance of the coatings is 1.3–2.0 orders of magnitude higher than the substrate parameters as follows from data of polarization resistance method and electrode impedance spectroscopy.Документ Composition and morphology of Fe-Co-Mo electrolytic alloys(Інститут хімії поверхні ім. О. О. Чуйка, 2016) Sachanova, Yu. I.; Yermolenko, I. Yu.; Sakhnenko, N. D.; Ved, M. V.Документ Composition, Morphology, and Topography of Galvanic Coatings Fe–Co–W and Fe–Co–Mo(2017) Yermolenko, I. Yu.; Ved, M. V.; Sakhnenko, N. D.; Sachanova, Yu. I.Ternary coatings Fe-Co-W with an iron content of 40–55 at.%, cobalt 39–44 at.%, and tungsten 4–12 at.% and Fe-Co-Mo with an iron content of 40–55 at.%, cobalt 39–44 at.%, and tungsten 4–12 at.% were obtained by galvanostatic and pulse electrolysis on the mild steel substrate from iron(III) citrate-based electrolyte. The influence of electrolysis mode and parameters on composition of deposited alloys was studied. The competing reduction of iron and tungsten in Fe-Co-W coatings as well as the competitive deposition of iron and cobalt in Fe-Co-Mo coatings at various current densities were defined. Simultaneously, the alloy enrichment with molybdenum is more marked at a pulse mode. Atomic force microscope analysis of the Fe-Co-W alloy coating morphology and surface topography indicates their globular structure with spherical grains in the range of 2.5–3.5 μm. The surface of Fe-Co-Mo is characterized by parts of a globular structure with an average conglomerate size of 0.3–0.5 μm and singly located cone-shaped hills with a base diameter of 3 μm. Sites with a developed surface were detected within the same scan area which topography is identical to the crystal lattice of cobalt with the crystalline conglomerate sizes in the range of 0.2–1.75 μm.Документ Copper (nickel) based composite coatings reinforced with nanosized oxides(Institute for Single Crystals, 2015) Sakhnenko, N. D.; Ovcharenko, O.; Ved, M.The work reports the method for copper and nickel based coatings reinforced by ultrafine particles of alumina or zirconia deposition. The electrolytes’ compositions as well as electrosynthesis modes are grounded. Considerable enhance in the both physical-mechanical properties and corrosion resistance of synthesized composite systems over traditional monolayer coatings by copper and nickel is shown.Документ Corrosion properties of galvanic Fe–Mo(W), Fe–Mo–W coatings(Науково-технологічний комплекс "Інститут монокристалів", 2019) Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.; Pershina, K. D.; Yermolenko, I. Yu.The methods of analysis of polarization dependences, the electrode impedance spectroscopy and gravimetry were used for the investigation of the corrosion properties of galvanic binary Fe–Mo(W) and ternary Fe–Mo–W coatings in the media of a different acidity. It was shown that the corrosion rate of Fe–Mo–W and Fe–Mo(W) alloys is decreased with an increase in the pH of the solutions and with the enrichment of the alloys by doping refractory components. The dependence of the control of corrosion process on the composition of electrolytic alloys has been specified. It was established that the corrosion resistance of binary alloys is 1.1 to 1.5 orders of magnitude higher in comparison with the parameters of substrate materials, in particular the mild steel. The corrosion resistance indices for the coatings applied using the ternary Fe–Mo–W alloys substantially prevail over those for mild steel, individual metals and binary Fe–Mo and Fe–W coatings. The corrosion resistance of Fe–Mo–W system is equal to 8300 Ohm·cm² and it is conditioned by the formation of the two-component layer film consisting of molybdenum oxides and tungsten oxides. Using the data of gravimetric investigations we constructed the diagrams "the corrosion depth index kh, mm/year – the composition" for the Fe–Mo–W system that allow us to define the metal content ratio for Fe–Mo(W), Fe–Mo–W alloys in order to provide an appropriate corrosion resistance depending on service conditions.Документ Corrosion-electrochemical properties of cobalt-molybdenum-zirconium deposits(Kyiv National University of Technologies and Design, 2016) Koziar, M. A.; Slavkova, M. A.; Sakhnenko, N. D.; Ved, M. V.Документ Effect of doping metals on the structure of PEO coatings on Ti(Publishing House SME "Burlaka", 2017) Karakurkchi, A. V.; Sakhnenko, N. D.; Ved, M. V.; Mayba, M. V.Документ Effect of Doping Metals on the Structure of PEO Coatings on Titanium(2018) Sakhnenko, N. D.; Ved, M. V.; Karakurkchi, A. V.The structure and properties of the oxide films formed on titanium alloys by means of plasma-electrolytic oxidizing in alkali electrolytes based on pyrophosphates, borates, or acetates of alkali metals with the addition of dopants’ oxides or oxoanions of varying composition have been studied. Anodic polarization in the spark discharge (microarc) mode at application of interelectrode potential 90 to 160V has been used to obtain mixed-oxide systems TiOₓ·WOᵧ, TiOₓ ·MoOᵧ, TiOₓ ·ZrO₂, and TiOₓ ·V₂O₅. The possibility to obtain the oxide layers containing the alloying elements by the modification of the composition of electrolytes has been stated. The chemical and phase composition as well as the topography, the microstructure, and the grain size of the formed layers depend on the applied current, interelectrode voltage, and the layer chemical composition. The effect of formed films composition on the resistance of titanium to corrosion has been discussed. Catalytic activity of mixed-oxide systems was determined in the model reaction of methyl orange dye MO photodestruction.Документ Effect of Electrodeposition Parameters on the Composition and Surface Topography of Nanostructured Coatings by Tungsten with Iron and Cobalt(Institute of Combustion Problems, Kazakhstan, 2020) Yar-Mukhamedova, G. Sh.; Ved, M. V.; Yermolenko, I. Yu.; Sakhnenko, N. D.; Karakurkchi, A. V.; Kemelzhanova, A.The electrodeposition of binary and ternary coatings Fe-W and Fe-Co-W from mono ligand citrate electrolyte has been investigated. The Fe-Co-W coatings were formed from electrolytes, which composition differs in the ratio of the concentrations of the alloying components and the ligand content. The investigation results indicate a competitive reduction of iron, cobalt and tungsten, the nature of which depends both on the ratio of electrolyte components, and electrolysis parameters. The effect of both current density amplitude and pulse on off time on quality, composition and surface morphology of the galvanic alloys was determined. Coatings deposited on a direct current with a density of more than 6.5 A/dm², crack and peel off from the substrate due to the inclusion of Fe (III) compounds containing hydroxide anions. The use of non-stationary electrolysis allows us to extend the working range of current density to 8.0 A/dm² and form electrolytic coatings of sufficient quality with significant current efficiency and the content of the refractory component. The presence of the Co₇W₆, Fe₇W₆, α-Fe, and Fe3C phases detected in the Fe-Co-W deposits reflects the competition between the alloying metals reducing from hetero-nuclear complexes. The surface of binary and ternary coatings is characterized by the presence of spherical agglomerates and is more developed in comparison with steel substrate. The parameters Ra and Rq for electrolytic alloy Fe-W are of 0.1, for Fe-Co-W are 0.3, which exceeds the performance of a polished steel substrate (Ra = 0.007 and Rq = 0.010). These properties prospect such alloys as a multifunctional layer are associated with structural features, surface morphology, and phase composition.Документ The effect of the electrolysis regime on the composition and morphology of Fe–Co–Mo(W) coatings(Publishing House SME "Burlaka", 2017) Yermolenko, I. Yu.; Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.Документ The electrochemical behavior of Fe³⁺ – WO₄²⁻ – Cit³⁻ and Fe³⁺ – MoO₄²⁻ – WO₄²⁻ – Cit³ systems(Украинский государственный химико-технологический университет, 2017) Yermolenko, I. Yu.; Ved, M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.; Kolupayeva, Z. I.The kinetic parameters of electrochemical behavior of tungsten at the deposition of Fe–W and Fe–Mo–W alloys were determined using linear voltammetry and analyzing polarization relationships. In the presence of citrate ions the cathode process was shown to proceed with the participation of [FeHCitWO₄]⁻ clusters. An optimal concentration ratio of the components in electrolyte required for the Fe—W alloy deposition was defined as c(Fe³⁺):c(Cit³⁻):c(WO₄²⁻) = 1:1.5:0.3. The deviation from this ratio by an increase in the concentration of tungstate ions results in the formation of dimer forms W₂O₇²⁻ and [FeW₂O₇HCit]⁻ clusters; as a result the concentration of electrode active particles [FeWO₄HCit]⁻ diminishes and the cathode process is inhibited. A peculiar feature of the formation of electrolytic alloy Fe–Mo–W is a competitive reduction of molybdates and tungstates. Based on the analysis of the kinetic parameters and characteristic criteria of electrochemical reactions, we proposed the mechanism for the co-deposition of alloy containing iron with molybdenum and tungsten; this mechanism is a sequence of coupled reactions of irreversible reduction of intermediates with slow charge transfer stage and previous chemical step of the ligands release. The data of X-ray phase analysis show that the binary alloys Fe–W are solid solutions of tungsten in iron and ternary alloys Fe-Mo- W are X-ray amorphous.Документ Electrochemical deposition of Fe–Mo–W alloy coatings from citrate electrolyte(Allerton Press, 2016) Karakurkchi, A. V.; Ved, M. V.; Yermolenko, I. Yu.; Sakhnenko, N. D.Peculiarities of the electrochemical deposition of Fe–Mo–W coatings from citrate electrolyte containing iron (III) on the substrates of mild steel and gray cast iron are investigated. The effect of the salt concentration of alloying components and electrolysis modes on the quality, composition, and properties of the alloys is determined. It is shown that the alloys formed via nonstationary electrolysis exhibit a more uniform surface and lower content of impurities. The improved physical and mechanical properties as well as corrosion resistance of Fe–Mo–W coatings in comparison with the base metal can be considered as promising technologies for surface hardening and repair of worn items.Документ Electrochemical synthesis of nickel-based composite materials modified with nanosized aluminum oxide(Pleiades Publishing, 2015) Sakhnenko, N. D.; Ovcharenko, O. O.; Ved, M. V.Electrochemical synthesis of nickel-based composite coatings and foil reinforced with nanosized aluminum oxide is reported. Ni-Al₂O₃ composites with different content of the modifying phase were prepared by chemical dispersion of aluminum oxide using the “from above down” principle. The influence of the aluminum oxide concentration in the electrolyte on the physicomechanical properties of the reinforced foil was determined. Incorporation of reinforcing phase particles into the metal matrix leads to a decrease in the grain size and enhances by a factor of 2–6 the strength characteristics of the coatings and foil. The topography of the surface and the cross section profile of the composites were examined, and the influence of these characteristics on the properties of the materials was determined.Документ Electrodeposited cobalt alloys as materials for energy technology(Cambridge University Press, 2013) Glushkova, M. A.; Bairachna, T.; Ved, M. V.; Sakhnenko, N. D.The influence of electrodeposition parameters on chemical composition, morphology and functional properties of such binary cobalt alloys as CoAg, CoW, and CoFe has been investigated. The alloys are shown to possess catalytic properties. Catalytic actuvity was preliminary estimated in the electrolytic hydrogen evolution reaction and tested by CO to CO2 conversion during the catalytic benzene oxidation.Документ Electrodeposition and properties of nickel coatings and foil reinforced with alumina(Kyiv National University of Technologies and Design, 2016) Ovcharenko, O. O.; Sakhnenko, N. D.; Ved, M. V.
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