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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 Galvanic ternary Fe−Co−W coatings: structure, composition and magnetic properties(Науково-технологічний комплекс "Інститут монокристалів", 2018) Yermolenko, I. Yu.; Ved, M. V.; Sakhnenko, N. D.; Fomina, L. P.; Shipkova, I. G.Principles of Fe–Co–W alloys electrodeposition from complex Fe (III) based citrate electrolytes are discussed. The effect of both current density and pulse on/off time on the quality, composition and surface morphology of the electrolytic alloys were determined. The application of pulsed electrolysis provides increasing ungsten content up to 13 at.%, at current efficiency of 70-75 %. Globular surface 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 coherent-scattering region size of the amorphous part is 2-8 nm. Magnetic characteristics of amorphous Fe–Co–W coatings were measured in dependence of deposition ime. The conclusion was made that the content of magnetic phase in upper layers of coating is greater than in the bottom ones due to decreasing W atom concentration.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 Electrodeposition of catalytic ternary cobalt based coatings(Украинский государственный химико-технологический университет, 2015) Ved, M. V.; Sakhnenko, N. D.; Glushkova, M. A.; Hapon, Yu. K.; Kozyar, M. A.Consistent patterns for electrodeposition of Co-Mo-W and Co-Mo-Zr coatings from polyligand citrate-pyrophosphate bath were investigated. The effect of both current density amplitude and pulse on/off time on the quality, composition and surface topography of the galvanic alloys were determined. It was established the coating Co-Mo-Zr enrichment by alloying components with current density increasing as well as the rising of pulse time promotes the content of zirconium, and pause – molybdenum because of subsequent chemical reduction of its intermediate oxides by hydrogen ad-atoms. It was found that the content of the refractory metals in the coating Co-Mo-W depends on the current density and on/off times extremely and maximum Mo and W content corresponds to the current density interval 12–18 A·dm−2, on-/off-time 5–10 msec. It was shown that Co-Mo-W alloys exhibits the greatest level of catalytic properties as cathode material for hydrogen electrolytic production from acidic media which is not inferior a platinum electrode. The galvanic alloys Co-Mo-Zr with zirconium content 1.5–2.0 wt.% demonstrate high catalytic properties in the carbon oxide (II) oxidation. This confirms the efficiency of materials as catalysts for the gaseous wastes purification and gives the reason to recommend them as catalysts for hydrocarbon combustion.Документ Iron binary and ternary coatings with molybdenum and tungsten(Elsevier Inc., 2016) Ved, M.; Sakhnenko, N. D.; Karakurkchi, A.; Yermolenko, I. Yu.; Yar-Mukhamedova, G.Electrodeposition of Fe-Mo-W and Fe-Mo layers from a citrate solution containing iron(III) on steel and iron substrates is compared. The utilization of iron(III) compounds significantly improved the electrolyte stability eliminating side anodic redox reactions. The influence of concentration ratios and electrodeposition mode on quality, chemical composition, and functional properties of the alloys is determined. It has been found that alloys deposited in pulse mode have more uniform surface morphology and chemical composition and contain less impurities. Improvement in physical and mechanical properties as well as corrosion resistance of Fe-Mo and Fe-Mo-W deposits when compared with main alloy forming metals is driven by alloying components chemical passivity as well as by alloys amorphous structure. Indicated deposits can be considered promising materials in surface hardening technologies and repair of worn out items.