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Документ Synthesis of catalytic cobalt-containing coatings on alloy AL25 surface by plasma electrolytic oxidation(Інститут хімії поверхні ім. О. О. Чуйка НАН України, 2017) Ved, M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.; Gorohivskiy, A. S.The study aims at the investigation of the influence of electrolyte composition and plasma electrolytic oxidation modes on the composition and morphology of a mixed aluminum and cobalt oxides at the AL25 alloy. Composition, morphology and surface roughness of the oxide systems are examined by scanning electron microscopy, X-ray analysis and atomicforce microscopy. Mixed oxide coatings Al₂O₃·CoOₓ formed from the diphosphate electrolytes at various concentration ratio diphosphate/cobalt sulfate contain cobalt of 8-30 at. % (in terms of metal) in the matrix of alumina. Plasma electrolytic oxidation in a two-stage mode of the incident power provided formation of strongly adhered coatings characterized by non-stoichiometry ratio of cobalt and oxygen as well aslow content of silicon in deposits. Obtained mixed oxide systems have developed surface with alternating the spheroid and torus-shaped structures which is associated with a large number of catalytic sites. They exhibit catalyticbehavior in the model reactions of CO conversion to CO₂ and benzene oxidation not inferior to the contacts with noble metals. The coatings Al₂O₃·CoOₓ contribute to fuel economy and improve the environmental performance of the internal combustion engine thus can be recommended for use in the neutralization of gas emissions systems and as coatings for pistons of combustion chamber.Документ Synthesis and functional properties of mixed titanium and cobalt oxides(Institute for Single Crystals, 2017) Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.; Mayba, M. V.; Galak, A. V.Peculiarities of plasma-electrolytic oxidation of the aluminum alloys in diphosphate electrolytes are discussed. It is shown that PEO parameters depend on the composition and concentration of the components of the working solutions. The mechanism of cobalt oxides incorporation into the composition of surface layers is proposed. It has been established that the oxidation of titanium in citrate-diphosphate electrolytes promotes the formation of mixed oxide layers TiOx·CoOy. The obtained mixed oxide systems have a developed microporous globular-toroidal surface and are characterized by a complex of enhanced functional properties - corrosion and abrasion resistance, catalytic activity in the carbon (II) oxide conversion reaction.Документ Mixed alumina and cobalt containing plasma electrolytic oxide coatings(IOP Publishing Ltd, 2017) Yar-Mukhamedova, G. Sh.; Ved, M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.Principles of plasma electrolytic oxidation of the AL25 aluminum alloy in diphosphate alkali solutions containing cobalt(2+) cations are discussed. It has been established that a variation in the concentration of the electrolyte components provides the formation of mixed-oxide coatings consisting of the basic matrix materials and the cobalt oxides of different content. An increase in the cobalt oxide content in the coating is achieved by the variation in electrolysis current density as well as the treatment time due to both the electrochemical and thermo-chemical reactions at substrate surface and in spark region. Current density intervals that provide micro-globular surface formation and uniform cobalt distribution in the coating are determined. The composition and morphology of the surface causes high catalytic properties of synthesized materials, which confirmed the results of testing in model reaction CO and benzene oxidation as well as fuel combustion for various modes of engine operation.Документ Functional mixed cobalt and aluminum oxide coatings for environmental safety(Institute for Single Crystals, 2017) Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.; Myrna, T. Yu.Principles of plasma-electrolytic oxidation of the aluminum alloys in diphosphate electrolytes are discussed. It has been established that a variation in concentration of the electrolyte components and electrolysis parameters (current density and treatment time) provides the formation of oxide coatings consisting of the basic matrix materials and the cobalt oxides of different composition and morphology that are expected to affect their functional properties. Mixed oxide coatings formed in a plasma-electrolytic mode characterized by microglobular structure with reducing the conglomerate size have an increased abrasion and wear resistance and an intense catalytic activity. Thus, there is a prospect of using such coatings in the process of burning fuel in internal combustion engines and reduce the toxicity of emissions improving fuel efficiency and environmental performance of engines and in the industrial systems of catalytic purification of exhaust gases of industrial plants and power system facilities.