Публікації співробітників (ВІТВ НТУ "ХПІ")

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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.
Корозійно-електрохімічні властивості метал-оксидних і композитних систем
(Фізико-механічний інститут ім. Г. В. Карпенка НАН України, 2016) Ведь, Марина Віталіївна; Сахненко, Микола Дмитрович; Овчаренко, Ольга Олександрівна; Зюбанова, Світлана Іванівна; Горохівський, Андрій Сергійович; Каракуркчі, Ганна Володимирівна; Славкова, Марина
The results of the research aimed to establish a patterns of electrochemical synthesis coatings both mono- and doped oxides in the modes of plasma electrolytic oxidation (PEO), as well as composite systems of metal matrix reinforced with an oxide phasearepresented. The influence of external conditions and internal factors on the structure, element composition, morphology and operating properties of the obtained materials is analyzed. It was established that the composition, surfacemorphology and functional properties of oxide coatings on titanium and aluminum alloys depend on the composition of electrolytes andoxidation mode. It is proved the possibility obtaining multicomponent oxide coatings with high adhesionin one-stageusing PEO. Doping of a titanium matrix with zirconium and zinc oxides allows to raise essentially their photocatalytic properties both due to the formation of large globules on the smoothed surface of mixed oxide systems Ti/TiOₓ, ZnO and Ti/TiOₓ, ZrO₂ containing dopant to 3 at.% in terms of metal, as well as by the synergetic effect. Increased corrosion and abrasion resistance for PEO systems Ti/TiOₓ, ZrO₂ is caused by chemical properties of the dopant and uniform micro globular surface morphology. It is found that mixed oxides coatings systems Al/Al₂O₃, CoOₓ and Al/Al₂O₃, MnOₓ, CoOₓ as promising materials for heterogeneous catalysis can be prepared by electrochemical technology on metal substrates in PEO mode. It was noted increase of their corrosion and abrasion resistance in comparison with Al/Al₂O₃ caused by homogenization of the surface layer and the formation of smooth micro globular structure. The system Al/Al₂O₃, MnOₓ, CoOₓ identified the highest catalytic properties with the total content of the dopants to 6 at.% in a bench test of the diesel engine in the forced modes reduces fuel consumption by 1-3%, decreases NOₓ emissions and substantially improves environmental performance. Composite coatings based on electrochemical metal copper and nickel matrices reinforced by 1,5 at.% nano-sized particles of the hardening phase Al₂O₃, have a significantly higher physical and mechanical properties – micro-hardness, tensile strength and yield strength compared with monometallic materials. It is found that one of the factors contributing to almost doubling of these characteristics is a decrease in the grain size which also improves corrosion resistance of the coatings in spite of their heterogeneity.
Плазмово-електролітичний синтез гетерооксидних покривів на високолегованих сплавах алюмінію
(Фізико-механічний інститут ім. Г. В. Карпенка НАН України, 2018) Сахненко, Микола Дмитрович; Каракуркчі, Ганна Володимирівна; Ведь, Марина Віталіївна; Ярошок, Тамара Петрівна; Руднєва, Світлана Іванівна; Горохівський, Андрій Сергійович
The scientific principles of control of the composition of heteroxide coatings on aluminum alloys with transition metals are substantiated by varying the formulation of electrolytes, modes and parametersof synthesis by the method of plasma-electrolytic oxidation (PEO). The results of the research aimed to establish a patterns of electrochemical synthesis coatings both mono- and doped oxides in the modes of PEO. The influence of external conditions and internal factors on the structure, element composition, morphology and operating properties of the obtained materials is analyzed. It was established that the composition, surfacemorphology and functional properties of oxide coatings on aluminum alloys depend on the composition of electrolytes andoxidation mode. It is proved the possibility obtaining multicomponent oxide coatings with high adhesionin one-stageusing PEO. It was established that the inclusion of cobalt on the oxide coatings on the aluminumalloy АК12М2МgN leads to formation of a mosaic three–dimensional surface structure, in which the PEO coating contain maximum of cobalt. It is found that mixed oxides coatings systems Al/Al₂O₃, CoOᵧ and Al/Al₂O₃, MnOᵧ, CoOᵧ as promising materials for heterogeneous catalysis can be prepared by electrochemical technology on metal substrates in PEO mode. According to the spectroscopy of the electrode impedance, equivalent schemes of substitution of hetero-oxide systems in different acidity medium have been established. Parameters of multicomponent oxide coatings have been determined, based on which the deep and current corrosion rates have been calculated. It was noted increase of their corrosion resistance in comparison with Al/Al₂O₃ caused by homogenization of the surface layer and the formation of smooth micro globular structure. The system Al/Al₂O₃, MnOᵧ, CoOᵧ identified the highest catalytic properties with the total content of the dopants to 6 at.% in a bench test of the diesel engine in the forced modes reduces fuel consumption.
Study of the influence of oxidizing parameters on the composition and morphology of Al₂O₃·CoOₓ coatings on AL25 alloy
(Технологический центр, 2018) Karakurkchi, A.; Sakhnenko, M.; Ved, M.
The influence of operating parameters of plasma-electrolytic oxidation in diphosphate cobalt-containing electrolyte on the process of formation of oxide coatings on alumosilicon alloy AL25 (GOST 1583) was studied. It was shown that inclusion of cobalt into the composition of surface oxide layers leads to a change of morphology and topography of the surface. Variation of current density and PEO time allows flexible control of the process of incorporation of the catalytic component into the matrix of oxide of basic metal. It was shown that at an increase in oxidation time, cobalt content in the surface oxide layer increases. The rational mode of plasma-electrolytic treatment of piston alloy in diphosphate electrolyte for obtaining oxide coatings, enriched with cobalt, was substantiated. It is advisable to perform formation of PEO-coatings on AL25 with developed globular-mosaic surface, maximum cobalt content, with minimizing impurities in the range of current densities of 3–5 A/dm² within 20–40 min. The obtained cobalt-containing oxide coatings can be used in the air and water purification systems, specifically, for intracylinder catalysis of gas emissions of internal combustion engines.
Study into formation of cobalt-containing peo-coatings on AK12M2MgN from a pyrophosphate electrolyte
(Технологический центр, 2017) Karakurkchi, A.; Sakhnenko, M.; Ved, M.; Horokhivskyi, A.; Galak, A.
We studied the process of formation of cobalt-containing oxide coatings using plasma-electrolytic oxidizing of the aluminum alloy AK12M2MgN in pyrophosphate electrolytes. It was established that the use of given type solutions contributes the homogenization of silumin surface and creates preconditions for the dopants incorporation to the growing oxide coating. It is shown that PEO parameters depend on the concentration ratio of cobalt sulfate and potassium pyrophosphate in a working solution. Based on the results of experimental study, we demonstrated the ways to control the structure and surface morphology of cobalt-containing PEO coatings through the variation in the concentrations of electrolyte components. The composition of a pyrophosphate electrolyte for the formation of oxide PEO-coatings with a high cobalt content and developed surface morphology is substantiated. It is noted that the obtained oxide coatings could be used in catalytic reactions in order to decompose natural and technogenic toxicants.
Surface analysis of Fe-Co-Mo electrolytic coatings
(IOP Publishing Ltd, 2017) Yar-Mukhamedova, G. Sh.; Sakhnenko, N. D.; Ved, M. V.; Yermolenko, I. Yu.; Zyubanova, S. I.
Coatings Fe-Co-Mo with a composition of 47 at.% iron, 28 at.% Cobalt and 25 at.% Molybdenum were deposited from citrate electrolyte using pulse electrolysis mode. Scanning electron and atomic force microscopy have established the surface morphology and topography. It was identified the parts with a globular structure which have an average size of 0.2-0.5μm and singly located sharp grains. Within the same scan area sites with developed surface were detected the topography of which is identical to the crystal structure of cobalt with the crystallites size of 0.2–1.75μm. The parameters Ra and Rq for parts with different morphology as well as average characteristics of coatings demonstrated the low roughness of the surface. It is found that the coercive force of Fe-Co-Mo films is 7-10 Oe, which allow us to classify the Fe-Co-Mo coatings as soft magnetic materials.
Особливості одержання металоксидних каталітичних систем плазмово-електролітичним оксидуванням алюмінію та титану в пірофосфатних електролітах
(НТУ "ХПІ", 2016) Сахненко, Микола Дмитрович; Ведь, Марина Віталіївна; Каракуркчі, Ганна Володимирівна; Горохівський, Андрій Сергійович; Галак, Олександр Валентинович
В роботі розглянуті особливості формування конверсійних покривів на сплавах алюмінію та титану методом плазмово-електролітичного оксидування у пірофосфатних електролітах. Досліджено вплив концентрації і співвідношення компонентів електроліту та режимів обробки на склад та морфологію поверхневих шарів. Визначено чинники, які забезпечують каталітичні властивості окремих і змішаних оксидних систем та окреслено перспективи їх використання у технологіях знешкодження токсичних речовин.