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The work is presented by the V. I. Vernad­skii Institute of General and Inorganic Chemi­stry of the National Academy of Sciences of Ukraine for the State Prize of Ukraine in the field of science and technology. A new paradigm of the processes of electrochemical synthesis of functional materials has been created on the basis of the proposed theory of discharge-ionization of electrochemically active complexes and the laws of correlation between the functional properties of coatings and the fundamental characteristics and parameters of electrochemical kinetics. New approaches of surface engineering to the electrochemical synthesis and processing of materials that are capable of operating under extreme thermomechanical conditions under the simultaneous action of an aggressive medium have been developed. Innovatively promising technologies have been proposed for the formation of nanomaterials of new generation based on superalloys, metal oxide composites, photosensitive hetero- and nanostructures, electrically conductive polymers and their composites, etc. The main research directions in this work concern electrochemistry, both directly the me­thod for the synthesis of new materials and the study and design of the electrochemical pro­perties of materials / coatings / nanoparticles that cannot be obtained by other methods. The aim of the work was to develop the theoretical foundations of directed synthesis and to create a wide range of new competitive materials and systems on the basis of establishing the structural and functional patterns of their electrochemi­cal formation. А number of novel compe­titive electrochemical materials (electrode and electrolyte materials for electrochemical po­wer sources and supercapacitors, electro- and photocatalysts, sorption and optical materials, functional coatings, etc.) have been created as a result of the performed research. These materials are used in various fields of science and technology, namely, for alternative po­wer ge­neration, electrochemical power sources, nano- and microelectronics, electrochromic systems, electrocatalysis, ecosensorics, electro­chemical synthesis of commercial products, photoelectrochemical systems, corrosion protection. The number of publications: 700, including 30 monographs (7 of them published abroad) and 39 chapters in collective monographs (30 of them published abroad), 36 textbooks (manuals), and 500 articles (350 of them published in foreign periodicals). The total number of refe­rences to the publications of the authors/h-index/i10-index (regarding the whole work) according to the databases is, respectively: Web of Science, 1856/21/52; Scopus, 2185/22/71; Google Scholar, 4903/33/148. The novelty and competitiveness of the technical solutions are protected by 33 valid patents (7 patents of Kazakhstan, China, USA). Eight doctoral dissertations (DSc) and 47 candidate's dissertations (PhD theses) on this subject matter have been defended.

We study the corrosion behaviors of electrolytic composite coatings based on ternary cobalt alloys under different conditions and analyze the distribution of metals over the thickness of the coating and the parameters of their surface roughness. The accumulated results show that, in alkaline and neutral media, the corrosion potentials shift in the negative direction as compared with the potentials measured in an acid media but corrosion resistance does not undergo any significant changes. This can be explained by the fact that tungsten and molybdenum oxides formed on the surface are unstable in alkaline media. In view of the fact that in neutral solutions, the subsurface layer becomes alkaline due to the reduction of oxygen and chlorides provoke local fractures of the protective film, we can assert that alloying metals exert a synergistic effect on the rate of corrosion of the composites. According to the computed values of the depth indicator of corrosion rate, the analyzed coatings can be referred to the group of highly resistant, whereas the composites based on Co64Mo33Zr3 alloy in neutral and alkaline media belong to the group of very stable materials. This opens wide possibilities for their application as protective coatings on metals in aggressive media.

The processes of plasma-electrolytic formation of heteroxide coatings on titanium alloys for the photocatalytic disintegration of natural and technogenic toxicants are studied. Synthesis of coatings was carried out from aqueous diphosphate solutions in the galvanostatic mode. For a quantitative description of photocatalytic reactions, reaction rate constants were calculated from the linearized dependences lnCt/C0, where Ct is the current concentration of the azodye and C0 is the initial concentration of the reactant. The surface morphology of the coatings was studied by atomic force microscopy and visualized the results by reconstructing the relief in the form of 2D and 3D topographic maps. The morphological features of titanium (IV) oxide coatings and heteroxide composites containing zinc and / or copper oxides are analyzed. It has been shown that the specific surface remains an effective factor in controlling the photocatalytic activity of coatings; therefore, the establishment of the morphology of heteroxide composites, as well as methods for controlling this parameter of the target product, is an invariable component of a systematic study of such materials when establishing their functional properties. It is established that, in comparison with titanium oxide coatings, whose surface layers are characterized by toroidal mesostructures, heteroxide compositions have a more developed surface, which positively affects their functional properties. Subsequent heat treatment also has the same effect on coating properties. The rate constants of the photocatalytic decomposition of the methyl orange azodye, determined under similar conditions, were used to rank coatings of various compositions according to their functional properties. Thus, for the reaction on the surface of titanium oxide, the rate constant is 1.56∙10–3 min–1, while for the heterooxide layer TiO2·ZnO it increases to 5.8∙10–3 min–1. The coating of TiO2·ZnO is the most catalytically active, although the TiO2·ZnO·CuO system also accelerates the decomposition process with a degree of degradation of 25% for 60 minutes, further, the efficiency of the catalyst decreases.

possibility of electrosynthesis and control of the composition and surface morphology of the composite electrolytic coatings of cobalt with refractory metals by varying the pulse current density has been proved. Composites deposited on copper substrate from biligand citrate-pyrophosphate electrolytes at 4 A/dm 2 are distinguished by a developed surface and a more uniform distribution of components on the surface, increased tungsten content, almost 5 times higher than coatings deposited at 10 A/dm 2 , and a half reduction in oxygen percentage (up to 5.5%). This is explained by the inhibition of the hydrogen gas evolution reaction and the participation of hydrogen ad-atoms in the chemical reduction of intermediate tungsten oxides to metal when polarization is interrupted. Coatings obtained using pulsed current can be considered as composites of the composition Co-W-ZrO 2 , in which the oxide phase is formed directly in the electrode process as an intermediate for the incomplete reduction of tungstates. The topography of the films is characterized by the presence of grains of elliptical and spherical shape with crystallite sizes of 80 – 180 nm. On the main surface there are protrusions (large grains) with a diameter of 1 – 3 microns. The fractal dimension of the surface is 2.77, which indicates the 3D crystal growth mechanism during coating formation. According to the surface roughness parameters Ra and Rq, coatings belong to the 9th roughness class. By phase composition, composites are predominantly amorphous materials, which include nanocrystalline cobalt and intermetallic compounds Co3W and Zr 3 Co. Due to the quantitative and phase composition, surface morphology and fractality, the microhardness and corrosion resistance of Co-W-ZrO 2 systems deposited at a current density of 4 А/dm 2 are 20% higher than the coatings obtained at 10 A/dm 2 , and 3 times higher than the corresponding characteristics of the substrate.

The possibility of electrosynthesis and control of the composition of galvanic coatings by alloys based on metals of the iron group with refractory metals, in particular molybdenum, from a complex citrate electrolyte by varying the electrolysis modes has been proved. It has been established that coatings with a high oxygen content are formed by direct current, namely, more molybdenum oxides are fixed in these coatings in comparison with coatings used in unipolar pulsed electrolysis. In the latter case, the oxygen content on the protrusions and depressions is much lower and is respectively 21 at.% And 25 at.%. It was shown that during pulsed electrolysis, the content of the metal form of molybdenum is higher as a result of the reduction of molybdenum oxides with intermediate oxidation levels by hydrogen ad-atoms, which are formed in the partial cathodic reaction. The reduction occurs due to the spillover effect, the implementation of which is most effective during a current interruption. The formation of the oxide phase of inclusions directly during electrolysis without introducing it into the electrolyte as a second phase is justified. Depending on the completeness of this process, conditions are created for the formation of a metal coating from ternary alloys or metal oxide composites, the second phase of which consists of molybdenum oxides of an intermediate oxidation state, that is, a process is formed directly in the electrode. According to the results of atomic force microscopy, it was found that coatings synthesized in the galvanostatic mode can be classified as composite electrolytic materials, and the cathode deposit obtained as a result of unsteady electrolysis can be attributed to metal. The doped coatings obtained in a pulsed mode are characterized by lower porosity. The surface free energy for metal and composite coatings was calculated, the values of which are 127.74 mJ/m2 and 118.10 mJ/m2. When testing the electrocatalytic activity of Fe-Co-Mo ternary alloys in the reaction of electrolytic hydrogen evolution, high values of the hydrogen exchange current density were obtained both for metal and composite coatings.

We propose efficient regimes of the formation of mixed-oxide conversion coatings by plasma-electrolytic oxidation (PEO) of aluminum alloys in pyrophosphate and alkaline electrolytes. It is shown that the variations of the concentrations of electrolyte components and the parameters of PEO (current density and the duration of treatment) lead to the appearance of oxide coatings formed by the material of the metal matrix and oxides of transition metals of various compositions and morphologies, which definitely affect their functional properties. Mixed oxide coatings formed as a result of PEO are characterized by microglobular structures, small sizes of conglomerates, and elevated microhardness. Moreover, they are corrosion and wear resistant. In view of the microglobular structure of the surface and the composition of Al Al2O3·MnOx and Al Al2O3·CoOx oxide coatings, we can expect that the obtained materials may exhibit catalytic activity in the redox reactions with participation of oxygen and, in particular, in the working processes running in internal-combustion engines.

The process of mixed oxide coatings formation on a high-silicon aluminum alloy in a cobalt-containing pyrophosphate electrolyte by the plasma-electrolytic oxidation (PEO) method is studied. It was shown that AL25 chemical composition heterogeneity causes the consumption of a part of the anode current to homogenize the treated surface, which is reflected in minimizing the content of doping components at the initial processing stage. It was established that the growth of mixed oxides Al2O3·CoxOy relative mass is a function of time with a maximum at 55 minutes. The chemical, phase composition and surface morphology of the formed oxide layer depend on the oxidation time. The catalytic component content in the surface oxides varies from 0.2 to 23.3 at.% with an increase in processing time of 10 to 60 minutes. Maximum cobalt incorporation into the oxide layer occurs at PEO of 35–50 minutes, while the silicon content in the surface layers does not exceed 2 at.%, which is favorable for the catalytic properties. The cobalt oxide, preferably Co3O4, incorporation in the alumina α-Al2O3 matrix is visualized by the blue-violet color steroidal surface structures in the sites of micro-arc discharges. The alumina cobalt oxide mixture layers are characterized by a developed micro-globular surface which consists of spheroid conglomerate with an average size of 1–2 microns. There are some amorphous phases in the structure of mixed oxides due to non-equilibrium PEO conditions. The set of detected factors is a prerequisite for the high catalytic properties of oxide coatings. A promising field of Al2O3·CoxOy systems application is intra-cylinder catalysis in internal combustion engines.

The ternary Co–Mo–W(Zr) coatings with total content of refractory metals of 30–40 wt.%, and Co–W–Zr alloys (12–26 wt.%) are deposited from pyrophosphate-citrate electrolytes in pulse regime. The composition of the coatings as well as the surface morphology depends on the current density. The X-ray diffraction patterns reflect the amorphous-and-crystalline ternary alloys structure. Phases of α-Co, Co–Mo intermetallic compounds, and traces of metallic molybdenum were detected in the Co–Mo–Zr coatings. Phase composition of Co–Mo–W deposits differs by emergence of Co7W6 phase and traces of metallic tungsten, and there is no metallic W in Co–W–Zr electrolytic alloys. The corrosion behavior of ternary coatings in alkaline medium studied by EIS shows that Co–Mo–Zr alloys are characterized by highest corrosion resistance among deposited coatings due to presence of metallic molybdenum and stoichiometric ZrO2 with both high electrical resistivity and chemical stability. The coatings Co–Mo–W and Co–Mo–Zr containing phases of Mo or W are characterized by higher corrosion resistance as compared with that without metallic molybdenum and tungsten. The cyclic voltammetry data confirm stability of ternary coatings in alkaline solution under anodic polarization. Such properties as well as the developed globular surface make materials promising for use as anodes in fuel cells in particular based on alkali electrolytes.

The patterns of changes in the morphology and strength characteristics of oxide coatings for the aluminum alloy AD-0 under conditions of different duration of plasma-electrolytic oxidation in a 1.0 M alkaline electrolyte K 4 P 2 O 7 solution have been established. The changing of the molding voltage has a classic view – four stages, the first three (pre-spark, spark, microarc) contributes to the gradual hardening of the alloy surface, and at the fourth (arc) stage microhardness decreases and becomes instable, as well as delamination of the surface layer occurs. According to the experiment, the best combination of the PEO coating properties (microhardness H V = 109.98 kg/mm 2 , maximum homogeneity, no surface roughness) is reached at an initial current density of i = 5 A/dm 2 , followed, in 9 minutes, reducing up to i = 3 A/dm 2 to maintain the process in the microarc mode; the total duration of treatment is 11 – 13 min. In doing so the hardness of the oxide layer surface in comparison with the unprotected alloy increases up to four times. The study of the influence of temperature and heat treatment time indicates that the resulting oxide coatings are not recommended to be used as hard and wear-resistant at temperatures above 300 °C. The research of the surface morphology of the samples shows that in the process of PEO a fine-grained structure is formed, which with a prolonged processing time tends to enlarge and agglomerate the cells. With a 10 min. duration of oxidation the formed oxide coating has a light gray color, its surface is uniform, which is explained by the incorporation of phosphates from the working electrolyte solution into the defective structure of the surface. However, the transition to the arc mode with a duration of oxidation more than 13 min. leads to substantial roughness and heterogeneity of the coating structure. The aggregate of the identified factors indicates the prospect of the research direction, further work will be aimed at obtaining oxide coatings with desired functional properties for aluminum alloys in various electrolytes with a minimum duration of oxidation.

Встановлено вплив режимів електролізу на склад і морфологію поверхні бінарних Co(Fe)-W і тернарних Fe-Co-W сплавів. Доведено, що нанесені в імпульсному режимі покриви бінарними сплавами відрізняються більш рівномірним розподілом компонентів по поверхні, меншим вмістом оксигену і глобулярною морфологією. Це пояснюється особливостями електрокристалізації сплавів в умовах нестаціонарного електролізу: під час імпульсу відбувається відновлення Fe 3+ до Fe 2+ , а оксовольфраматів – до оксидів вольфраму у проміжному ступені окиснення. В період паузи реалізуються процеси адсорбції реагентів, відновлення Fe 2+ до металічного стану, хімічного відновлення проміжних оксидів вольфраму ад-атомами гідрогену та хімічна реакція вивільнення лігандів. Застосування імпульсного струму дозволяє осаджувати тернарні Fe-Co-W з більш рівномірною поверхнею і розширити діапазон вмісту тугоплавкого компоненту в сплаві, а вихід за струмом процесу підвищується практично вдвічі до 70 – 75 % порівняно із гальваностатичним. Показано, що за фазовим складом бінарні покриви є твердими розчинами вольфраму в α-Fe або α-Co, тоді як тернарний Fe-Co-W є аморфно-кристалічним і містить фази інтерметалідів Co 7 W 6 і Fe 7 W 6 , а також α-Fe та цементиту Fe 3 C. Доведено можливість керування складом і морфологією поверхні вольфрамвмісних покривів із залізом та/або кобальтом застосуванням різних режимів та параметрів електролізу – постійного та імпульсного струму з варіюванням густини струму, тривалості імпульсу/паузи. Імпульсний електроліз сприяє підвищенню вмісту тугоплавкого компоненту та ефективності електролізу. Електролітичні сплави переважають за мікротвердістю основу зі сталі у 3–4 рази, причому підвищення вмісту вольфраму забезпечує підвищення механічних характеристик, за рахунок утворення інтерметалідів та аморфної структури покривів. За показниками покриви сплавами Co(Fe)-W і Fe-Co-W можуть ефективно використовуватись для зміцнення поверхонь зі сталі та чавуну, а також у ремонтних технологіях для відновлення спрацьованих деталей з наданням поверхні підвищених фізико-механічних властивостей.

The electrolysis modes affect on the quantitative and phase composition of the ternary Fe-Co-W and Fe-Co-Mo coatings is studied. It was established that the distribution of refractory components over the thickness of the coating varies in the opposite way with increasing duration of electrolysis – the molybdenum content increases and the tungsten one decreases. Amorphous-crystalline structure of alloys has been visualized by X-ray spectroscopy, including inter-metallic phases Co7W6, Fe7W6, Fe7Mo, Fe7Co, FeCo along with α-Fe and Fe3C. The size of coherent-scattering region of the amorphous part is of 6–8 nm. The formation of metallic tungsten and molybdenum additional phases has been detected for alloys deposited at pulse current which contributes microhardness Hμ increase up to 700 compared with direct current mode. Magnetic characteristics of Fe-Co-W(Mo) films were measured depending of deposition time. It was concluded that the content of magnetic phases in upper layers of Fe-Co-W deposits is higher than in the bottom ones and superior Fe-Co-Mo coatings. It qualitatively corresponds to W(Mo) content changes over the thickness.

Analyzing of composition electrolytic coatings’ application for the metal surface protection is considered. It is established that using different components for coatings’ modification gives possibility to obtain surfaces with expanding exploitation properties, in particular, with improved wearing and anticorrosion resistance. The new approach for protecting details which are made from cast irons by obtaining two kinds of composition coatings from binary alloys iron-molybdenum and iron-tungsten is proposed. It is found that the modification of iron by refractory metals up to 37 wt. % leads to a noticeable change in the microstructure of the coatings’ surface. It is established that the incorporation of refractory metals into the iron matrix is a good way to increase the microhardness of the surface by 2.5–3.5 times and rising of the wear resistance by 40%, as well as decreasing the friction coefficient by 3-4 times in comparison with the cast iron substrate. The research results can be used for surfaces hardening and protection in different industries.

This chapter introduces the investigation of Al alloys plasma electrolytic oxidizing (PEO) and analysis of process characteristics. The research directs to set regularity of electrochemical obtaining (forming or formation) of nanostructured coatings mono- and mixed oxides which are incorporated with transition metals namely manganese. It is shown that the alloys surface and bulk composition heterogeneity complicates the alloys processing to produce a uniform layer of oxides. Electrolytes containing K4P2O7 and KOH as the basic component were used to homogenize the outer surface layer of aluminum alloys and to form uniform conversion covers, predominantly oxides. PEO in these electrolytes in the range of current densities 5…20 A/dm2 allows obtaining mixed oxide coatings which contained both matrix and doping metal oxides. It was found that the rising of both the permanganate concentration in the electrolyte and current density of treatment allows to enrich the surface layer of the coatings with oxides. The X-ray analysis confirms the incorporation of MnOx into the matrix of aluminum oxide. The modes for PEO of aluminum alloys have been proposed for producing conversion coatings containing Mn up to 36 wt%. Mixed oxide covers exhibit a developed surface and increased catalytic properties and corrosion stability. The complex of functional properties determines the possibility of their usage as promising materials for emission control technologies and also in systems of ICE waste gas purification.

Development of quantum selective sensors requires a detailed study of nature, kinetic parameters, and activation mechanisms of all phases of the cyclic switchover effect. Yanson point contact is the main tool to solve emerging tasks. When placed in an ion-conducting medium, it can function as an electrochemical gapless electrode system (GES). The transformations in the Yanson point-contact nanostructure are shaped by the quantum shell effect and the GES processes. We show that a GES in an electric field is as a system with a positive feedback which determines the dynamics of the point-contact resistance variation in an ion-conducting medium. Analysis of the experimental data on the dynamics of electric conductance and lifetime of dendritic Yanson point contacts during the cyclic switchover effect allows one to study the peculiarities of the processes that can enable the realization of the quantum mechanism of selective detection and lead to an enhanced sensitivity of point-contact sensors to liquid and gaseous analytes. A mathematical model for the anode destruction of dendritic copper point contacts during the cyclic switchover process is proposed and discussed.

The ternary Co–Mo–W (Zr) and Co–Fe–Mo coatings with the total content of refractory metals of 30–40 wt%, Co–W–Zr alloys with that of 12–26 wt% and Co–Fe–Mo are deposited from pyrophosphate–citrate electrolytes in pulse regime. The composition of the coatings as well as the surface morphology is shown to depend on the current density. A uniformly cone-shaped developed surface characterizing the coatings is due to the tungsten and molybdenum incorporation, but molybdenum-containing ternary coatings differs by the network of shallow cracks. The X-ray diffraction patterns reflect the amorphous and crystalline structure of ternary alloys. Phases of α-Co, intermetallic compounds Co3Mo, Co7Mo3, Co7Mo6, and traces of metallic molybdenum were detected in the coatings Co–Mo–Zr. The phase composition of Co–Mo–W deposits differs by the emergence of Co7W6 phase and traces of metallic tungsten, and there no any metallic W in the phase composition of Co–W–Zr electrolytic alloys. The corrosion behavior of the ternary coatings in alkaline medium studied by EIS shows the Co–Mo–Zr alloys are characterized by the highest corrosion resistance among the materials studied, and the results are more reproducible. Such behavior is due to the presence on the surface stoichiometric zirconium oxide ZrO2 with high both electrical resistivity and chemical stability. The coatings Co–Mo–W(Zr) and Co–Fe–Mo containing metallic phases of Mo or W are characterized by higher corrosion resistance. The mechanism and kinetics of electrolytic oxidation of methanol on electrodes with electrolytic ternary alloys coatings is determined. Based on the experiments carried out, we can conclude that the reaction of (CH3OH)S → (HCHO)S is the limiting stage, and it allows us to provide the process cycling and prevent the formation of carbon dioxide. The obtained data are indicative of a rather high electrocatalytic activity of ternary alloys, in particular, Co–Mo–Zr, for the reaction of methanol oxidation in the alkaline medium. Such catalytic properties can be explained by a higher degree of the surface branching, and the synergetic effect of the metals, in particular cobalt, molybdenum, and zirconium that are characterized by the different stable oxidation states and the affinity to oxygen.

Technological approaches to surface electrochemical treatment of aluminum alloys are analyzed. It is shown that directed modification of the carrier surface allows expanding the functional properties of the treated material. The mechanisms of treatment of aluminum alloys of different composition are investigated and technological models of processes using generalized phenomenological schemes are developed. Methods surface forming treatment of aluminum alloys by pulse current forming in chloride-containing electrolytes and plasma electrolytic oxidation in alkaline solutions of diphosphates are proposed. It is shown that the use of pulse electrolysis promotes the formation of a developed mesh and porous structure. Control methods and factors of the treatment process are generalized. The resulting systems can be used as carriers of catalytic material provided that a secondary catalytically active layer is applied. It is found that using plasma electrolytic oxidation, it is possible to change the shape and homogenize the surface layers of the carrier and apply a tightly adhered layer of catalytic material in one technological process. It is shown that the characteristic parameters of PEO depend on the composition of the treated material. It is revealed that the morphology and phase structure of surface oxide layers change during PEO. The formed oxide coatings consist of α-Al2O3 and have a high degree of surface development, which is a prerequisite for increasing their functional properties. The proposed approach can be used in surface engineering technology and for obtaining materials for environmentally friendly technologies, Проанализированы технологические подходы к поверхностной электрохимической обработке сплавов алюминия. Показано, что направленное модифицирование поверхности носителя позволяет расширить функциональные свойства обрабатываемого материала. Исследованы механизмы обработки сплавов алюминия различного состава и разработаны технологические модели процессов с использованием обобщенных феноменологических схем. Предложены способы поверхностной обработки сплавов алюминия путем формообразующей обработки импульсным током в хлорид-содержащих электролитах и плазменно-электролитного оксидирования в щелочных растворах дифосфатов. Показано, что использование импульсного электролиза способствует образованию развитой сетчатой и пористой структуры. Обобщены пути управления и факторы влияния на технологический процесс обработки. Полученные системы могут быть использованы как носители каталитического материала при условии нанесения вторичного каталитически активного слоя. Установлено, что с использование плазменно-электролитного оксидирования возможно в одном технологическом процессе изменить форму и гомогенизировать поверхностные слои носителя и нанести плотно адгезированный слой каталитического материала. Показано, что характеристические параметры ПЭО зависят от состава обрабатываемого материала. Установлено, что морфология и фазовая структура поверхностных оксидных слоев меняется в процессе ПЭО. Сформированные оксидные покрытия состоят из α-Al2O3 и имеют высокую степень развития поверхности, что является предпосылкой повышения их функциональных свойств. Предложенный подход может быть использован в технологии инженерии поверхности и для получения материалов для экотехнологий, Проаналізовано технологічні підходи до поверхневої електрохімічної обробки сплавів алюмінію. Показано, що спрямоване модифікування поверхні носія дозволяє розширити функціональні властивості оброблюваного матеріалу. Досліджено механізми обробки сплавів алюмінію різного складу та розроблено технологічні моделі процесів з використанням узагальнених феноменологічних схем. Запропоновано способи поверхневої обробки сплавів алюмінію шляхом формотвірної обробки імпульсним струмом у хлорид-вмісних електролітах та плазмо-електролітного оксидування у лужних розчинах дифосфатів. Показано, що використання імпульсного електролізу сприяє утворенню розвиненої сітчастої та поруватої структури. Узагальнено шляхи керування та фактори впливу на технологічний процес обробки. Одержані системи можуть бути використані як носії каталітичного матеріалу за умови нанесення вторинного каталітично-активного шару. Встановлено, що з використанням плазмо-електролітного оксидування можливо в одному технологічному процесі змінити форму і гомогенізувати поверхневі шари носія та нанести міцно адгезований шар каталітичного матеріалу. Показано, що характеристичні параметри ПЕО залежать від складу оброблювального матеріалу. Встановлено, що морфологія та фазова структура поверхневих оксидних шарів змінюється під час ПЕО. Сформовані оксидні покриття складаються із α-Al2O3 та мають високий ступінь розвинення поверхні, що є передумовою підвищення їх функціональних властивостей. Запропонований підхід може бути використаний в технології інженерії поверхні та для одержання матеріалів для екотехнологій

Доведено можливість електросинтезу і керування складом та морфологією поверхні композиційних електролітичних покривів (КЕП) кобальту з тугоплавкими металами варіюванням густини імпульсного струму. Композити на основі кобальту, осаджені на підкладку з міді з білігандних цитратно-пірофосфатних електролітів при густині імпульсного струму 4 А/дм2, відрізняються розгалуженою поверхнею і більш рівномірним розподілом компонентів по поверхні, підвищеним вмістом вольфраму, який майже у 5 разів більш ніж у покривах, осаджених при 10 А/дм2, та зниженням відсотку кисню удвічі (до 5,5 %). Це пояснюється гальмуванням реакції виділення газоподібного водню та участю ад-атомів водню у хімічному відновленні проміжних оксидів вольфраму до металу під час переривання поляризації. Покриви, осаджені із застосуванням імпульсного струму, можна вважати композитами складу Co-W-ZrO2, в яких оксидна фаза утворюється безпосередньо в електродному процесі як інтермедіат неповного відновлення вольфраматів. Топографія плівок відрізняється наявністю зерен еліптичної і сферичної форми з розмірами кристалітів 80 – 180 нм. На основній поверхні зустрічаються виступи (крупні зерна) діаметром 1 – 3 мкм. Фрактальна розмірність поверхні становить 2,77, що свідчить про 3D механізм росту кристалів при формуванні покриву. За параметрами шорсткості поверхні Ra і Rq покриви відносяться до 9 класу шорсткості. Завдяки кількісному складу, морфології й фрактальності поверхні мікротвердість і корозійна стійкість систем Co-W-ZrO2, одержаних за густини струму 4 А/дм2 на 20 % перевищують параметри покривів, одержаних при 10 А/дм2, і у 3 рази перевищує відповідні характеристики підкладки. Показано, що вольфрамвмісним КЕП притаманні каталітична активність у реакції окиснення етанолу і корозійна стійкість у середовищах різної кислотності., The possibility of electrosynthesis and control of the composition and surface morphology of the composite electrolytic coatings (CEC) of cobalt with refractory metals by varying the pulse current density has been proved. Composites deposited on copper substrate from biligand citrate-pyrophosphate electrolytes at 4 A/dm2 are distinguished by a developed surface and a more uniform distribution of components on the surface, increased tungsten content, almost 5 times higher than coatings deposited at 10 A/dm2, and a half reduction in oxygen percentage (up to 5.5%). This is explained by the inhibition of the hydrogen gas evolution reaction and the participation of hydrogen ad-atoms in the chemical reduction of intermediate tungsten oxides to metal when polarization is interrupted. Coatings obtained using pulsed current can be considered as composites of the composition Co-W-ZrO2, in which the oxide phase is formed directly in the electrode process as an intermediate for the incomplete reduction of tungstates. The topography of the films is characterized by the presence of grains of elliptical and spherical shape with crystallite sizes of 80 – 180 nm. On the main surface there are protrusions (large grains) with a diameter of 1–3 microns. The fractal dimension of the surface is 2.77, which indicates the 3D crystal growth mechanism during coating formation. According to the surface roughness parameters Ra and Rq, coatings belong to the 9th roughness class. Due to the quantitative composition, surface morphology and fractality, the microhardness and corrosion resistance of Co-W-ZrO2 systems deposited at a current density of 4 А/dm2 are 20% higher than the coatings obtained at 10 A/dm2, and 3 times higher than the corresponding characteristics of the substrate. It was shown the catalytic activity of tungsten containing CEC in ethanol oxidizing reaction and corrosion resistance in media of different acidity.

The structure and the properties of the oxide films formed on titanium by means of plasma electrolytic oxidizing at direct current density of 1 – 5 A·dm−2 have been studied. Composition of citrate-pyrophosphate electrolytes with addition of iron triad metals’ sulfates were proposed for the formation of mixed oxide systems with the varied content of dopants. The range of voltages for the single-stage plasma-electrolytic oxidizing of titanium alloys VT1-0 and OT4-1 is of 120–160 V, and operating voltage decreases with rising concentration of dopant ions. As a result of oxidizing, metal-oxide systems TiOx·MOy (M=Fe, Co, Ni) we obtained. The surface morphology of mixed oxides was found to depend on the nature of a dopant and change from micro-porous for TiOx·CoOy to globular for TiOx·NiO, and at least toroidal relief for TiOx·FeOy coatings. It was established that the formed mixed oxide coatings of titanium with the metals of iron triad possess significant corrosion resistance; the highest value is inherent to the systems based on cobalt. It is shown that the incorporation of iron triad metals into the composition of oxide layers leads to an increase in the surface development degree. Obtained oxide systems exhibit catalytic activity in the model reaction of carbon (II) oxide conversion.

The influence of electrodeposition modes on the quantitative and phase composition of the ternary alloys Fe-Co-Mo (W) has been established. The application of pulsed electrolysis provides increasing molybdenum (tungsten) content up to 15–20 at%, at current efficiency of 70–75 %. The analysis of the refractory metals distribution over the coating thickness indicates an increase in molybdenum and decrease in tungsten content with an increase in the electrolysis time. The content of alloying metals in the growing deposits was simulated. The globular developed surface of Fe-Co-Mo(W) coatings is caused by refractory metals incorporation. The results of X-ray diffraction analysis indicate the amorphous-crystalline structure of alloys and intermetallic phases of Fe7Mo, Fe7Co, FeCo, Co7W6, Fe7W6 along with α-Fe and Fe3C. The coherent-scattering region size of the amorphous part is 2–8 nm. The magnetic characteristics of amorphous Fe-Co-W coatings have been established to be depending on deposition time. The conclusion, that the content of magnetic phase in upper layers of coating is greater than in the bottom ones due to decreasing tungsten concentration has been made. The Fe-Co-Mo coatings have been shown to be soft magnetic due to the presence of ferromagnetic phases in the surface layers. The microhardness of ternary coatings deposited in the pulsed mode exceeds the characteristics of ones obtained by direct current and is not inferior to the coatings with hard chromium.

We study the influence of the concentrations of the components of citrate electrolytes based on Fe(III) and the modes of electrolysis on the composition of the Fe–Co–Mo, Fe–Co–W, and Fe–Mo–W coatings. It is shown that the formation of ternary alloys is realized by the mechanism of competitive reduction of cobalt and tungsten (molybdenum) with iron. As the concentration of a ligand increases, the coating is enriched with a refractory component. However, the opposite trend is observed as the current density increases. The application of the pulsed electrolysis makes it possible to increase the rate of the process and to enhance the current efficiency by 70–75%. The dependence of the morphology of deposits on the nature and content of refractory components is determined by the methods of scanning electron microscopy and X-ray diffraction spectral microanalysis. The influence of the compositions of ternary coatings on their corrosion resistance in media with different acidities and on the catalytic activity in the electrochemical reaction of hydrogen release is analyzed. By the methods of polarization resistance and electrode impedance spectroscopy, it is established that the corrosion resistance of the coatings is higher than for the substrate material by 1.3–2.0 orders of magnitude. The dependence of the nature of corrosion inhibition on the composition of electrolytic alloys is investigated.

Создание газових сенсоров на основе точечных контактов существенно расширяет научные и технические возможности улучшения метрологических параметров чувствительных элементов. В ряду этих возможностей перспективным является использование нових газочувствительных материалов, в частности, тернарных металлических сплавов. В состав тернарного сплава Co – Mo – W входят металлы, которые широко известны в газовой сенсорике, но благодаря синергетическим эффектам , возникающим при электролитическом сплавообразовании, можно ожидать усиления специфических поверхностных свойств синтезированнных материалов. С целью разработки средств медицинской диагностики изучалась смесь газов, выдыхаемых человеком. При действии этого биологического материала на точечный контакт, матеріалом канала проводи мости котрого был сплав Co – Mo – W, получали отклики в виде сложных зависимостей сопротивления от времени с высоким уровнем воспроизводимости. Результат дает перспективу использования системы в диагностических целях. Вторым объектом изучения был газообразный водород. Исследования поведения точечного контакта, созданного на базе сплава Co – Mo – W, в среде этого газа позволяют сделать вывод о возможности использования сплава для разработки сигнализатора взрывоопасных концентраций водорода. В целом, полученные данные свидетельствуют о способности точечных контактов на базе исследуемого сплава показывать высокую чувствительность как по отношению к водороду, так и по отношению к отдельным веществам сложных газовых смесей., The creation of gas sensors based on point contacts significantly expands the scientific and technical possibilities for improving the metrological parameters of sensitive elements. Among these possibilities, the use of new gas-sensitive materials, in particular, ternary metal alloys, is promising.The composition of the ternary alloy Co - Mo - W includes metals that are widely known in gas sensorics, but due to the synergistic effects arising from electrolytic alloying, we can expect an increase in the specific surface properties of the synthesized materials. In order to develop medical diagnostic tools, breath gas was studied. Under the action of this biological material on a point contact, the material of the conduction channel of which was the Co – Mo – W alloy, received responses in the form of complex dependences of resistance on time with a high level of reproducibility. The result gives the prospect of using the system for diagnostic purposes. The second object of study was gaseous hydrogen. Studies of the behavior of a point contact created on the basis of Co-Mo-W alloy in the medium of this gas allow us to conclude that the alloy can be used to develop an indicator of explosive hydrogen concentrations. In general, the obtained data indicate the ability of point contacts based on the alloy to exhibit high sensitivity both to hydrogen and to individual substances of complex gas mixtures., Створення газових сенсорів на основі точкових контактів суттєво поширює наукові і технічні можливості покращення метрологічних параметрів чутливих елементів. В ряду цих можливостей перспективним є використання новітніх газочутливих матеріалів, зокрема, тернарних металевих сплавів. До складу тернарного сплаву Co – Mo – W входять метали, які широко відомі у газовій сенсориці, але завдяки сінергетичним ефектам, які виникають при електролітичному сплавоутворенні, варто очікувати посилення специфічних поверхневих властивостей синтезованих матеріалів. З метою розробки заходів медичної діагностики вивченню підлягала суміш газів, яку видихає людина. При дії цього біологічного матеріалу на точковий контакт, матеріалом каналу провідності якого був сплав Co – Mo – W, отримували відгуки у вигляді складних залежностей опору у часі з високим рівнем відтворюваності. Результат дає перспективу використання системи в діагностичних цілях. Другим об’єктом вивчення був газоподібний водень. Дослідження поведінки точкового контакту, створеного на базі сплаву Co – Mo – W, у середовищі цього газу дозволяють зробити висновок про можливість застосування сплаву для розробки сигналізатора вибухонебезпечних концентрацій водню. В цілому отримані дані свідчать про здатність точкових контактів на базі сплаву, який досліджувався, показувати високу чутливість як до газоподібного водню, так і до окремих хімічних речовин складних газових сумішей.

Electrodeposition of binary and ternary coatings Co-Mo, Co-W and Co-Mo-W from bi-ligand citrate-pyrophosphate electrolyte has been investigated. The effect of both current density amplitude and pulse on/off time on quality, composition and surface morphology of the galvanic alloys was determined. Current density increase up to 10 A dm−2 has been established to lead to the higher content of refractory metals in all coatings at an acceptable process efficiency. The highest Mo and W content in deposits obtained at current density of 8–10 A dm−2 with on/off time of 5–20 ms. Improvement in mechanical properties and corrosion resistance of ternary Co-Mo-W deposits when compared with binary and main alloying metals is driven by uniform surface morphology and chemical composition as well as by amorphous structure. The Co-Mo-W deposits with total Mo and W content of 15–20 at.% are the most catalytically active for electrolytic hydrogen evolution out of different media and can be comparable with platinum electrodes in this regard. These properties prospect such alloys as catalytic layer for cathode materials in hydrogen production. A significant increase in the microhardness of ternary alloys with respect to binary alloys is associated with structural features, surface morphology and phase composition.

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/dm 2 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.

The structure and the properties of oxide films formed on titanium in the diphosphate based electrolytes by plasma electrolytic oxidation in the spark-discharge regime at application of inter-electrode voltage 100 to 130 V have been studied. A possibility to obtain oxide layers containing alloying elements by the modification of the composition of electrolytes has been stated. It was found that the chemical and phase composition as well as the topography, the microstructure and the grain size of the formed layers depend on the electrolyte composition, applied current density and inter-electrode voltage. The effect of the chemical composition of the formed mixed oxide films on the corrosion resistance and catalytic activity has been discussed.

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.

The object of research is the processes of the piston alloy AK12M2MgH treatment by the method of plasma electrolytic oxidation (PEO) with the formation of ceramic underlying coatings. One of the most problematic places is the influence of the chemical composition of the Al-Si alloy on the process of treatment and formation of ceramic coatings. It is established that electrochemical technologies are widely used to modify the surface of silumins by forming coating of various composition and purpose. In the course of the study it was shown that PEO of piston silumin should be carried out in alkaline complex electrolytes with the addition of manganese and/or cobalt salts. This makes it possible to homogenize the surface layer of the alloy by composition, to reduce the content of its alloying components and to create conditions for the formation of a uniform oxide coating with incorporation of the admissible components. It has been established that oxidation in pyrophosphate cobaltous solution allows obtaining mosaic structures of blue-violet color with cobalt content up to 24 at %. PEO silumin in the manganous alkaline electrolyte provides the formation of a brown-black ceramic-like layer with manganese content up to 35 at %. Consecutive PEO treatment in these solutions leads to the formation of a mixed fine-dispersed porous oxide coating with a total content of dopant 25–30 at %. Based on the research results, it has been proposed to oxidize the piston silumin in a regime of incident power to form uniform coatings with a high content of dopant. Obtained oxide systems have a developed surface and a significant content of catalytically active components. In comparison with the known methods of PEO treatment of piston silumin, the silicon content in the surface oxide layers does not exceed 3 at %, which is one of the requirements for catalytically active materials. The ceramics-like coatings show high catalytic activity in model oxidation reactions of CO and benzene and reduce the emission of toxic gas emissions from internal combustion engines. The proposed systems are promising for use in intracylindrical catalysis technologies and improving the fuel economy of engines.

By means of scanning electron microscopy, atomic-force microscopy, X-ray fluorescence analysis, and X-ray spectral microanalysis it was shown that, under plasma-electrolytic oxidation (PEO) of titanium alloys in pyrophosphate electrolytes, well-adhered oxide coatings with microglobular morphology result. It was demonstrated that the chemical and phase composition of the coatings, as well as the surface topography and grain size, can be controlled by changing the concentration of a pyrophosphate electrolyte and a PEO current density. It was established that the resulting oxide layer is highly resistant to abrasive wear and enhances the titanium corrosion resistance in model media (Ringer’s solution) substantially, which suggests that the coatings are promising for use in biological applications.

The effect of the electrolyte composition and the stationary electrolysis parameters on the composition and morphology of Fe–Mo and Fe–Co–Mo coatings deposited from complex citrate electrolytes based on Fe(III) is studied. It is shown that, at a constant component ratio of с(Fe3+): с(Co2+): с(MoO2− 4): с(Cit3–) = 2: 2: 1: 4, an increase in the electrolyte concentration leads to a decrease in the pH of the solution in a range of 4.85–4.30 and in the molybdenum content in the coating. An increase in the current density contributes to the molybdenum enrichment of the electrodeposited alloy in the entire range of electrolyte concentrations. The Fe–Mo alloy coatings have a rough microporous surface; an increase in the current density does not lead to significant changes in the surface topography. It is found that the formation of ternary coatings is characterized by the competitive reduction of iron and cobalt in the alloy; the molybdenum content depends on the current density. At a metal ratio of 3: 2: 1 and a molybdenum content of up to 17 at % in the Fe–Co–Mo alloy, the surface has a fine-grained needlelike structure typical of cobalt. With an increase in i c, the atomic fraction of molybdenum increases, while the surface becomes microglobular. The Fe–Co–Mo electrodeposits with a metal ratio of 2.5: 1.5: 1.0 and a molybdenum content of 19–20 at % have a more developed surface with a high density of spheroids.

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.

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(Fe 3+ ):с(Co 2+ ):с(MoO 4 2– ) = 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 R a and R q 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 .

Some methodological approaches to the selection of alloying components, optimization of the parameters of electrosynthesis, and the prediction of properties are analyzed on the example of binary and ternary alloys. We establish the influence of the energy parameters of electrolysis on the phase composition and surface morphology of galvanic alloys of the triad of iron (iron, nickel, and cobalt) with refractory metals, such as tungsten, molybdenum, and zirconium. The results of testing of the synthesized coatings are presented depending on their application, and the synergistic factors caused by the interaction of alloying elements are evaluated. The influence of the compositions of coatings on their corrosion resistance in environments with different acidities is investigated and the roles of each alloying component and the surface morphology are analyzed separately. We also propose and substantiate recommendations concerning the application of the studied materials in various branches of industry.

Approaches to the use of electrochemical coatings in surface treatment technologies are analyzed. It is shown that directed surface modification allows expanding the functional properties of the treated material, in particular, increasing the strength, wear resistance, corrosion resistance, catalytic activity.The method for treating non-alloy steel and cast irons by forming thin-film coatings of ternary alloys of iron and cobalt with molybdenum and tungsten is proposed. It is shown that the incorporation of refractory metals up to 37 at. % into the surface layer leads to a change in the phase structure of the coating. This is found to provide an increase in wear resistance by 40 %, microhardness by 2.5–3.5 times, as well as a decrease in friction coefficient by 3–4 times in comparison with the substrate material. The resulting materials can be used for hardening and protection of surfaces in various industries.To modify the surface of piston silumins, it is proposed to use the method of plasma electrolytic oxidizing with the formation of ceramic-like coatings. It is shown that in the galvanostatic mode, from alkaline electrolyte solutions containing manganese and cobalt salts, it is possible to obtain uniform, dense, highly adhesive to the base metal, oxide coatings, doped with catalytic components whose content varies within 25–35 at. %. It is shown that the morphology and phase structure of the surface layers changes with the incorporation of dopant metals. The formed coatings have a high degree of surface development, which is a prerequisite for enhancing their functional properties. The proposed approach is used to modify the surface of the KamAZ-740 piston. It is found that the use of ceramic-like coatings of the engine piston leads to a decrease in hourly fuel consumption and amount of toxic substances with exhaust gases, which makes them promising for use in in-cylinder catalysis., Проаналізовано підходи щодо застосування електрохімічних покривів в технологіях поверхневої обробки. Показано, що спрямоване модифікування поверхні дозволяє розширити функціональні властивості оброблюваного матеріалу, зокрема підвищити показники міцності, зносостійкості, корозійної тривкості, каталітичної активності.Запропоновано спосіб поверхневої обробки нелегованих сталей та чавунів шляхом формування тонкоплівкових покривів тернарними сплавами заліза та кобальту з молібденом і вольфрамом. Показано, що введення тугоплавких металів до 37 ат.% в поверхневий шар призводить до зміни фазової структури покриття. Виявлено, що це забезпечують підвищення зносостійкості на 40 %, мікротвердості у 2,5-3,5 рази, а також зменшення коефіцієнту тертя в 3-4 рази у порівнянні з матеріалом підкладки. Сформовані матеріали можуть бути використані для зміцнення і захисту поверхонь в різних галузях промисловості.Для модифікування поверхні поршневих силумінів запропоновано використовувати метод плазмово-електролітичного оксидування із формуванням керамікоподібних покривів. Показано, що в гальваностатичному режимі із лужних розчинів електролітів, що містять солі мангану та кобальту, можливо одержувати рівномірні щільні з високою адгезією до основного металу оксидні покриви, доповані каталітичними компонентами, вміст яких варіюється в межах 25–35 ат.%. Показано, що морфологія та фазова структура поверхневих шарів змінюється із інкорпорацією металів-допантів. Сформовані покриви мають високий ступінь розвинення поверхні, що є передумовою підвищення їх функціональних властивостей. Запропонований підхід використано для модифікування поверхні поршня КамАЗ-740. Встановлено, що використання керамікоподібних покривів поршня двигуна приводить до зниження годинної витрати палива та кількості токсичних речовин з відпрацьованими газами, що робить їх перспективними для використання у внутрішньоциліндровому каталізі, Проанализированы подходы по применению электрохимических покрытий в технологиях поверхностной обработки. Показано, что направленное модифицирование поверхности позволяет расширить функциональные свойства обрабатываемого материала, в частности повысить показатели прочности, износостойкости, коррозионной стойкости, каталитической активности.Предложен способ обработки нелегированной стали и чугунов путем формирования тонкопленочных покрытий тернарных сплавов железа и кобальта с молибденом и вольфрамом. Показано, что введение тугоплавких металлов до 37 ат.% в поверхностный слой приводит к изменению фазовой структуры покрытия. Установлено, что это обеспечивает повышение износостойкости на 40 %, микротвердости в 2,5-3,5 раза, а также уменьшение коэффициента трения в 3-4 раза по сравнению с материалом подложки. Полученные материалы могут быть использованы для упрочнения и защиты поверхностей в различных отраслях промышленности.Для модифицирования поверхности поршневых силуминов предложено использовать метод плазменно-электролитического оксидирования с формированием керамикоподобных покрытий. Показано, что в гальваностатическом режиме из щелочных растворов электролитов, содержащих соли марганца и кобальта, возможно получать равномерные плотные с высокой адгезией к основному металлу оксидные покрытия, допированных каталитическими компонентами, содержание которых варьируется в пределах 25-35 ат.%. Показано, что морфология и фазовая структура поверхностных слоев изменяется с инкорпорацией металлов-допантова. Сформированные покрытия имеют высокую степень развития поверхности, что является предпосылкой повыщения их функциональных свойств. Предложенный подход использован для модификации поверхности поршня КамАЗ-740. Установлено, что использование керамикоподобных покрытий поршня двигателя приводит к снижению часового расхода топлива и количества токсичных веществ с отработавшими газами, что делает их перспективными для использования во внутрицилиндровом катализе

Проведено огляд існуючих підходів використання методів інженерії поверхні деталей поршневої групи двигунів внутрішнього згоряння. Показано, що застосування процесів спрямованого модифікування поверхні дозволяє розширити функціональні властивості оброблюваного матеріалу, зокрема підвищити показники міцності, зносостійкості, корозійної тривкості. Як ефективний метод інженерії поверхні запропоновано використання плазмово-електролітичного оксидування в лужних електролітах. Особливості обробки матеріалу у високоенергетичних режимах під дією короткоживучих електричних розрядів полягають у формуванні наноструктурованих оксидних композиційних покривів під час електрохімічних та термохімічних реакцій. Завдяки особливостям перебігу плазмово-електролітична обробка може розглядатися як комбінований метод інженерії поверхні за рахунок поєднання в одному процесі модифікування поверхневого шару оброблюваного матеріалу та формування покриву з інкорпорацією компонентів електроліту та продуктів термохімічного перетворення. Запропоновано спосіб поверхневої обробки поршневого силуміну АК12М2МгН у лужних електролітах методом плазмово-електролітичного оксидування. Показано, що в гальваностатичному режимі із лужних розчинів електролітів, що містять солі мангану та кобальту, можливо одержувати рівномірні щільні міцноадгезовані з основним металом керамікоподібні покриви, доповані каталітичними компонентами, вміст яких варіюється в межах 25–35 ат.%. Показано, що морфологія та фазова структура поверхневих шарів змінюється із інкорпорацією металів-допантів. Сформовані покриви мають високий ступінь розвинення поверхні, що є передумовою високих функціональних властивостей сформованих керамікоподібних покривів. Запропонований підхід використано для модифікування поверхні поршня КамАЗ-740. Встановлено, що використання керамікоподібних покривів поршня двигуна приводить до зниження годинної витрати палива та кількості токсичних речовин з відпрацьованими газами, що робить їх перспективними для використання у внутрішньоциліндровому каталізі., A review of the existing approaches to the use of surface engineering methods for parts of a piston group of internal combustion engines was made. It is shown that the use of processes of directional surface modification allows you to expand the functional properties of the material being processed, in particular, to increase the indicators of strength, wear and corrosion resistance. As an effective method of surface engineering, the use of plasma-electrolytic oxidation in alkaline electrolytes has been proposed. The features of material processing in high-energy modes under the action of short-lived electrical discharges consist in the formation of nanostructured oxide composite coatings during electrochemical and thermochemical reactions. Due to its features, plasma-electrolytic treatment can be considered as a combined method of surface engineering by combining the surface layer of the material being processed in one process and forming coatings with the incorporation of electrolyte components and thermochemical conversion products. A method of treating piston silumin AK12M2MgN in alkaline electrolytes by the method of plasma-electrolytic oxidation is proposed. It is shown that in the galvanostatic mode from alkaline electrolyte solutions containing manganese and cobalt salts, it is possible to obtain uniform dense ceramic adhesives with high base metal adhesion, doped with catalytic components, the content of which varies from 25-35 at.%. It is shown that the morphology and phase structure of the surface layers changes upon incorporation of dopant metals. Formed coatings have a high degree of surface development, which is a prerequisite for enhanced functional properties of ceramic-like coatings. The proposed approach is used to modify the surface of the KamAZ-740 piston. It has been established that the use of ceramic-like coatings of an engine piston leads to a decrease in hourly fuel consumption and the amount of toxic substances with exhaust gases, which makes them promising for use in intra-cylinder catalysis.

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. Покрытия сплавами Fe-Mo-W и Fe-Mo получены из цитратных электролитов на основе железа (III) на подложках из стали и чугуна. Использование солей железа(III) существенно повышает стабильность электролита за счет элиминирования побочных анодных реакций. Установлено влияние соотношения концентраций и режимов электроосаждения на качество, химический состав и функциональные свойства сплавов. Показано, что полученные в импульсном режиме сплавы характеризуются более равномерной поверхностью, распределением компонентов и содержат меньше примесей. Повышение физико-механических свойств и коррозионной стойкости покрытий Fe-Mo и Fe-Mo-W по сравнению со сплавообразующими металлами и подложкой обусловлено химической инертностью компонентов и аморфной структурой сплава. Полученные покрытия можно рассматривать как перспективные материалы для упрочнения поверхности и восстановления деталей.

The influence of the modes of electrodeposition on the morphology, topography, and structure of the galvanic alloys of iron with molybdenum and tungsten is discussed. It is shown that the increase in the corrosion resistance of Fe–Mo and Fe–Mo–W coatings in acid and neutral chloride-containing media is caused both by the elevation of their passivating ability caused by the process of alloying components and by the formation of globular surfaces with homogeneous chemical composition. The microhardnesses of Fe–Mo and Fe–Mo–W galvanic alloys prove to be 2–3 times higher than the microhardnesses of the substrates made of low-alloy steel, which can be explained by the formation of amorphous structures. The results of investigations and tribological tests show that it is reasonable to apply the coatings of double and triple iron alloys in order to reduce wear in friction couples and to increase the corrosion resistance and mechanical strength of the surfaces, which makes them promising for the repair and restoration technologies. Изучено влияние методов электроосаждения на морфологию, топографию и структуру гальванических сплавов железа с молибденом и вольфрамом. Показано, что рост коррозионной стойкости покрытий Fe–Mo и Fe–Mo–W в кислых и нейтральных хлоридсодержащих средах обусловлен увеличением их способности к пассивации в присутствии легирующих компонентов и формированием глобулярной равномерной по составу поверхности. Микротвердость гальванических сплавов Fe–Mo и Fe–Mo–W возрастает в 2-3 раза по сравнению с показателем подложки из низколегированной стали за счет формирования аморфной структуры. Результаты исследований и трибологических тестов показали целесообразность применения двойных и тройных сплавов железа для снижения износа в парах трения и увеличения коррозионного сопротивления и механической прочности поверхностей, что делает их привлекательными для технологий восстановления и упрочнения поверхностей.

The electrodeposition theory aspects of the ternary iron alloys with refractory metals are discussed. The kinetic parameters and characteristic criteria of electrode reactions occurring during the formation of ternary Fe-Co-W(Мо) alloys have been defined. It was shown that hetero-nuclear complexes [FeHCitMеO4]− [СоНCitМеO4]2− (where Ме is Мо, W) and [FeHCit]+ and [CoCit]− complexes are involved in cathode processes. The oxometalates show step-by-step reduction producing tungsten (molybdenum) oxides of variable oxidation states that are reduced electrochemically and chemically by hydrogen adatoms. The competitive reduction of iron with cobalt and iron with tungsten at the Fe-Сo-W alloy deposition and the competitive reduction of cobalt with molybdenum into the Fe-Сo-Mo alloy were established. A mechanism of iron and cobalt with tungsten and/or molybdenum co-deposition into ternary alloys has been substantiated as a set of the coupled reactions of intermediate irreversible reduction with the limiting stage of electron transfer and the previous stage of ligand release. It was found that the pulse current allows formation of a more uniform coating surface and a significant decrease in the oxygen contained in the coatings compared with the direct current mode. X-ray phase analysis showed the amorphous and crystal structure of Fe-Co-W(Мо) alloys with a zone of coherent dispersion of 2–8 nm and intermetallic compounds Co7W6 and Fe7W6 in Fe-Co-W alloy and the inter-metallic phases Fe7Мо, Fe7Co, FeCo in the Fe-Co-Мо alloy. A change in the phase composition of Fe-Co-W alloys obtained by a pulse current was found that consists in the additional formation of crystalline tungsten phase and inter-metallic Fe2W. The X-ray patterns of Fe-Сo-Mo alloys visualize lines corresponding to crystalline cobalt and molybdenum, but the lines of inter-metallic iron compounds with cobalt are disappearing.

The influence of pyrophosphate cobalt-containing electrolyte composition and operating parameters of plasma-electrolytic oxidizing on the process of formation of oxide coatings on silumin was studied. It was established that the use of given type solutions contributes to the homogenization of silumin surface and creates preconditions for the dopant 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. The formation of PEO coatings on high-silicon silumin with a maximum content of cobalt at minimizing the impurities is expedient to carry out from the electrolyte with a composition of 0.4 mol/dm3 K4P2O7, 0.1 mol/dm3 CoSO4. The rational mode of plasma-electrolytic treatment of silumin in pyrophosphate electrolyte for obtaining oxide coatings, enriched with cobalt, was substantiated. It is advisable to perform formation of PEO coatings of developed globular-mosaic surface, with maximum cobalt content and minimizing impurities in the range of current densities of 3–5 A/dm2 within 20–40 minutes.

This paper presents the results of studies on the electrochemical treatment characteristics of aluminum and alloys in alkaline electrolytes. It is shown that the heterogeneity of the alloys composition complicates the formation of the surface oxide layer. To homogenize the treated surface and obtain oxide coatings doped with manganese and cobalt, electrolytes based on KOH and K4P2O7 with the addition of KMnO4 and CoSO4 were used. Plasma electrolytic oxidizing (PEO) in these electrolytes in the range of current densities 5–20 A/dm2 allows to obtain mixed oxide coatings which contained both aluminum oxide matrix and doping metal oxides Al2O3·MnOx and Al2O3·CoOy. It is shown that an increase in the PEO current density and the concentration of manganate- and cobalt(II) ions in the solution leads to an increase the content of dopant metals in the coatings outer layer. The incorporation of manganese and cobalt oxides in the composition of the surface layers was confirmed by the results of X-ray structural analysis. The rational modes of aluminum alloys PEO treatment were substantiated to obtain coatings with manganese and cobalt contents up to 25–40 аt.%. Formed oxide systems have a developed surface and high adhesion to the base metal and show an increased corrosion resistance and catalytic activity. This allows us to view them as promising materials for air- and water-cleaning technologies and internal combustion engine waste gas purification systems.

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.

Покриття TiO2 мають високу адгезію до поверхні. Будь-яку поверхню з нанесенням TiO2 легко позиціонувати для опромінення світлом, на відміну від порошків, які треба ще якось розмістити і зафіксувати на поверхні. Доведено, що на поверхні ТiO2 можуть бути окиснені (мінералізовані) практично будь-які органічні сполуки. На практиці будь-який фотокаталітичний очищувач повітря включає в себе пористий носій з нанесеним ТiO2, який опромінюється ультрафіолетовими променями і через який продувається повітря. Фотокаталіз придатний для побутового використання, оскільки може відбуватися при кімнатній температурі. Наприклад, термокаталітичний спосіб руйнування шкідливих речовин вимагає попереднього нагрівання повітря до температури понад 200°С. Фотокаталіз руйнує речовини, які проникають навіть через фільтри на основі активованого вугілля. Розглянуті особливості формування оксидних покривів плазмово-електролітичним оксидуванням сплавів титану. Запропоновано дообладнати конструкцію систем колективного захисту на бронетехніці та стаціонарних об'єктів додатковим встановленням у фільтр-поглинач мережки з нанесеним шаром каталітичного матеріалу, що буде нейтралізувати різні види небезпечних хімічних речовин за рахунок фотокаталітичного очищення повітря., TiO2 coatings have high adhesion to the surface. Any surface applied with TiO2 is easy to position for irradiation with light, in contrast to powders that need to be somehow placed and fixed on the surface. It has been proved that practically any organic compounds can be oxidized (mineralized) on the TiO2 surface. In practice, any photocatalytic air purifier includes a porous carrier with TiO2 deposited, which is irradiated with ultraviolet rays and through which the air is blown. Photocatalysis is suitable for household use, as it can occur at room temperature. For example, the thermocatalytic way of destroying harmful substances requires preheating of air to temperatures above 200 ° C. Photocatalysis destroys substances that penetrate even through activated carbon-based filters. Peculiarities of for mation of oxide coatings by plasma-electrolytic oxidation of titanium alloys are considered. Therefore, it is proposed to equip the design of collective defense systems on armored vehicles and stationary objects with the additional installation in a filter-sink of a network with a deposited layer of catalytic material that will neutralize various types of hazardous chemicals by photocatalytic purification of air by titanium oxides., Покрытие TiO2 обладает высокой адгезией к поверхности. Любую поверхность с нанесением TiO2 легко позиционировать для облучения светом, в отличие от порошков, которые надо еще как-то разместить и зафиксировать на поверхности. Доказано, что на поверхности ТiO2 могут быть окислены (минерализованы) практически любые органические соединения. На практике любой фотокаталитический очиститель воздуха включает в себя пористый носитель с нанесенным ТiO2, который облучается ультрафиолетовыми лучами и через который продувается воздух. Фотокатализ пригоден для бытового использования, так как может происходить при комнатной температуре. Например, термокаталитический способ разрушения вредных веществ требует предварительного нагрева воздуха до температуры свыше 200 ° С. Фотокатализ разрушает вещества, которые проникают даже через фильтры на основе активированного угля. Рассмотрены особенности формирования оксидных покрытий плазменно-электролитическим оксидированием сплавов титана. Предложено дооборудовать конструкцию систем коллективной защиты на бронетехнике и стационарных объектов дополнительным установлением в фильтр-поглотитель сетки с нанесенным слоем каталитического материала, который будет нейтрализовать различные виды опасных химических веществ за счет фотокаталитической очистки воздуха.

The paper discusses the preparation of cobalt and manganese oxide catalytic systems on cast piston aluminum alloy for intra-cylinder catalysis. It has been considered the features of the conversion coatings formation on silumin by plasma electrolytic oxidizing in alkaline electrolytes based on potassium pyrophosphate. The effect of the electrolyte components and processing conditions on the composition and the morphology of the surface layers has been studied. Plasma electrolytic oxidizing of internal combustion engines pistons allows the formation of alumina matrix containing manganese and cobalt oxides which evinces high catalytic properties. Manganese-containing oxide system demonstrates the highest fuel economy at 3–4 %. When using a piston with a cobalt oxides coating, toxic gas emissions are reduced: NO x within 10 % and CO - of 15–18 %. The proposed systems can find application in intra cylinder catalysis technologies in order to reduce the toxicity of gas emissions of engines and increase their fuel efficiency.