Irina Lukiyanchuk

Russian Academy of Sciences | RAS · Institute of Chemistry of Far-Eastern Bransh RAS

“La + Mn-containing TiO2-layer/Ti” composites were formed by plasma electrolytic oxidation in silicate electrolytes with dispersed particles of lanthanum manganite of different composition. The influence of solid-state synthesis temperature on phase composition and magnetic characteristics of lanthanum manganite powder has been studied. An increase...

FexCo1−xWO4 films on the titanium were formed by one-step plasma electrolytic oxidation in tungstate electrolytes containing Fe(II)-EDTA and/or Co(II)-EDTA anions. The resulting composites were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscop...

The Ti/TiO2 + ZrO2, Ti/TiO2 + CeOx, and Ti/TiO2 + CeOx + ZrO2 composites, including Y-doped ones, have been fabricated by one-stage plasma electrolytic oxidation (PEO) of titanium in aqueous electrolytes based on Zr(SO4)2 and/or Ce2(SO4)3 with and without additives of Y(CH3COO)2 at effective anodic current density of 0.05 A/cm² for 10 min. SEM, XRD...

Ti/TiO2-Sb-SbOx multifunctional sensors were obtained by plasma electrolytic oxidation in the anodic–cathodic mode. The resulting films contain TiO2 and up to 5 at.% Sb in the form of Sb⁰ and Sb6O13. Electrode functions E vs pH are linear in the range of pH 2 ÷ 10 with slopes of 68 ± 6 and 48 ± 2 mV·pH⁻¹ for sensors formed at iC/iA = 1 and 1.2, res...

Fe- and/or Co-containing coatings have been formed on titanium by plasma electrolytic oxidation (PEO) in electrolytes-sols with colloidal particles of Fe(III) and/or Co(II) compounds. The influence of the electrolyte formula has been studied on the coatings' composition, surface morphology, and magnetic properties. It has been established that the...

The coating with a porous structure, having a good adhesion to the substrate and containing titanium dioxide in the modifications of rutile and anatase, has been obtained by plasma electrolytic oxidation of VT1-0 technically pure titanium in a 0.1 M neutral aqueous solution of Na2SO4. Gold 10-nm-layer has been deposited on surface by electron-beam...

The catalytic properties of Ti/TiO2/NiWO4 + WO3 composites fabricated by plasma electrolytic oxidation (PEO) of titanium in a solution containing 0.1 mol/L Na2WO4 + 0.1 mol/L CH3COOH + 0.05 mol/L Ni(CH3COO)2 were studied in model reactions of peroxide oxidation of thiophene (T), dibenzothiophene (DBT), methylphenyl sulfide (MPhS), and pyridine (Py)...

The catalytic properties of W- and NiW-layered structures obtained by laser electrodispersion (LED) and plasma electrolytic oxidation (PEO) are investigated in oxidative desulfurization reactions. A comparative analysis of the effect of the composition, the concentration of the active phase, and the structure of the composites on the model reaction...

Fe-, Ni-containing coatings have been formed on aluminum and titanium by the plasma electrolytic oxidation (PEO) technique in slurry electrolytes containing colloidal particles of Fe(III) and Ni(II) compounds including hydroxides. Their composition, surface morphology, and magnetic properties were studied and compared. In both cases, the concentrat...

Titanium-supported oxide coatings with MWO4 (M = Cu, Ni, or Co) were formed by the single-stage plasma electrolytic oxidation of titanium in alkaline tungstate-phosphate electrolytes with M(II)–EDTA complex ions. All formed coatings exhibited photocatalytic activity in the reaction of degradation of methyl orange (10 mg/L MO, pH = 6.8) in the prese...

V-, P-containing coatings on titanium have been formed through one-step method of plasma electrolytic oxidation in aqueous electrolyte containing 0.049 mol/L Na6P6O18 and 0.095 mol/L NaVO3 (рН = 6) at different current densities and processing times. The coatings have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), ener...

The work continues a series of studies aimed at enhancing catalytic properties of metal fibers formed by the pendant drop melt extraction (PDME) method. In this paper, we show that deposition of the thin gold film on the metal fibers leads to a change in the catalytic performance of the samples under study. Au-coated fibers of titanium, zirconium a...

The paper considers approaches that can lead to the growth of micro-and nanocrystals on the surface of coatings formed on valve metals by plasma electrolytic oxidation (PEO). Among these approaches, there are the use of electrolytes-suspensions, the addition of organic compounds to the electrolytes, the thermal annealing of ‘PEO layer/metal’ compos...

Co-, W-, and P-containing oxide heterostructures on titanium substrates have been obtained by plasma electrolytic oxidation at current densities of 0.1 and 0.15 A/cm². The heterostructures have been studied by the X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Conglomerates of nanoparticles with an elemental...

A new type of solid-state metal-oxide pH sensor based on TiO2-MoOx films on titanium has been fabricated by plasma electrolytic oxidation in the anodic-cathodic mode. The structural features of the films have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). According to XPS...

Information on the anodizing of sintered powders (SP) of niobium is limited by the study of the growth of barrier-type fi lms. The formation of a nanostructured anodic oxide fi lm (AOF) on the surface of powder particles should lead to a noticeable increase in the specifi c surface of the sample and an increase in the chemical activity of the mater...

Titanium-supported oxide layers of W, W + Zn and W + Mn, formed by plasma electrolytic oxidation, were established to catalyze the peroxide oxidation of thiophene. The most active compositions based on Zn-W-containing PEO layers were also tested in the oxidation of a number of organosulfur compounds and diesel fuel desulfurization. Preliminary cove...

Information on the anodizing of sintered powders (SP) of niobium is limited by the study of the growth of barrier-type fi lms. The formation of a nanostructured anodic oxide fi lm (AOF) on the surface of powder particles should lead to a noticeable increase in the specifi c surface of the sample and an increase in the chemical activity of the m ate...

Thermal behavior of the surface of coatings formed on titanium specimens by plasma electrolytic oxidation (PEO) in phosphate—borate—tungstate electrolyte containing manganese acetate as a precursor was studied. High-temperature annealing in air allows directional obtaining of ensembles of nano- and microcrystals of definite composition and geometry...

The influence of the nature of valve metals on the ferromagnetic characteristics of oxide coatings formed by plasma electrolytic oxidation (PEO) was studied for the first time. The coatings were obtained under the same current and time conditions in an alkaline electrolyte with colloidal particles of Fe(III) and Co(II) hydroxides. The magnetization...

A comprehensive study of the magnetic behavior, morphology, and composition of Fe-containing oxide coatings on aluminum and titanium has been carried out to investigate the origin of their ferromagnetism. The coatings have been formed by the plasma electrolytic oxidation (PEO) technique in slurry electrolytes containing colloidal particles of iron(...

The effect of the temperature of annealing in air on the surface architecture and composition of oxide layers has been studied. Copper-enriched nanosized crystals of triangular shape are present on the surface at the annealing temperatures of 500–700°С. Rectangular nano- and microcrystals of a possible composition of NiWO4 are formed on the surface...

Sn-containing oxide coatings were prepared via plasma electrolytic oxidation (PEO) of Ti plate in the electrolytes with [Sn II -EDTA] ²⁻ complex anions or SnO 2 particles in the anode and anodic-cathodic modes. The coatings formed in electrolyte with SnO 2 particles stabilized by SAS contain SnO 2 and Sn ⁰ . In the electrolyte with [Sn-EDTA] ²⁻ com...

The oxide layers on titanium were formed by plasma electrolytic oxidation technique in acid aqueous electrolytes containing sodium tungstate and copper acetate. The coatings with WO 3 -CuO or WO 3 -CuWO 4 oxide layers have been formed in the electrolytes with H 2 C 2 O 4 (pH~6) or H 2 SO 4 (pH~4) accordingly. The coatings with WO 3 -CuWO 4 have a d...

The functional properties of oxide coatings on metals depend on the composition and structure of their surface. In this work, the change with temperature of air annealing of the surface of NiO + CuO/TiO2/Ti composites formed by the combination of plasma electrolytic oxidation of titanium in the phosphate-borate-tungstate electrolyte containing nick...

A catalyst for oxidation of carbon black based on potassium dititanate has been synthesized. The catalyst has been fabricated by impregnation of oxidized titanium surface additionally modified with a sublayer of anatase nanoparticles by potassium hydroxide. It has been shown that the synthesized composites exhibit high capacity for oxidation of die...

It has been shown that triangular nanocrystals with a thickness of ~ 50 nm and a height of ~ 500 nm, mainly containing copper oxides, are formed on the surface of Ni-and Cu-doped plasma electrolytic oxide (PEO) coatings on titanium during air annealing at 500-700 °C. Upon the annealing at 750-850 °C, rectangular nanoand micro-sized crystals presuma...

Oxide coatings formed on aluminum alloy in electrolyte with colloidal particles of iron hydroxides show ferromagnetic properties. Iron distribution have been studied using electron scanning microscopy and magnetic force microscopy. It is found that the iron localized in the areas exposed to spark and microarc electric discharges makes the main cont...

Ti/TiO 2 ,Au electrodes were prepared via plasma electrolytic oxidation (PEO) of Ti plate, followed by deposition of a thin (10 nm) Au layer by electron beam evaporation (EBE). The electrodes obtained were used for potentiometric indication of different types of chemical reactions. Ti/TiO 2 ,Au electrodes showed an excellent performance for end poi...

The data on the composition of polytetrafluoroethylene (PTFE) + Al2O3 coatings obtained on an aluminum alloy by the single-stage method of plasma electrolytic oxidation (PEO) are presented. The coatings are formed in an alkaline silicate electrolyte with introduction of dispersed PTFE particles stabilized with siloxane–acrylate emulsion. The compar...

The synthesis of catalyst K2Ti2O5 + K2Ti4O9/TiO2/TiO2 + SiO2/Ti for the oxidation of black carbon was carried out. The composition was prepared by the impregnation of an oxidized titanium surface with additionally modified sublayer consisted of anatase nanoparticles by potassium hydroxide. The initial and completion temperature of the catalytic soo...

Fe-containing oxide coatings fabricated by the plasma-electrolytic oxidation (PEO) method have been studied by means of scanning electron and magnetic force microscopy. The data comparison has demonstrated that ferromagnetic properties of the coatings are mainly associated with concentrating of iron in specific pores. A scheme has been suggested th...

Ferromagnetic oxide coatings were formed on aluminum alloy by the plasma-electrolytic oxidation technique in an electrolyte with colloidal particles of iron and cobalt hydroxides. Iron and cobalt are concentrated in the coating pores as a part of nanosized crystallites. The size of individual crystallites in the pores was ∼50–100 nm. The deficit of...

The catalytic activity of both copper fibers and copper-coated fibers of a diameter of 50–100 μm made of aluminum alloy, technical grade titanium, and FeCrAl alloy in CO oxidation has been estimated. Metal fibers have been fabricated by the method of pendant drop melt extraction (PDME). The fibers copper plating was carried out by chemical and elec...

A series of Ni- and/or Cu-containing coatings formed by plasma electrolytic oxidation on aluminum and titanium are examined by X-ray photoelectron spectroscopy. Binding energies of core electrons, elemental composition, chemical state of elements, and features of the structural organization of the surface and nearsurface layers of the coatings are...

The effect of iron sulfate and citrate addition into the base alkaline phosphate-borate-tungstate electrolyte on the peculiarities of plasma-electrolytic formation of coatings on titanium, their thickness, surface morphology, composition, and magnetic characteristics has been investigated. In the first electrolyte, dispersed particles of iron hydro...

The results of studies of the composition and magnetic characteristics of coatings formed in different time periods on titanium in suspension electrolytes of compositions Na3PO4 + Na2B4O7 + Na2WO4 + Fe2(C2O4)3 (PBWFe, рH 7.8) and Na2НPO4 + Na2B4O7 + Na2WO4 + Fe2(C2O4)3 (P*BWFe, рН 7.4), as well as the characteristics of coatings fabricated in filtr...

W-containing oxide layers fabricated on titanium and aluminum alloys by Plasma electrolytic oxidation (PEO) have been tested in the reaction of the peroxide oxidation of thiophene. Samples with two types of coatings have been investigated. Coatings I contained tungsten oxide in the matrix and on the surface of amorphous silica-titania or silica-alu...

The effect replacing Na3PO4 with Na2HPO4 in aqueous phosphate–borate–tungstate electrolyte that additionally contains Fe2(C2O4)3 on the magnetic and magnetoresistive characteristics of oxide coating/ titanium composites formed by means of plasma electrolytic oxidation (PEO) is investigated. It is established that PEO coatings with ferromagnetic cha...

Metallic fibers fabricated by the method of directly suspended melt-droplet extraction are promising for application in catalysis as carriers of catalytically active compounds and as catalytic systems themselves due to their physicochemical properties, structure, surface defects, and low hydrodynamic resistance of porous permeable materials formed...

The parameters of wetting of oxide coatings on titanium formed by the method of plasma electrolytic oxidation (PEO) in an aqueous silicate electrolyte with subsequent deposition of a layer of TiO2 nanoparticles and ultrasonic treatment by a polymer–salt gel including copper and molybdenum compounds have been investigated. The effect of the oxidized...

Manganese dioxide has been deposited on the surface of an aluminum foil anodized in 3% solution of oxalic acid using the methods of thermal decomposition of manganese nitrate and potassium permanganate, as well as chemical synthesis, in the same solutions with intermediate drying and subsequent annealing. It has been demonstrated that the method of...

The paper presents some of the directions of developing the plasma electrolytic oxidation (PEO) technique to form the coatings with magnetic, catalytic, biocompatible or biocidal properties on the valve metals and alloys. It reflects the relationships between the structure, composition and functional properties of PEO coatings. The data presented s...

The possibility of applying the extraction-pyrolysis method combined with the plasma electrolytic oxidation method in fabrication of layers with required chemical composition and properties on various materials has been investigated. The coatings have good prospects for improving the corrosion resistance, chemical inertness, and biocompatibility of...

The paper overviews the various approaches for obtaining the metal-supported PEO layers with a developed surface. They are following: (1) pre-etching the metal surfaces, (2) using the electrolytes in which linear discharges are realized under certain conditions of PEO processing, (3) the use of oxide-forming electrolytes for obtaining ornamental st...

The composition, structure, and magnetic characteristics of oxide layers on titanium formed in electrolytes containing colloid particles of iron hydroxo-compounds and their filtrates have been investigated. The obtained results corroborate that formation of Fe-containing crystallites in coating pores occurs due to ingress of negatively charged part...

In present work, new method of fabricating metal phosphates via interaction of metal oleates with tributylphosphate solution is presented. Developed method is the universal one for fabrication of nanosized powders and thinlayered coatings based on hydroxyapatite, which is doped with metal traces (Sr, Cu, Zn) and presenting essential basis of bone t...

Layered coatings of the composition Ca- and Sr-phosphate/Ta2O5/TiO2 have been obtained by sequential application of plasma electrolytic oxidation (PEO) in an electrolyte with fluoride complexes of tantalum (stage I) and in one with tripolyphosphate complexes of Ca(II) and Sr(II) (stage II). Calcium and strontium phosphates are contained in the coat...

Layered oxide coatings containing europium ferrite multiferroic have been synthesized on titanium plates through plasma electrolytic oxidation and extraction pyrolysis. The composites have weak ferromagnetic properties: the coercive force attains 45–78 Oe in the temperature range 3–340 K. Their luminescence properties are typical of inorganic mater...

The coatings manifesting ferromagnetic characteristics have been formed on titanium and aluminum by plasma electrolytic oxidation (PEO) in alkaline electrolytes additionally containing iron oxalate and cobalt or nickel acetate. The metals of iron subgroup are found to be concentrated in pores of PEO coatings, as a rule, in form of crystallites. In...

Coatings on aluminum alloy containing one or several crystalline oxides of cobalt, copper, and cerium deposited in different sequences have been obtained by a combination of methods of plasma electrolytic oxidation and impregnation followed by annealing. It has been established that the composition of surface layers and the catalytic activity of co...

Peculiarities of plasma electrolytic oxidation of stainless steel (grade 12Kh16N10T) in an aqueous electrolyte-suspension with tantalic acid and the composition and structure of formed surface layers have been investigated. Under the effect of bipolar anodic–cathodic current, thin interference films are formed on steel within 10 min. The surface ha...

SiO2 + TiO2/Ti composites have been formed by plasma electrolytic oxidation (PEO) of titanium in alkaline aqueous solution of sodium silicate. By modifying them using impregnation in nitrate solutions followed by annealing, the oxide composites Co3O4/SiO2 + TiO2/Ti, CuO/SiO2 + TiO2/Ti, and Co3O4 + CuO/SiO2 + TiO2/Ti have been obtained. The latter c...

The coatings manifesting ferromagnetic characteristics have been formed on titanium and aluminum by plasma electrolytic oxidation in alkaline electrolytes additionally containing iron oxalate and cobalt or nickel acetate. The metals of iron subgroup are found be concentrated in pores of PEO coatings, as a rule, in form of crystallites. In a number...

A Ti surface treated by plasma electrolytic oxidation (PEO) in silicate electrolyte has been coated with the nanostructural TiO2 layer and then impregnated using the sol–gel method with Cu and Mo, which are active ingredients for soot combustion. The layer TiO2 consists of anatase crystals of up to 50 nm, and has a mosaic-like structure with interc...

Iron-modified TiO2 coatings on titanium exhibiting ferromagnetic properties are formed by combining plasma electrolytic oxidation (PEO) and impregnation with subsequent annealing. It is found that iron is contained in the composition of dispersed particles with sizes of 1-10 μm distributed over the surface of the coatings. It is shown that the coer...

Coatings with up to 20 at.% of tantalum and phases of Ta2O5, Ta2O5·TiO2, and TiO2 have been formed on titanium in an aqueous electrolyte containing NH4[TaF6] by means of the method of plasma electrolyte oxidation (PEO). The addition of ethylene glycol into the electrolyte enables one to change the morphology and phase composition of resulting coati...

Two approaches have been examined for obtaining titanium- or aluminum-supported catalysts with transition and noble metals using the plasma electrolytic oxidation (PEO) technique. Elemental compositions, distribution of active elements and catalytic activity in CO oxidation have been compared for composites formed by one-stage PEO technique and tho...

PdOx/SiO2+TiO2/Ti composites with different palladium contents have been fabricated by a combination of plasma electrolytic oxidation and template sal-gel synthesis on titanium substrates. The effect of multiplicity of deposition of titanium hydroxide gel with palladium nanoparticles on the composite composition and the surface morphology has been...

Oxide catalysts, which, in addition to Al2O3 + SiO2, contain from one (Ni) to four oxides or compounds of transition metals (Ni, Cu, Mn, and Co) and oxides or compounds of rare-earth elements (Ce, La), are produced on D16 aluminum alloy by plasma electrolytic oxidation combined with impregnation and subsequent annealing. The composites formed begin...

The effect of the nature of the supporting electrolyte in the composition of electrolytic suspensions containing dispersed particles of Fe(III) and Co(II) hydroxides, and of anodic and bipolar anodic-cathodic polarization on features of the formation, composition, and magnetic characteristics of oxide coatings is studied. In all cases, iron and cob...

In this paper we research the process of magnetization of iron-containing coatings obtained on aluminum and titanium plasma electrolytic oxidation. It is shown that the formation of a remnant magnetic moment mainly determined by the magnetostatic interaction particles (phases). This interaction leads to a decrease of the blocking volume of particle...

Oxide coatings modified with cobalt and copper oxides are obtained on titanium and aluminum by means of combining plasma electrolytic oxidation (PEO) in silicate and zirconate electrolytes and impregnation in nitrate solutions followed by annealing. The effect of PEO coatings that were preliminarily formed on aluminum and titanium in different elec...

The thermal behavior of Ni- and Cu-containing coatings on titanium formed by plasma electrolytic oxidation and additionally modified with nickel and copper oxides is studied. Annealing of the produced multiphase coatings in air at a temperature of 750°C or higher is shown to result in the growth of surface nanowires, the main components of which ar...

Using plasma electrolytic oxidation technique we obtained ferromagnetic coatings on titanium and alluminium. The measured coercive force, ~ 100 Oe at room temperature, is closer to the values corresponding to magnetically hard materials. The coatings are of interest as protective electromagnetic screens. The coatings were studied by XRD, XPS, XSA a...

Possibility is considered of obtaining multicomponent oxide systems as afterburning catalysts for automobiles by flame-electrolytic oxidation and impregnation of oxide structures on aluminum.

Bioinert, biocompatible, chemical-resistant oxide coatings containing Ta2O5, which are promising to be applied to titanium implants, were produced on titanium by plasma electrolytic oxidation in an aqueous electrolyte. An effect of formation conditions on the elemental and phase composition, thickness, and roughness of the coatings was researched....

Plasma electrolytic oxidation (PEO) technique and impregnation in nitrate solutions with next air calcinations have been used to obtain the composites with binary oxides of transition metals on aluminum and titanium. The general composite formula is as follows: CuO + MxOy/PEO-layer/Ti(Al), where MxOy is oxide of transition metal (Mn, Fe, Co, Ni). S...

The combination of two methods, the plasma electrolytic oxidation (PEO) technique for the oxide film formation on titanium and the extraction-pyrolytic (EP) technique for catalytic active layers coating are suggested to use. After covering with Cu and Mo by equimolar mixture of extracts and subsequent pyrolysis the copper molybdate phase grains wit...

(Fe+Co)-containing oxide coatings are formed on aluminum alloy. It is established that at a temperature of ∼2 K, the coatings manifest ferromagnetic properties. The coatings, formed within 5 min, are characterized by an anomalously high coercive force H c = 1300 Oe. At room temperature (300 K), they manifest ferromagnetic properties, whereas in ext...

The technique of system parametrization of a microrelief of surfaces plasma electrolytic oxidation coverings on the titan is offered. Correlation of topology of surfaces of oxidic coverings with their thickness and magnetic properties is established.

It was shown that the extraction pyrolysis method and the combined method of plasma electrolysis and extraction pyrolysis are suitable technologies for the formation of functional complex oxide composites exhibiting catalytic activity in CO conversion.

CuO+Mx Oy /TiO2+SiO2/Ti composites (M = Mn, Fe, Co, Ni) were produced by plasma-electrolytic oxidation and impregnation, followed by annealing. The elemental and phase composition of these composites were examined and their activity series in CO oxidation was determined.

A combination of plasma-electrolytic oxidation method with extraction-pyrolytic technique was used for preparation of layered coatings with a developed surface relief. The coating surface is composed of segments enriched in tantalum oxide, alternating with those containing titanium oxides and calcium and phosphorus compounds.

Oxide coatings with a thickness of about 30 μm were deposited. The coatings contain approximately 21 at % Fe and 2.3 at % Cu and exhibit, together with ferromagnetic properties, a catalytic activity in CO oxidation at temperatures higher than 260°C.

The effect of annealing in air at T an temperature up to 800°C on the magnetic characteristics, elemental and phase composition, and surface morphology of iron-containing oxide coatings on titanium is studied. Annealing at T an ≤ 500°C does not seem to affect the composition and morphology of coatings. The coercive force (H c ) of specimens equals...

In this work the effect of thermal annealing on the surface composition, structure and catalytic activity in CO oxidation of NiO + CuO/TiO2/Ti composites is studied. The composites have been obtained by a plasma electrolytic oxidation (PEO) technique, followed by impregnation in a solution of nickel (II) and copper (II) salts and air annealing. The...

Oxide coatings formed on titanium by plasma-electrolytic oxidation in a Na3PO4 + Na2B4O7 + Na2WO4 + Fe2(C2O4)3 electrolyte-suspension at different current densities and different durations of treatment are shown to have ferromagnetic properties. The coercive force of the specimens reaches maximum values of 124 and 380 Oe at 300 and 10 K, respective...

We report the synthesis of needle-shaped nanocrystals of Ni(5)TiO(7) utilizing a solid-phase reaction of NiO with a porous and rough TiO(2) surface produced by plasma electrolytic oxidation. The single crystalline orthorhombic nanocrystals are grown along the [010] axis, featuring a length of ∼10 μm and diameters varying from several tens of nanome...

Specific surface structures of ZrO2 + TiO2 (I) and ZrO2 +CeOx + TiO2 (II) coatings on titanium before and after annealing at 850°C for 24 h in air are studied. Whiskers are found on the surface of type-I coatings before annealing, and perfectly edged crystals composed of TiO2 and ZrO2 oxides are found upon annealing. Pores in both coatings have a m...

The possibility of forming Co-containing coatings on titanium by plasma electrolytic oxidation and by a combination of oxidation and impregnation methods using an aqueous solution of sodium silicate as the base electrolyte was examined. Comparative analysis of the composition and structure of the systems obtained and of their activity in oxidation...