Ukrainian State University of Chemical Technology

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Dnipropetrovsk, Ukraine
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Kolesnyk Ie.V.,Ukrainian State University of Chemical Technology
Metallofizika i Noveishie Tekhnologii | Year: 2016

Structural investigations of electrodeposited binary and ternary iron-based alloys containing chromium and nickel are accomplished by the methods of scanning electron microscopy and X-ray diffractometry. Joint effect of the alloying elements on the surface morphology and preferred crystal orientations in Fe-Cr-Ni alloys' coatings electrodeposited from sulphate electrolyte on steel substrate is shown and explained. The surface morphology of the investigated Fe-Cr-Ni alloys with b.c.c. crystal structure is represented solely by spherulites and is accompanied by prevalence of <111> crystal orientation in contrast to electrodeposited iron where regular fine crystal structure is characterized by preferred <211> crystal orientation.


Girin O.B.,Ukrainian State University of Chemical Technology
Surface Engineering and Applied Electrochemistry | Year: 2017

The phenomenon of phase formation through a liquid state stage in metals being electrodeposited has been discussed. In order to provide further evidence on the existence of this phenomenon, a set of experiments are conducted to reveal the predicted structural features in metals exposed to a minor external force during electrodeposition. In the second part of the research, the results of structural studies of metals electrodeposited under the action of an external force directed perpendicular to the crystallization front are discussed. It is found that electrodeposition of metals exposed to a minor external force perpendicular to the crystallization front leads to a refinement of their intracrystalline structure and surface morphology. The experimental results prove the existence of the phenomenon of phase formation through a liquid state stage in metals being electrodeposited. © 2017, Allerton Press, Inc.


Apostolova R.D.,Ukrainian State University of Chemical Technology
Voprosy Khimii i Khimicheskoi Tekhnologii | Year: 2017

With the development of the technical progress the extensively claimed lithium ion batteries (LIB) lose their importance in power supply for portable electronic devices and autonomous vehicles because of insufficient power intensity, capacity, high costs and the absence of the guarantee safety. Magnesium-ion batteries (MIB) belong to promising alternatives to common accumulator systems. The literature data on the negative and positive electrodes, the electrolytes used in MIB and the whole battery behavior have been analyzed in this review. The problem of the synthesis of new magnesium electrolytes exists since the unfitness of magnesium electrolytes for MIB, these electrolytes might be analogues to usual lithium electrolytes. The electrolytes should be compatible with both magnesium and the materials of the positive electrodes. Ensuring a high coulomb efficiency of the magnesium deposition/dissolution processes is connected with the solution of the problem of oxide film formation on magnesium that is impermeable for Mg2+ ions. Searching for the material for positive electrode providing high energy MIB remains a problem. A number of the compounds investigated in magnesium electrolytes as electrode materials for MIB are shown in the review. One can judge the readiness of MIB to substitute LIB by achieved electrochemical characteristics of the investigated Mg-accumulator systems. The progress of MIB based on Chevrel phases (Mo6S8) is associated with long reversible cycling (2000-3000 cycles), low discharge capacity (Q=100 mA h g-1) and voltage (E=1.1-1.2 V) which are, nevertheless, not adequate to those of commercial LIB (Q= =140 mA h g-1, E=3.7 V). Oxides with high degree of the oxidation, such as MnO2 and V2O5, seem to be the most promising; MnO2 is described in this review in detail. Their high start capacity (270-310 mA h g-1) rapidly decreases in the course of the first 10-20 cycles. The choice of hybrid magnesium-lithium-ion battery attracts attention by the possibility to realize long stable cycling; but the cost of the required membrane is high and the technical complication of the system is a lack. A number of problems should be solved to provide MIB era, but the prognosis is optimistic.


Goleus V.I.,Ukrainian State University of Chemical Technology
Voprosy Khimii i Khimicheskoi Tekhnologii | Year: 2017

A review of known compositions of industrial enamel coatings showed that the basis for their production by suspension firing technology are borosilicate glass frites in which the total content of base oxides, such as SiO2, B2O3 and Na2O, is within the range of 70-90 mol.%. Therefore, these components have a great effect on the values of viscosity, surface tension, temperature coefficient of linear expansion and water resistance of glass frit; these properties should be taken into account when developing new compositions of anticorrosive enamels. As a result of the performed study, the changes in the abovementioned properties of borosilicate enamel glass frit as a function of the content of basic oxides (SiO2, B2O3 and Na2O) in their composition have been established. It was noted that the viscosity values of the melts of enamel glasses primarily depend on the content of SiO2 in their composition; the values of surface tension chiefly depend on the content of B2O3; and the values of the temperature coefficient of linear expansion of glasses are mainly determined by the content of Na2O. The analysis of the established characteristics revealed that the most preferable content of base components in glass frit to obtain both ground and cover enamel coatings on steel with a firing temperature of 850 ± 30 °C should be as follows (mol.%): 14-24 Na2O, 5-15 B2O3, 40-60 SiO2 at the ratio of Na2O/B2O3= 1.1-2.8.


Kasian O.,Ukrainian State University of Chemical Technology | Luk'yanenko T.,Ukrainian State University of Chemical Technology | Velichenko A.,Ukrainian State University of Chemical Technology
Chemistry and Chemical Technology | Year: 2012

The kinetics of complexing agents anodic decomposition in electrolytes based on Cr(III) salts was investigated. In Cr(III) electrolytes urea was shown to be fixed in complexes with Cr 3+-ions. It was found that the main way of free carbamide degradation was hydrolysis characterized by a high rate (k = 4.5·10 -3 min -1). Decrease in formic acid concentration during electrolysis at composite TiO x/PtO y-anodes was insignificant. © Kasian O., Luk'yanenko T., Velichenko A., 2012.


Anisimov V.,Ukrainian State University of Chemical Technology
Chemistry and Chemical Technology | Year: 2012

The interrelation between structures and strength, deformation, rheological, and tribotechnical characteristics of thermoplastic polyurethanes based on oligoether blends has been studied. A notable change of properties over the whole concentration range was observed. The best compositions have been found. © Anisimov V., 2012.


Protsenko V.S.,Ukrainian State University of Chemical Technology | Gordiienko V.O.,Ukrainian State University of Chemical Technology | Danilov F.I.,Ukrainian State University of Chemical Technology
Electrochemistry Communications | Year: 2012

Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and carbamide (urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by "chemical" mechanism. © 2012 Elsevier B.V.


Apostolova R.,Ukrainian State University of Chemical Technology | Peskov R.,Ukrainian State University of Chemical Technology | Shembel E.,Ukrainian State University of Chemical Technology
Journal of Solid State Electrochemistry | Year: 2014

We reported previously the superiority of electrochemical characteristics of the mechanical mixtures of micrometer LiMn2O4 spinel with multiwall carbon nanotubes (MCNT) over those of spinel compositions with natural graphite in the prototypes of the Li-ion batteries. In the presented work, we extended the investigation of the kinetic and interfacial characteristics of the spinel in the redox reaction with the Li ion. Slow-rate scan cyclic voltammetry and impedance spectroscopy were used. Carbon electroconductive fillers, their nature, and particle sizes play the key role in the efficiency of the electrochemical transformation of spinel in Li-ion batteries. Electrodes based on the composition of the spinel and MCNT show a good cycling stability and efficiency at the discharge rate of 2C. Chemical diffusion coefficients of Li ion, which were determined in spinel composite with MCNT and graphite near potentials of peak activity in deintercalation/ intercalation processes, change within one order of 10-12 cm 2 s-1. The value of this chemical diffusion coefficient for the composition of the spinel with MCNT and with graphite change within one order of 10-12 cm2 s-1. The data of the impedance spectroscopy shows that the resistance of surface films on the spinel (R s) is low and does not considerably differ from R s in composites of the spinel with MCNT and graphite. The investigation shows that the resistance of charge transport (R ct) through the boundary of surface film/spinel composite is dependent on the conductive filler. Value of R ct in spinel electrode decreases by the factor of thousand in the presence of carbon filler. Exchange current of spinel electrode increases from the order of 10-7 to 10-4 A cm-2 under the influence of MCNT. At the potentials of maximum activity in deintercalation processes, exchange current of spinel composite electrode with MCNT is 2.2-3.0 times more than one of the composite with graphite. Determining role of the resistance of charge transport in electrode processes of spinel is established. The value of R ct is dependent on the resistance in contacts between spinel particles and also between particles and current collectors. Contact resistance decreases under the influence of MCNT with more efficiency than under the influence of graphite EUZ-M because of small the size of its particles with high surface area of the MCNT. © 2013 Springer-Verlag Berlin Heidelberg.


Protsenko V.S.,Ukrainian State University of Chemical Technology | Danilov F.I.,Ukrainian State University of Chemical Technology
Journal of Electroanalytical Chemistry | Year: 2011

Equations are derived and analyzed that interrelate the quantities of the ideal activation energy W (determined at a constant Galvani potential value), the real activation energy A (measured at a constant overpotential value) and the so-called formal activation energy Ω (measured at a constant electrode potential vs. an arbitrarily chosen reference electrode). The mathematical forms of dependence of apparent formal activation energy on electrode potential are established. It is shown that using formal activation energy (measured at a constant electrode potential) is applicable for kinetics analysis of various electrode processes. The expressions obtained in this study may be used when processing temperature dependences of highly irreversible electrochemical reactions. © 2010 Elsevier B.V. All rights reserved.


Olevskyi V.,Ukrainian State University of Chemical Technology
AIP Conference Proceedings | Year: 2014

We propose the method of modeling, which provides a meromorphic continuation of the asymptotic polynomial solution of differential equations based on 2D Padé approximants in nonlinear shell theory. We represent calculations of displacements, stability and vibration of inhomogeneous loaded shells with developable surface by means of this method. Accuracy of theoretic results is confirmed by means of holographic experiments with specimens made from stainless steel. © 2014 AIP Publishing LLC.

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