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Transformation of Metal-Oxide Nanostructures in the Process of Afteroxidation of Iron Reactively Evaporated in Oxygen Atmosphere V. A. Kotenev, D. N. Tyurin, A. Yu. Tsivadze, M. R. Kiselev, V. V. Vysotskii, and V. I. Zolotarevskii Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, 119991 Moscow, Russia e-mail:
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Received July 10, 2008 Abstract — The methods of atomic force microscopy combined with the digital processing of images were used to study the change in the morphology of nanostructured metal-oxide coatings obtained by reactive evaporation at 10 6 torr in the atmosphere of oxygen and further low-temperature iron afteroxidation in an air atmosphere at different temperatures. It is shown that a nanostructured layer with a unimodal distribution according to the size and degree of nonsphericity of the particle is formed in the case of sputtering. Using the sample detection methods, it is shown that a unimodal distribution is transformed into a bimodal distribution at an increase in the reoxidation temperature from 50 to 200°C, after which it becomes a trimodal distribution, which proves that the building blocks of a nanostructured layer are nanoparticles and four- and 16-particle surface nanoparticle conglomerates. This structure can explain the functional properties of these coatings, which are of practical importance. PACS numbers: 81.07.Bc DOI: 10.1134/S2070205109060112
11/12/2009 | 526 Hits | Print
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12.
Surface Structure of Multicomponent Oxide Coatings on Titanium V. S. Rudneva, I. V. Lukiyanchuka, L. M. Tyrinaa, S. Wybornovab, T. Staedlerb, and M. S. Vasil’evac a Institute of Chemistry, Far East Branch, Russian Academy of Sciences, pr. 100 let Vladivostoka 159, Vladivostok, 690022 Russia b Institute of Materials Engineering Chair of Surface and Materials, Technology University, Paul-Bonatz Str. 9–11, Siegen, 57076 Germany c Far East State University, ul. Oktyabr’skaya 27, Vladivostok, 690091 Russia e-mail:
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Received July 9, 2008 Abstract — Data on the surface structure of Cu–Ni containing oxide films formed on titanium under the effect of electric spark and arc discharges are considered at the scale of tens to hundreds nanometers. The surface sites of films around electric discharge channels are perforated with pores of diameters around 10 nm. Spheroids with diameters of tens to hundreds of nanometers, which chiefly elements contain involved in the electrolyte components including heightened amounts of copper and carbon, are distributed over the surface. Furthermore, agglomerates formed by planar particles with sizes of tens to hundreds of nanometers of irregular geometric shapes are also present on the surface. Elemental compositions of the film surface and planar agglomerates coincide. The particles are supposedly the products of the electric-discharge erosion of the film material. PACS numbers: 82.45.Cc DOI: 10.1134/S2070205109060124
11/12/2009 | 598 Hits | Print
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13.
Formation of Silver Nanoparticles in Solutions of Carboxymethylcellulose A. V. Guselnikova, V. V. Visotskiy, O. Ya. Uryupina, and V. I. Roldugin Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninskii pr., Moscow, 119991 Russia e-mail:
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@ Received 19.03.2009 Abstract — An investigation is reported on the relation between the size and potential for silver nanoparticles prepared in aqueous solution of carboxymethylcellulose to pH of the solution by virtue of dynamic light dissipation. The changes in the size distribution for nanoparticles and their potential were monitored over time. The size of particles was found to degrease linearly with increasing pH; a similar effect was created by the maturation of colloidal solution. The potential of the maturation process tended to take an identical value for all hydrosol samples studied. A procedure is proposed for the numerical calculation of the relative concentration of nanoparticles that is applicable for the investigation of samples with various types of distribution for particle sizes. The degree of reduction for silver ions was found to depend significantly on the quantity of AgNO3 presented and the ration between the precursor and the reducing agent. PACS numbers: 81.07.-b DOI: 10.1134/S2070205109060136
11/12/2009 | 591 Hits | Print
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14.
Electroplating of Catalytically Active Nickel Coatings from Baths of Various Anionic Compositions O. V. Dolgikha, N. V. Sotskayaa, Vu Thi Duyena, E. A. Kotlyarovaa, and B. L. Agapova,b a Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia b Voronezh State Technological Academy, pr. Revolyutsii 19, Voronezh, 394017 Russia e-mail:
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Received November 6, 2008 Abstract — The effect of the nature of bath anions (Cl , and CH3COO ) on the characteristics of the electrochemical plating of nickel coatings, namely, parameters of the cathodic polarization curves, bath stability, and current efficiency, as well as the composition and morphology of deposits and their catalytic activity in the anodic oxidation of hypophosphite ions and cathodic evolution of hydrogen, is studied. The anionic composition of the baths is found to substantially affect not only the kinetics of the deposit growth, but also the properties of the deposit. The differences observed are determined by the complex-forming and buffering properties of the anions. PACS numbers: 81.15.Pg DOI: 10.1134/S2070205109060148
11/12/2009 | 559 Hits | Print
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15.
Effect of Plasma Treatment on Corrosion Electrochemical Behavior of Titanium in Molten Mixture of Cesium and Sodium Chlorides L. A. Elshina, V. Ya. Kudyakov, and V. B. Malkov Institute of High-Temperature Electrochemistry, Urals Branch, Russian Academy of Sciences, ul. Sof’i Kovalevskoi 22, Ekaterinburg, 620219 Russia e-mail:
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Received May 5, 2008 Abstract — The effect of high-temperature pulsed plasma (HTPP) on the corrosion–electrochemical behavior of titanium in a molten eutectic mixture of cesium and sodium chlorides in an argon atmosphere at temperatures of 790–810 K is studied. Upon the HTPP treatment in an oxygen or helium environment, a modified corrosion resistant layer with a thickness up to 20 m is formed on the titanium surface and decreases the corrosion rate of titanium in a chloride melt by a factor of 10–16. PACS numbers: 52.77.Dq; 81. 65. Kn DOI: 10.1134/S207020510906015X
11/12/2009 | 621 Hits | Print
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16.
Oxide Coatings on Al/SiC Composite Formed by Plasma-Electrochemical Method V. S. Rudneva, S. A. Karimovaa,b, T. P. Yarovayaa, P. M. Nedozorova, and Yu. A. Abuzina,b a Institute of Chemistry, Far East Branch, Russian Academy of Sciences, pr. 100 let Vladivostoka 159, Vladivostok, 690022 Russia e-mail:
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b All-Russian Scientific Research Institute of Aviation Materials, ul. Radio 17, Moscow, 105005 Russia Received April 10, 2008 Abstract — The processes of film growth and characteristics of film formation in an aqueous phosphate–borate or borate electrolyte are studied. After 2 h, films with thicknesses of 30–40 m and surface microhardnesses of 9–13 GPa are obtained. The elemental and phase compositions of the films and their corrosion resistance estimated using thes drop technique are discussed. PACS numbers: 82.45.Cc DOI: 10.1134/S2070205109060161
11/12/2009 | 622 Hits | Print
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17.
Mechanism of the Corrosion Exfoliation of a Polymer Coating from a Carbon Steel A. P. Nazarov and D. Thierry French Corrosion Institute, 220 Rue Pierre Rivoalon, Brest, F-29200 France e-mail:
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Received October 30, 2008 Abstract—A mechanism of the atmospheric corrosion of a carbon steel under polymer (paint and varnish) coatings is studied. The potential distribution around an artificial coating defect was measured in situ with a scanning Kelvin probe (SKP). The potential gradient between the steel surface at the defect and under the coating determines the mechanism of the subfilm corrosion. Measuring the galvanic currents in a steel under coating–steel at defect model system revealed the spatial separation of partial electrochemical reactions. The separation was additionally confirmed by the elemental analysis of the metal surface upon removing the coating. The mechanism of corrosion exfoliation is shown to differ depending on the kind of rate, which determines the electrochemical reaction at the coating defect. In the presence of aqueous NaCl electrolyte, the defect acts as an anode, which results in the cathodic exfoliation of the coating. In the case of drier corrosion in an atmosphere at a humidity of 95%, the steel at a defect acts as a cathode with respect to the surrounding interface, which leads to the development of anodic zones around the defect. PACS numbers: 81.65.Kn DOI: 10.1134/S2070205109060173
11/12/2009 | 593 Hits | Print
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18.
Anodic Dissolution of a Metal Accompanied by the Formation of Unstable Anionic Complexes A. V. Noskov and S. A. Lilin Institute of Solution Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia e-mail:
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Received November 27, 2008 Abstract — Transport processes that take place during the anodic dissolution of a metal accompanied by the formation of negatively charged intermediate particles are theoretically considered. Distributions of the component concentrations and electric potential in the diffusion layer during the quasi-equilibrium decomposition of intermediate particles are calculated. Analysis predicts the existence of the admissible concentration limit of anions depending on the stability constant of intermediate particles. The effect of the stability constant on the potential distribution within the diffusion layer and on the shape of voltammetric curves of the process is found to be complex. PACS numbers: 82.45.Bb DOI: 10.1134/S2070205109060185
11/12/2009 | 585 Hits | Print
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19.
Aluminum Hydroxide and Hydrogen Produced by Water Electrolysis R. R. Salem e-mail:
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Received October 12, 2007 Abstract — Thermodynamic and kinetic peculiarities of the water electrolysis in a reactor with aluminum electrodes are considered. The possibility of low-cost hydrogen evolution and aluminum hydroxide production is shown. PACS numbers: 82.45.Hk DOI: 10.1134/S2070205109060197
11/12/2009 | 517 Hits | Print
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