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1.
Electrocatalysis under Conditions of Ion Co-discharge with the Formation of an Alloy Yu. M. Polukarov, A. A. Edigaryan, and E. N. Lubnin Institute of Physical Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia e-mail:
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Received April 1, 2004 Abstract — The distribution of elements in Ni–Cr alloy deposits is studied with the use of x-ray photoelectron spectroscopy and electron Auger spectroscopy. Nickel is shown to catalyze the deposition of chromium, while chromium catalyzes the reduction of oxalates to carbon. The alloys have nanocrystal fcc structures based on nickel lattice. At a high chromium content (88 at. %), a phase with hexagonal lattice forms.
15/12/2008 | 1217 Посещения | Печать
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2.
Information-Optical 3D-Techniques for Corrosion Monitoring V. A. Kotenev Institute of Physical Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia Received December 20, 2003 Abstract — Methodical basis of using information-optical 3D-techniques and computer optical video microprobes in a high-performance monitoring of the thickness, topography, and statistical properties of thin corrosion layers on microscopic surface areas of a metal or semiconductor is considered. Forming a microscopic video image of such an area of an electrode and measuring the intensity distribution of the reflected optical signal in its field, one can obtain a 3D relief-map of the thickness and other properties of islets, new phase nuclei, and secondarily deposited layers on the electrode area in real time. The possibilities of combining the scanning and reflectometric 3D video microprobe techniques, diffuse-reflection infrared spectroscopy with a sharply focused probing beam, as well as photo-EMF technique, ellipsometry, and electrochemical methods when studying the corrosion behavior of metals and alloys, enable one to monitor the nonuniformity of the thickness and chemical composition of the corrosion layers. The information-optical 3D techniques of treating the images provides highly informative monitoring of the nonuniformity degree of the thickness, defectiveness, and chemical composition of the layer on the whole studied microscopic surface area of a corroded metal.
15/12/2008 | 1159 Посещения | Печать
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3.
Indirect Amperometry of Free Corrosion as a Method for Its Laboratory Investigation G. N. Markos’yan Russian Federation Scientific Center “Karpov Research Institute of Physical Chemistry,”
ul. Vorontsovo Pole 10, Moscow, 103064 Russia e-mail:
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Received December 18, 2003 Abstract — A formerly developed electrochemical cell able to continuously measure the oxygen corrosion rate of a metal through the absorbed oxygen quantity is described. By the example of various metals and alloys, the cell is shown to be applicable to clarifying the effect of various factors on their corrosion rate in acidic aqueous solutions. The rate constants are also determined for a series of homogeneous chemical reactions consuming oxygen. Peculiarities of hydrogenation and dehydrogenation processes under cathodic polarization conditions with access for air are investigated. It is shown that substituting chlorine for oxygen enables one to investigate chlorination of rubbers and chlorine corrosion of a great many metals and alloys.
15/12/2008 | 1208 Посещения | Печать
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4.
Peculiarities of Intergranular Corrosion of Silicon-Containing Austenitic Stainless Steels O. V. Kasparova Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow, 103064 Russia Received January 23, 2004 Abstract — Experimental data collected for the past two decades and a half are generalized, and the mechanism of intergranular corrosion (IGC) of austenitic silicon-containing (quenched and sensitized) steels in the envi-ronments with various redox characteristics is discussed. The synergistic intensification of IGC by the alloying silicon additives and carbon admixtures is experimentally revealed. The cause of the bivariant effect of silicon on the resistance of grain boundaries in sensitized steels at active–passive transition potentials is clarified. The effect of silicon on the electronic structure of a solid solution (including intergranular domains) is supposed to account for some peculiarities in the electrochemical behavior of the steels.
15/12/2008 | 1220 Посещения | Печать
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5.
Justifying the Model of Spatial Separation of Metal Dissolution and Passivation Processes R. M. Lazorenko-Manevich, A. N. Podobaev, and L. A. Sokolova FGUP State Scientific Center of the Russian Federation “Karpov Institute of Physical Chemistry,”
ul. Vorontsovo Pole 10, Moscow, 103064 Russia e-mail:
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Received February 18, 2004 Abstract — Results of studying the dissolution of fresh-formed iron surface and voltammetry of liquid and solid gallium are used to justify the concept of the direct participation of surface charge-transfer complexes, resulting from water adsorption, in the anodic dissolution of hydrophilic metals. The concept also implies both the effect of steady-state surface morphology on the kinetic parameters of the anodic dissolution and the effect of potential on the surface morphology. This concept underlies a model of spatial separation of processes of metal dissolution and passivation. Using this model, anodic voltammograms for iron in solutions with different concentration of chloride ion and pH were calculated. The calculated curves are in close agreement with experimental ones.
15/12/2008 | 1145 Посещения | Печать
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6.
Electrochemical Behavior of Nickel Hydride in Sodium Hydroxide Solutions D. S. Sirota and A. P. Pchel’nikov Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow, 103064 Russia e-mail:
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Received December 18, 2003 Abstract — Electrochemical behavior of nickel hydride Ni2H ( -phase) is studied in 0.01–1 N NaOH by using common (VA) and cyclic (CVA) voltammetry, chronocoulometry, amperometry, and potentiometry. The limiting anodic and cathodic currents in VA and CVA curves are caused by the hydride decomposition via the fol-lowing scheme Ni2H   '-phase  Ni + Habs, where the intermediate '-phase contains 0.003 at. % H, that is, one tenth that in the saturated -phase (0.03 at. %). At open circuit, the hydride maintains the equilibrium hydrogen potential. In the first 30 min, the hydrogen ionization from hydride is limited by solid-state diffusion and, later, the hydride decomposition. The anodic process involves ionization of sorbed hydrogen, while the cathodic process represents its electrochemical desorption: H2O + Hads + e  H2 + OH–. The hysteresis observed in the cathodic CVA and open-circuit chronograms of the hydride potential in the beginning of anodic dissolution reflect the changes in the surface coverage of hydride with adsorbed hydrogen. The rate constant of hydride decomposition k, the rate V itself, and the equilibrium constant K are as follows: k = k = 8  10–5 s–3, V= 3 10–5 C/cm2 , and K = 10. The kinetic parameters of hydrogen electrochemical ionization from the hydride are ba = 0.12 V and = 0.5.
15/12/2008 | 1182 Посещения | Печать
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7.
The Effect of Nonmetal Inclusions and Microstructure on Local Corrosion of Carbon and Low-alloyed Steels I. I. Reformatskaya*, I. G. Rodionova**, Yu. A. Beilin***, L. A. Nisel’son***, and A. N. Podobaev* * Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow, 103064 Russia e-mail:
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** Bardin Central Research Institute of Ferrous Metallurgy, Moscow, Russia *** Oil Company YuKOS, Moscow, Russia Received March 23, 2004 Abstract — The resistance of carbon and low-alloyed steels to local corrosion is shown to be directly determined by their phase-structure, rather than chemical, composition. A correlation between the presence of various nonmetal inclusions in steels and the local corrosion rate is revealed. Inclusions containing Ca and S are shown to be the most corrosive, manganese sulfide inclusions act less corrosively, and silicates are the least active. The formation of lamellar pearlite in the steel structure also impairs its resistance to local corrosion. By providing metal pure of corrosive nonmetallic inclusions at a melting stage and ensuring the pearlite spheroidizing during the stages of thermal treatment and processing, it is possible to enhance its resistance to total and local corrosion.
15/12/2008 | 1231 Посещения | Печать
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8.
Some Features of the Local Depassivation of Binary Alloys Yu. I. Kuznetsov* and M. V. Rylkina** * Institute of Physical Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia e-mail:
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** Udmurt State University, Universitetskaya ul. 1, Izhevsk, 426034 Russia e-mail:
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Received December 19, 2003 Abstract — Pitting resistances of Fe–Cr, Fe–Ni, Fe–B, Cu–Ni, and Cu–Zn binary alloys were studied. The effects of the composition and protective properties of a passive film, the phase composition of the alloy, and the nature and concentration of an activating anion were analyzed. It was demonstrated that the basic concepts of complexation are applicable to the depassivation of binary alloys in aqueous solutions.
15/12/2008 | 1215 Посещения | Печать
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9.
Cooperative Effects in the Problem of Acid Corrosion of Metals M. A. Pletnev and S. M. Reshetnikov Udmurt State University, Universitetskaya ul. 1, Izhevsk, 426034 Russia e-mail:
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Received December 11, 2003 Abstract — The phenomenon of acid corrosion of metals is analyzed with consideration of the cooperative nature of the proton subsystem of aqueous acid electrolytes and the electronic subsystem of a metal. The necessity of studying the cathodic evolution of hydrogen in terms of solvent reorganization is justified. The concepts of the anodic dissolution of iron metals are reviewed retrospectively. An important role of the solvation of dissolved metal ions in the anodic dissolution is shown. The limiting currents of the kinetic nature at high anodic overpotentials are discussed in terms of the dynamics of atomic steps and the motion of dissolution solitons.
15/12/2008 | 1206 Посещения | Печать
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10.
Peculiarities of the Corrosion Protection of Steel Underground Pipelines N. P. Glazov Scientific-Research Institute on Construction and Operation of Heat-power Objects Ltd VNIIST,
Okruzhnoi pr. 19, Moscow, 105187 Russia e-mail: cpkz@ mail.ru Received March 1, 2004 Abstract — The topics of enhancing the corrosion protection efficiency of pipelines are examined. Improuving the quality of the protective coatings enables one to preclude corrosion under the disbonded insulation, as well as the stress corrosion cracking, but causes the increase in the stray-current corrosion and other undesirable effects that are easily removed with the aid of electrochemical protection. Checking the insulation of pipelines upon completed construction by cathodic polarization ensures the reproducibility of the design parameters of the cathodic protection. The topics of the influence of insulating components, as well as protective and anodic groundings, on the effectiveness of corrosion protection are considered.
15/12/2008 | 1369 Посещения | Печать
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