The Radiation Oxidation of Aluminum in Contact with Water

N. N. Gadzhieva

Institute of Radiation Problems, Azerbaijan National Academy of Sciences,
pr. G. Dzhavida 31a, Baku, AZ 1143 Azerbaijan;
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Received October 10, 2005

Abstract — The aluminum oxidation in the aluminum–water system under the action of radiation is studied using the radiothermoluminescence and IR-reflection absorption spectroscopy methods. The specific features of the radiothermoluminescence peaks observed in a 100–250 K temperature range (the activation energy E_a = 0.38–0.65 eV) corroborate the significance role of superficial oxygen hole-type centers and chemisorbed oxygen in the oxide film formation. Based on the dose dependence of the chemisorbed oxygen thermal quenching, the kinetics of aluminum radiative oxidation and its chemisorptive passivation are revealed. The oxide film formation and the heterogeneity of its structure are traced using the IR-reflection spectra. A possible scheme of the radiation oxidation of aluminum in the aluminum–water system is suggested.

PACS numbers: 81.45.Bb

DOI: 10.1134/S003317320704011X

Electrodeposition of NickelFullerene C₆₀ Composition Coatings

V. N. Tseluikin, N. D. Solov’eva, and I. F. Gun’kin

Engel’s Technological Institute (Branch) of Saratov State Technical University,
pl. Svobody 17, Engel’s, Saratov oblast, 413100 Russia

Received March 28, 2006

Abstract — A method of preparing composition electrodeposits (CED) nickel–fullerene C₆₀ is proposed. The kinetics of electrodeposition of CED under potentiostatic conditions and the deposit structure are studied. It is shown that fullerene species are hydrogenated during the deposition. The corrosion and electrochemical behavior of CED in 0.5 M H₂SO₄ is studied.

PACS numbers: 73.61.Wp, 81.15.Pq, 82.45.Yz

DOI: 10.1134/S0033173207040121

Corrosion Inhibitors in Conversion Coatings. IV

S. V. Oleinik and Yu. I. Kuznetsov

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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Received July 31, 2006

Abstract — This review covers main approaches to development of inhibited conversion formulations for chemical oxidation of aluminum alloys. A mechanism explaining the formation of conversion coatings on aluminum alloys from chromate conversion baths is proposed; the protective properties of the resulting coatings are characterized. It is demonstrated that various modified methods for the preparation of chromate conversion coatings on aluminum enhance their protective properties, however, without solving ecological problems. Among alternative corrosion inhibitors used in chemical oxidation of aluminum alloys, molybdate-containing formulations are worth noting and have been much investigated. The most promising approach is to develop corrosion inhibitors for use during both the formation of a conversion coating and its subsequent filling with compounds chemisorbable at the modified oxide.

PACS numbers: 82.45.Bb

DOI: 10.1134/S0033173207040133

Applying a Theory of Generalized Variables to Electrochemical Kinetics: Interpreting the Results of Studying Chromium Deposition from Cr(III) Baths

V. S. Protsenko, T. E. Butyrina, and F. I. Danilov

Ukrainian State Chemicotechnological University, pr. Gagarina 8, Dnepropetrovsk, 320640, Ukraine

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Received April 23, 2005

Abstract — By using the theory of generalized variables (the similarity theory and dimensional analysis), universal system of dimensionless complexes (the similarity criteria) is derived, which allows describing the kinetics of multistage reaction (metal electrodeposition at rotating disc electrode). The proposed mathematical apparatus can be flexibly adapted to describing the kinetics of virtually any complicated electrochemical system. The dimensionless complexes derived are used in interpreting the results of our studies on the chromium electrodeposition from Cr(III) oxalate and formate salt solutions at a rotating disc electrode. Possible mechanism of the electrodeposition from the oxalate and formate electrolytes is offered.

PACS numbers: 81.15.Pq; 82.20.Le

DOI: 10.1134/S0033173207040145

An Improved Grey Model for Corrosion Prediction of Tank Bottom¹

S. M. Liu and G. Y. Zhang

Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China

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Received December 17, 2006

Abstract — Leakage of a storage tank caused by the corrosion of its bottom contaminates soils and underground waters. The tank operators must monitor and control the underground corrosion of the tank bottom. Though it is difficult to observe the underground corrosion of a tank bottom, the corrosion depth progress can be predicted by forecasting models. An improved first-order one-variable grey prediction model (IGM (1, 1) model) was proposed for the corrosion prediction of the tank bottom. The IGM model used the synthesizing grey correlation degree as weights to modify the results from GM (1, 1) models based on long and short son data sequence from the identical original data. The IGM model was applied to simulate the corrosion depth progress of a tank bottom from 1994 to 1999. Results showed the IGM dynamic model be more precise than the existing GM (1, 1) one. It is an effective tool to predicting the tank bottom corrosion. The corrosion depth values of tank bottom from 2000 to 2001 were well predicted.

PACS numbers: 81.15.-z

DOI: 10.1134/S0033173207040157

A Theory of Pit Initiation. Part I. The Mechanism of Local Depassivation of Metals

Yu. A. Popov

State scientific center of the Russian Federation “Karpov Institute of Physical Chemistry,”
ul. Vorontsovo Pole 10, Moscow, 103064 Russia

Received June 13, 2006

Abstract — Electrochemical kinetics at a surface of newly initiated pits is analyzed; the effect of the surface energetical heterogeneity and the self-acceleration kinetics of the surface local depassivation are discussed.

Keywords: pitting, kinetics, potential, self-acceleration, equation, local character, passivity

PACS numbers: 82.45.Bb

DOI: 10.1134/S0033173207030010

Conditions and Mechanism of the Ionization and Dissociation of Water. Predictions Based on Nonempirical Calculations

Yu. V. Novakovskaya

Laboratory of Quantum Mechanics and Molecular Structure, Chair of Physical Chemistry,
Faculty of Chemistry, Moscow State University, Leninskie gory, Moscow, 119992 Russia

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Received October 12, 2006

Abstract — Based on the results of quantum chemical modeling of neutral and charged water clusters, mechanisms of the ionization and dissociation of water explaining the regularities discovered in experiments are proposed. There are two possible ways of the water and ice ionization, namely, (i) directly from the ground elec-tronic state of the neutral system provided that the high-frequency stretching vibrations of molecules, which determine the formation of H₃O⁺ and OH ionic fragments, are sufficiently excited, and (ii) via the intermediate transfer to the excited electronic state where hydronium radicals may appear at a certain excess energy. The formation of atomic hydrogen may also take place in the processes of two kinds, namely, (i) the dissociation of the electronically excited water clusters and (ii) the recombination of an electron, appeared upon ionization, with a hydronium cation that leads to the spontaneous detachment of a hydrogen atom. The processes may proceed either successively or simultaneously in a time period compared to the characteristic or even resolution time of the experiment, which may result in incorrect estimation of the quantum yields of hydrated electrons and hydrogen atoms in terms of standard procedures.

PACS numbers: 33.20.Lg; 33.20.Ni; 33.80.-b; 33.80.Rv

DOI: 10.1134/S0033173207030022

The Selfconsistency of the Interface Atomic Relief and the Kinetics of Material Exchange between the Solid and Liquid or Gas Phases

Yu. V. Alekseev^a, G. Yu. Alekseev^b, and V. A. Bityurin^b

^a Karpov Institute of Physical Chemistry, Vorontsovo Pole 10, Moscow, 103064 Russia

^b Institute of High Temperatures, Russian Academy of Sciences, Moscow, Russia

Received September 7, 2005

Abstract — Analyzing and clarifying the basic concepts of the statistical method in the theory of material exchange between the solid (ordered) and liquid (disordered) phases noticeably modifies the problem of the metal dissolution and deposition. Taking a surface position of an atom and accordingly the number of its closest neighbors in the phase as an elementary object of statistics, one can derive a system of kinetic equations relating the concentration of diverse positions. Solving the system in a steady-state case provides a selfconsistent description of the topography of the atomic relief and the metal dissolution rate. The problem is solved for a perfect crystal, but the method proposed enables one to formulate and solve the problems of the metal corrosion in the presence of linear and point-wise defects.

PACS numbers: 68.08.-p; 68.35.Ct; 82.45.Jn

DOI: 10.1134/S0033173207030034

Specifities of Forming Electrochemical Dissolution Zones at FerriteCementite-Structured Alloys in Sulfuric Acid Solutions

N. V. Tarasova and S. N. Saltykov

Lipetsk State Technical University, Lipetsk, Russia

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Received January 13, 2006

Abstract —  Specific features of the formation of electrochemical dissolution zones at steels CT20 and CT45 with a ferrite–cementite structure, were revealed by combining electrochemical and metallographic methods. A possibility of developing the self-dissolution process at the ferrite/cementite boundary is shown. A spontane ous sequence of the anodic dissolution of structural constituents of the alloys is found.

PACS numbers: 81.05.Bx

DOI: 10.1134/S0033173207030046

New Concept of the Mechanism of Intergranular Corrosion of Stainless Steels

O. V. Kasparova^a and Yu. V. Baldokhin^b

^a State Scientific Center of the Russian Federation “Karpov Institute of Physical Chemistry,”
ul. Vorontsovo Pole 10, Moscow, 103064 Russia

^b Semenov Institute of Chemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117977 Russia

Received October 24, 2006

Abstract — The electronic structure of chromium–nickel austenite stainless steels of type X20H20 and X10H20, in particular, added with 4 to 6% Si, is studied using nuclear -resonant (Mössbauer) spectroscopy. The structure varies significantly depending on the chromium and silicon content. Low-chromium steels are used for the modeling of chromium-depleted boundary zones that neighbor chromium-rich excess phases. Eventually, a mechanism of the intergranular corrosion of stainless steels that takes into account the changes in the electronic structure of the chromium-depleted boundary zones is first suggested. These changes in the chemisorption interaction of the iron carcass ions with corrosive components of the medium, cannot but affect the zones’ stability. It is this interaction that synergistically intensifius the intergranular corrosion of austenite stainless steels containing combinations of silicon dopant and carbon impurity, or the phosphorus and carbon impurities.

PACS numbers: 33.45.+x; 82.45.In