The Effects of the Cementite Phase of IronCarbon Alloys on Their Electrochemical Behavior in an Oxalic Acid Medium

S. N. Saltykov and M. S. Putilina

Lipetsk State Technical University, ul. Moskovskaya 30, Lipetsk, 398600 Russia

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Received April 11, 2005

PACS numbers: 82.45.Kn

Corrosion Degradation of Chromium Coatings on Steel in NaCl Concentrated Solution

I. V. Petukhov^a, M. G. Shcherban’^a, V. I. Kichigin^a, A. V. Zaitseva^a,  E. V. Mikhailov^b, and S. V. Zavodchikov^c

^a Perm’ State University, ul. Bukireva 15, Perm’, 614990 Russia

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^b Institute of Continuous Media Mechanics, Ural Branch, Russian Academy of Sciences,
ul. Akademika Koroleva 1, Perm’, 614061 Russia

^c Perm’ Branch of All-Russian Research Institute of Drilling Equipment,
ul. Karpinskogo 24, Perm’, 614000 Russia

Received August 2, 2004

Abstract — Corrosion-electrochemical behavior of chromium coatings at steel substrates (40, 2013, and 121810) in concentrated (318 g/l) NaCl solution at elevated temperatures is studied, in particular, under conditions of friction against rubber (thus modeling the mine screw-driller rotor operation conditions). By and large, the chromium coatings in the studied solution have fairly good corrosion stability. However, when through pores occur in the coatings, chromium–steel galvanic couples are formed, in which chromium is the anode, and steel, the cathode. This causes intense corrosion damage to the coating in close proximity to the pores. Steel undergoes no corrosion here. It is the Cr-coating porosity that gives rise to its accelerated degradation under the friction, although friction as such does not accelerate the corrosion catastrophically.

PACS numbers: 82.45.Bb

The Kinetics of Phosphate Film Formation on the Type MA 21 MagnesiumLithium Alloys

L. A. Isaicheva, N. M. Trepak, L. K. Il’ina, and A. L. L’vov

Saratov State University, ul. Universitetskaya 42, Saratov, 410601 Russia

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Received June 8, 2005

Abstract — Kinetics of phosphating MA 21 magnesium–lithium alloys in a zinc–nitrate–phosphate solution (0.25 Zn²⁺ + 0.34 + 0.17 N + 0.02 F, pH = 2.7) at 25°C is studied with various surface preparation procedures. The effect of the alloy surface pretreatment in titanium-containing activating solutions on the electrochemical process rate and the initial stage of the phosphate film crystallization is revealed. Peculiarities of the phosphate film growth during different stages of the magnesium–lithium alloy phosphating are elu-cidated. Combining the activating pretreatment with zinc–phosphate bath allows accelerated applying finegrain thin phosphate conversion layers with enhanced protective effect on magnesium–lithium alloys.

PACS numbers: 81.65.Rv

Electrochemical Production of Ultradisperse Copper-Containing Particles from Organo-Aqueous Electrolyte Solutions

S. A. Chulovskaya^a, A. V. Balmasov^b, S. A. Lilin^{a, b}, and V. I. Parfenyuk^{a, b}

^a Institute of Chemistry of Solutions, Russian Academy of Sciences,
ul. Akademicheskaya 1, Ivanovo, 153045 Russia

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^b Ivanovo State University of Chemical Technology, pr. Engelsa 7, Ivanovo, 153460 Russia

Received October 20, 2005

Abstract — A possibility of the cathodic deposition of copper-containing nanopowders from organo-aqueous electrolyte solutions is studied. The dimension of particles is corroborated with a transmission electron microscope. Additions of low-molecular surfactants to aqueous electrolyte solutions lead to a decrease in the limiting cathodic currents thus promoting the formation of finely dispersed powder.

PACS numbers: 81.16.c/82.45.Yz

Immersion Potential

R. R. Salem

The Higher Chemical College, Moscow, Russia

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Received November 30, 2004

Abstract — A novel interpretation of the nature of Billiter’s potential is proposed.

Investigation of the Oxidation Kinetics of Steel during Its Preliminary Roasting before Enameling

O. R. Lazutkina^a , P. I. Buler^b , A. K. Kazak^c , and N. B. Mullagalieva^a

^a VPO Ural State Technical University–Ural Polytechnical Institute,
ul. Mira 19, Yekaterinburg, 620002 Russia
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^b Erlangen University, Nurenberg, D-81058 Erlangen Martenstrasse 5, Deutschland

^c State Scientific Center, OAO Ural Institute of Metals,
ul. Gagarina 14, Yekaterinburg, 620062 Russia

Received January 28, 2005

Abstract — The oxidation kinetic peculiarities of traditional and prospective steels utilized in manufacturing hot-rolled enameled pipes are considered. The oxidation conditions, as well as its limiting stages, in a temperature range of 500–900°C, are determined. The x-ray diffraction analysis was applied to determine the composition of the scale formed. Ways of selecting the optimum temperature–time conditions of roasting the metal before its enameling are recommended.

Modeling of Linear Correlation in Stray Current Circuits

A. M. Kerimov, P. A. Spirin, and R. A. Kerimov

Azerbaidzhan State Oil Academy, ul. D. Alievoi 235/9, Baku, AZ-1010 Azerbaidzhan

Received April 23, 2005

Relationship between the Parameters of Stray Current Circuits and the Traction Load

A. M. Kerimov, P. A. Spirin, and R. A. Kerimov

Azerbaidzhan State Oil Academy, ul. D. Alievoi 235/9, Baku, AZ-1010 Azerbaidzhan

Received April 24, 2005