Adsorption Properties of AluminaAluminum Cermets Prepared

in the Aluminum Powder Reaction with Water

in the Presence of Surfactants

T. F. Kuznetsova*, A. I. Rat’ko*, V. E. Romanenkov*, S. F. Tikhonov**, and V. A. Sadykov**

*Institute of General and Inorganic Chemistry, Belarusian Academy of Sciences, Minsk, Belarus

**Boreskov Institute of Catalysis, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrent’eva 5,

Novosibirsk, 630090 Russia

Received June 23, 2007

Abstract — By a method of low-temperature nitrogen adsorption–desorption at the gas/solid interface, the trends in the adsorption and capillary-condensation properties of Al₂O₃/Al composites are studied as a function of the way of conjugate stages, namely, the metal hydrothermal oxidation and the replication of colloidal aluminum hydroxide by surfactants of the anionic, cationic, and non-ionogenic types.

PACS numbers: 81.05.Mh

Oxide Sublimation during the High-temperature Oxidation

of Nickel Alloys with Protective Coatings

E. G. Ivanov

Zhukovskii Air Force Academy

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Received October 16, 2006

Abstract — It is shown that the oxidation of heat-resistant alloys is accompanied by a sublimation of the oxides MoO₃, WO₃, Al₂O₃, and CrO₃. The determinant in the sublimate is the molybdenum content, exceeding that in scale by a factor of 50–100. Protective coatings diminish the sublimation, rather than fully eliminate it. To diminish the molybdenum oxide sublimation decisively, it is expedient to alloy the coating with magnesium or magnesium oxide.

Enhancement of the Adsorption Selectivity of Nanoporous

Clinoptilolite by Hydrophobization with Organosiloxanes

L. I. Bel’chinskaya*, O. Yu. Strel’nikova*, L. A. Novikova*,

F. Ressner***, and O. V. Voishcheva**

* Voronezh State Academy of Forestry Engineering, Voronezh, Russia

** Voronezh State Agrarian University, Voronezh, Russia

*** Carl von Ossietzky Universityat, Oldenburg, Germany

Received June 13, 2007

Abstract — The adsorptivity of natural nanoporous clinoptilolite modified with polymethyl- and polyethylsi-loxanes was studied. The surface of modified clinoptilolite is less hydrophilic, which lowers the selective adsorption of water from a mixture with toluene. The specific surface area and porosity of natural clinoptilolite were determined. The IR spectra of natural and modified clinoptilolites were recorded. Hydrophobization of the natural zeolite surface with organosiloxanes made it more adsorption-selective to formaldehyde. Polyethyl-siloxane was found to be a better surface modifier than polymethylsiloxane.

PACS numbers: 68.43.-h

Extracting Heavy Metals with Cellulose-Containing Materials

N. A. Bagrovskaya, O. V. Alekseeva, O. V. Rozhkova, A. N. Rodionova, and S. A. Lilin

Institute of Solution Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia

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Received October 26, 2007

Abstract — Sorptivity of cellulose-containing materials of heavy metal ions from diluted electrolyte solutions is studied. Capacity and kinetic characteristics of the sorbents are estimated. The limiting stage of the adsorption of copper and nickel ions is shown to have a mixed nature. These sorbents are found to provide a high degree of metal ion removal.

PACS numbers: 68.43.-h

Study of Corrosion Protection of Different Stainless Steels by Nanocrystalline Plasma Electrolysis

M. Kh. Aliev, A. Sabour, and T. Shahrabi

Faculty of Engineering, Tarbiat Modares University, Tehran, Iran, P.O. Box: 14115-143

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Received June 01, 2007

Abstract — The effect of nitrogen and carbon bombardment on the corrosion behavior of three different stainless steels (AISI 304, AISI 316L and AISI 430) is discussed in this work. Nitrogen and Carbon was entered into the lattice in order to generate a rich region near the surface by a relatively new method called plasma electrolysis. Different ion bombardment doses under different applied voltages and thus different electrical fields (230, 245, 260 volts) at 330 mS/Cm of electrical conductivity of specific electrolyte have been tested to optimize the ion bombardment doses for each steel. The corrosion measurements were carried out in sodium chloride solution by using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS). The experimental results showed that the effect of N and C ion bombardment mainly depends on the microstructure and/or composition of the stainless steels. Less compact structures and/or less amount of alloying elements (as occurs with the body centered cubic, ferritic AISI 430) achieve bigger changes with this modification, whereas on stainless steels with a larger amount of alloying elements and / or more compact structures (like the face centered cubic, austenitic AISI 316L) ion bombardment slightly modifies the corrosion behavior.

Mathematical Model and Algorithm for Computing the Electric Field of Pipeline Cathodic Protection with Extended Anodes

A. M Bolotnov*, N. N. Glazov, N. P. Glazov, K. L. Shamshetdinov, and V. D. Kiselev

*Bashkortostan State University, Ufa, Bashkortostan, Russia

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Scientific-Research Institute of Construction and Operation of Heat-Power Objects Ltd VNIIST

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Received June 10, 2006

Abstract — A mathematical model and a numerical method for computing the electric fields of the pipeline cathodic protection with extended anodes in a three-dimensional semirestricted domain. The developed algorithm and program allow one to assess the effect of geometrical parameters on the effectiveness of the cathodic protection of main pipelines.

PACS numbers: 02.60.Lj, 81.65.Kn

Work Function and Its Measurement in a Galvanic Cell

R. R. Salem

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Received October 16, 2006

Abstract — Different methods of estimating the work function are considered. The electrochemical technique of measuring the work function as the most promising is discussed.

PACS numbers: 73.30.+y

Study of Corrosion Protection of Different Stainless Steels by Nanocrystalline Plasma Electrolysis

M. Kh. Aliev, A. Sabour, and T. Shahrabi

Faculty of Engineering, Tarbiat Modares University, Tehran, Iran, P.O. Box: 14115-143

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Received June 01, 2007

Abstract — The effect of nitrogen and carbon bombardment on the corrosion behavior of three different stainless steels (AISI 304, AISI 316L and AISI 430) is discussed in this work. Nitrogen and Carbon was entered into the lattice in order to generate a rich region near the surface by a relatively new method called plasma electrolysis. Different ion bombardment doses under different applied voltages and thus different electrical fields (230, 245, 260 volts) at 330 mS/Cm of electrical conductivity of specific electrolyte have been tested to optimize the ion bombardment doses for each steel. The corrosion measurements were carried out in sodium chloride solution by using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS). The experimental results showed that the effect of N and C ion bombardment mainly depends on the microstructure and/or composition of the stainless steels. Less compact structures and/or less amount of alloying elements (as occurs with the body centered cubic, ferritic AISI 430) achieve bigger changes with this modification, whereas on stainless steels with a larger amount of alloying elements and / or more compact structures (like the face centered cubic, austenitic AISI 316L) ion bombardment slightly modifies the corrosion behavior.

PACS numbers: 81.65.Kn

The Effect of Anionic Composition of Electrolytes on the Anodic Dissolution of Iron-Family Metals

D. A. Tkalenko, Yu. P. Vishnevskaya, and M. V. Byk

National Technical University of Ukraine (Kiev Polytechnical Institute), pr. Pobedy 37, Kiev-56, 03056 Ukraine

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Received July 24, 2006

Abstract — The anodic dissolution rate of the iron-family metals is analyzed depending on the anionic composition of aqueous electrolyte solutions. Investigation of the process in a broad range of potential values (including the limiting current range) in solutions with the controlled content of cations and anions enables us to discover the diffusion limitations at a stage of anion supply to the electrode–electrolyte interface and show the importance of processes in the electrolyte layer near the electrode. During the anodic process, anions, which are present in the solution, act not only as counterions balancing for change balancing of the positive metal ions formed at the interface, but also as depolarizers of the anodic process. Upon the formation (or at the moment of appearance), metal ions interact with the anions to form ion pairs that may exist and move independently. The supply of “free” anions to the electrode surface controls the process rate in the limiting current range.

PACS numbers: 82.45.Qr

Corrosion of Uranium and Its Low Content Zr, Nb, and Ru Alloys in Aqueous Solutions

V. F. Peretrukhin, A. G. Maslennikov, A. Yu. Tsivadze, C. H. Delegard*, A. B. Yusov, V. P. Shilov,  A. A. Bessonov, K. E. German, A. M. Fedoseev, L. P. Kazanskii, N. Yu. Budanova, A. V. Kareta, A. V. Gogolev, K. N. Gedgovd, and G. S. Bulato

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

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*Pacific Northwest National Laboratory, P. O. Box 999, Richland, WA, USA

Received August 14, 200

Abstract — Corrosion of uranium and its alloys with low content (0.5–5.0 at %) of Zr, Nb, and Ru in water and bicarbonate aqueous solutions is studied; the effect of hydrogen peroxide, the main product of radiation pro-cesses, on the corrosion rate is elucidated. The rate of the primary corrosion process U + (2 + n)H₂O = UO₂ · nH₂O + 2H₂ is measured by electrochemical methods in anaerobic and aerobic conditions for uranium metal and its alloys containing 0.5 to 5.0 at % of Zr, Nb, and Ru. It is shown that the corrosion rates for the alloys are lower than that of reactor-grade uranium; however, the difference is rather close to the measurement error. The corrosion mechanism is studied; U(III) is shown to be rather unstable in neutral solutions when uranium(III) hydroxide is precipitated and no significant amount of U(III) and UH₃ is present among the products of the metallic uranium corrosion in water. The kinetics of the second corrosion stage U(IV) + O₂ U(VI) is studied by spectrophotometric method. It is shown that the reaction of U(IV) oxidation by atmospheric oxygen is similar in weakly acid solutions (pH 1.5–4.0) and in bicarbonate media: in particular, it has an induction period for uranium (IV) accumulation, after which the reaction accelerates; it is formally a first-order reaction with respect to uranium. The reaction mechanisms differ in the two media: in weakly acid solutions, after the appearance of U(VI), the reproportionation reaction proceeds; thus formed U(V) interacts with O₂ faster than U(IV). In the bicarbonate medium, the acceleration of the reaction is due to the formation of a [U(IV)U(VI)] complex whose reactivity is higher than that of uranium (IV). In the absence of bicarbonate, of great importance is the formation of a copolymer of U(IV) and U(VI), which at pH 4 prevents formation of U(V). It is shown that on the introduction of hydrogen peroxide to aqueous solutions, the metallic uranium surface becomes transpassive, which increases the rate of corrosion process by at least an order of magnitude,. The introducing of oxidants and platinum mesh lowers the hydrogen accumulation at 120150C and, hence, the hydrogen-explosion danger of the uranium–water–corrosion-products system. Methods of deposition of metal oxide (Tc, Ru, Mo, W)  films onto uranium surfaces by immersing uranium metal into Tc(VII), Ru(VI), or Mo and W heteropoly compound solutions are studied.

PACS numbers: 82.45.Bb, 81.65.Kh