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(17/04) Курс “Анализ геномных данных”, Москва, 2 – 11 июля 2012
Уважаемые коллеги, Со 2 по 11 июля 2012 года Учебный центр Института биологии гена РАН организует практический десятидневный курс по статистическому анализу геномных дан...
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(12/03) Впервые получено изображение атомов, движущихся в молекуле
Исследователи из Университетов Огайо и Канзаса впервые смогли получить изображения атомов, движущихся в молекуле. С помощью ультрабыстрого лазера исследователи выбивали элек...
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(12/03) Наблюдение за распределением зарядов в молекуле
Исследователи из Швейцарии впервые с помощью экспериментов смогли визуализировать распределение зарядов отдельной молекуле. Предполагается, что результаты работы могут при...
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(22/01) Простой способ разделения углеродных нанотрубок
Существуют одностенные углеродные нанотрубки [single-walled carbon nanotubes (SWCNT)] с металлическим и полупроводниковым типом проводимости, однако для использования этих...
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Результаты 1 - 10 из 13
1.

Corrosion Resistance and Dezincing of Brasses

I. K. Marshakov

 

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received March 23, 2004

 

Abstract — The corrosion behavior of brasses in aerated electrolyte solutions (where dezincing is frequently observed) is studied. In this case, a layer of fine-grained copper forms on the brass surface. Ignoring this copper as the corrosion product, that is, calculating corrosion loss by the sample weight loss, one underestimates actual corrosion rate by 1.5–2 times. However, in closed systems, in the absence of dezincing, oxidized copper accumulates in solution and acts as a catalyst of cathodic process increasing significantly the corrosion rate. The following methods of reducing the corrosion rate and brass dezincing are considered: deoxygenation of medium, the use of zinc anodes, and the alloying of brasses with the third component. The conditions, under which these methods are the most efficient, are determined.
30/09/2008 | 843 Посещения | Печать

2.

Chronoammetry and Chronopotentiometry on Electrodes with a Microrough Surface: Theoretical Consideration

O. A. Kozaderov and A. V. Vvedenskii

 

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received August 17, 2004

 

Abstract — The problem of transient two-dimensional diffusion to a microrough electrode under galvano- and potentiostatic polarization conditions is solved. The effect of the scale and morphology of roughness, as well as the diffusivity on the time dependences of I current and overpotential is analyzed. Both of them are found to be practically independent of the type of the roughness, while its degree (the microroughness factor fr) decisively affects the shape of the current- and overpotential-decay curves. At a relatively short polarization when the diffusion front profile repeats the electrode surface relief, the parameters of transient electrochemical methods (the I current in the potentiostatic measurements and the 1/2 rooted transient time in the galvanostatic ones) linearly depend on the microroughness factor. Upon a relatively long polarization when the diffusion front is noticeably distant from the surface and almost planar, the current and overpotential values fit in with classical equations of chronoammetry and chronopotentiometry, being independent of fr . At a thickness of the diffusion layer comparable to the height of surface irregularities, the current (as well as the rooted transient time) ratio of the microrough to perfectly smooth electrode surface looses its linear dependence on the surface parameters. The time location of this range is chiefly determined by the diffusivity and the mean distance between the microscopic surface irregularities.
30/09/2008 | 839 Посещения | Печать

3.

2D Atomic-Topological Model of the Dissolution Kinetics of a Metallic Crystal: Typical Atomic Relief Positions and Fragments 

G. Yu. Alekseev*, Yu. V. Alekseev*, **, and V. A. Bityurin*

 

* Institute of High Temperatures, Russian Academy of Sciences, Moscow, Russia

** Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow, 103064 Russia

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Received November 11, 2003; in final form November 15, 2004

 

Abstract — The atomic-topological kinetics problem of the self-consistency between the dissolution kinetics and the atomic relief of the dissolving boundary is solved for an imaginary two-dimensional crystal in two ways: (i) in terms of the model of atomic positions determined by the number of the nearest neighbors and (ii) in terms of the typical atomic relief structures (steps, kinks, etc.). To a sufficient accuracy, the results provided by these two models coincide. The approaches developed are aimed at solving the problem of the dissolution of an actual three-dimensional crystal.
30/09/2008 | 820 Посещения | Печать

4.

Electrochemical Behavior of Manganese Silicides in Sulfuric Acid Solution

A. B. Shein and E. N. Zubova

 

Perm State University, ul. Bukireva 15, Perm, GSP, 614990 Russia

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Received December 23, 2002

 

Abstract — The corrosion-electrochemical behavior of Mn5Si3 and MnSi silicides in the sulfuric acid electrolyte is studied by using the steady-state and cyclic voltammetry in combination with atomic absorption analysis. The following main regularities of the anodic dissolution of silicides are revealed: Mn dissolves selectively from the sublattice in silicide and, then, the process is controlled by diffusion of Mn in the compound and oxidized Mn through a layer of hydrated SiO2 oxide formed at the surface.
30/09/2008 | 807 Посещения | Печать

5.

Settling Peculiarities of Silver Sulfide Potential in Acetate Media

G. V. Makarov and I. G. Soboleva

 

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

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Received May 26, 2003

 

Abstract — Peculiarities of the argentite (-frame0g2S) electrode potential settling in acetic acid–acetate solutions are revealed by electroless chronopotentiometry, voltammetry at low polarization, and measuring the rim (wetting) angle. The process rate and the rate constant for the chalcogenide dissolution in a pre-equilibrium state are calculated from the self-dissolution current and the potential transient, respectively. The zero charge potential is found; the pH effect on the above parameters is revealed. It is shown that the potential-determining reaction involves the metal, rather than sulfide, ions.
30/09/2008 | 794 Посещения | Печать

6.

Electroplating of Chromium-Cobalt Alloy Coatings from Sulfate Solutions

B. A. Spiridonov

 

Voronezh State Technical University, Voronezh, Russia

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Received March 20, 2003

 

Abstract — The kinetics of electroplating of chromium-cobalt alloy from sulfate solutions containing monoet-hanolamine is investigated. The effect of electrolysis conditions on the composition, current efficiency, and protective properties of coatings is studied.
30/09/2008 | 851 Посещения | Печать

7.

A Computer System Measuring the Electrical Parameters of Microplasma Processes in Solutions

A. I. Mamaev* , V. N. Borikov** , V. A. Mamaeva* , and T. I. Dorofeeva*

 

* Institute of Strength Physics and Material Science, Siberian Division, Russian Academy of Sciences,
Akademicheskii pr. 8/2, Tomsk, 634070 Russia

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** Tomsk Polytechnical University, Tomsk, 634006 Russia

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Received January 12, 2004

 

Abstract — A computer-aided system developed measures the electrical parameters of high pulse-current processes in solutions, including precisely determining the shape and form of high-voltage signals of the electrochemical cell. The shape changes in the electrical signals of microplasma processes are revealed as a function of the bath, as well as working electrode, composition and the process time.
30/09/2008 | 869 Посещения | Печать

8.

Corrosion Resistance of Hastelloy-B in the Ozonized Medium

G. O. Tatarchenko1 and K. V. Cherkas2

 

1 North-Donetsk Technological Institute of the East Ukrainian State University,
Sovetskii pr. 59a, North-Donetsk, Lugansk oblast, 93400 Ukraine

2 North-Donetsk State Industrial Enterprise “Nitrogen Company”,
ul. Pivovarova 5, North-Donetsk, Lugansk oblast, 93403 Ukraine

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Received September 25, 2003

 

Abstract — Corrosion–electrochemical behavior of Hastelloy-B and its components nickel and molybdenum is investigated at various concentrations of sulfuric acid in the presence of ozone. It is found that in ozonized solutions of sulfuric acid the alloy is corrosion-proof, and the effect of molybdenum reduces to ordinarily dimin-ishing the anodic dissolution of nickel.
30/09/2008 | 829 Посещения | Печать

9.

Corrosion of Highly Dispersed Systems Based on Iron and Feframe0Si Alloys in Neutral Electrolytes. II. Iron-Based Systems Obtained by Grinding in Heptane with an Organosilicon Additive

 

A. V. Syugaev*, S. F. Lomayeva*, and S. M. Reshetnikov**

* Physicotechnical Institute, Ural Division, Russian Academy of Sciences,
ul. Kirova 132, Izhevsk, 426000 Russia

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** Udmurt State University, ul. Universitetskaya 1, Izhevsk, 426034 Russia

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Received November 18, 2003

 

Abstract — The corrosion behavior of highly dispersed iron powders obtained by mechanical grinding in a solution of triethoxy(vinyl)silane (0.3 wt %) in heptane was studied in 0.85% NaCl at 37°C. The protective properties of the layer covering the powder particles were found to be determined by oxide and organosilicon compounds. This layer is significantly less effective than the layer formed in the presence of oleic acid.
30/09/2008 | 908 Посещения | Печать

10.

Protective Effects of 2-Thioquinazolin-4-One Derivatives on Steel 20 in Various Corrosive Media

O. I. Sizaya, O. L. Gumenyuk, and L. Yu. Chumakova

 

Chernigov State Technological University, ul. Shevchenko 95, Chernigov, 14027 Ukraine

e-mail: verv@ mail.cn.ua

Received May 20, 2004

 

Abstract — The dependence of the inhibitive effects of new 2-thioquinazolin-4-one derivatives on the corrosivity and pH of the medium was studied. The test compounds were found to effectively inhibit the acid corrosion of steel 20; when combined with (NH4)2MoO4 , 2-thioquinazolin-4-one derivatives inhibit both the cathodic and anodic processes of electrochemical corrosion in neutral (0.3 to 0.6% NaCl) and alkaline media (0.1 M NaOH). In 3% NaCl, the test compounds stimulated corrosion.
30/09/2008 | 846 Посещения | Печать

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