Результаты 1 - 10 из 17
1.

Physicochemical Aspects of the Protection of Metals from Corrosion with the Use of Nano- and Microsize Coatings1

Yu. I. Kuznetsov

 

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

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Received April 1, 2004

 

Abstract — The formation of thin protective layers at metals, which could be successfully used for corrosion control, has long been the focus of attention for physical chemists. Those layers are formed either during the adsorption of corrosion inhibitors (CIs) or in reactions of the cations of the metal to be protected with some components of the medium. The latter case involves not only nanosized layers formed by CIs but also thick conversion (oxide, phosphate, etc.) coatings. Let us restrict our consideration to conversion coatings (CCs) with a thickness of< equal5 µm. Apparently, it is methods designed to form thin and ultrathin protective layers that will be in the best demand by the technologies of the XXI century. We will consider only a few important problems that physical chemists face with when studying the possibilities of the protection of metals from corrosion.

20/09/2008 | 1235 Посещения | Печать

2.

Relaxation Processes and Kinetics of the Thermal Oxidation of Niframe0Moframe1B Alloys Obtained by Chemical Catalytic Reduction

 

V. A. Arslambekov, A. B. Drovosekov, M. V. Ivanov, V. M. Krutskikh,
E. N. Lubnin, B. F. Lyakhov, and Yu. M. Polukarov

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

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Received July 4, 2005

 

Abstract — Kinetics of the high-temperature oxidation of Ni–Mo–B alloys containing 11 wt. % Mo (obtained by means of chemical catalytic reduction with the use of dimethylamine borane) is investigated. A strong dependence between the oxidation rate and the sublimation of volatile compounds on the prehistory of deposits is disclosed. Freshly obtained deposits exhibit an anomalous short-term weight loss caused by the “explosive” character of the removal of water vapors, evolved as a result of the reduction of molybdenum and boron oxides with hydrogen at heightened temperatures. Preliminarily heating the specimens in a vacuum decreases the intensity of or completely eliminates the anomalous phenomenon. When oxidizing the coatings in air at 600°C, two processes take place, namely, the oxidation of the coating components (a growth of the oxide layer) and the sublimation of volatile compounds.

 

20/09/2008 | 1263 Посещения | Печать

3.

Prospects of Applying Low-Waste Technologies in Nuclear Power Industry when Treating Its Loop Equipment

A. A. Lysenko

 

Joint-Stock Company “Design and Research Institute” (“OrgstroiNIIproekt”),
Kholodil’nyi per. 3a, Moscow, Russia

Received December 25, 2004

 

Abstract — The prospects for application of low-waste technologies for passivation, conservation, and deactivation of loop equipment of atomic power plants are considered. It is shown that, if they are properly used, their efficiency exceeds the efficiency of multireagent technologies, which were applied for hot loops of nuclear power plants.

 

20/09/2008 | 1136 Посещения | Печать

4.

A Relation between the Hyperfine Magnetic and Electronic Structure and the Passivability of the Heat Treated Feframe023% Cr Alloy

 

O. V. Kasparova*, Yu. V. Baldokhin**, and A. S. Solomatin**

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

** Semenov Institute of Chemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, Russia

Received February 8, 2005

 

Abstract — The effect of heat treatment conditions (quenching and tempering at 475°C for 200 h or at 650°C for 10 h) on the hyperfine magnetic structure, electron density distribution at 57Fe nuclei, and passivability of Fe–23% Cr alloys in either a highly pure state or with a heightened content of impurity elements is studied with  the use of Mössbauer -resonance spectroscopy combined with voltammetric measurements in a 1mol/lHClO4+ 0.25 mol/l NaCl solution at room temperature. Mössbauer spectra are processed (decomposed in three subspectra) with the help of Normos computer program, and the following parameters are estimated: the effective magnetic field intensity Heff (kOe); the half-width of the first subspectrum peak (mm/s); the first-to-third (W13) and second-to-third (W23) ratios of the subspectrum peaks; the isomeric (chemical) shift (mm/s) with respect to -Fe; the quadrupole electric splitting eq (mm/s); and the area part S (%) of the hyperfine structure subspectrum in the summary spectrum. Hyperfine magnetic structure and electron density distribution at iron nuclei are found to change depending on the alloy purity and heat-treatment conditions. The frame1spectroscopy data are considered in relation to the passivating characteristics of the alloy.

 

20/09/2008 | 1188 Посещения | Печать

5.
Modification of the Means for Prevention of Corrosion of Aluminum Alloys. 2. Diagnostics of the Corrosion Process. Enhancement of the Efficiency of Protective Means

 

A. A. Gerasimenko and T. E. Yampol’skaya

 

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

Received October 1, 2004

 

Abstract — The risk of the evolution of exfoliation corrosion under the operating conditions of structures made of aluminum alloys was estimated. Possible ways of modifying anticorrosion means (ACMs) were studied to enhance their effectiveness and prevent the corrosion evolution under severe climatic conditions.

 

20/09/2008 | 1142 Посещения | Печать

6.

Choice of Effective Corrosion Inhibitors for Acid Treatment of Wells

A. B. Shein and A. V. Denisova*

 

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

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* OOO FLEK, Perm, Russia

Received October 1, 2004

 

Abstract — Protective effects of some commercial corrosion inhibitors (VNPP-2V, KI-1, and IKU) in fluids used for acid treatments of oil wells were studied by gravimetric and electrochemical measurements. The inhibitors were tested in the presence of Fe3+ ions and in “aged” inhibited fluids.

 

20/09/2008 | 1136 Посещения | Печать

7.

Contact Corrosion of Steel 3 Caused by Its Different Aeration or Chloride Concentration Conditions

 

N. N. Glazov, S. M. Ukhlovtsev, I. I. Reformatskaya, A. N. Podobaev, and I. I. Ashcheulova

FGUP GNTs RF—Karpov Research Institute of Physical Chemistry,
ul. Vorontsovo Pole 10, Moscow, 103064 Russia

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Received March 17, 2005

 

Abstract — Corrosion processes caused by a contact of metal samples with initially different potentials were studied with specially designed electrochemical simulator. Probable corrosion cells were determined for carbon and low-alloyed steels. It is shown that irrespective of factors causing the initial potential difference between the samples in contact, the corrosion type and rate are determined by their potentials settled upon the contactand referred to the corresponding anodic polarization curve. Any current measured in the external circuit corresponds to a difference in the dissolution rates of surface areas in contact rather than to the metal dissolution rate. A local corrosion of phase-heterogeneous carbon, as well as low-alloyed, steels at their active dissolution potentials is caused by the different dissolution rates of their phase components at the corresponding potential.

 

20/09/2008 | 1144 Посещения | Печать

8.

Long-Term Inside Corrosion Attack of an Oil Main Operation

V. A. Andriashin1 , A. A. Kostyuchenko2, A. I. Komarov1 , and V. V. Vorob’ev2

 

1 Institute of Mechanics and Reliability of Machines, Belarussian Academy of Sciences,
ul. Academicheskaya 12, Minsk, 220072 Belarus

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2 Gomel Republican “Druzhba” Unitary Enterprise

Received September 16, 2004

 

Abstract — X-ray diffraction and metallographic analyses were applied when investigating the corrosion type and products of the cut-offs from an oil main with welded joints after its 33-year operation. Such a long-term effect of the transported medium and varying dynamic loading led to a considerable corrosion-mechanical damage to the inner surface of the pipe. The highest was the knife-line type of damage to the filler-parent boundaries of welded joints. The main corrosion products were Fe2O3 and Fe3O4 oxides that formed layers 300 to 350 µm thick. Beside the oxides, the deposits of hydrocarbon products (asphaltenes, resins, and paraffins), as well as calcium salts (CaCO3 and CaSO4), were present.

 

20/09/2008 | 1093 Посещения | Печать

9.

The Phase Composition of a Diffusion Zinc Coating Alloyed with Nickel on Steel 20

B. D. Antonov, Ya. B. Chernov, A. A. Pankratov, and A. P. Shurygin

 

Institute of High-Temperature Electrochemistry, Ural Division, Russian Academy of Sciences,
ul. S. Kovalevskoi 22, Yekaterinburg, 620219 Russia

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Received July 20, 2004

 

Abstract — Peculiarities of the phase composition of a corrosion-resistant coating at a steel 20 are investigated. The coating was formed by the solid-phase thermodiffusion in a mixture of zinc and nickel powders. An x-ray microspectral analysis of a transverse microsection showed that both the surface layer of the base metal and the coating itself are formed by two elements: iron and zinc taken in varying ratios. The contents of nickel in the coating and on its surface are considerably lower than its fraction in the starting mixture. Four phases were identified by means of layer-by-layer x-ray diffraction analysis from the substrate to the coating surface. The coating becomes single-phase only in its superficial layers.

 

20/09/2008 | 1177 Посещения | Печать

10.

Electrolytic-Plasma Oxidation in Borate Electrolytes1

V. S. Rudnev, I. V. Lukiyanchuk, and V. G. Kuryavyi

 

Institute of Chemistry, Far East Division, Russian Academy of Sciences,
pr. Stoletiya Vladivostoka 159, Vladivostok, 690022 Russia

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Received May 18, 2004

 

Abstract — Changes in the temperature and concentration of the aqueous tetraborate electrolyte, particularly, its transition from true to supersaturated solution range affect the voltage at the electrodes, the elemental and phase composition and surface structure of oxide layers formed at anodically polarized aluminum alloys under the effect of electric discharges. The results are of interest as regards controlling the characteristics of oxide plazma-electrolitic structures at valve metals.

 

20/09/2008 | 1170 Посещения | Печать

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