A Quantum-Chemical Model of Active Centers of Electrochemical Corrosion of Metals

On the atomic level, we consider a model of the formation of active centers on the surface of a metal, which control the course of corrosion and electrochemical processes. Our quantum-chemical computations demonstrate that a foreign tin atom in a Sn - Ni₈ - Ni cluster can favor the dissolution of nickel in an acid medium, and a zinc atom in a Zn - Ni₈ - Ni cluster induces its passivation. We also show that the introduction of an oxygen atom into a cluster favors the passivation of nickel.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 1, pp. 12–18, January–February, 2005.     

Specific features of the selective dissolution of 12Kh18N10T steel in ozonized sulfuric acid

We study the laws of corrosion-electrochemical behavior and selective dissolution of 12Kh18N10T steel in ozonized aqueous 20, 30, 40, and 70% sulfuric acid solutions. Ozone retards the corrosion rate of the steel only for acid concentrations lower than 40%. In ozonized 30 and 40% H₂SO₄ solutions, the dissolution of nickel and chromium in the course of corrosion of 12Kh18N10T steel becomes slower, but the amount of dissolved chromium is twice as great as that of nickel. We propose a hypothesis on the influence of ozone on the dissolution of components of the steel through the formation of OH⁻ ions, favoring the oxidation of iron and chromium to higher valences, which limits the anodic process. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 5, pp. 69–73, September–October, 2005.     

Corrosion Resistance of Hastelloy-B in the Ozonized Medium

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 diminishing the anodic dissolution of nickel.__________Translated from Zashchita Metallov, Vol. 41, No. 3, 2005, pp. 284–288.Original Russian Text Copyright © 2005 by Tatarchenko, Cherkas.     

Thermal conditions for producing articles from a melt

The temperature distribution is indicated through directly measurable values from consideration of convection equations for the steady-state process. The impossibility of stabilization of the interface when the extraction rate changes is shown.     

The Effect of Ozone on the Corrosion of Steels in the Processes of Oxidation of Pyridines

The corrosion-electrochemical behavior of austenitic and ferritic steels and their weld joints in model systems of oxidation of pyridines in the presence of ozone is investigated. Possibilities of applying structural steels to the implementation of organic synthesis processes in ozonated acetic acid media are assessed. __________ Translated from Zashchita Metallov, Vol. 41, No. 5, 2005, pp. 515–519. Original Russian Text Copyright ? 2005 by Tatarchenko, Shapovalova.     

Corrosion-Electrochemical Behavior of Nickel in Ozonized Sulfuric Acid Solutions

Ozonization of sulfuric acid solutions increases the corrosion rate of nickel, in the mean, by an order of magnitude but, at the same time, decreases its hydrogenation. Cathodic processes are responsible for the active part of hydrogen ions in ozone reduction with the formation of hydroxyl ions and hydrogen peroxide in the near-electrode layer.