查看更多>>摘要：This paper is devoted to a theoretical analysis of equilibrium adsorption of the components of the W-F system on the basal planes of a tungsten single crystal. A complete data bank of thermochemical constants has been compiled for tungsten fluorides in the monomeric and oligomeric forms and for fluorine. Equilibrium pressures of gaseous components of the W-F system have been calculated in a wide temperature range; the gaseous phase has been shown to mainly contain WF_6, WF_3, WF_4, and F. Equilibrium parameters of adsorption for all components on W (100) and (110) planes have been calculated to show that these planes are saturated mostly by tungsten pentafluoride and elementary fluorine. The degree of coverage depends only moderately on the temperature and the total pressure of the reaction mixture. There is a specific feature of the adsorbed layer in fluoride systems in the existence of very strong lateral interactions between the adsorbed fluorides and fluorine.
查看更多>>摘要：The results of atmospheric corrosion tests on a series of metals and alloys in marine and industrial atmospheres of the Earth's regions with cold and very cold climate (Antarctic, sub-Arctic, Russian Far East) are considered. The class of most dangerous corrosive damage includes special types such as pitting, exfoliation corrosion, crevice corrosion and corrosion-induced cracking. Long-term prognosis is made concerning the influence of global warming on the atmospheric corrosion in cold climate regions.
查看更多>>摘要：The effect of the degree of cold deformation on the structure and mechanical and corrosive properties of the corrosion-resistant alloy KhN30MDB have been studied in detail. Deformation regimes that provide for a high level of strength properties and satisfactory plasticity, combined with high corrosion resistance, including general and pitting corrosion and sulfide corrosion cracking in hydrogen sulfide, have been determined.
查看更多>>摘要：The protective properties of corrosion inhibitors have been studied in stratal waters of some oil fields located in the Perm region and the Timano-Pechorsk oil and gas bearing province, which are characterized by a high level of mineralization and contain corrosion- aggressive components. The ability of inhibitors to produce protective aftereffect is evaluated. The dependence of the anodic and cathodic processes on steel on the composition of medium, corrosive agents, temperature, and inhibitors has been studied by electrochemical techniques.
查看更多>>摘要：Results of testing for resistance to atmospheric corrosion in a humid-tropical climate (in experimental chambers and under outdoor conditions) have been performed for templates of ribbed pipes made of a carbon steel with various types of anticorrosion (paint, diffusional, metallic) coatings. An optimum type of coating has been determined, its properties have been investigated, and the optimum thickness was found that proved to be good at corrosion resistance in ribbed pipes and allowed for the specificity of structural and service features of the equipment to be protected.
查看更多>>摘要：The degradation of nanodimensional platinum catalysts in concentrated phosphoric acid and the related changes in the kinetics of cathodic oxygen reduction have been studied in the course of accelerated corrosion tests. The results of structural and electrochemical investigations showed that the stability of such electrocatalytical systems substantially depends on the type of supporting carbon and the metal phase composition.
查看更多>>摘要：The influence of salts of substituted benzoic acids on steel behavior in chloride-containing solutions Ca(OH)_2 was studied. It was shown that the studied compounds inhibit local metal depassivation, elevating its potential and extending its induction period. The efficiency of inhibiting protection decreases when both hydrophilic and hydrophobic substituents are introduced in the aromatic nucleus of benzoic acid. The possible mechanism of the influence of substituent nature on protective properties of the studied compounds was considered.
查看更多>>摘要：The protective properties of a quaternary ammonium salt (dimethyl alkyl benzyl ammonium chloride, or catamin AB) have been studied in wide intervals of concentrations of H_2S (from 10 to 2000 mg/1) and of the inhibitor (from 25 to 500 mg/1). It is shown that catamin AB, which effectively slows down the corrosion of steels and preserves their plastic properties in aqueous solutions saturated by hydrogen sulfide to approximately C_(H_2S) = 2000 mg/1, does not possess high protective properties in the same solutions at C_(H_2S)= 0.0-50.0 mg/1. According to the results of XPS studies, this fact is connected to the weak adsorption of this inhibitor on the surface of steel in the absence of a film of iron sulfides on it. Based on the XPS data, it has been shown that, in media containing high concentrations of H_2S, a thin (a few nanometers thick) film of iron sulfides is formed on steel. This film is covered with a monomolecular layer of catamin AB, impeding the dissolution of the steel and further growth of the sulfide film.
查看更多>>摘要：Stationary oxygen concentration in a closed heat-supply system, which is filled and replenished with non-deaerated water at a temperature of 20 deg C, has been calculated. The calculation takes into account the system surface-to- volume ratio and the relative added makeup water volume fraction. In the case of a system using corrosion inhibitors, the stable oxygen concentration at a preset makeup rate falls within 400-800 mu g/dm~3. Experiments performed in a special setup for polarization measurements showed that, at an oxygen concentration of 600 mu g/dm~3, a decrease in the general internal corrosion rate can be achieved using IOMS-1 and PAF-13A inhibitors at a concentration of 4-5 mg/dm~3, or a zinc complex of oxyethylidenediphosphonic acid at 25 mg/dm~3.
查看更多>>摘要：The influence of treating the coatings obtained by plasma electrolytic oxidation (PEO) and various fractions of polytetrafluoroethylene on the state of the surface of formed composite layers has been studied by electrochemical impedance spectroscopy, differential thermal analysis, and thermogravimetry. Differences in the resistance to charge transfer at the oxide heterostructure/electrolyte interface for various composite layers have been found. The obtained data significantly enlarge and complement the possibilities of directly forming protective coatings, including antiscale ones, on the surface of titanium alloys operating in aggressive media at high temperatures.
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