Search

The etching of iron alloy items in a H3PO4 solution is used in various human activities (gas and oil production, metalworking, transport, utilities, etc.). The etching of iron alloys is associated with significant material losses due to their corrosion. It has been found that an efficient way to prevent the corrosion of iron alloys in a H3PO4 solution involves the formation of thin complex compound films consisting of the corrosion inhibitor molecules of a triazole derivative (TrzD) on their surface. It has been shown that the protection of iron alloys with a mixture of TrzD + KNCS in a H3PO4 solution is accompanied by the formation of a thin film of coordination polymer compounds thicker than 4 nm consisting of TrzD molecules, Fe2+ cations and NCS−. The layer of the complex compound immediately adjacent to the iron alloy surface is chemisorbed on it. The efficiency of this composition as an inhibitor of iron alloy corrosion and hydrogen bulk sorption by iron alloys is determined by its ability to form a coordination polymer compound layer, as experimentally confirmed by electrochemical, AFM and XPS data. The efficiency values of inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 at a temperature of 20 ± 1 °C are 97% and 98%, respectively. The kinetic parameters of the limiting processes of hydrogen evolution and permeation into an iron alloy in a H3PO4 solution were determined. A significant decrease in both the reaction rate of hydrogen evolution and the rate of hydrogen permeation into the iron alloy by the TrzD and its mixtures in question was noted. The inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 decreased the total hydrogen concentration in the iron alloy up to 9.3- and 11-fold, respectively. The preservation of the iron alloy plasticity in the corrosive environment containing the inhibitor under study was determined by a decrease in the hydrogen content in the alloy bulk. [ABSTRACT FROM AUTHOR]

Background: Marine atmospheres are the most corrosive, primarily because they contain sea salts. To assess the category of atmospheric corrosivity, the deposition rate of chloride ions should be measured by experimental methods for at least 1 year, which requires significant expenses and is not always feasible due to the time frame required for the design and erection of structures. Methods: In this study, a fairly simple model for predicting the chloride deposition rate in the coastal zone depending on the wind pattern of the test site, namely wind direction, average speed, and duration in each wind speed range, the distance from the coastline, and the magnitude of marine aerosol generation for each wind speed range, has been developed. The results of comparing the calculated chloride deposition rates with experimental data obtained by the ‘wet candle’ method are presented. Significant findings: The applicability of the model for predicting the categories of atmospheric corrosivity toward typical metals (carbon steel, zinc, copper and aluminum) using dose-response functions has been demonstrated. [ABSTRACT FROM AUTHOR]