In this article, the results of studying the polarization characteristics of magnesium covered with corrosion film in aqueous solutions of MgSO4 and Na2SO4 are presented. The absence of a corrosion-free magnesium surface was shown; in this connection, it was proposed to interpret the larger values of Tafel’s coefficients obtained in the experiment from the point of view of limiting the electrochemical process by charge transfer in the film phase. Charge transfer in corrosion films obeys the regularities of particle movement in high electric fields, and it is not only cationic. According to the impedance measurements, the resistance of the oxide and hydroxide layer of the magnesium-based corrosion film in the studied solutions was calculated. The largest contribution to the restriction of charge transfer in the initial stages of corrosion is made by a dense primary film defining the polarization resistance. Correlation of transfer parameters in high electric fields with thickness and resistance of corrosion film was demonstrated.
The present study reports a synthetic condensation process of a vegetable oil (waste) reacted with triethanolamine, maleic anhydride and acrylonitrile in (1 : 1.2 : 2 : 1) mole ratios to obtain N-(β-ethoxypropionitrile)-N,N-bis(2-hydroxyethylethoxy) fatty amide as a major inhibitory product. Corrosion property of steel in a 3% NaCl solution in the presence of a potential inhibitor was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. These methods gave consistent results, from which it is noticeable that inhibition efficiency increases with the increasing concentration of the inhibitor. Gravimetric studies show an increase in the sample mass at an inhibitor concentration of 10 mM, indicative of adsorbed film formation on the surface. The polarization curve results showed that the compound demonstrates itself as an anodic-type inhibitor. A rise in polarization resistance values in the EIS measurements also confirmed that the compound acts as an effective inhibitor of steel corrosion. Furthermore, the R(CR)(QR) equivalent circuit was used to interpret the results obtained in the investigation of the corrosion behaviour of steel in solution with an inhibitor. The standard adsorption free energies calculated from the Langmuir isotherm indicate that adsorption takes place by physical and chemical mechanisms. The presence of adsorbed protective film was confirmed by FT-IR spectrum and SEM micrographs.
A synthesis of bismuth selenide with a thickness of 3-4 nm on the surface of mica taken as a matrix was investigated using the gas-solid mechanism. Since discovery of two-dimensional atomic crystals of graphene in 2004, scientists have grown interested in exploring methods for synthesis of two-dimensional atomic crystal nanofilms. Among them, of particular interest are sulfides and transition metal selenides, such as molybdenum sulfide, tungsten selenide, bismuth selenide. Bismuth selenide possesses special thermoelectric, photoelectric properties, therefore there are wide possibilities for its use in such areas as thermoelectric devices, photosensitive elements, optical information keepers, etc. In this connection, there are many studies on the search for optimal methods for the synthesis of bismuth selenide. Each of the proposed methods has its own advantages and disadvantages. In the article, a variety of the recently used gas-liquid-solid mechanism (V-L-S) is used as a method for the synthesis of bismuth selenide. When using amorphous silicon dioxide as a matrix, the synthesized bismuth selenide is not uniform, and the synthesis process is uncontrollable. Therefore, in the work fluorinated gold mica was used as a matrix. The effect of temperature, gas feed rate on the size, shape and thickness of the film was investigated.
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