Vladimir I. Vigdorovich

The corrosion and the kinetics of electrode processes on a St3 steel with a superhydrophobic coating based on laser texturing of the surface and subsequent hydrophobization with fluorooxysilane (wetting angle is 165° ± 2° and roll angle is 3° ± 1°) in a highly mineralized chloride medium (50 g/L of NaCl) without and in the presence of hydrogen sulfide as an additive (400 mg/L) are studied. The influence of the duration of exposure of electrodes in solution (0.25–96 h) on the kinetics of electrode processes and the corrosion rate of steel is considered. The superhydrophobic coating on steel without hydrogen sulfide decreases the corrosion rate by a factor of 67, 13, and 2 after 0.25, 24, and 48 h exposure in a chloride solution. The cathodic process slows down in time and the anode process accelerates; this is especially important in the case of electrodes with a hydrophobic coating. The steel with a superhydrophobic coating in the presence of hydrogen sulfide in a chloride solution has more than an order of magnitude low corrosion rate compared to unprotected samples during 96 h exposure of electrodes. In this case, there is a decrease in anodic reaction rate and an increase in cathodic one in comparison with a solution without hydrogen sulfide. The corrosion process proceeds under anodic control.

The absolute majority of modern studies dealing with the interpretation of experimental data on the basis of the Freundlich isotherm ignore the fact that the data obtained for regions of low and moderate adsorbate concentration/pressure can be analytically continued within the Freundlich adsorption model to the adsorptive saturation area with coverages tending to 100%. Needless to say, this would give valuable extended information about the corresponding adsorption process. This message proposes a framework to comprehensively analyse experimental data first recognised as complying with the Freundlich adsorption model. An algorithm-driven method is presented which enables one to translate the data obtained in the area of small and moderate the coverages of the area of adsorptive saturation regime. As examples, three sets of experimental data for adsorption of mercury (II) on N-rich porous organic polymers and of protein on carrier nano-Mg(OH)₂ have been processed and presented according to the framework developed.

Using experimental data for the adsorption of phosphates out of wastewater on waste recycled bricks, published independently in MDPI Processes before (2020), this message re-visits the mathematical theory of the Freundlich adsorption model. It demonstrates how experimental data are to be deeper treated to model the saturation regime and to bridge a chasm between those areas where the data fit the Freundlich power function and where a saturation of surface adsorption centers occurs.

The universality of inhibitors is understood as their ability to inhibit several types of corrosion attack: hydrogen sulfide and carbon dioxide corrosion, hydrogen diffusion into metal, development of sulfate-reducing and other types of bacteria, negative impact on the mechanical properties of metals. Indicators of universalism of new inhibitor have been studied. Producer of the inhibiting compositions is Limited Liability Company «INCORGAZ» (S-Petersburg, Russia). The efficacy of the inhibitor in the concentration of 25 - 200 mg/L has been studied with respect to carbon steel in a highly mineralized chloride medium (pH= 6) and NACE medium (5 g/L NaCl, 0.25 g/L CH₃COOH, pH =3.5) containing H₂S (50-400 mg/L) and CO₂ (1at) separately and together. The bactericidal properties of the inhibitor were studied with respect to sulfate-reducing bacteria in the Postgate medium. The investigations were carried out by the methods of linear polarization resistance, electrochemical impedance spectroscopy, gravimetry, potentiodynamic polarization. The protective effectiveness of the inhibitor reaches 80% in the presence of CO₂ and 90% in hydrogen sulphide environments. The inhibitor repeatedly reduces the number of sulfate-reducing bacteria and the production of biogenic hydrogen sulfide and inhibits the diffusion of hydrogen into steel.

Corrosion and kinetics of partial electrode reactions on carbon steel St3 with superhydrophobic coatings of three types were studied in 0.5 M NaCl and 50 g/L NaCl +400 mg/L H ₂ S solutions. The investigations were carried out on electrodes made of carbon steel St3 with a chemical composition, wt. %: C – 0.20; Mn – 0.50; Si – 0.15; P – 0.04; S – 0.05; Cr – 0.30; Ni – 0.20; Cu – 0.20, and Fe – 98.36. To obtain the type I coating, the metal surface was textured by an IR laser radiation of nanosecond duration followed by chemisorption of fluorobutylsilane out of a solution in n ‐decane. To obtain a coating of type II, a nanoscale composite layer consisting of aggregates of aerosil nanoparticles was applied additionally to the outcome of type I method. To obtain a coating of type III, the metal surface after being textured by the infrared (IR) laser radiation of nanosecond duration was followed by chemisorption of fluoroxy silane. The influence of duration τ of the medium corrosive impact on protective effect of the superhydrophobic coating is considered. It was shown that upon reaching a steady state (after 72 h), the corrosion rate of steel with a superhydrophobic coating of I and II types in a 0.5 M NaCl solution is reduced by 23 ± 3 times compared with unprotected samples. Approximately the same picture is characteristic of electrodes with a coating of type III in a solution of 50 g/L NaCl +400 mg/L H ₂ S.

To simulate conditions for evaluating the inhibition efficiency of an IFKhAN-114 volatile inhibitor under atmospheric corrosion of copper in the presence in the air of two corrosion promoters CO2 + NH

The protective ability of the volatile IFHAN-114 inhibitor in the corrosion of models of macrogalvanic steel/brass, steel/copper, and copper/brass pairs under conditions simulating the...

At room temperature, moisture, SO2, and oxygen permeability of mineral oils, i.e., industrial I‑20A, M-10G2(K)(product and waste, MWO), rapeseed, and sunflower are studied. It is shown that all the...

Using the chemical, electrochemical, and X-ray phase analysis, it has been shown that intermetallic compounds in Zn–Sb, Cd–Sb, Mg–Sb, and Al–Sb systems dissolve mainly with metal ionization,...

The influence of the nature of an apolar solvent on the rheological properties of oil protective compositions containing residues of synthetic carboxylic acids has been studied. It has been...