Surface Engineering and Applied Electrochemistry最新文献

This paper describes the study of corona electrets made of a polyethylene terephthalate (PET) laminate film with an aluminum oxide nanolayer with a protective coating based on acrylic copolymers. Those films showed rather high and stable electret properties. Furthermore, dipole polarization prevailed at the acrylic layer due to the orientation of oxygen-containing groups of atoms and macromolecular segments under the corona discharge, while injected charge carriers were located predominantly in polyethylene terephthalate layer at interfaces of both PET-aluminum oxide and amorphous-crystalline regions of the polymer.

The comparative corrosion resistance and electrochemical behavior in acidic, alkaline, and neutral media of both pure metals and the Ni–Re alloys doped with zirconium, hafnium, tungsten, and palladium were investigated. A positive effect of zirconium on the corrosion resistance of the Ni–Re alloy in all studied media was demonstrated. It is shown that the Ni–Re alloy doped with hafnium also improves corrosion resistance and compensates its reduction at introduction to a tungsten alloy. It is shown that the Ni–Re alloy doped with zirconium together with palladium has the maximum corrosion resistance.

The influence of temperature on the properties of nanocrystalline Co–W coatings obtained from a citrate electrolyte at pH 6.7 and deposited under natural convection conditions was studied. The influence of the electrolyte temperature on the morphology, composition, structure, and roughness of coatings, as well as their corrosion and tribological properties, is demonstrated. It is shown that the structure of the coating can change from the X-ray amorphous to the crystalline one when the deposition temperature of the coating is increased to 90°С. The average value of the mass wear of Cо–W coatings formed at 80°С and measured under the linear friction condition of 0.08 mg is 62 times lower than that of a Cr coating (4.95 mg) and 84 times lower that at the surface of steel SK-5 (6.71 mg). When testing by the reciprocating wear method, the value of the volumetric wear of Co–W coatings obtained in the 50–70°С temperature range was 0.00109 mm³, which is 55 times lower than the wear value of a Cr coating (0.0596 mm³) and 41 times lower than that of the steel SK-5 surface (0.0449 mm³). The paper also shows a slight decrease in the currents of corrosion coatings and a decrease in the dispersion values of the corrosion potentials obtained after mechanical polishing of the surface of the coatings at temperatures in the range of 20–90°С. Under the corrosive effect of 3.5% sodium chloride, an increase in the deposition temperature of the coating is accompanied by a slight increase in the corrosion current.

Here, by the example of galvanostatic electrodeposition of Co–W coatings from a citrate bath, we demonstrate experimentally that when using the results on the deposition rate and the composition and properties (microhardness) of resulting coatings observed under laboratory conditions to develop this type of an electrodeposition process on a larger (industrial) scale the bath volume must be scaled in proportion to the increase in the cathode area. In this case, the current loading on the electrolyte, which is quantitatively expressed as the volume current density, does not increase.

The equations of magnetohydrodynamics (MHD) are presented as continual modeling for slow motions. The original equations of the MHD environment are linearized, reduced, and applied to the analysis of environments characterized by the phenomena of electrolysis and turbulence. A continual approach for electrolysis and turbulence is presented, and the real-life ongoing studies are considering local models. The formulation of the problem and its analysis are presented as the density of the MHD-field decreases from a flat wall. Experimental studies with respect to propulsion devices in sea water are characterized.

In asymptotic calculations of the first order of smallness in the dimensionless amplitude of water droplet oscillations, the effect of the dynamic surface tension on the oscillation parameters was investigated using a model of an ideal incompressible liquid. It was shown that the effect of the dynamic surface tension strongly manifests itself at frequencies of external influences that are inversely proportional to the water relaxation time. At such frequencies, under the action of external influences, the electrical double layer is destroyed (the ordering of water molecules in the near-surface layer is disrupted). As a result, the free energy of the surface increases, and so does the liquid surface tension. The dynamic surface tension affects the acoustic radiation from the droplet by altering the coefficient of surface tension. The contribution to the electromagnetic radiation of the oscillating droplet is made by the disruption of the order of near-surface water molecules in the electrical double layer.

The features of materials leading to the strong correlation effect and the phenomena realized in them are considered: the metal-insulator Mott transition and high-temperature superconductivity. The history of their study is traced. Particular attention is paid to studying the role of the interorbital correlation effect and the Hund’s coupling in multiorbital systems as well as the electron-phonon interaction in systems with strong Coulomb interaction. The development of the strong coupling diagram technique is analyzed and the results obtained based on the approach used are presented.

To improve the performance of the CompoNiAl-M5-3 alloy produced from nickel monoaluminide, protective coatings were applied by electrospark deposition (ESD) using electrodes made of the Zr–18%Ni eutectic alloy. The coatings were applied in an argon environment using tools for manual treatment both of vibrational and rotational types with the connection of direct and reverse polarities. It was determined that the maximum total deposition on the cathode of 11.17 × 10^–4 cm³ is achieved when using a tool of the rotational type with a direct polarity of connection. The obtained coatings are characterized by 100% continuity at a thickness of 20–25 μm, hardness of 11.6–14.6 GPa, and elastic modulus of 162–174 GPa. Electrospark treatment increases the hardness of the CompoNiAl-M5-3 alloy by a factor of 1.4 to 1.8, wear resistance by factor of 3.3 to 16.2, and heat resistance at a temperature of 1150°C for 5 h decreases coefficient of friction.

The corrosion process of steel St. 3 in water with the addition of a heteronuclear salicylate complex {[FeSr₂(SalH)₂(Sal)₂(NO₃)(DMA)₄]}_n by gravimetric, electrochemical, and physicochemical methods (X‑ray phase analysis, UV, IR and Mössbauer spectroscopy) has been studied. It has been shown that the introduction of the additive under study into a corrosive environment significantly reduces steel corrosion. Depending on the duration of the tests and the concentration of the inhibitor, the corrosion rate is reduced by 5.1–11.1 times with a degree of protection of 80.5–91.0%. A mechanism of inhibition has been proposed. The inclusion of products of interaction of ionized iron with the complex in the coating layers has been proven.

The prospects of utilizing electric current treatment of molten metal simultaneously with multiple types of current in foundry production were studied. This principle in combination with various designs of electrode systems allows the formation of a multivariant topology of the electromagnetic field in the molten metal, qualitatively and quantitatively shaping differently the thermomechanical load on the melt. Conditions for improving the performance of the cast metal were found. Simulation modeling methods identified treatment options capable of actively improving the incubation processes of crystallization. The results of simulation modeling were experimentally confirmed. It was determined that simultaneous treatment with two types of current at energy consumption three times lower than that in treatment with a single current source increases the tensile strength by 13% and the relative elongation by a factor of 1.5. The relative narrowing of the specimen was 4.4%, which cannot be achieved for an alloy in the Al–Si system by other treatment methods. The eutectic structure was modified, and α-Al grains acquired a rounded shape.