Protection of Metals and Physical Chemistry of Surfaces最新文献

This paper presents the results of quantum-chemical modeling and experimental study of the optical properties of amphiphilic spironaphthoxazines in organic solvents. For the first time, a predictive model has been developed for calculating the spectral characteristics of photochromes of this class. It is shown that taking into account multiconfigurational interaction by the CASSCF method allows obtaining information about the complex nature of photo-induced electronic transitions in spironaphthoxazines.

This paper studies phenol sorption on VSK-400 and Norit GAC 1240W activated carbons obtained from various raw materials at different temperatures under static conditions. Sorption capacity for a number of inorganic substances is determined, indicating the number of functional acid and basic groups, and also giving a preliminary characteristic of the surface area of sorbents by the amount of adsorbed molecular iodine. Surface morphology of carbon particles from various raw materials is assessed using microphotographs obtained by scanning electron microscopy. When comparing the equilibrium characteristics in the studied concentration range, a greater ability to extract phenol for VSK-400 carbon is noted. At the same time, its sorption characteristics are not affected by temperature and the presence of mineral salt.

In this work, nine new binder compositions were synthesized based on a cycloaliphatic epoxy matrix (EP) modified with methylene diphenyl diisocyanate (MDI) and polydimethylsiloxane rubber (PDMS) with different ratios of components. The modification of the composition was confirmed by IR and NMR spectroscopy. A correlation was established between hardness, contact angle and coating composition based on binder data. Fillers such as muscovite mica and titanium dioxide were introduced into the composition of the developed binders to evaluate the physical and mechanical properties of the coatings. The influence of curing conditions (hardener, curing temperature) on the physical and mechanical properties of the coating was studied. The corrosion resistance of coatings was assessed using electrochemical methods. The weather resistance of the filled composition EP-10MDI-10PDMS was studied under humid tropical climate conditions. The coating composition is EP-10MDI-10PDMS with fillers (muscovite mica, ({text{Ti}}{{{text{O}}}_{2}})) previously synthesized biologically active substances ({text{Cu}}left( {{text{II}}} right)), ({text{Zn}}left( {{text{II}}} right),) and ({text{Co}}left( {{text{II}}} right)) complexes of tris(2-hydroxyethyl)amine (hydrometallatranes) were also introduced to enhance antifouling properties and their evaluation in the natural conditions of Nha Trang Bay (Dam Bai Bay).

The structure and properties of a nickel–boron coating with an immersion-deposited gold–cobalt film were studied. It has been shown that the application of a thin gold film (30–32 nm) protects the functional nickel–boron coating from oxidation during long-term storage under normal conditions and annealing for 1 h in an air atmosphere in the temperature range of 250–350°C. It has been established that, during annealing of the modified coating, no mutual diffusion of the elements of the substrate and coating occurs. X-ray structural analysis of the modified Ni–B coating showed that the diffraction patterns contain diffraction lines from gold, broadened lines from a solid solution of boron in nickel of the interstitial-substituted type. Low temperature annealing (250–300°C) the Ni–B coating modified with an Au–Co film leads to a decrease in the width of the diffraction lines of the matrix solid solution of boron in nickel, as well as to an increase in the values of its crystal lattice parameter and an increase in the microhardness of the coating to 850–890 HV 0.025. Annealing of the coating at 350°C leads to the release of nanosized particles of the nickel boride phase and is accompanied by a decrease in microhardness to 720–750 HV 0.025. It was concluded that the nickel–boron coating with a gold–cobalt protective film applied after annealing has increased microhardness (850–890 HV 0.025), high wear resistance under boundary friction conditions (linear wear intensity of the coating I_h = 1.6 × 10¹⁰ µm/m) and a low coefficient of friction (f = 0.15), which makes Ni–B/Au–Co coatings comparable in their tribotechnical characteristics to chromium coatings. Modified Ni–B/Au–Co coatings retain the ability to be soldered using low-temperature solder and non-active alcohol–rosin flux, and also have low contact electrical resistance after long-term storage.

The article is devoted to the presentation of statistical mechanics as applied to nanomaterials, based on multivariate statistical studies. The fundamentals of statistical nanomechanics and their application to the theory of self-organization of nanodispersed media are presented.

By direct-current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS) methods at peak currents of 50 and 100 A, as well as by applying a negative bias voltage of –500 V to a substrate with a target compound of Ti₂AlC, nanostructured coatings in the Ti–Al–C system with a thickness of 1.8–6.4 μm were obtained. The main phase in the coatings was titanium carbide; when using HIPIMS, the intermetallic compound TiAl was additionally formed. It was found that the coatings deposited by the DCMS method have a maximum hardness of 31 GPa and an elastic modulus of 294 GPa, as well as a low friction coefficient of 0.2, while the HIPIMS method, when using optimal conditions, provides a minimum wear rate of 5.1 × 10^–6 mm³ N^–1m^–1, thermal stability, and oxidation resistance up to 1000°С. The protective properties are associated with the formation of dense surface films based on aluminum oxide. The use of HIPIMS by applying a high negative bias voltage to the substrate promotes the precipitation of Ti₂AlC and Ti₃AlC₂ MAX-phase crystallites with a crystallite size of less than 100 nm during vacuum annealing of coatings at 1000°С.

The review presents the classification, characteristics, and range of sorbents and wound dressings of various natures developed and used in application therapy. New trends and developments in carbon-based vulnerosorption materials are demonstrated.

The effect of the structure on the inhibitory properties of ketoximes in a simulated NACE formation water saturated with carbon dioxide and hydrogen sulfide has been studied. The influence of medium temperature and exposure time on inhibitory properties has been established. The influence of the “structure–property,” kinetic and physico-chemical parameters of interaction, as well as the mechanism of adsorption on the metal surface are investigated. Based on the obtained values, it is proved that the neutral form of acetophenonoxime is more preferable for the adsorption process on the metal surface than the protonated one. This phenomenon is explained by the fact that neutral molecules are more “soft” compounds and have low stability, and, consequently, tend to transfer electrons by iron atoms with electron deficiency.

The sorption capacity of a synthesized polymer based on starch and glycidyl acrylate in relation to heavy-metal ions is studied. It is shown that the sorption of metal ions is reliably described by the Langmuir model, while the process itself has a physical character. It is found by thermogravimetric analysis that the process of thermal destruction of the polymer occurs in three stages, and that of its complex with copper, in four stages. The activation energy of decomposition of the initial polymer is in a range of 24–38 kJ/mol for each stage, while for its complex with copper it is 46–68 kJ/mol. The introduction of Cu(II) increases the thermal stability of the obtained polymer based on starch.