Protection of Metals and Physical Chemistry of Surfaces最新文献

Experimental and theoretical studies of the physical and mechanical properties of a Resione D01 photopolymer resin before and after photocuring under the action of UV irradiation are conducted. In the first part of the study, internal friction spectra (lambda = fleft( T right)) and temperature dependences of frequency ({{nu }} = fleft( T right)) of a freely decaying oscillatory process are obtained in a temperature range of −150 to 250°C using a method of dynamic mechanical relaxation spectroscopy. It is found that spectra ({{lambda }} = fleft( T right)) of all the studied systems are characterized by the presence of several local dissipative processes with different intensities which manifest themselves in different temperature ranges. The correlation of the abnormal change in frequency ({{nu }} = fleft( T right)) with shear modulus defect (Delta G = fleft( T right)) and mechanisms of internal friction for the most intensive processes of dissipative losses is for the first time analyzed. Based on the obtained experimental results, the temperature ranges in which photopolymer materials possess stable physical and mechanical properties are found. The theoretical analysis that will be performed in the second part of the study of the physical and mechanical properties of the photopolymer takin into account the obtained experimental data will be a development of the experimental study.

Graphene oxide nanopowder (GO) was synthesized using Hummer’s method. Comprehensive characterization employed: X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) for elemental composition; transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) for morphological imaging; photoluminescence spectroscopy (PL) for optical properties; Fourier- transform infrared (FTIR) and Raman spectroscopy (RS) for molecular vibrational analysis; and ultraviolet-visible spectroscopy (UV–Vis) for absorption spectrum evaluation. Filtration performance was also assessed. XRD analysis confirmed successful GO synthesis and subsequent reduction to reduced graphene oxide (rGO), revealing an interlayer spacing of 0.84 nm for GO and 0.36 nm for rGO. FESEM and TEM imaging revealed exfoliated GO sheets and confirmed the two-dimensional structure of both materials, with rGO exhibiting a characteristic wrinkled morphology attributed to oxygen functional group removal. EDS quantified a significant increase in the C : O ratio from 0.64 (GO) to 3.0 (rGO), confirming effective reduction. FTIR identified oxygen functionalities in GO (O–H, C=O, C–OH, C–O–C) and their attenuation in rGO. RS indicated an increased I_D/I_G ratio for rGO (0.96 vs. GO’s 0.93), signifying defect formation and restoration of sp² domains. PL intensity decreased markedly in rGO, accompanied by a blue shift. Filtration tests demonstrated that both GO and rGO suspensions exhibited effective fluid loss control properties.

A theoretical analysis of the physical and mechanical properties of a photopolymer resin before and after photocuring under the action of UV irradiation is conducted considering experimental spectra of internal friction (lambda = fleft( T right)) and temperature dependences of frequency ({{nu }} = fleft( T right)) of a freely decaying oscillatory process in a temperature range of from −150 to 250°C. Based on the phenomenological model of a standard linear body, a calculation of the physical and mechanical (temperature position of the maximum of the loss peak, its intensity and frequency of the oscillatory process in the loss maximum, shear modulus defect) and physicochemical (energy of activation, discrete relaxation time) characteristics for each of the dissipative processes found in the internal friction spectrum is conducted; the mechanisms of internal friction are determined, and a plausible structural interpretation of the appearance of each dissipative process that results in a drastic change in the ratio of the elastic and inelastic characteristics of the studied materials in the spectrum is proposed. Based on the obtained experimental and theoretical results, it turns out to be possible to find out the temperature ranges in which photopolymer materials possess stable physical and mechanical properties.

The demand for superhydrophobic fabric for people is increasing with the development of society, but complex manufacturing process, poor durability, and high cost limit their application. This study presented a cost-effective and durable solution by treating polyester fabric with hexadecyltrimethoxysilane-modified silica (H-SiO₂) and triethoxyvinylsilane-modified titanium dioxide (T-TiO₂). The treatment, achieved through dip-coating and baking, created a superhydrophobic surface with exceptional chemical durability. Fourier-transform infra-red (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were conducted to verify the morphology and rough structure and elemental analysis of treated surfaces, respectively. Performance tests revealed a water contact angle of 163.4°, and contact angle was maintained above 149° after 24 h of corrosion with strong acids or alkalis, 129.1° and 125.7° after 30 soaping cycles and 150 rubbing cycles, as well as superior self-cleaning and anti-fouling properties. These results demonstrated the potential of this fabric for practical applications in various industries, overcoming the limitations of current superhydrophobic materials.

Zr–Ti–B–C–N coatings were obtained by reactive pulsed magnetron sputtering at frequencies of 0, 50, and 350 kHz. The coatings contained a high total concentration of non-metallic elements in the range of 80–84 at % and had a dense, low-defect amorphous structure. The coatings were dominated by B–N, B–C, and Zr–O bonds. The hardness of the coatings was 8–9 GPa, and the modulus of elasticity and elastic recovery were within the ranges of 126–144 GPa and 36–40%, respectively. The coating deposited at a frequency of 350 Hz had the lowest coefficient of friction (~0.15). The maximum optical transmittance of ~90% was demonstrated by a coating obtained at 50 kHz characterized by minimal thickness and increased oxygen concentration. The Zr–Ti–B–C–N coatings with the optimal composition outperformed the Zr–B–N comparison samples in terms of transmittance.

This study presents a green synthesis of three of (Z)-5-arylidene-rhodanine derivatives in an aqueous medium and evaluates their efficacy as corrosion inhibitors for carbon steel in 0.5 M H₂SO₄. The synthesis, optimized using ammonium acetate as a catalyst, yielded ten derivatives (3a–3c) with excellent efficiency (86–90% yield). Spectroscopic techniques (¹H NMR, MS) and theoretical calculations confirmed the (Z)‑configuration of the products. Corrosion inhibition performance was assessed via weight loss studies, and scanning electron microscopy (SEM). Among the tested compounds 3c, 5-(4-hydroxy-3-methoxybenzylidene)-3-phenyl-2-thioxothiazolidin-4-one, exhibited superior inhibition efficiency (99.65% after 72 h), attributed to its strong chemisorption (ΔG_ads = −43.70 kJ/mol) and high equilibrium constant (K_ads = 617.26 m³/mol). Density functional theory (DFT) calculations, revealing high E_HOMO (–5.83 eV), low E_LUMO (–2.37 eV), low energy gap (ΔE_gap = 3.46 eV), and significant electron transfer (ΔN = 3.21 eV) for 3c, elucidated the molecular interactions promoting adsorption. Thermodynamic and kinetic analyses revealed an endothermic, non-spontaneous adsorption process, with 3c significantly increasing the activation energy (E_act = 85.40 kJ/mol). SEM confirmed the formation of a protective layer, minimizing surface degradation. These findings highlight the potential of rhodanine derivatives as eco-friendly, high-performance corrosion inhibitors for industrial applications.

The aim of the study was to compare the effectiveness of flax shive modification with alkaline solutions of sodium bisulfite and hydroxymethylsulfinate in relation to solving current problems of sorption treatment of wastewater from divalent metal ions and cationic organic compounds. Using methods of selective extraction and photometry of polycarbohydrates, scanning electron microscopy, and low-temperature nitrogen adsorption, changes in the polymer composition of the shives, the state of the xylem cell walls, and the distribution of the specific surface area by pore size were assessed. The elements of the development of the pore system of the substrate are shown with the achievement of a specific surface area of more than 170 m²/G. Using the method of Fourier-transform IR spectroscopy with decomposition of overlapping signals, the functionalization of lignin macromolecules was traced, and the complex occurrence of reactions of reduction, hydrolysis, sulfonation and demethylation under the action of sodium hydroxymethylsulfinate was confirmed, which provide a content of grafted sulfo groups four to five times higher than treatment with a sodium bisulfite solution, with an increase of 6.6–8.6 times in the absorption of phenolic hydroxyls. The sorption properties of native and modified botrytis samples were studied in a steady state with respect to Cu²⁺ ions, methylene blue dye, and the cationic detergent cetylpyridinium chloride. The most adequate description of the sorption kinetics is provided by the pseudo-second-order kinetic model. The chemisorption indices on native pectin and on transformed lignin in modified samples were differentiated and compared, confirming the significant advantages of replacing the sorption-active biopolymer when treating the shives with a sodium hydroxymethylsulfinate solution.

The synergistic corrosion inhibition effect of lavender essential oil (LEO) and cocamidopropyl betaine (CAPB) on carbon steel in 3.5% NaCl solution was investigated. The inhibitors were characterized by GC–MS and FTIR, revealing linalyl acetate as the major LEO component and the functional groups responsible for metal interaction. Corrosion inhibition efficiency was evaluated using potentiodynamic polarization and Tafel analysis. The highest efficiency, up to 95%, was achieved by the LEO/CAPB mixture, compared to 78 and 67% for LEO and CAPB, respectively. The inhibition efficiency of LEO/CAPB remained high (87%) at 328 K, confirming its good thermal stability. Adsorption followed the Flory–Huggins isotherm (R² = 0.999), suggesting multilayer adsorption. Thermodynamic parameters showed negative (Delta G_{{{text{ads}}}}^{0}) values, confirming spontaneous adsorption, with magnitude indicating a mixed physisorption–chemisorption mechanism for LEO/CAPB. Surface analyses by optical microscopy and profilometry showed that the mixture forms a uniform, protective film on the steel surface, in contrast to severe corrosion in the blank solution. DFT calculations on LEO components identified linalyl acetate as the most reactive, due to its high HOMO, low LUMO, and narrow energy gap, favoring donor–acceptor interactions. A synergistic mechanism is proposed where CAPB acts as a molecular bridge, enhancing LEO adsorption and reducing corrosion. The results confirm the LEO/CAPB system as a highly efficient, eco-friendly corrosion inhibitor for carbon steel in saline environments.

The surface free energy of powders is an important thermodynamic characteristic that determines their physical properties and provides the possibility to predict the formation of given structural and morphological properties. The work presents the results of a comparative study of the surface free energy (SFE) of two aluminum-containing powder systems: the initial aluminum powder (ASD-4), which consists of spherical particles, and an aluminum–activated carbon–graphite composite powder with plate-shaped particles and a significantly more developed surface. The difficulties encountered in measuring contact angles for powder systems to determine the SFE values lead to the search for methods to avoid these problems. In this regard, the dispersion component of the surface energy of aluminum-containing powders was estimated using the capillary elevation method based on a theoretical approach using the modified Washburn equation and the Fowkes adhesion formula. The results of the experiments showed a significant increase in the dispersion component of the SFE for the aluminum–activated carbon–graphite composite powder with an extremely developed surface compared to the initial ASD-4 aluminum.

Nanotube photoanodes made of titanium dioxide (TNTs/Ti) are fabricated by anodic treatment of a titanium foil at a voltage of 60 V in an electrolyte based on ethylene glycol according to a two-step scheme that includes intermediate removal of an amorphous coating and subsequent calcination at 450°C. TNTs in the form of anatase have a length of 20–22 μm, an averaged diameter of 90–100 nm, and a wall thickness of 20 nm. The activity of the obtained photoanode in a reaction of photoelectrocatalytic oxidation of urea in aqueous 0.1 M KOH and 0.9% NaCl solutions is studied. A scheme of parallel oxidation of urea with hypochlorite formed during photoelectrooxidation of chloride ions is proposed. It is found that the overvoltage of the reaction of photoelectrooxidation of urea on TNTs/Ti in neutral chloride and alkaline solutions is 0.6 V lower in comparison with that upon electrochemical oxidation on a platinum electrode. It is shown that a TNTs/Ti photoanode provides efficient photoelectrooxidation of urea, including from solutions with low concentrations of the latter, which is an advantage in comparison with electrooxidation on a Pt electrode.