Protection of Metals and Physical Chemistry of Surfaces最新文献

The review summarizes the physicochemical properties, characteristics of selective, nonselective and multimodal hemosorbents and sorption systems approved for use in the Russian Federation in comparison with other materials used in medical practice. The main share of the materials studied for outside-body blood purification is occupied by sorbents based on carbon, natural and synthetic polymers. Research continues on expanding the types of materials for hemosorption, synthesis methods, improving their physical and chemical properties and structure, increasing adsorption characteristics, selectivity and biocompatibility. Among the methods for synthesizing new sorbents, methods of surface functionalization with various specific substances (ligands) of already known hemosorbents or newly developed matrices of various natures are distinguished. The review presents literary data on the creation of new materials for hemosorption over the past 5 years in Russia and abroad. The experience of successful application of outside-body blood purification methods using sorbents, both separately and in combination with other methods, for the treatment of patients with COVID-19 is shown.

A new 1,2,3-triazole compound namely 3-[4-(4-amino-phenyl)-[1,2,3]triazol-1-yl]-propyl}-phosphonic acid diethyl ester (APTP)), was synthesized under click chemistry regime and effectively tested as potential inhibitor for structural steel (S355) in 3.5% sodium chloride solution. The corrosion-inhibiting properties were examined through a combination of weight loss measurements and the electrochemical impedance spectroscopy (EIS). The results demonstrated that APTP significantly suppresses the structural steel corrosion, with an inhibition efficiency of 92.8% observed after 30 min of immersion. A blend of statistical analysis was employed to gain a comprehensive understanding of the corrosion parameters, providing a detailed insight into their effects and interactions. The maximum inhibition efficiency (IE %) of 93.06% was predicted by the full factorial design (FFD) with the conditions of 10 h of immersion time (A), an inhibitor concentration of 0.005 M (B), and a temperature of 25°C (C). The statistical model used to predict IE % proved to be advantageous, demonstrating strong accuracy and reliability in its prediction. DFT calculations and molecular dynamics simulations support the experimental finding.

The new study, focuses on dental titanium (cp-Ti) against corrosion with 2000 ppm α-pinene, citric acid (0.005 M; 0.01 M), and fluoride (1% NaF) in artificial oral conditions. The study performed by using electrochemical methods investigated with open-circuit (E_OCP-t(s) time) potential, impedance spectroscopy (EIS), current–potential (CP) and linear polarization (R_LPR) curves. The aim of this study is to prevent the corrosion of multi-Ti with more natural and accessible materials and to support it with the density functional theory (DFT). Electrochemical study results demonstrated that α-pinene acted as anodic inhibitor. It increased the corrosion resistance from 2.4 to 1450 kΩ cm² at 0.01 M citric concentration (99.8%). Also, ICP-MS analysis indicated that cp-Ti cations decreased from 246 to 14 ppb at this concentration. Additionally, the cations reduced significantly and covered on the surface thanks to the α-pinene at citric acid concentrations according to scanning electron microscopy (SEM/EDX) analysis. The results showed that DFT calculations and electrochemical are compatible with each other. Computational DFT study applied for α-pinene and fluoride on cp-Ti with Gaussian 09W, PBEPBE/6-311G(d,p) version.

Electric discharge machining (EDM) is a prominent machining process for machining hard to cut materials. This process is mainly used for fabrication of cooling holes, lubricating oil holes, and press tools and dies. In EDM process tool wear is inevitable and research on reduction of tool wear and increasing the accuracy gains an importance in manufacturing industries. This research, focus on coating of brass electrode with zinc and nickel through electrochemical method. The coated electrode is subjected in EDM performance analysis such as machining speed (MS), tool wear rate (TWR) and surface roughness (R_a). Artificial neural networks (ANN) with desirability function analysis (DFA) is used to analysis the EDM performance. The successful set of parameters determined were a gap voltage of 25 V, a current of 10.73 A, a pulse-on duration of 60 µs, and a pulse-off time of 10 µs. The application of the zinc- and nickel-coated electrodes attributed for the reduced TWR. The inclusion of ANN–DFA gives in accurate forecasts of the largely encouraging machining setting, providing a flexible structure for prospect EDM procedures.

The electronic characteristics of the Ga_n (n = 3–6), Be₁₂O₁₂, and GaBe₁₁O₁₂ clusters were examined by applying the DFT calculations with the B3LYP-D3/6-31G(d, p) method. The sensing performances of these clusters to the phenytoin (Phy) molecule were also evaluated in gas and water phases. The results show the adsorption of the Phy molecule over the Ga_n and Be₁₂O₁₂ clusters was viewed as a great chemical adsorption with E_ads which vary from –1.120 to –1.602 eV. While the interaction between the Phy molecule and the surface of the GaBe₁₁O₁₂ fullerene is considered as a moderate chemisorption. Due to the strong interaction between the adsorbent and the adsorbate, the energy gaps of the Ga_n, Be₁₂O₁₂, and GaBe₁₁O₁₂ clusters were significantly altered after the adsorption process, thus leading to a high sensitivity towards the chemisorbed molecule. The presence of water led to a little bit reduction in the adsorption energy of Phy molecule onto the clusters compared with the values observed in the gas phase, while maintaining their high-sensing performances. The comparison of the recovery time of the three types of clusters studied revealed that the Ga_n (n = 4, 5, and 6) and Be₁₂O₁₂ clusters possess a long recovery time, rendering them inappropriate nanomaterials to build regenerable biosensors for the Phy molecule detection, whereas the Ga₃ and GaBe₁₁O₁₂ clusters displayed a short recovery time (8.3 s and 5.7 × 10^–3 s), making them highly efficient nanosensors for capturing the Phy molecule in an aqueous solution.

Ni—TiO₂ composite films were electrodeposited from a nickel-plating bath containing various amounts of TiO₂ particulates of different particle sizes. The films deposited from a bath that contained 10 g/L TiO₂ did not contain any TiO₂. On the other hand, all films deposited from a bath with 40 g/L TiO₂ contained some TiO₂. Current density and cathode rotation speed did not seem to have much effect on the incorporation of TiO₂ in the nickel matrix film, but the amount of TiO₂ powder in the bath and also their particle size appeared to be very influential parameters in the incorporation of TiO₂ particulates. The Ni–TiO₂ composite films showed some “cauliflower-type” globular grains, which were compact without any cracks or pits. They were smaller for the films deposited from a bath containing small particle-size TiO₂ particles. Using Monte Carlo simulation, it can be concluded that in the Ni–TiO₂ composite coating, nickel atoms are first deposited on the TiO₂ particulates and then a Ni–TiO₂ colony will be formed on the surface of the substrate and the final structure of cauliflower was created.

The paper presents the results of interpretation and analysis of IR-ATR spectra of composite ultrafiltration (UF) membranes made of polysulfone (PS) and polyethersulfone (PES) in air-dry and water-saturated states in order to assess structural changes in the active layer caused by static and dynamic water saturation. A comparative analysis of the IR spectra of air-dry and water-saturated samples revealed that no shifts occur in the region of skeletal oscillations of the frequency of absorption bands of the functional groups of PS and PES. This allows us to affirm the stability of the chemical structure of the active layer matrix of membranes of this type. Manifestation in the IR-ATR spectra of UF membranes in the air-dry state of a wide absorption band at ~3305 cm^–1 suggests the presence of a superposition of various OH^– groups in the active layer of the PS and PES involved in the formation of N-dimensional hydrogen bonds. Relative changes in the shape and intensity of the band on the high-frequency side of the spectrum for water-saturated samples conceal the redistribution of hydrogen bonds of adsorbed water and OH^— groups of polyethylene glycol (PEG) and suggest that the structure of water in the pore space of the active layer of the membrane changes significantly, demonstrating an increase in weakly bound “liquid water.” The decrease in the number of PEG molecules is regular, most likely due to significant hydration of PEG molecules in adsorbed water, and indicates partial washing out (leaching), but not complete disappearance.

The paper presents the results of a study of 1,2,3-benzotriazole (BTA) films formed on a real copper surface under various conditions. It has been established that BTA molecules, depending on the conditions, form adsorption (Cu–BTA_ads) or surface-associated (Cu–BTA_surf) films. The coordination forms of BTA molecules on the copper surface were established using Raman spectroscopy and density functional theory (DFT) modeling. By counter synthesis, complex compounds BTA–Cu²⁺ were obtained in aqueous solutions at different pH values and their properties were studied using IR and Raman spectroscopy. On a real copper surface, adsorption and surface-associated films of copper and 1,2,3-benzotriazole complexes were formed at different pH values and temperatures, and their structure and properties were studied. The SERS effect was registered and its explanation was given based on the differences in the structure of the synthesized complexes of BTA–Cu²⁺, Cu–BTA_ads adsorption films, and surface-associated Cu–BTA_surf structures. Quantum-chemical modeling of possible adsorption of Cu–BTA_ads and surface-associated Cu–BTA_surf structures was carried out using the DFT method, and a DFT calculation of their Raman spectra was performed. The geometries of surface structures have been established. Energy states of Cu–BTA_ads and Cu–BTA_surf structures were analyzed. It is shown that the predictions of DFT modeling successfully correlate with experimental results.

Magnesium and its alloys have gained significant prominence as promising biomaterials for healthcare applications due to their advantageous mechanical properties, notably their compatibility with bone tissue. Despite these advantages, their rapid rate of corrosion in physiological environments remains a substantial barrier, leading to the formation of hydrogen gas and elevation of pH levels that impede the process of tissue healing. Plasma electrolytic oxidation (PEO) has emerged as an effective surface treatment to improve the corrosion resistance of magnesium as it creates a protective oxide layer. Recent studies have revealed that the incorporation of hydroxyapatite (HA) and alumina (Al₂O₃) nanoparticles into PEO coatings significantly enhances the mechanical and electrochemical properties of magnesium alloys, improving biocompatibility, corrosion resistance, and surface hardness. This research aims to investigate and optimize the corrosion resistance and mechanical performance of a HA-Al₂O₃ composite coating on AZ31 magnesium alloy, with a focus on composition, morphology, adhesion, and corrosion resistance via advanced characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical testing. Preliminary results demonstrate significant improvements in surface hardness and corrosion resistance, highlighting the potential for this composite coating to enhance the longevity and performance of magnesium-based biomedical implants.

Salicylidene-p-toluidine (SPT) was evaluated in this work as a corrosion inhibitor for APl X70 carbon steel in an acidic setting at 25°C using 1M hydrochloric acid. The study was based on gravimetric analysis, electrochemical techniques and DFT (density functional theory) calculations using the 6-311G+(d,p) basis set carried out in both gas and aqueous phases. This method was employed to investigate the intrinsic properties of corrosion inhibitors and their adsorption mechanisms. The findings revealed that both the molecular structure and the concentration of the SPT, significantly affect the corrosion rate of steel. The highest value of 98.78% is reached by the inhibitory efficiency of SPT at 10^–2 M. Polarization curve shape suggests that SPT functions primarily as an anodic inhibitor.