Protection of Metals and Physical Chemistry of Surfaces最新文献

Nanocomposite coatings of Ni–B/SiC on St-37 steel substrates were electrodeposited using a Watts’ nickel bath modified by the addition of borane-trimethylamine as a borane source and dispersion of SiC nanoparticles (20 nm). The effects of electrodeposition current density (i_d) and bath concentration of SiC nanoparticle (C_SiC) on different properties of the electrodeposited coatings such as boron content (C_B), SiC nanoparticle content; X_SiC (wt %), surface roughness; R_a, surface morphology, thickness, corrosion behavior and hardness were examined using inductively coupled plasma (ICP), energy dispersive spectroscopy (EDS), surface roughness profilometry, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, potentiodynamic polarization and microhardness testing. The achievements revealed a uniform dispersion of SiC nanoparticle agglomerates throughout the coating cross-section and the formation of spherical surface morphology. A close relationship between coatings’ surface morphology, roughness, hardness, and corrosion resistance with their SiC content has been established. The SiC nanoparticle content of the coatings initially is raised and then lowered via raising both the C_SiC and i_d. While the C_B is decreased monotonically with increasing the i_d. Optimal properties were observed in coatings electrodeposited at i_d = 1 A/dm² and C_SiC = 4 g/L with a maximum X_SiC of 3.6 wt %. These coatings exhibited the finest nodule size, maximum roughness (R_a = 1.94 µm), hardness (930 HV), and corrosion resistance (minimum corrosion current density of 0.2 µA/cm²).

As applied materials for storage energy in solar cells, hetero clusters of GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN can attract considerable attention in materials science. A comprehensive investigation on energy grabbing by GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN was carried out including using DFT computations at the CAM-B3LYP-D3/6-311+G(d,p) level of theory. Electromagnetic and thermodynamic properties of GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN hetero clusters have been evaluated. The hypothesis of the energy adsorption phenomenon was confirmed by density distributions of CDD, PDOS, and ESP for GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN hetero clusters. The two hetero clusters of GaInZnN and GaInAgN with the fluctuations of In, Ga, N and transition metals of Zn, Ag have indicated the same sensitivity graph of electric potential via charge distribution with (R_{{{text{Zn}}/{text{Ag}} - {text{GaInN}}}}^{2}) = 0.9998. Therefore, it can be considered that zinc and silver atoms in the functionalized GaInZnN and GaInAgN may have more effective sensitivity for admitting the electrons in the status of energy adsorption mechanism. Furthermore, GaInAgN is potentially advantageous for certain high-frequency applications requiring solar cells for energy storage. The advantages of silver over indium gallium nitride include its higher electron and hole mobility, allowing silver doping devices to operate at higher frequencies than silicon and zinc doping devices. As a matter of fact, it can be observed that doped hetero clusters of GaInZnN and GaInAgN might ameliorate the capability of GaInN in solar cells for energy storage.

Nonstoichiometric manganese oxide (MnO_2–x) layers with different ratios of MnO₂, Mn₂O₃, and MnO were prepared by step isothermal annealing at 850°C in 20 min points. A gradual change in surface morphology and crystal structure from bixbyite to hausmannite with increasing annealing time from 5 to 65 min is shown. The manganese oxides layers demonstrated p-type conductivity due to the presence of hydroxyl groups, which was confirmed by XPS spectra. According to the gas sensing study, all the obtained layers had H₂S-selectivity at 200°C among other gases: nitrogen dioxide, ammonia, and vapors of phenol, acetonitrile, and formaldehyde. At the 2nd and 3–4th annealing cycles, MnO₄ and Mn₂O₃ oxides predominated on the surface, respectively. Between these transitions, the response to hydrogen sulfide increased at least 2 times. The maximum response to 800 ppm hydrogen sulfide was found after 3rd isothermal treatment and averaged 94%.

To meet the lightweight requirement of large hydraulic cylinder barrels and piston rods, precise control of Cr content in low alloy steel was carried out. Material structure and comprehensive mechanical properties were analyzed using EBSD, XRD, SEM, EDS, etc. The results showed that an increase in Cr content refines the grain size of ferrite and pearlite, reduces the precipitation of inclusions like MnS, increases the precipitation of Cr₂₃C₆, induces grain orientation changes, and elevates the proportion of low-angle grain boundaries. The Cr contents of 0.0312, 0.111, and 0.22% correspond to the yield strengths of 303.56, 324.32, and 346.69 MPa, and the tensile strengths are 496.03, 536.993, and 595.238 MPa, with hardness values of 175.32, 186.31, and 201.95 HV, and scratch widths of 531, 518, and 506 µm respectively.

In recent years, transparent anti-fouling coatings have attracted significant attention due to their potential applications in various fields. However, the development of multifunctional transparent anti-fouling coatings that meet practical requirements without compromising their properties remains a major challenge. This paper presents an innovative approach to address this issue by combining self-cleaning and durability through the incorporation of specific functional materials. Polydimethylsiloxane (PDMS) and methyl o-aminobenzoate (MA) were introduced to achieve these desired properties, respectively. Additionally, bisphenol A diglycidyl ether (BADGE) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (TMDS) were employed as coating substrates to enhance the mechanical strength of the coating. The structural composition, elemental analysis, and surface morphology of the coatings were thoroughly characterized using advanced techniques. The hydrophobicity, optical transparency, self-cleaning ability, and durability of the coatings were extensively evaluated. Experimental results demonstrated that the developed fluorine-free transparent hydrophobic coating exhibited excellent performance across multiple criteria: it showed outstanding hydrophobicity and transparency, superior self-cleaning capability, exceptional resistance to wear, water shock, and strong acid and alkali properties.

In the use of materials containing nanodiamonds, particles and their agglomerates can enter the environment and affect the development of cells of living organisms. Therefore, it was interesting to evaluate the influence of surface modification of detonation nanodiamonds on their interaction with biological objects. The detonation nanodiamonds were graphitised, chlorinated and aminated, and thoroughly investigated. The application of a complex of research methods of scanning electron microscopy SEM + EDX, IR spectroscopy, dynamic light scattering, X-ray diffractometry (XRD) allowed to reveal the peculiarities of physical chemistry of DND surface. It was found that during chlorination of DND the concentration of chlorine atoms increased from 0.05 to 6.60 wt %. Differences in the agglomeration of particles in water medium were found for the original and modified samples. The study of biological properties revealed the following. It was determined by the MTT method that DND-Cl had the most negative effect on Vero cell culture and DND-NH₂ had the least negative effect on Vero cell culture. At DND-NH₂ concentrations of 0.01 mg/mL and below, up to 75% of MDCK cells did not lose their functionality and were able to reproduce influenza A/Moscow/212/2014(H3N2) virus, and the virus titre after leaving the cells ranged from 16 to 64 HA. The range of effects of different concentrations of modified DND on the structure of Danio rerio fish embryos was revealed.

In this work, we have studied basically, the effect of the variation of the NaOH soda concentration, the influence of annealing temperature variation on the structural, morphological and electrochemical properties of copper oxide obtained by chemical immersion. Initially, we have obtained the nanostructures of copper oxide by chemical immersion into the electrolytes at room temperature with different concentration of NaOH: C1 (2.5 M) and C2 (0.9 M) followed by heat treatments at various temperatures. The main results were obtained by following technics X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) coupled with an energy-dispersive spectroscopy (EDS) analyzer, this study have shown that the decrease of NaOH concentration decreases the necessary temperature to obtain the Cu₂O oxide. The increase of annealing temperature for the two studied electrolytes C1 and C2 influences the crystallinity of obtained layers as well as their microstructures. The current density responses revealed good dark current density values under the most basic conditions. The best value (58.24 mA/cm²) found from the nanostructures which obtained after immersion in the electrolyte C1 followed by treatment at 650°C for 1 h (58.24 mA/cm²) is due to the good crystallinity and to the crystallite size obtained after this annealing (D_CuO = 34.08 nm and ({{D}_{{{text{C}}{{{text{u}}}_{{text{2}}}}{text{O}}}}}) = 31.04 nm). The good result of current density has also obtained from the samples immersed in C1 then annealed at 180°C for 1 h (43.76 mA/cm²) and at 250°C for 1 h (37.87 mA/cm²) where the CuO layer is solely appeared after these annealing.

Viscose fiber, a regenerated cellulose material, has attracted significant attention for its potential in adsorption applications due to its tunable hydrophilicity, adsorption capacity, and mechanical properties. This study systematically characterizes six different yarns’ composition, physical properties, and adsorption capabilities and investigates the structure-property relationships. It confirmed the fibers’ composition and revealed distinct hydrophilic-hydrophobic variations. Mechanical testing showed 50% strength reduction in wet states compared to dry states due to water-induced disruption of hydrogen bonding. The adsorption behaviors of farnesol, a model of flavor molecule, were governed by the initial rapid surface attachment via hydrogen bonding and van der Waals forces, followed by slower intra-fiber diffusion through the amorphous regions. Temperature-dependent studies (25–45°C) demonstrated a transition from multilayer adsorption (Freundlich model) to monolayer coverage (Langmuir model) at elevated temperatures, with thermodynamic analysis confirming the endothermic nature of the process. The adsorption follows the pseudo-second-order kinetics, indicating chemisorption-dominated adsorption. These findings elucidate the fundamental mechanisms underlying viscose fiber performance and provide a scientific basis for designing advanced cellulose-based functional materials.

To replace the traditional Alodine chemical conversion coating on aircraft, this paper uses potassium fluotitanate and potassium fluorozirconate as main salts, potassium permanganate as an oxidizing agent and coloring agent, acrylic acid as a complexing agent, and magnesium sulfate as a promoter to prepare a chromium-free environmentally friendly chemical conversion coating on 7075 aluminum alloy. Methods such as drop test, electrochemical analysis, electron microscopy, and elemental analysis were used to determine the optimal film-forming formula and process conditions through single-factor experiments and orthogonal experiments: 6 g/L K₂TiF₆, 6 g/L K₂ZrF₆, 4 g/L KMnO₄, 10 mL/L acrylic acid, 2 g/L MgSO₄; pH 3.7, temperature 35°C, film formation time 6 min. The resulting conversion film is golden yellow, with significantly improved corrosion resistance. This paper also adopts a chromium-free pre-clean instead of the traditional triacid deoxidation pre-clean, achieving chromium-free throughout the entire production process. This has significant guiding implications for future practices in environmental protection in aircraft surface treatment processes.