Protection of Metals and Physical Chemistry of Surfaces最新文献

In an effort to enhance the corrosion resistance of carbon steel in hostile environments, researchers have incorporated doped conductive polymers with sulfo-5-salicylic acid, such as polyaniline (PANI) and poly(ortho-ethoxyaniline) (POEA), into a conventional epoxy resin dissolved with xylene solvent. The primary objective was to develop more effective anticorrosion films compared to traditional zinc phosphate (ZP) coatings. The newly created epoxy resin coatings underwent thorough characterization methods; including techniques such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and immersion tests. To assess the corrosion resistance of these coatings, a range of tests were performed, as did the open circuit potential (OCP), linear polarization resistance (LPR), potentiodynamic polarization curves (Tafel plots), electrical impedance spectroscopy (EIS), and solution iron analysis extended to 3.5 wt % NaCl solution at pH 4.5. The results clearly demonstrated a substantial improvement in the corrosion resistance when the PANI and POEA coatings were applied, outperformed the ZP coating. These enhancements were attributed to a tenfold increase in the impedance of the ZP coating, a significant reduction in substrate degradation, and a threefold decrease in iron loss into the solution. These findings suggest that PANI−TiO₂/epoxy and POEA−TiO₂/epoxy coatings hold great promise as potential replacements for traditional zinc phosphate-based anticorrosion coatings, thanks to their superior protective barrier and enhanced performance.

The effectiveness of zinc carboxymethylchitosan metal complex (ZCMC) as a copper corrosion inhibitor in 3.5% NaCl solutions was investigated using electrochemical impedance spectroscopy, Tafel extrapolation techniques and SEM/EDX. The potentiodynamic polarisation investigations demonstrate that ZCMC is a good inhibitor for copper in neutral media. In 3.5% NaCl solutions, it more significantly reduces the anodic reaction rate than the cathodic reaction rate and increases the open circuit potential of copper. This Cu(II) is generated by oxidation of the Cu(I) ion formed at the beginning of the corrosion process in the aerated solution of NaCl. SEM-EDX studies confirmed the absence of the deterioration products on the copper surface.

Localized corrosion behaviors of Hastelloy X and stainless steel 316 in Persian Gulf coastal water were compared fundamentally using cyclic potentiodynamic polarization (CPC), electrochemical impedance spectroscopy (EIS), Mott–Schottky analysis. X-ray diffraction spectroscopy and scanning electron microscopy techniques. The results showed that passive films that are formed on Hastelloy X and stainless steel 316 are mainly include nickel and chromium oxides that exhibit p-type semiconducting behavior. The films that are formed on the surface of former include less crystal defects than those on the latter one surface. In both cases, films with more crystal defects will form when their respective formation temperature increases. Such passive films’ characteristics lead to find Hastelloy X to be more resistant to localized corrosion than stainless steel 316 in Persian Gulf water as was proved by the CPC and EIS test results; i.e. as the temperature increases from 25 to 75°C, pitting corrosion resistance (R_pit) and film resistance (R_film) values decreased in the case of Hastelloy X and stainless steel 316 samples while the former is more resistant to corrosion than the latter.

In this study, five surfactants containing two pyridinium groups and one of which has a carbon chain of different lengths were synthesized in order to counteract the corrosion that occurs more rapidly on the metal surface in acidic environment. By using spectroscopic methods (FT-IR and NMR), the products’ chemical structures were verified. Gravimetric measurements were then applied to assess how well they resisted metal corrosion. The experiment involved immersing metal plates in 1.0 M HCl solutions with varying inhibitor concentrations for a day at room temperature. The weight loss of each plate was then measured. By utilizing these weight losses, both corrosion rate and corrosion inhibition efficiency were calculated. As a result of the calculations, it was realized that their ability to inhibit metal corrosion gradually increased due to the decrease in corrosion rates as the long carbon chain in their structure increased. However, in order to determine the type of adsorption on the metal surface, which is a factor directly affecting their corrosion inhibition, a Langmuir adsorption isotherm study was performed, which was found to be compatible. In order to visually support that they protect the metal surface against corrosion, 1600-fold magnified surface images of the metal surfaces removed from the corrosion test were taken with an optical microscope camera.

Some new organic triethylammonium salts, with names: triethylammonium 4-((4-(aminomethyl)phenyl)amino)-4-oxobut-2-enoate (B4); triethylammonium5-((4-(aminomethyl)phenyl)amino)-5-oxopentanoate (B5); and triethylammonium 4-((4-(aminomethyl)phenyl)amino)-4-oxobutanoate (B6) were synthesized and identified successfully. They were applied as corrosion organic inhibitors for mild steel in acidic environment. The new organic triethylammonium salts were tested in 1M sulfuric acid for 24 h at room temperature by applying the weight loss measurements. The high efficiency of inhibition values of all triethylammonium salts (B4, B5 & B6) were revealed at the maximum organic triethylammonium salts concentrations. The decreasing of corrosion rates of mild steel were associated with increasing the concentration of organic inhibitors (B4-B6), as well as, the increasing with coverage surface degree. The adsorption free energy values were explained the effects of physisorption for organic salts (B4, B5, and B6). The correlation between experimental results and theoretical data was considered via semi-empirical molecular orbital calculations for the three studied inhibitors. Theoretical calculations were used to understand the nature of interaction among organic corrosion inhibitor molecules and the metal surface of the mild steel.

A comparison was made of the physicochemical and physicomechanical properties of films and coatings based on latex polyacrylates before and after their modification water-soluble tetrasodium salt of copper–phthalocyanine–tetrasulfonic acid. Using atomic-force microscopy methods, Raman spectroscopy and thermogravimetry showed that phthalocyanine is localized on the surface of latex particles in the interparticle regions of films and coatings due to interaction between phthalocyanine and polyacrylate. Using the method of dynamic mechanical relaxation spectroscopy, an increase in the intensity of α-relaxation was established upon modification of polymer films as a result of disruption of the relaxation homogeneity of the polymer material. Adhesion of unmodified and modified polymers to a metal substrate causes a decrease in the intensity of α-relaxation and frequency of the oscillatory process. Modification of the polymer and its adhesion to the substrate are accompanied by a decrease in its elasticity.

In order to improve the surface quality of copper after laser surface remelting, this article takes laser frequency, pulse width and current as the research objects, and uses scanning electron microscopy (SEM), laser confocal three-dimensional measurement instrument, and friction and wear measurement instrument to study the surface morphology, surface roughness, and wear resistance of copper under different parameters. The results indicate that the frequency, pulse width, and current of laser surface remelting can directly affect the surface quality of the sample, but the influence of frequency and pulse width is more significant. When the laser remelting frequency is 10 Hz, the pulse width is 10 ms, and current is 100 A, the sample exhibits good surface morphology, roughness, and wear resistance. The relevant research in this article can provide a good reference for laser surface treatment of copper-based materials.

In this work, the following coatings were obtained by magnetron sputtering of (MoTaNbZrHf)SiB and SiBC targets: single-layer (MoTaNbZrHf)SiB, double- and multilayer (MoTaNbZrHf)SiB/SiBC, and nanocomposite (MoTaNbZrHf)-Si-BC coatings. Particular attention was paid to studying the effect of increased silicon content on the structure and oxidation resistance of developed coatings. Results showed that single-layer and nanocomposite coatings have a homogeneous structure with a uniform distribution of elements across the thickness. Double- and multilayer coatings contained (MoTaNbZrHf)-Si-B/Si-B-C layers with a thickness of 9.1/3.9 and 1.7/0.6 μm, respectively. Introduction of additional silicon-containing phases into the composition of (MoTaNbZrHf)-Si-B coatings led to a decrease in the specific mass change from –3.1 to 0.15–0.20 mg/cm² at a temperature of 1000°C. Annealing at a temperature of 1500°C showed that the double-layer (MoTaNbZrHf)-Si-B/Si-B-C coatings have a minimum oxide layer thickness of 9.2 μm and a specific mass loss of 0.95 mg/cm², which is 1.5 and 1.8 times lower than the values obtained for the single-layer (MoTaNbZrHf)-Si-B coating. At 1600°C, the single-layer (MoTaNbZrHf)-Si-B coating was completely oxidized, while the double- and multilayer (MoTaNbZrHf)-Si-B/Si-B-C coatings were partially preserved, which is due to the high silicon content in their composition.

A new class of materials known as composition modulated multilayer (CMM) alloy coatings has created an ever-increasing interest in materials research due to their improved functional properties. In this direction, an effort has been made to improve the poorer corrosion resistance performance of conventional monolayer nickel–titanium (NiTi) alloy coatings (due to inherent induced type of codeposition), their multilayer alloy coatings have been developed. CMM (NiTi) alloy coatings have been fabricated electrolytically on mild steel (MS) from a citrate bath, using the glycerol as additive. Multilayer alloy coatings of varying matrices have been developed by periodic modulation of direct current (DC), in terms of pulse height and pulse duration. Coating configurations in both composition and thickness of alternate layers were optimized for best performance of the alloy coatings against corrosion. Corrosion behaviours were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. Experimental study revealed that the corrosion rate (CR) of CMM coatings decreased successively with increase in number of layers up to certain limit, and then started increased. Experimental findings demonstrated that CMM (NiTi) alloy coating having optimal configuration, represented as (NiTi)_2.0/4.0/120 is approximately five times more corrosion resistant than its monolayer counterpart, deposited from the same bath for same duration. Development of coatings in layered pattern was confirmed by scanning electron microscopy (SEM) analyses. EDX and XRD techniques confirms the composition and phase structure of alloy coatings. The corrosion mechanism responsible for delayed corrosion of multilayer coatings has been explained, and experimental results are discussed.

This paper presents a model of an electrode material for a hybrid capacitor and experimentally confirmed ways to improve cell parameters, such as increasing the energy capacity of the cell; increasing the operating voltage in cells with aqueous electrolyte up to 2.6 V, twice the water decomposition potential; and reducing internal resistance. The technology of manufacturing electrode materials for hybrid capacitors is also presented, and its choice is justified.