Protection of Metals and Physical Chemistry of Surfaces最新文献

The corrosion and inhibition processes of cold rolled steel was investigated by gravimetric weight loss measurement in 1 M HCl solution, at a temperature range of 303–333 K, in the absence and presence of potassium iodide (KI) inorganic halide salt (8.67 × 10^–3–2.17 × 10^–2 M), formaldehyde (FA: CH₂O) organic surfactant (1.00 × 10^–3 M), and KI (2.17 × 10^–2 M)–FA (1.00 × 10^–3 M) inhibitors mixture. The exposed surfaces of steel samples were inspected by scanning electron microscopy (SEM) and Raman micro-spectroscopy techniques. The inhibition efficiency (IE(%)) increased with KI concentration and temperature suggesting that the KI inhibitor efficiencies are temperature-dependent. The adsorption of KI on steel surface was found to obey Langmuir isotherm. The calculated adsorption free energy ((Delta G_{{{text{ads}}}}^{^circ })) is included between ‒20 and −40 kJ mol^–1 indicating that the adsorption of KI inhibitor is a combination of both physisorption and chemisorption. It was also found that the FA inhibitor efficiency decreased with the increase of temperature, and the calculated value of activation energy (({{E}_{{text{a}}}})) demonstrated that the mechanism of FA adsorption is physical adsorption. It was further observed that there is a synergism for FA mixing with KI, and all calculated synergism parameters are high than unity for the entire temperature range studied. It more showed that SEM and Raman microanalyses confirmed the adsorption mechanisms of KI, FA, and FA + KI on the steel surfaces. Therefore, the more probable mechanisms of corrosion inhibition were proposed.

This study deals with the corrosion inhibition nature of a terpolymer of methyl methacrylate (MMA), vinyl benzoyl chloride (VBC), and N-2-methyl-4-nitrophenyl maleimide (MI) on carbon steel in a 1 M HCl solution. The genesis of the study is based on organic terpolymers used as corrosion inhibitors reiterating the synergistic effects on corrosion inhibition contributed by different monomers and their adsorption behaviors on the metal surface. The polymer termed P(MMA–VBC–MI) was synthesized via solution radical polymerization in varying molar ratios of MMA/VBC of 60 : 10, 50 : 20, 40 : 30, with MI being constant at 30%. Some of the characterization methods used were FTIR for terpolymer structure elucidation, thermal analyses (TGA, DTG, and DSC) for thermal stability studies, and electrochemical experiments, such as potentiodynamic polarization and EIS, for inhibition studies. The primary results showed that the terpolymer with 30% VBC content had greater thermal stability and corrosion resistance compared to pure polymethyl methacrylate (PMMA) because of the decrease in the mobility of polymer chains, in addition to the formation of a passive protective layer on the steel surface. EIS and polarization results indicated that terpolymer Ter3 with an MMA/VBC ratio of 40 : 30 exhibited the highest inhibition efficiency, and the adsorption behavior of this terpolymer followed the Langmuir isotherm model (adsorption free energy between –34.48 and –39.35 kJ/mol), suggesting physical along with chemical adsorption phenomena. These findings underscore the significance of organic terpolymers as biocompatible and nontoxic alternatives to conventional inhibitors like chromates, providing environmentally friendly alternatives for corrosion protection of carbon steel in acidic media. The findings of this study can result in the creation of new inhibitor materials for industrial applications, particularly in oil and gas industries, and in furthering the understanding of corrosion inhibition mechanisms.

With the acceleration of urban construction in China, subway lines across waters (rivers, lakes and oceans) have been built by many water-containing cities to meet the development needs. This paper is targeted at this issue, and relevant literature is comprehensively analyzed, and the current situation of cross-water subway construction is arranged, and it is found that there are many complex technical problems in such subway lines, among which the stray current problem is the key. Due to the special environment, the stray current distribution and corrosion characteristics of cross-water subway lines are significantly affected. Firstly, the distribution law of stray current in cross-water environment is deeply explored. Secondly, the corrosion characteristics of stray current in cross-water environment are studied. Finally, the harm and protection measures of stray current to buried pipelines in cross-water subway lines are introduced, and a theoretical reference is provided for the safe operation and maintenance of cross-water subway system.

Climate change poses a threat to the water security by altering the precipitation patterns and other weather variables, which affect stream flow and freshwater availability. In this study, a soil and water assessment tool was used for the scarcity of blue and green water for future periods for sustainable management of freshwater resources away from lead pollution. Indeed, the presence of Pb²⁺ is an environmental problem and we have explored the use of natural phosphates (NP) as adsorbents for its elimination. The adsorbent NP was characterized by FTIR spectroscopy, scanning electron microscopy (SEM) and BET analysis. Batch adsorption experiments were performed to examine the effects of physical parameters namely the contact time, pH, stirring speed, temperature, adsorbent dose and initial Pb²⁺ concentration on the uptake capacity. Different models were used to fit the experimental data and to evaluate the kinetics, isotherms and thermodynamics of the Pb²⁺ adsorption. A high adsorption capacity of 66.66 mg/g was reached at 25°C and pH 6 and follows the Langmuir isotherm with a pseudo-second order kinetic. The adsorption is spontaneous and endothermic, indicating a structural exchange between NP and Pb²⁺ ions. Such results suggest that NP is a promising adsorbent for Pb²⁺ removal from wastewater.

Green self-assembled monolayers (SAMs) were formed on the copper surface using Passiflora edulis Sims peel extract (PESPE). The functional groups of active constituents in PESPE and their self-assembly behavior were characterized by Fourier-transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The effects of PESPE-SAMs on the surface roughness and hydrophobicity of copper were investigated utilizing atomic force microscopy (AFM) and a contact angle goniometer. The corrosion protection performance of PESPE-SAMs for copper in a 3.5% NaCl solution was evaluated through electrochemical measurements and an analysis of the corrosion morphology. Results indicate that functional groups such as C–O, C=O, and C=N within PESPE are adsorbed onto the copper substrate, forming a hydrophobic protective film (i.e., PESPE-SAMs). Notably, the corrosion rate of copper is significantly reduced, with a corrosion protection efficiency of approximately 86.7%. Pitting and flocculent corrosion products on the copper surface are almost entirely inhibited. Therefore, PESPE serves as an effective and renewable agent for SAMs formation, demonstrating extensive potential applications.

The influence of heat treatment in carbon dioxide atmosphere (900°C) and low-temperature graphitization (1500°C) on the transformation of primary particles in N375 carbon black was studied. According to TEM, the outer layer of primary particles increases in the length of the graphene layers from 0.96 to 1.28 nm under the influence of carbon dioxide treatment. The carbon in the inner part of the particles is intensively oxidized, which leads to the formation of micropores and an increase in the specific surface area of the material by almost 11 times. Further low-temperature graphitization of oxidized carbon black leads to the formation of polyhedral particles in its structure, consisting of extended graphite-like nanocrystallites with an interlayer distance d₀₀₂ of 0.37—0.38 nm. The specific surface area of the obtained carbon black samples reached 216 m²/g, which is 2.5 times more than that for the original N375.

A study of the effect of the rare earth element Ce on the corrosion resistance of medium Mn-TRIP was carried out in this work. In order to elucidate the role of Ce and the corrosion behaviour of medium Mn-TRIP, the effect of Ce on the corrosion resistance of medium Mn-TRIP was investigated by neutral salt spray corrosion experiments, electrochemical experiments, and X-ray diffractometer and scanning electron microscope, respectively. The results show that the addition of Ce can reduce the corrosion rate of medium Mn-TRIP at the early stage of corrosion, increase the corrosion rate at the middle stage of corrosion, and at the late stage of corrosion, the difference in corrosion rate between the two is not significant, and the electrochemical properties of medium Mn-TRIP are less changed.

This research aims to improve the mechanical characteristics of surfaces coated with nickel-graphene (Ni-G) nanocomposite material by using a single post-heat treatment surface hardening approach combined with oil quenching. The nanocomposite coating was developed using a pulse reverse electrodeposition technique using a Watts bath. The surface morphology of the coatings was analyzed with the help of X‑ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) with EDAX. The coated surface properties like micro-hardness, surface roughness, wear, and corrosion resistance were assessed by Vickers microhardness tester, roughness tester, pin-on-disk equipment, and electrochemical impedance spectroscopy. Specimens with Ni-G nanocomposite coating were post-heat treated at 400°C for 1 h, and oil quenched. With heat treatment, the coated surface exhibited superior properties in comparison with specimens that are not heat treated with a hardness of 467.3 HV, surface roughness of 0.638 µm, wear rate of  8.10 × 10^–7mm³/N m, and corrosion protection efficiency of 96.50%. The improved surface properties were due to the grain refinement and particle strengthening, with an increased average crystallite size of 19.6 to 23.82 nm, with a 75.59% reduction in average coefficient of friction achieved for the post-heat-treated surface than the bare surface.

This study explores, for the first time, the synergistic effect between myrrh gum extract (MG) and iodide ions to enhance corrosion inhibition for API 5CT P110 tubing steel in 0.5 mol/L sulfuric acid. The interaction between MG and iodide ions was analyzed using potentiodynamic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Results show that the inhibition efficiency of 6 g/L MG at 20°C is 82%, but it significantly increases to 98% upon adding 5 mmol/L potassium iodide at 20°C. The system follows the Langmuir adsorption isotherm, involves both physisorption and chemisorption, and functions as a mixed-type inhibitor. The findings confirm that the combination of Ghars date extract and iodide ions provides substantial corrosion protection for API 5CT P110 tubing steel in sulfuric acid through a synergistic effect.