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Q235 carbon steel is a commonly used engineering material, but its application in marine environments is limited by its susceptibility to corrosion, especially localized corrosion that can lead to material perforation. Effective inhibitors are crucial to addressing this issue, particularly in acidic environments where localized areas become increasingly acidic. This study reports the synthesis of a new imidazole derivative corrosion inhibitor and evaluates its effectiveness in corrosion inhibition performance using potentiodynamic polarization curve and electrochemical impedance spectroscopy techniques. High-resolution optical microscopy and scanning electron microscopy were employed for surface morphology analysis. Fourier-transform infrared spectroscopy was used to explore the protection mechanisms. The results demonstrate that the self-synthesized imidazole derivative corrosion inhibitor offers an excellent corrosion protection performance for Q235 carbon steel in a 3.5 wt. % NaCl acidic solution. This inhibitor can provide a new strategy for carbon steel corrosion protection. [ABSTRACT FROM AUTHOR]

In this study, Oregano (Origanum vulgare) leaf essential oil was studied as an environmental-friendly anticorrosion agent for carbon steel in aggressive hydrochloric acid. The corrosion inhibition of O. vulgare was characterized by surface morphology, electrochemical, weight loss, theoretical and computational methods. It was found that the highest inhibition performance of O. vulgare was 85.64% at 2 g/l in 1 M HCl. The results of Langmuir isotherm and adsorption thermodynamics investigation demonstrated that the O. vulgare inhibitor adsorbed on the metal surface by the formation of rigid covalent bonds. The adsorption and inhibition centers of the selected inhibitor were studied by the computational methods, resulting in that the hydroxyl functional groups and benzoyl rings are mainly responsible for the high inhibition efficiency. [ABSTRACT FROM AUTHOR]

The influence of branched N, N′-bis(p-hydroxybenzoyl) containing propylenediamine (PDA) and triethylenetetramine (TETA) composites for corrosion inhibition of carbon steel in acidic solution (1 M HCl) was investigated using several quantum chemical, electrochemical impedance spectroscopy and potentiodynamic polarization as electrochemical techniques. The investigated molecules were posteriorly characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) while the surfaces of carbon steel test coupons were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The obtained results revealed that the two amino compounds, N, N′-bis(p-hydroxybenzoyl) propanediamine (N, N′-HBPDA) and N, N′-bis(p-hydroxybenzoyl) triethylenetetramine (N, N′-HBTETA), have significant efficiency toward steel corrosion attack and its inhibition performance was significantly boosted by increasing concentration of di- and tetramine containing inhibitors. The two inhibitors achieved a maximum corrosion inhibition efficiency of 99.1% as indicated from polarization measurements. The isotherm feature of Langmuir adsorption appeared to be proper factor for associating the experimental gains with an applicable mechanism of inhibition process. The free energy ∆Gads was calculated to be − 27.5, 29.1 kJ/mol based on the adsorption isotherm model, indicating physical adsorption on the carbon steel surface. Further, images of the morphological analysis exhibited various features of attack owing to the aggressive medium and the employed concentration of the inhibitor. These synthesized amines supplied many favorable scores in the fabrication of functional mixed-type inhibitors. The computational studies reveal that N, N′-HBPDA and N, N′-HBTETA molecules could absorb via several lone pairs and π clouds, confirming their ability to be good corrosion inhibitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two novel triazine derivatives (BTT-1 and BTT-2) were synthesized as corrosion inhibitors by a facile one-step method. • BTT-1 and BTT-2 exhibit high inhibitive performance with the inhibition efficiency of 97.9 % and 98.4 %. • The adsorption mechanism of BTT-1 and BTT-2 was explored by theoretical calculations in the aqueous environment. • The effect of substituents on the inhibitive performance of BTT-1 and BTT-2 was unveiled. In this work, two triazine derivatives (BTT-1 and BTT-2) were synthesized by the simple one-step condensation of three components and used as high-efficient corrosion inhibitors to deal with the corrosion issue of carbon steel (CS) in petroleum industry. Electrochemical tests indicate that both BTT-1 and BTT-2 present superior inhibition performance with the inhibition efficiency of 97.9 % and 98.4 % at a low concentration of 0.18 mM, respectively. Quantum chemical calculations reveal that compared to BTT-1 molecule with a butyl chain, the introduction of benzyl group endows BTT-2 molecule with more adsorption sites, which favors the adsorption of BTT-2 molecule on CS surface. Furthermore, the GFN-xTB calculations demonstrate that BTT-1 and BTT-2 could adsorb on CS surface through the formation of Fe−N and Fe−S bonds. Compared to BTT-1, BTT-2 exhibits stronger adsorption on CS surface by forming more and shorter bonds with a more negative adsorption energy, which accounts for the better inhibitive performance of BTT-2. [ABSTRACT FROM AUTHOR]

The corrosion of N80 steel in polymer flooding is studied, and the safe service life of N80 steel tubing is calculated. The results show that the temperature is the main factor affecting the corrosion of tubing during the process of polymer flooding, and the safe service life of N80 carbon steel tubing at 75°C is only 11.1 years. The polymer is connected by molecular chains to form a network structure and then adsorbed on the surface of the steel. As the polymer concentration increases, the space between polymer molecules becomes smaller; the exposed surface area decreases; and the corrosion rate of N80 steel decreases. Both temperature and Cl− ions destroy the adsorption capacity of the polymer on the carbon steel substrate. The negatively charged chloride ion repels the negatively charged polymer, leading to the resolution of the polymer and reduction of the corrosion inhibition of the polymer. High temperature destroys the polymer's intramolecular and intermolecular aggregation, and also wrecks the long molecular chain polymer structure, significantly inhibiting the corrosion inhibition effect of the polymer. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA) has been reported as a corrosion inhibitor of carbon steel. The combined effect of AA and potassium iodide (KI) in the dynamics of the corrosion process of 1018 carbon steel is studied by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) in an acid medium. EN data were used for nonlinear analysis by means of recurrence plots and their corresponding parameters, as well as by delay maps. Important information about the corrosion process of carbon steel corrosion in the presence of these two substances was obtained. AA does not behave as an inhibitor in this system, but the influence of KI is significant in inhibitor efficiency. The dynamics is established mainly by the adsorption of the I− ions on the steel surface and confirmed by the information entropy. The action of AA is to increase the degree of chaos when concentration increases. A relevant aspect determined is the relationship between the nonlinear dynamics of a corrosion process and its intensity. [ABSTRACT FROM AUTHOR]

Corrosion of metals is considered a global dilemma that is attracting an increasing number of researchers in the scientific community. One of the fundamental solutions against corrosion is using corrosion inhibitors. Corrosion inhibitors are the substances added to the medium or the metal to inhibit corrosion through different mechanisms, most commonly by the formation of a protective layer on the metal surface. Organic corrosion inhibitors constitute most of the known and used corrosion inhibitors, however, due to the toxicity and cost of synthesis, green replacements are needed. Green nanomaterials corrosion inhibitors provide a green and sustainable solution for corrosion. The low toxicity, availability, and cost-effectiveness of green nanoparticles made them a growing research field. This review article highlights the synthesis, use, and application of green nanomaterials in corrosion inhibition. Moreover, the article provides insight into the different types of green nanomaterials inhibitors and their common characterization techniques. [ABSTRACT FROM AUTHOR]

In water resource allocation engineering, the flow velocity is the most important factor influencing corrosion damage in the elbow sections of steel pipes. This study reports the effect of flow velocity on the corrosion performance of carbon steel at different pipe elbow section locations though which freshwater flows. The corrosion damage of carbon steel was accelerated in flowing freshwater; however, this accelerating effect was weakened with high flow velocity. Furthermore, the corrosion rate at the outer wall was higher than that of the inner wall of the pipe elbow section with low flow velocity; when high flow velocity was used, more uniform corrosion damage was found at the pipe elbow section. The influence of flow velocity on the corrosion performance of the carbon steel was closely related to the hydrodynamic parameter distribution and the nonuniform accumulation of corrosion products at different locations of the pipe elbow section in flowing freshwater. [ABSTRACT FROM AUTHOR]

Despite corrosion being an inevitable process, researchers strive to control corrosion. In this study, our goal was to prepare two amido Gemini cationic surfactants, LAPG and MAPG, each with different alkyl chains and multiple carbonyl groups as rich electronic rich centers. We aimed to evaluate these surfactants as potential corrosion inhibitors for carbon steel (CS) in 1 M HCl at temperatures of 25–55 ± 0.1 °C. In theoretical investigations, DFT parameters and Mont Carlo simulation were run to predict the adsorption affinity and reactive sites of the LAPG and MAPG molecules. Their efficacy was investigated experimentally considering weight loss and electrochemical techniques. The Tafel polarization revealed that at 0.1 mM of LAPG and MAPG, the corrosion current density (icorr) of CS was reduced to the lowest extent (75.56 and 53.82 μA cm−2) compared to 529.3 μA cm−2 in the absence of the inhibitors. EIS data suggests the enhancement of the thickness of the adsorbed layers of the studied compounds from the decrease of the double-layer capacitance Cdl values. The Langmuir isotherm explained the adoption phenomena of these compounds at 25–55 ± 0.1 °C. Activation and adsorption thermodynamic parameters predicted the chemisorption behavior of these molecules onto the steel surface. AFM and XPS tools confirm the CS surface protection due to these inhibitors' adsorbed layer. A parallel study showed the superiority of these corrosion inhibitors in HCl compared with those reported earlier, making these compounds highly promising corrosion inhibitors, especially in high-temperature acidic environments. [ABSTRACT FROM AUTHOR]

The anti-corrosion features of 1-dodecyl-3-phenylquinoxalin-2(1H)-one (QO12) for carbon steel CS were evaluated in a 1 M HCl solution using potentiodynamic polarization (PDP), electrochemical impedance (EIS) and UV-visible spectroscopy, and scanning electron microscopy (SEM), as well as quantum-chemical methods. The inhibition performance achieves a maximum of 95.33% at 0.001 M. The PDP study revealed that QO12 acts with the character of a mixed-type inhibitor. The EISs mention that the process of corrosion for CS is essentially predominated by the transfer-of-charge mechanism. Moreover, quinoxalinone adsorption follows the Langmuir adsorption isotherm. SEM snapshots show no deterioration after the contribution of QO12 compared to the reference electrolyte. Theoretical calculations suggest that the envisaged inhibitor presents a perfect arrangement capacity through the structure of quinoxalinone. [ABSTRACT FROM AUTHOR]

The inhibition efficiency and adsorption affinity were investigated for two novel compounds, namely: 6-methoxy-2-naphthyl-[2, 2'-bithiophene]-5-carboxamidine hydrochloride salt (MA-1440) and 5'-(4-chlorophenyl)-2, 2'-bifuran-5-carboxamidine hydrochloride salt (MA-1456). The inhibition study was conducted on carbon steel surface in 1.0 M HCl with different inhibitor doses and different temperature levels, to investigate the optimum dose and preferable temperature. The performed investigation included chemical, electrochemical, instrumental, and quantum computation techniques. A chemical technique was accomplished by using weight-loss measurements. Different factors were studied using weight-loss measurements in order to reach the maximum inhibition efficiency. The adsorption study revealed that the examined inhibitors obey the Langmuir adsorption isotherm and are chemically adsorbed on the steel surface. The electrochemical measurements were accomplished through the electrochemical impedance (EIS) and potentiodynamic polarization (PDP) techniques. Based on the electrochemical measurements, the examined compounds were categorized as mixed inhibitors. The instrumental examination using different techniques namely: scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) confirmed that the considered inhibitors are excellently adsorbed over the carbon steel surface. The extent of the adsorption affinity of these compounds on the carbon steel surface was studied theoretically using quantum computations and Monte Carlo simulation. The theoretical investigation results of quantum chemistry were validated with those obtained by chemical and electrochemical methodologies. All investigations prove that, the tested compounds were adsorbed chemically on the steel surface and achieved maximum inhibition efficiency of, 94.69% and 90.85% for M-1440 and MA-1456, respectively, at the optimum concentration 30 × 10–6 mol L−1 and temperature 328 K. [ABSTRACT FROM AUTHOR]

Chamber protection is a promising and quickly developing method of vapor-phase protection of metals against atmospheric corrosion by inhibitors. It was shown that chamber treatment with 2-ethylhexanoic acid (EHA) efficiently inhibits the initiation of zinc corrosion. The optimum conditions (temperature and duration) of zinc treatment with vapors of this compound were determined. If these conditions are met, adsorption films of EHA with thicknesses up to 100 nm are formed on the metal surface. It was found that their protective properties increase during the first day as zinc is exposed to air after chamber treatment. The anticorrosive action of adsorption films is due both to the surface being shielded from the corrosive environment and to the inhibition of corrosion processes on the active surface of the metal. Corrosion inhibition was caused by the ability of EHA to convert zinc to the passive state and inhibit its local anionic depassivation. [ABSTRACT FROM AUTHOR]

In this study, a self‐healing nanocomposite hydrogel (NC hydrogel) loaded with sodium citrate (SC) corrosion inhibitor was developed. NC hydrogels were synthesized through free‐radical polymerization of N, N'‐Dimethylacrylamide (DMA) within a dispersion of silica nanoparticles. FT‐IR, SEM and TGA were applied to evaluate the loading of SC, self‐healing test was used to confirm the self‐healing capability of NC hydrogel. NC hydrogels were coated on the surfaces of Q235 steel, the exposure test results suggest that the corrosion protection of NC hydrogel improves with the loading of SC. Macro, micro morphologies prove that with the releasing of SC, a layer of adsorptive film was formed on the steel surface to prohibit the corrosion of carbon steel. Electrochemical results signify that NC (0.9 wt.% SC) hydrogel possesses the optimum corrosion resistance. The authors consider that as carrier, NC hydrogel can fulfill better corrosion inhibitive action of SC, meanwhile, effectively provide corrosion protection for carbon steel. [ABSTRACT FROM AUTHOR]

The corrosion behavior of Q235B carbon steel is investigated in water, LB medium, and oilfield produced water adding Pseudomonas fluorescens FSYZ01. After immersion at 30 °C for 13 days, the weight loss of carbon steel with this strain decreased by 32.23%, 54.07%, and 78.34%, respectively. X-ray diffraction (XRD) results show that P. fluorescens FSYZ01 inhibited conversion of iron oxides by hindering oxygen from approaching metal surface. Fourier transform infrared (FT-IR) and X-ray photoelectron spectrometer (XPS) results show that specific functional groups and bonds reacted with Fe(II/III) to form a dense and stable chelate-oxide protective layer, thereby inhibiting corrosion. Pyrolysis gas chromatography-mass spectrometer (Py-GCMS) results demonstrate the bacteria degraded C12 to C20 alkanes in oil. The inhibitory mechanism of crude oil-degrading bacteria P. fluorescens FSYZ01 on the carbon steel corrosion was proposed, so as to slow corrosion of oilfield produced water system pipeline and prolong its service life, helping to comprehend the microbial corrosion in the actual environment. [ABSTRACT FROM AUTHOR]

In order to assess the durability of concrete structures reinforced by different types of steel in aggressive environments, the galvanic corrosion of mill-scaled carbon steel was investigated when it was connected to AISI 304 stainless steel characterized by various cathode/anode surface area ratios (As:Ac) in chloride-contaminated mortars. The galvanic potential and the galvanic current density of the coupling carbon steel were measured, and the corrosion state of the mill-scaled carbon steel was inspected after 1,450 days. The results indicated that the potential of the carbon steel was slightly positively shifted by the stainless steel. High As:Ac ratios promoted the passivation of the coupling carbon steel and lowered the corrosion current density in the chloride-contaminated mortars. The galvanic current densities of the carbon steel-stainless steel couples increased with As:Ac ratio. Because the corrosion current density of the mill-scaled carbon steel was nearly one order of magnitude higher than the galvanic current density, the total corrosion current density of the coupling mill-scaled carbon steel generally decreased, and its overall corrosion diminished with increasing As:Ac ratio. Finally, based on the results of this study, the As:Ac ratio is recommended to be higher than 2:1 to ensure the sufficient durability of submerged concrete structures in an aggressive concrete environment. Corrosion of reinforcement is one of the key factors that cause the failure of marine concrete structures. The concrete structure needs to be repaired when rebar corrosion is evident. The application of stainless-steel reinforcement was thought to be a reliable method to improve the durability of the repaired concrete structures because of the high-corrosion resistance of stainless steel. However, the long-term galvanic corrosion between carbon steel and stainless steel in marine concrete structures is a major concern for engineers because of the high different potential between the two types of steel. In this study, the corrosion behavior of the mill-scaled carbon steel coupled to AISI 304 stainless steel in chloride-contaminated mortars simulating the marine environment was investigated. The results suggested that when the cathode/anode surface area ratio is higher than 2:1, the carbon steel-stainless steel couples can ensure sufficient durability of the repaired concrete structures in the simulated marine environment. The results of this study can provide guidance to the design of the repair works of corroded concrete structures by the application of stainless-steel reinforcements. [ABSTRACT FROM AUTHOR]

In the Iberian Pyritic Belt (SW Europe), Acid Mine Drainage (AMD) is the consequence of the interaction of physical-chemical and biological factors, where aerobic Fe and/or S oxidizing chemolithotrophic and anaerobic sulfate reducing bacteria play an essential role. As a result, the polluted waters are highly acidic (pH 2–3) and contain numerous dissolved or suspended metals, which gives them a powerful corrosive action on constructions related to mining activities with high economic losses. To verify the role of bacteria in the corrosion of carbon steel, a common material in buildings exposed to corrosion in acidic waters, several experiments have been carried out under controlled conditions using carbon steel bars and acidic water containing bacteria consortia from an AMD river of the Iberian Pyritic Belt. In all the experiments carried out, a remarkable oxidation of supplemented iron was observed in the presence of bacteria. Using carbon steel as the sole iron source, we observed a slight corrosion of the bars, but when culture media was supplemented with elemental sulfur, steel bars was severely damaged. Since the bacteria inoculum come from the surface water, well oxygenated, nutrient-poor river, the obtained results are discussed based on facultative metabolism of acidophilic chemolithotrophic bacteria. [ABSTRACT FROM AUTHOR]

Carbon steels are widely used as infrastructure components owing to their high strength, ductility, and weldability. However, as corrosion degrades critical infrastructure components, exploring the relationship between the microstructure and corrosion resistance of carbon steel is of particular interest in engineering. To analyze this relationship, it is first essential to evaluate the corrosion resistance of each microstructure in a carbon steel specimen with a single chemical composition to eliminate the effects of alloying elements. In this study, we compared the pitting corrosion resistance of four microstructures (water‐quenched martensite, tempered martensite, bainite and degenerate pearlite, and ferrite–pearlite) of an AISI 1045 medium‐carbon steel. The pitting corrosion resistances of the microstructures in near‐neutral pH solutions containing NaCl were ordered as follows: (high) water‐quenched martensite > bainite and degenerate pearlite > tempered martensite > ferrite–pearlite (low). Elucidating the effect of the microstructure on the pitting corrosion resistance may contribute to the development of corrosion‐resistant carbon steels with excellent mechanical properties. [ABSTRACT FROM AUTHOR]

The ethylenediamine derivate inhibitor for carbon steel was synthesized with cysteamine hydrochloride, glycol diglycidyl ether as raw materials.The structure was characterized by infrared spectrometer.And the corrosion behaviours on Q235 carbon steel in reclaimed water by using UF-RO process were studied by means of corrosion weight-loss measurement, polarization curve measurement and electrochemical impedance spectroscopy.The results showed that the corrosion inhibitor was an anodic adsorption type corrosion inhibitor, and the electrode reaction was controlled by the process of charge-transfer.When the dosing concentration of synthetic product was 50 mg/L, the corrosion rate of Q235 carbon steel was 0.026 6 mm/a, superior to the control index requirement of GB/T 50050—2017 that the corrosion rate of carbon steel pipeline must be less than 0.075 mm/a. [ABSTRACT FROM AUTHOR]

The current laboratory experiments investigated the corrosion resistance of carbon steel in artificial seawater (ASW) using the steel coupons hanging on a closed glass reactor of ASW with volume-to-specimen area ratios ranging from 0.20 to 0.40 mL/mm2. These coupons were immersed in ASW for varying time durations (7 and 14 d) at room temperature without agitation. Further, the corrosion rates based on the weight loss and electrochemical analytical method were determined. Following exposure to carbon steel for 7 and 14 d, corrosion rates were 0.2780 mmpy and 0.3092 mmpy, respectively. The surfaces appeared to be not protected by oxides based on this result. The electrochemical impedance spectrometer in potentiostatic/galvanostatic mode, in conjunction with EDX analysis, predicted the evolution of oxygen reduction. The 7th-day immersion sample had a higher oxygen content, and the 14th-day immersion sample had a slightly lower oxygen content. Methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterized the surface morphology and composition of their corrosion product. Corrosion products derived from rust minerals hematite, lepidocrocite and magnetite appeared to cover the carbon steel surface after exposure. This result can get insight into the corrosion behavior of low-carbon steel used in marine environments. [ABSTRACT FROM AUTHOR]

A study has been conducted to measure the distribution of temperature, relative humidity and corrosivity due to uniform corrosion along the Mass Rapid Transit (MRT) North East Line (NEL) tunnel in Singapore. The corrosion rates of carbon steel 1010 and zinc coupons at the buffer areas of ten stations and five cross passages along the NEL were monitored over a period of one year. The median temperatures were between 31 and 36°C while the median relative humidity varied between 43 and 53%. At all exposure sites, the values of relative humidity corresponding to the 75th percentile values were below 60%, with very few data points registering above 80%. The cross passages showed a lower degree of fluctuations in the temperature and relative humidity compared to the buffer areas. The corrosivity levels showed some differences between exposure sites, but their values were generally low and could be categorised as C1 according to the ISO 9223:2012 categorisation. A set of procedures for an accelerated laboratory test to approximate the corrosion in the tunnel was also studied. The test procedures involved the exposure to a salt fog containing 0.12% Na2SO4 + 0.05% NaCl, followed by a drying phase and subsequent exposure to a constant temperature of 40°C and a constant relative humidity of 60%. It was found that after exposure for 80 h, the accelerated tests were able to generate the degree of corrosion observed in the most severe conditions in the field. [ABSTRACT FROM AUTHOR]

The random forest (RF) algorithm was used to develop two models for predicting the first-year corrosion losses (C1) of carbon steel in open air in various regions of the world. The first RF model built using combined databases of international programmes ISO CORRAG, MICAT and ECE/UN and tests conducted in Russia is intended for estimation of C1 in various types of atmospheres in various regions of the world. The second RF model enables the prediction of C1 in continental areas of the world. The accuracy of C1 predictions by the two RF and two dose–response functions, i.e. the function presented in ISO 9223 standard and the new version for a non-marine atmosphere, was compared. The reliability of the two RF models was shown to be significantly higher than that of the dose–response functions with exception of the predictions for corrosion losses of carbon steel in regions of Russia with a cold climate. [ABSTRACT FROM AUTHOR]

During the mandatory acidification process in the oil and gas industry, carbon steel unfortunately suffers significant corrosion damage. From this perspective, for the first time a new ionic liquid called 1-(2-(4-bromophenyl)-2-oxoethyl)-4-(tert-butyl)pyridin-1-ium bromide (ILB) has been used as an effective inhibitor for the carbon steel corrosion in aggressive HCl solution (15%) at 298 K. The experiments were managed with a number of different chemical and electrochemical techniques including weight loss, potentiodynamic polarization (PDP), and impedance spectroscopy (EIS). ILB has good inhibitory performance as an acidizing corrosion inhibitor for carbon steel even at low dosing levels of 1 × 10−3 M. The findings were promising as an inhibition efficiency of about 97% was achieved when ILB was added at low concentrations to the corrosive media. EIS results showed a significant rise in charge transfer resistance (Rct) values with increasing doses of ILB. PDP studies confirmed that ILB is a mixed type and obey Langmuir adsorption isotherm with chemical nature. The metal surface morphologies were inspected using a Scanning Electron Microscope (SEM) and an Atomic Force Microscope (AFM). Additionally, Density Functional Theory (DFT) and Molecular Dynamic Simulation (MDS) indicates that ILB molecules function as inhibitors more successfully. There is a high degree of concordance between practical and theoretical studies. [ABSTRACT FROM AUTHOR]

The influence of surface roughness on the static corrosion behavior of J55 carbon steel in CO2-containing geothermal water environment was investigated with respect to average corrosion rate, morphology, chemical composition, corrosion depth, and the cross section of corrosion products. The influence of surface roughness on the CO2 corrosion of J55 carbon steel was then proposed based on the understanding of corrosion at 65 °C. The results show that the static corrosion rate of J55 carbon steel in CO2-containing geothermal water increases with increasing surface roughness. The surface roughness of J55 carbon steel increases 5.3-fold and the CO2 corrosion rate increases by 1.4-fold under different exposure times. The static corrosion rate of J55 carbon steel in CO2-containing geothermal water changes with exposure time. The corrosion rate of J55 carbon steel decreases with the increase in exposure time, and there is little change in the corrosion rate after immersion for 2 days. At the initial stage of corrosion, the corrosion rate of J55 carbon steel was mainly affected by surface roughness. The greater the roughness, the greater the corrosion driving force and the corrosion reaction surface area and therefore the greater the corrosion rate of J55 carbon steel. After immersion for 2 days, a continuous corrosion product layer was formed on the surface of J55 carbon steel and the corrosion rate was mainly affected by the corrosion product layer. The corrosion products of J55 carbon steel are not altered by surface roughness in a CO2-containing geothermal water environment. The corrosion products of J55 carbon steel are FeCO3 and a minute amount of CaCO3. [ABSTRACT FROM AUTHOR]

A newly designed smart self-healing epoxy coating system comprised of modified halloysite nanotubes (HNTs) having capping is proposed for corrosion protection of steel. In the first step, HNTs were loaded with 8-hydroxyquinoline (8HQ), used as a corrosion inhibitor. Then the HNTs were sealed/capped using cobalt (II), aiming for an efficient and controlled release of the loaded inhibitor. The smart coatings were developed by reinforcing loaded HNTs into the epoxy matrix. The structural, thermal, mechanical, and electrochemical properties of capped modified HNTs and smart coatings were studied using various techniques. UV–Vis analysis depicted that the capping of the metal-inhibitor complex was decomposed at acidic pH resulting in a controlled release of the loaded inhibitor into HNTs. Electrochemical impedance spectroscopic (EIS) analysis of blank and smart coatings demonstrated that the low-frequency impedance modulus of smart coatings is 109 Ω.cm2 for 20 days compared to blank coatings (105 Ω.cm2), reflecting their excellent corrosion inhibition performance. The superior corrosion protection properties of these smart coatings can be ascribed to the controlled and efficient release of the loaded inhibitor from the capped HNTs. Finally, X-ray photoelectron spectroscopy (XPS) analysis of the steel substrate after the corrosion analysis revealed the adsorption of 8HQ on the steel surface, confirming the formation of iron complex due to the release of loaded inhibitor. This work demonstrated the adeptness of 8HQ in mitigating the corrosion due to the controlled and effective release of the inhibitor from capped HNTs because of dissociation of the metal-inhibitor complex (Co-8HQ).Kindly check and confirm the authors names are correctly identified.Checked [ABSTRACT FROM AUTHOR]

Here, potential metallic bipolar plate (BP) materials were manufactured by laser coating NiCr-based alloys with different Ti additions on low carbon steel substrates. The titanium content within the coating varied between 1.5 and 12.5 wt%. Our present study focussed on electrochemically testing the laser cladded samples in a milder solution. The electrolyte used for all of the electrochemical tests consisted of a 0.1 M Na2SO4 solution (acidulated with H2SO4 at pH = 5) with the addition of 0.1 ppm F−. The corrosion resistance properties of the laser-cladded samples was evaluated using an electrochemical protocol, which consisted of the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) measurements, and potentiodynamic polarization, followed by potentiostatic polarization under simulated proton exchange membrane fuel cell (PEMFC) anodic and cathodic environments for 6 h each. After the samples were subjected to potentiostatic polarization, the EIS measurements and potentiodynamic polarization were repeated. The microstructure and chemical composition of the laser cladded samples were investigated by scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX) analysis. [ABSTRACT FROM AUTHOR]

In this work, nickel‐modified graphene nanosheets (Ni−G) were prepared by hydrothermal method for the first time. The microscopic morphological analysis showed that the nickel nanoparticles were successfully reductively deposited on the surface of Ni−G with uniform distribution. Ni−G can be uniformly and stably dispersed in the electrodeposition solution. Then Ni/Co/Ni−G composite coating was prepared by pulsed current co‐deposition method to provide corrosion resistance protection for Q235 carbon steel. The microstructure and morphology analysis of the composite coating shows that Ni−G were homogeneously incorporated in the coating and the composite coatings were uniform, dense and crack‐free. The hardness test results showed that the doping of Ni−G improved the hardness of the composite coating. The influence of the added amount of Ni−G in the electrodeposition solution on the anti‐corrosion performance of the composite coating was investigated. The electrochemical results illustrated that the composite coating prepared by adding 20 mL Ni−G dispersion achieved 98.04 % protection efficiency (η ${\eta }$ EIS) against carbon steel substrate in 3.5 wt.% NaCl solution, the Ni/Co/Ni−G20 composite coating has the best corrosion resistance. [ABSTRACT FROM AUTHOR]

Corrosion Resistance Enhancement for low carbon steel is very important to extend its life service, the coating process is one of the methods which can using to achieve this, and it's the most important in surface treatments to improve the properties of metals and alloys surfaces such as corrosion resistance. In this work, low carbon steel was nitrided and coated with nano zinc using gas phase coating technical, to enhance the resistance of corrosion. The process included adding two layers. The first, a nitride layer, was added by precipitating nitrogen (N) gas, and the second, a zinc (Zn) layer, was added by precipitating Zn. The process of precipitating was carried out at different periods (5, 10, and 15 minutes). Scan electron microstructure (SEM), X-ray diffraction (XRD) and corrosion tests were carried out. The SEM and XRD results showed a new microstructure with the emergence of new phases (C3N4, Zn(N3)2, and γN). Also, the results of the corrosion test showed a significant improvement in corrosion resistance through a reduction in the corrosion rate (CR) and corrosion current density (icorr) which reached (1.598x10-3 mmpy) and (1.422x10-7 Amp/cm2) respectively, for coated samples, compared with 1.803×10-1 and 1.604x10-5, respectively, for the base metal. also found an appreciable increase in corrosion protection efficiency (CPE), which reached 99.11%. [ABSTRACT FROM AUTHOR]

Glebionis Coronaria extract (GCE) has been evaluated as a potential green corrosion inhibitor for carbon steel in 1 M HCl and 0.5 M H2SO4 mediums. Phytochemical screening, total flavonoids, polyphenols contents investigation, and FT-IR analysis were assessed to explore the diversity of the secondary metabolite compounds present in the GCE extract. The assembled data evinced the phytochemical abundance of the aqueous extract in terms of organic secondary metabolites including flavonoids, tannins, polyphenols, and coumarin. EIS and PDP measurements were performed in both acidic media in the presence of GCE, yielding a maximum efficiency of 79% and 86.6% for the hydrochloric and sulfuric media, respectively, using 2 g/L of GCE at 293 K, suggesting the mixed type action of GCE via adsorption towards the steel surface following the Langmuir model. The rise in IE% was noted with the increase of temperature in both media, reaching 84.4% and 92.2% for the hydrochloric and sulfuric media, respectively, at 313 K using the optimal concentration. The thermodynamic parameters disclosed the chemisorption action occurred at the steel-solution interface. Synergistic behavior between GCE and KI was evaluated for the lowest concentration of GCE in each medium, unveiling the cooperative action established between the halide ions and GCE. Surface morphology examination of carbon steel was conducted using the SEM–EDX technique in both media, and the results complement the study findings by demonstrating the establishment of a preventive coating through the adsorption process of GCE molecules onto the surface of the carbon steel. [ABSTRACT FROM AUTHOR]

In the present research work, the temperature effect on the corrosion inhibition process of API 5L X60 steel in 1 M H2SO4 by employing three vinylimidazolium poly(ionic liquid)s (PILs) was studied by means of electrochemical techniques, surface analysis and computational simulation. The results revealed that the maximal inhibition efficiency (75%) was achieved by Poly[VIMC4][Im] at 308 K and 175 ppm. The PILs showed Ecorr displacements with respect to the blank from −14 mV to −31 mV, which revealed the behavior of mixed-type corrosion inhibitors (CIs). The steel micrographs, in the presence and absence of PILs, showed less surface damage in the presence of PILs, thus confirming their inhibiting effect. The computational studies of the molecular orbitals and molecular electrostatic potential of the monomers suggested that the formation of a protecting film could be mainly due to the nitrogen and oxygen heteroatoms present in each structure. [ABSTRACT FROM AUTHOR]

Corrosion products that form on carbon steel in sweet (CO2) environments can protect the steel by retarding interactions between the substrate steel and a corrosive electrolyte. Such protective films could become damaged at local sites leading to potential differences and the emergence of galvanic currents with the consequence of pitting in certain envfironments. The large protected surface (with a higher positive potential) becomes a cathode while the tiny exposed surface (with a lower positive potential) becomes the anode. Films formed in a Ca2+‐rich environment often comprise mixed calcium and iron carbonates in the form, CaxFe(1−x)CO3. This work utilized an artificial pit to investigate pitting under CaxFe(1−x)CO3 film conditions. Mixed carbonate films were grown on cathode discs (25‐mm diameter) for 96 h at pH 7.5, 50°C. Freshly polished anode pins were screwed onto the cathode disc and the galvanic currents were measured for 24 h. The anode/cathode area ratios were varied by using pins of 1, 2, and 3 mm diameter. Scanning electron microscope, X‐ray powder diffraction, and energy‐dispersive X‐ray were employed to examine the electrode surfaces after the test while surface profilometry was conducted to obtain pit profiles on the anode pins. Galvanic current increased with the addition of 682 ppm Ca2+ to the solution while pseudopassivation occurred under mixed calcium–iron carbonate films. The galvanic current was observed to drop as corrosion products formed on the anode electrode. Profilometry revealed the emergence of pits on the anode electrode. The pitting threshold was commensurate with the magnitude of the galvanic current density recorded. [ABSTRACT FROM AUTHOR]

N,N'-Bis(3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-oxalamide (NNB) was synthesized via a non-solvent reaction mechanism. NNB was characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1HNMR) spectroscopy. Inhibition of corrosion in carbon steel was studied in the presence and absence of NNB in 1 M HCl solution using standard gravimetric technique and potentiodynamic polarization at 303–323 K. This was further subjected to quantum chemical parameters using density functional theory (DFT). FTIR and 1HNMR results confirmed the synthesis of NNB. The inhibition of carbon steel corrosion by NNB obeyed Langmuir isotherm at an efficiency of 78.10%. Lowest unoccupied molecular orbital (LUMO) as well as the highest occupied molecular orbital (HOMO) revealed insight into the interaction between NNB and the corroded carbon steel. The free energy of adsorption () increased as the temperature increased while the enthalpy () revealed the inhibition process to be exothermic. [ABSTRACT FROM AUTHOR]

Corrosion behaviour of carbon steel (CS) exposed in the tidal zone of Beibu Gulf was investigated by experimental method. Q235 CS specimens were designed and exposed for 12 months. The corrosion mechanism of CS was characterised by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-Ray diffraction (XRD). Results show that the corrosion performance of CS can be verified by the formula D = atn. The corrosion products are mainly composed of α-FeOOH, γ-FeOOH, β-FeOOH, Fe3O4 and γ-Fe2O3. Significantly, Cl– is an intermediate in the corrosion process and promotes the formation of the characteristic product β-FeOOH. [ABSTRACT FROM AUTHOR]

This study investigates an environment-centered, state-driven corrosion prognosis framework to predict the long-term atmospheric corrosion loss of metal materials, and this paper takes carbon steel as an example to show the establishment process of the framework. Unlike traditional power-linear prediction models that seldomly consider environmental impacts, the proposed model quantitatively establishes the correlations between corrosion loss and dynamic atmospheric environmental factors. A comprehensive power-linear function model integrating multiple atmospheric environmental factors is constructed, following the corrosion kinetics robustness. Under the proposed framework, the steady-state start time is evaluated, followed by the long-term corrosion loss prediction under different corrosivity categories and test sites. The applicability is justified via a case study of long-term field exposure tests of metal materials in China, as well as the experimental results of the ISO CORRAG program. By comparing with the traditional power model and ISO model, the experimental results demonstrate the capability and effectiveness of the proposed prognosis methodology in acquiring accurate corrosion state information and corrosion loss prediction results with less input corrosion information. [ABSTRACT FROM AUTHOR]

Featured Application: Specific applications for the oil and gas industry. Testing of corrosion inhibitors to select the one with the best performance simulating field conditions. Corrosion inhibitors are evaluated in the oil industry with electrochemical tests of resistance to linear polarization with rotating cylinders following ASTM G170 and NACE 3T199 standards. With these tests, we can determine the corrosion rate (CR) and efficiency of corrosion inhibitors. In this work, a corrosion test protocol used by hydrocarbon-producing companies for the testing of corrosion inhibitors was used. This protocol consists of a 1045 carbon steel working electrode in a NACE solution composed of 9.62% NaCl, 0.45% CaCl2, 0.19% MgCl2, and 89.74% H2O, at a temperature of 65 °C and saturated with CO2. Each inhibitor tested was subjected to a series of 6000-4000-2000-4000-6000 rpm tests using rotating cylinder electrodes (RCEs). These electrochemical studies were carried out with the rotating cylinder to evaluate the ability of the inhibitor to prevent the corrosion of carbon steel in the presence of a centrifugal force. In our opinion, this test does not provide corrosion engineers with enough information to be used as a predictive tool, since what is obtained is the CR in a very short testing time. This document proposes the use of two more appropriate test methodologies, the rotating cylinder electrode (RCE) and the flow loop (FL), to evaluate the performance of the corrosion inhibitor. For the FL, the selected flow rate was 1.2 m/s, the same rate that fluids have in oil company pipelines installed in Neuquén, Argentina. Firstly, according to the company's protocol, inhibitors are required to have an efficiency greater than or equal to 90% in RCE tests; therefore, inhibitors that meet these requirements were tested in the FL test. Unlike the RCE test, the FL test represents the experimental conditions of the laboratory that are closest to reality, for the evaluation of the performance of the inhibitors used in the pipelines of the oil and gas industry. FL tests have several problems involving corrosion, erosion, abrasion, biphasic fluids, the time it takes for the inhibitor to become effective, and the duration of its effectiveness. [ABSTRACT FROM AUTHOR]

Methods for preliminary modification of the surface of structural metals with formulations based on organosilanes, including both solutions of individual organosilanes and two-component mixtures consisting of two organosilanes or an organosilane with an organic corrosion inhibitor, have been developed. As a result of this modification, a self-assembling siloxane polymeric/oligomeric nanoscale layer is formed on the metal surface. Such layers are capable of changing the physicochemical properties of the metal surface, in particular reducing the susceptibility of the metal to corrosive destruction. In this work, the mechanism of formation of organosilicon nanolayers and their effect on the electrochemical and corrosion behavior of metals have been studied in detail by a set of electrochemical methods, while laboratory studies and accelerated corrosion tests of carbon steel and zinc, modified with formulations based on organosilanes, have been carried out. The greatest inhibitory effect is demonstrated by two-component modifying formulations, namely mixtures of vinyl with aminosilane and vinylsilane with benzotriazole. The mechanism of corrosion inhibition by surface nanolayers formed upon surface modification with two-component mixtures has been considered. [ABSTRACT FROM AUTHOR]

The corrosion behavior of carbon steel X36 (CSX36) in solutions of soils collected from different areas linked to the main pipe network of a water distribution system in Jeddah City (Obhour Al Shamaliyah, Ob-Sh; Al Shateie, Sh; Al Safa, Sf; Al Samer, Sa; and Al Jameaah, Ja) at an ambient temperature (23 ± 1 °C) was studied. The corrosion behavior was monitored using various techniques, such as weight loss and electrochemical (open circuit potential [OCP]; electrochemical impedance spectroscopy; and potentiodynamic polarization) measurements. Visual and microscopic examinations of the surface morphology of the studied metals were evaluated and discussed. The corrosion rates in all the studied soil solutions decreased with an increase in the immersion period over 80 weeks. The corrosivity of the studied soils based on weight loss measurements followed the order Sh > Ja > Ob-Sh > Sa > Sf. The value of the OCP gradually shifted to more negative values, indicating a higher tendency to corrode. For the soil solutions studied, the Ecorr shifted to more negative values, indicating that the corrosion process was under cathodic control. The values of icorr and 1/Rp tended to increase as the soil resistivity decreased. Moreover, there was good consistency between the corrosivity order of the studied soil solution obtained from electrochemical impedance spectroscopy and PDP measurements in the following order: Ob-Sh > Sh > Ja > Sa > Sf. A comprehensive assessment of the soil corrosivity based on various soil variables revealed that soil solutions of Ob-Sh and Sh are extremely corrosive, while the rest of the soil solutions are noncorrosive. [ABSTRACT FROM AUTHOR]

The corrosion of carbon steel causes dramatic economic losses each year. Since conventional corrosion prevention approaches may cause pollution problems to the environment, ecofriendly and effective corrosion approaches are desired. Microbiologically influenced corrosion inhibition (MICI) has been reported as a sustainable corrosion prevention method. This work aims to evaluate the corrosion inhibition effect of two bacterial strains, Tenacibaculum mesophilum D-6 and Bacillus sp. Y-6 by choosing Q235 carbon steel as a model system. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and a series of electrochemical techniques were applied to study the corrosion prevention effect. The electrochemical and pitting results indicated that T. mesophilum D-6 displayed a better corrosion protection effect. T. mesophilum D-6 formed a denser and thicker biofilm on the Q235 surface than Bacillus sp. Y-6. The maximum thickness of the T. mesophilum D-6 biofilms was 11.6 ± 0.7 μm, which is about twice as thick than that of Bacillus sp. Y-6. The corrosion prevention mechanism was ascribed to the formation of biofilms as a barrier to block corrosive agents such as O2. This study provides a theoretical foundation for the application of biofilms as green and effective corrosion inhibitors for carbon steel. [ABSTRACT FROM AUTHOR]

In order to evaluate the effect of chromium content in carbon steel on the corrosion resistance of carbon steel materials, the corrosion behavior of 1Cr and N80 steels was investigated in this study by immersion weight loss method under three different CO2 partial pressure and temperature conditions in formation water for 72, 168 and 336 h. Detailed material surface morphological characterization was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and confocal laser scanning microscopy (CLSM). The results show that the pitting corrosion of N80 carbon steel is serious at medium temperature and low CO2 partial pressure (50 °C, 0.30 MPa), and the corrosion rate is significantly higher than that of 1Cr steel. However, at high-temperature and high CO2 partial pressure (100 °C/0.63 MPa and 114 °C/0.73 MPa), 1Cr steel is more inclined to the mesa corrosion dominated by local corrosion characteristics, and the corrosion rate is seriously higher than that of N80 steel with uniform corrosion. From the experimental results, we can know the corrosion resistance of carbon steel and 1Cr steel is not only affected by the corrosion environment, but also depends on the formation process of the product film, as well as its compactness and integrity characteristics. At low-temperature and low CO2 partial pressure, 1 wt.% chromium content can provide a certain degree of corrosion resistance, while high temperature and high partial pressure can broaden the application window of carbon steel N80 and weaken the corrosion inhibition effect of chromium. [ABSTRACT FROM AUTHOR]

The cutting saw blade with diamond blade and carbon steel matrix is widely used in stone cutting because of its high strength, impact resistance and good thermal stability. However, the carbon steel matrix is easy to corrode in the circulating cooling water, which shortens its service life. In this study, a new highly efficient benzotriazole-based (BMN) composite inhibitor was synthesized and investigated against the corrosion of carbon steel in stone processing wastewater. The corrosion inhibition properties and mechanism of prepared BMN for carbon steel in real stone processing wastewater were evaluated and deduced using the experimental weight loss, electrochemical and surface morphology characterization techniques. Weight loss methods results showed that a high inhibition efficiency of 99.59% in stone processing wastewater was achieved at ambient temperature, with the stirring speed 200 rpm, the immersion time 7 d, and the BMN concentration is 50 mL·L–1. Electrochemical impedance spectroscopy indicated that resistance from the surface films (R2 ) and charge transfer resistance (R3 ) were enhanced with increase in BMN concentration. Polarisation results revealed the BMN acted as an anodic inhibitor, owing to the addition of BMN resulted in the significant change of anodic Tafel slopes (βa ). Scanning electron microscopy results indicated BMN formed a protective film on the surface of carbon steel through adsorption. In short, the prepared BMN composite inhibitor exhibited superior anti-corrosion performance for saw blade corrosion in stone processing wastewater, which had great application potential in industries. [ABSTRACT FROM AUTHOR]

Circulating cooling water consumes a large amount of water in thermal power plant, and there are some problems such as scaling and corrosion in the system. This study presents a novel circulating cooling water treatment process based on microbes. The mechanism and influencing factors of microbial treatment process of circulating cooling water is studied. Water from circulating cooling system of a 300 MW thermal power unit was used, dynamic simulation test was carried out and compared between the microbial treatment process and the traditional chemical treatment process. The results showed that nutrient solution dosage on calcium hardness is positive, while the interaction between nutrient solution dosage and aeration rate has negative effect. When ammonia concentration is 10–50 mg/L and aeration rate is 1–3 L, and the minimum calcium hardness is 18.3 mmol/L. Reducing the concentration of nutrient solution and increasing the aeration rate are beneficial to slow down the corrosion of carbon steel and stainless steel. When ammonia concentration is 10–50 mg/L and aeration rate is 1–3 L, the minimum corrosion rates are 0.01552 and 0.00110 mm/a, respectively. Compared with traditional chemical treatment process, the microbial treatment process can achieve the scale inhibition and corrosion inhibition target at high concentration ratio, the highest concentration ratio can reach 5.4, and the corrosion rate of carbon steel and stainless steel is low. The green, efficient and environment-friendly microbial treatment process provides a new method for circulating cooling water treatment, which can obtain stable and economical operation of circulating cooling water system under high concentration ratio. [ABSTRACT FROM AUTHOR]

The protective coating with a self-organized microtubular structure was formed using plasma electrolytic oxidation (PEO) on AlMg3 aluminum alloy in the tartrate-fluoride electrolyte. This protective layer was further modified using corrosion inhibitors of the azole group (1,2,4-triazole, benzotriazole) and polymer material (polyvinilidene fluoride, PVDF). X-ray diffraction analysis and scanning electron microscopy with energy dispersive spectroscopy were used to study the morphology and composition of the obtained oxide coatings. The presence of the inhibitor in the PEO-layer was confirmed using micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The level of corrosion protection of formed coatings as well as the effect of loaded inhibitors on the anticorrosion efficiency was evaluated using electrochemical impedance spectroscopy (EIS) and localized scanning techniques (SVET/SIET). The coating impregnation with corrosion inhibitors of the azole group significantly improves the corrosion characteristics of the material. Impregnation of the base PEO-layer with 1,2,4-triazole during 24 h results in a 36 times increase in the impedance modulus measured at the lowest frequency (|Z|f=0.1Hz). Additional sealing of impregnated coating with polymer improves the corrosion stability of the treated material. On the base of the obtained data, the optimal way of protective inhibitor- and polymer-containing formation using surface treatment was suggested. The best barrier properties were established for hybrid coatings obtained by the immersion of a PEO-coated sample in 1,2,4-triazole solution for 24 h and following spraying the PVDF solution. The value of |Z|f=0.1Hz for this protective layer increased by more than two orders of magnitude in comparison with the base PEO-layer. The three-stage mechanism of corrosion inhibition of the sample with smart inhibitor-containing coating was established. [ABSTRACT FROM AUTHOR]

Two new acrylamide derivatives were prepared namely: "N-(bis(2-hydroxyethyl) carbamothioyl) acrylamide (BHCA) and N-((2-hydroxyethyl) carbamothioyl) acrylamide(HCA) and their chemical structures were analyzed and confirmed using IR and 1H NMR". These chemicals were investigated as corrosion inhibitors for carbon steel (CS) in 1 M HCl medium using chemical method (mass loss, ML), and electrochemical techniques including potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The results showed that the acrylamide derivatives work well as corrosion inhibitors, with inhibition efficacy (%IE) reaching 94.91–95.28% at 60 ppm for BHCA and HCA, respectively. Their inhibition depends mainly on their concentration and temperature of the solution. According to the PDP files, these derivatives function as mixed-type inhibitors that physically adsorb on the CS surface in accordance with the Langmuir adsorption isotherm, creating a thin coating that shields the CS surface from corrosive fluids. The charge transfer resistance (Rct) increased and the double layer capacitance (Cdl) decreased as a result of the adsorption of the used derivatives. Calculated and described were the thermodynamic parameters for activation and adsorption. Quantum chemistry computations and Monte Carlo simulations were examined and discussed for these derivatives under investigation. Surface analysis was checked using atomic force microscope (AFM). Validity of the obtained data was demonstrated by the confirmation of these several independent procedures. [ABSTRACT FROM AUTHOR]

This paper synthesizes a Ce (III) complex with 1,10-phenanthroline (phen) as the ligand, whose chemical formula is confirmed as Ce(NO3)3(phen)2, and evaluate its inhibition effects on the corrosion of P110 carbon steel in 0.5 M HCl by electrochemical measurements, surface analyses and theoretical calculations. The results show that the Ce(NO3)3(phen)2 complex exhibits high corrosion inhibition efficiencies of ~ 95% at 298 K (25 °C) and ~ 90% at relatively high temperature of 328 K (55 °C), outperforming its cerium salt and ligand of phen. The highest corrosion inhibition efficiency of Ce(NO3)3(phen)2 corresponds to its highest thermodynamics parameters of activation energy (Ea), activation enthalpy (ΔHa) and activation entropy (ΔSa) and the equilibrium constant of adsorption (Kads). Surface analyses further confirm the superior corrosion inhibition performance of Ce(NO3)3(phen)2. Moreover, the X-ray photoelectron spectroscopy analysis indicate that Ce(NO3)3(phen)2 can inhibit corrosion by simultaneously forming adsorption film via its phen ligand and precipitation film via its Ce (III) complex, which could be the reason for its high corrosion inhibition performance at high temperature. DFT calculations and molecular dynamic simulation show a good correlation with the experimental results. [ABSTRACT FROM AUTHOR]

This work demonstrated a workable approach for the synthesis of a re-healing polyaniline-modified epoxy resin coating material via photopolymerization. The prepared coating material exhibited low water absorption, allowing it to be used as an anti-corrosion protective layer for carbon steel. First, graphene oxide (GO) was synthesized through the modified Hummers' method. It was then mixed with TiO2 to extend its light response range. The structural features of the coating material were identified using scanning electron microscopy (SEM), X ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT IR). The corrosion behavior of the coatings and the pure resin layer were tested by using electrochemical impedance spectroscopy (EIS) and the potentiodynamic polarization curve (Tafel). The presence of TiO2 reduced the corrosion potential (Ecorr) toward lower values in 3.5% NaCl at room temperature, which was due to the photocathode of titanium dioxide. The experimental results indicated that GO was successfully compounded with TiO2 and that GO effectively improved the light utilization capacity of TiO2. The experiments showed that the presence of local impurities or defects can reduce the band gap energy, resulting in a lower Eg for the 2GO:1TiO2 composite (2.95 eV) compared to that of TiO2 alone (3.37 eV). After applying visible light to the coating surface, the change in the Ecorr value of the V-composite coating was 993 mV and the value of Icorr decreased to 1.993 × 10−6 A/cm2. The calculated results showed that the protection efficiency of the D-composite and V-composite coatings on composite substrates was approximately 73.5 and 83.3%, respectively. More analyses revealed that under visible light, the coating had better corrosion resistance. This coating material is expected to be a candidate for carbon steel corrosion protection. [ABSTRACT FROM AUTHOR]