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Nanoscale, localized corrosion underpins billions of dollars in damage and material costs each year; however, the processes responsible have remained elusive due to the complexity of studying degradative material behavior at nanoscale liquid-solid interfaces. Recent improvements to liquid cell scanning/transmission electron microscopy and associated techniques enable this first look at the nanogalvanic corrosion processes underlying this widespread damage. Nanogalvanic corrosion is observed to initiate at the near-surface ferrite/cementite phase interfaces that typify carbon steel. In minutes, the corrosion front delves deeper into the material, claiming a thin layer of ferrite around all exposed phase boundaries before progressing laterally, converting the ferrite to corrosion product normal to each buried cementite grain. Over the following few minutes, the corrosion product that lines each cementite grain undergoes a volumetric expansion, creating a lateral wedging force that mechanically ejects the cementite grains from their grooves and leaves behind percolation channels into the steel substructure.

The concrete electrical resistivity is a prominent parameter in structural health monitoring, since, along with corrosion potential, it provides relevant qualitative diagnosis of the reinforcement corrosion. This study proposes a simple expression to reliable determine resistivity from the concrete electrical resistance (R E ) provided by the corrosion sensor of the Integrated Network of Sensors for Smart Corrosion Monitoring (INESSCOM) we have developed. The novelty here is that distinct from common resistivity sensors, the cell constants obtained by the proposed expression are intended to be valid for any sensor implementation scenario. This was ensured by studying most significant geometrical features of the sensor in a wide set of calibration solutions. This embedded-sensor approach is intended to be applicable for R E measurements obtained both using potential step voltammetry (PSV, used in the INESSCOM sensor for corrosion rate measurement) and alternating current methods. In this regard, we present a simple protocol to reliably determine R E , and therefore resistivity, from PSV measurements. It consists in adding a very short potentiostatic pulse to the original technique. In this way, we are able to easy monitor resistivity along with corrosion rate through a single sensor, an advantage which is not usual in structural health monitoring.

Three anionic chitosan surfactant with different hydrophobic tails labeled Chitosan-R8, Chitosan-R12 and Chitosan-R16 were prepared and their surface behavior in aqueous solution was determined by surface tension measurements at three different temperatures 20, 40 and 60 °C. The affinity of the synthesized anionic chitosan surfactant to form micelle enhanced with increasing the hydrophobic chain length as well as raising the solution temperature up to 60 °C. The anionic chitosan surfactant showed a great influence as capping agent for the in-situ preparation of silver nanoparticles (AgNPs) based on photochemical reduction method using sunlight as reducing agent. The chemical structure of chitosan surfactant showed a great effect on the size and stability of the prepared AgNPs. The Chitosan-R16 with longer hydrophobic tail, produce a uniform, small size & stable AgNPs compared to shorter tail Chitosan-R12 & Chitosan-R8. The prepared anionic chitosan showed good inhibiting effect against the steel corrosion in the 1.0 M HCl. The corrosion inhibition efficiency was determined using three different techniques, proving the ability of the new chitosan surfactant to inhibit the steel corrosion. The XPS results confirmed the formation of chitosan inhibitor on the steel surface., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Marine is the harshest corrosive environment where almost all marine underwater equipment and facilities undergo corrosion caused by marine microorganisms. With the development of marine resources globally, the marine engineering and relevant infrastructures have increased exponentially. Microbiologically influenced corrosion (MIC) leads to severe safety accidents and great economic losses. The specific aggregation of corrosive microbial communities and their interactions with materials conform to a typical ecological adaptation mechanism. On the one hand, corrosive biofilms in the marine environment selectively colonize on a specific steel substrate by utilizing their complex community composition and various extracellular polymeric substances; on the other hand, the elemental composition and surface microstructure of different engineering steels affect the microbial community and corrosive process. MIC in the marine environment is a dynamic process evolving with the formation of corrosive biofilms and corrosion products. In this mini-review, the interactions between corrosive biofilm and steel substrates are explored and discussed, especially those conducted in situ in the marine environment. Herein, the important role of iron in the dynamic process of marine corrosion is highlighted.

The effects of chlorides on the corrosion of steel bars within a matrix comprising modified magnesium oxysulfide (MMOS) cementitious materials was investigated. The phase composition, morphology and distribution of steel corrosion products (SCPs) were studied. There was basically no corrosion of the steel bars in the MMOS cement without chlorides. A high chloride content and a high water/cement (w/c) ratio in the MMOS matrix had adverse effects on the steel bar corrosion. The primary SCPs in the MMOS mixes were iron oxyhydroxides (FeOOH) and ferric oxide (Fe2O3), while ferrous oxide (FeO) was only observed at low w/c ratios, indicating a lower degree of oxidation. The presence of di-iron nonacarbonyl (Fe2(CO)9) at high w/c ratios suggested a higher degree of oxidation. At lower w/c ratios, rust products readily diffused. Conversely, at higher w/c ratios, these products accumulated close to the steel bars, resulting in a compact structure. [ABSTRACT FROM AUTHOR]

Corrosion is a spontaneous process that can be slowed down, though not entirely prevented, through various methods. The most common method for protecting metals against corrosion involves the application of coatings, with nearly three-quarters of metal structures currently benefiting from organic coatings. In addition to providing effective corrosion protection, modern coatings are expected to be environmentally friendly. Presently, there is growing interest in researching coatings based on water-soluble natural polymers containing active chemical compounds, such as corrosion inhibitors. One such polymer is chitosan, which exhibits excellent film-forming ability in acidic aqueous solutions, making it well suited for diverse protective coating applications. This study explores the possibility of applying a chitosan-based coating with the addition of TiO2 and eucalyptol for the protection of steel against acid corrosion. The results confirmed that the tested chitosan-based coatings must incorporate an inhibitor to have a protective effect on the steel surface, since these coatings show a corrosive effect without an inhibitor. Although coatings based on chitosan and titanium dioxide with the addition of eucalyptol demonstrate protective effects, the duration of these effects is limited. Consequently, this method of protection could be suitable only for temporary protection of steel against acid corrosion. [ABSTRACT FROM AUTHOR]

Corrosion poses a significant challenge, causing severe damage to steel infrastructures across various industries, particularly those involved in delivering fossil fuel sources. The present study introduces an innovative approach to the development of corrosion inhibitors through the synthesis of a zinc nanoparticle (Zn NP) and polystyrene (PS) composite (ZnNPs@PS composite). The synthesized composite was characterized, revealing a surface area (SBET) of 33.62 m2 g−1 and an average pore diameter (Dp) of 9 nm. The analysis was conducted using several techniques including Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and transmission electron microscopy (TEM). The successful immobilization of Zn NPs, with an average size range of 4–50 nm, within the PS matrix was confirmed. The composite's corrosion inhibition efficiency (CIE) was evaluated using the weight loss method. Treated steel samples, after immersion in formation water, diesel fuel, and sulfuric acid (H2SO4) for 10 days at 25 °C, demonstrated CIE percentages of 94.27%, 88.18%, and 85.05%, respectively. This novel composite thus shows promising potential as an effective corrosion inhibitor for steel in various corrosive environments. [ABSTRACT FROM AUTHOR]

The corrosion behavior of Q345qNH steel and Q420qNH steel in simulated industrial atmospheric environment medium was studied by periodic immersion+infrared aging corrosion experiment. The results show that the corrosion type of both samples is uneven comprehensive corrosion, and the rust layer formed in the later stage of corrosion is relatively dense. But average corrosion rate of Q345qNH steel is always lower than that of Q420qNH steel, and the ratio of Iα‐FeOOH/Iγ‐FeOOH in rust layer is always higher. Compared with Q420qNH steel, Q345qNH steel has fewer surface pits but deeper local pits. The self‐corrosion potential of Q345qNH steel increases obviously, the resistance of the rust layer is larger, and protection to the matrix is stronger. This is because the formation of a large number of corrosion microcells induced by fine lamellar sorbite tissue that uneven distributed in Q420qNH steel, which increases the corrosion rate and makes corrosion uneven, while the larger pearlitic group in Q345qNH steel increases the local corrosion rate. However, the higher chromium/carbon ratio in Q345qNH steel promotes the conversion of lepidocrocite to goethite and inhibits the cathode reaction in the infrared drying stage, improving the density and stability of the rust layer. [ABSTRACT FROM AUTHOR]

The study concentrated on the fabrication of an environmentally friendly inhibitor, namely ethyl 4-(4-methoxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate derivative of quinoline (MQC), in a single step, and assessed its inhibiting property in highly acidic fluid (15 % HCl) for protecting Q235 steel at 1500 rpm rotation speed. Weight reduction, Potentiodynamic polarization, and electrochemical impedance spectroscopy were utilized in the study to investigate the inhibiting impact of MQC. The estimated findings corroborated the inhibiting data of 93.54 and 98.38 % at 308 K with 100 mg/L/only MQC and MQC + KI/75 mg/L + 0.5 mM, respectively, and the impact of temperature upon the inhibitory capability possessed little impact at larger dose quantities. According to the electrochemical outcomes, the MQC is a mixed-type corrosion inhibitor. The findings of the SEM, EDX, and AFM examinations demonstrated that the MQC established a barrier over the surface of Q235 steel by adsorption, changing the hydrophilic and hydrophobic attributes of the Q235 steel surface. An additional XPS assessment demonstrated MQC molecule adsorption on the Q235 steel surface. Density functional theory (DFT) and molecular dynamic simulations (MD) calculations were further performed to justify the experimental results. [ABSTRACT FROM AUTHOR]

The study was designed to explore the corrosion prevention capabilities of Citrullus colocynthis seeds alkaloid-rich extract (CSEA) on MS in a 1 M HCl environment by use of electrochemical and theoretical methods. Notably, Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization were used to probe the impact of immersion time and temperature. Energy-dispersive X-ray spectroscopy (EDX) and spanning electron microscopy (SEM) were used to confirm the presence of a protective layer on the substrate surface. Density functional theory (DFT) method was used to optimize the investigated species by use of B3LYP/6–31 + G(d, p) level of theory. The global and local quantum chemical reactivity descriptors were calculated to explore the inhibition corrosion efficiency and to identify the most favorable sites for electrophilic and nucleophilic attacks. Monte Carlo (MC) and molecular dynamics simulation (MDS) methods were used to study the interactions between corrosion inhibitor and metal surface. Noteworthy, results showed that CSEA exhibited an impressive inhibition efficiency, which reached 94.3% with a concentration of 2 g/L at 298 K. Potentiodynamic polarization revealed that the extract acted as a mixed-type inhibitor. Nyquist graphs showed that charge-transfer resistance and dæouble-layer capacitance both rised with increasing CSEA concentration, suggesting better inhibition efficiency. Notably, the Langmuir adsorption isotherm is well-aligned with the adsorption of inhibitor compounds. Importantly, all aforementioned theoretical methods were in agreement with the experimental findings. The outcome of the present work supported using Citrullus colocynthis seeds alkaloid-rich extract as ecofriendly agents to prevent corrosion. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the corrosion inhibitor effect of migrating corrosion inhibitor (MCI) on Q235 steel in high alkaline environment under cathodic polarization. Design/methodology/approach: This study investigated the electrochemical characteristics of Q235 steel with and without MCI by polarization curve and electrochemical impedance spectroscopy. Besides, the surface composition of Q235 steel under different environments was analyzed by X-ray photoelectron spectroscopy. In addition, the migration characteristic of MCI and the adsorption behavior of MCI under cathodic polarization were studied using Raman spectroscopy. Findings: Diethanolamine (DEA) and N, N-dimethylethanolamine (DMEA) can inhibit the increase of Fe(II) in the oxide film of Q235 steel under cathodic polarization. The adsorption stability of DMEA film was higher under cathodic polarization potential, showing a higher corrosion inhibition ability. The corrosion inhibition mechanism of DEA and DMEA under cathodic polarization potential was proposed. Originality/value: The MCI has a broad application prospect in the repair of damaged reinforced concrete due to its unique migratory characteristics. The interaction between MCIs, rebar and concrete with different compositions has been studied, but the passivation behavior of the steel interface in the presence of both the migrating electric field and corrosion inhibitors has been neglected. And it was investigated in this paper. [ABSTRACT FROM AUTHOR]

The corrosion behavior of 20G and TP347H materials was investigated in molten LiCl-NaCl-KCl salt. The corrosion rates of these materials in molten chloride salt are high and are strongly affected by the alloying surface oxide formation. The 20G shows uniform surface corrosion with almost no protective oxide formation on the surface. In contrast, the austenitic steel TP347H exhibits better corrosion resistance in molten chloride salts due to its high Cr content. Owing to the highly corrosive nature of molten chloride salts, the Cl− in molten salt could react with oxides and alloy, inducing intergranular corrosion of austenitic steel in molten chloride salt environments. [ABSTRACT FROM AUTHOR]

Steel structures are susceptible to corrosion due to their exposure to the environment. Currently used non-destructive techniques require inspector involvement. Inaccessibility of the defective part may lead to unnoticed corrosion, allowing the corrosion to propagate and cause catastrophic structural failure over time. Autonomous corrosion detection is essential for mitigating these problems. This study investigated the effect of the type of encoder–decoder neural network and the training strategy that works the best to automate the segmentation of corroded pixels in visual images. Models using pre-trained DesnseNet121 and EfficientNetB7 backbones yielded 96.78% and 98.5% average pixel-level accuracy, respectively. Deeper EffiecientNetB7 performed the worst, with only 33% true-positive values, which was 58% less than ResNet34 and the original UNet. ResNet 34 successfully classified the corroded pixels, with 2.98% false positives, whereas the original UNet predicted 8.24% of the non-corroded pixels as corroded when tested on a specific set of images exclusive to the investigated training dataset. Deep networks were found to be better for transfer learning than full training, and a smaller dataset could be one of the reasons for performance degradation. Both fully trained conventional UNet and ResNet34 models were tested on some external images of different steel structures with different colors and types of corrosion, with the ResNet 34 backbone outperforming conventional UNet. [ABSTRACT FROM AUTHOR]

Corrosion behavior is critical to the application of lightweight aluminum/steel joints using new resistance spot welding (RSW) technology. The study investigated the corrosion mechanism and the shear strength of RSW joints comprising 1.2 mm 5182 aluminum and 1.5 mm DP780 galvanized steel. Electrochemical corrosion tests were conducted on the base materials and various positions of the welds in a 3.5% NaCl solution. This result revealed that the corrosion susceptibility of the interfacial intermetallic compound (IMC) layer was not accelerated by the aluminum nugget because of the noble corrosion potential. Subsequently, the spray acceleration test was employed to investigate the corrosion mechanism. It is noteworthy that microcracks, as well as regions enriched with silicon and oxygen at the interface front, are preferential to corrosion during salt spray exposure, instead of the IMC layer. Moreover, the shear strength of the joints decreases with the reduction in the effective joint area after the salt spray exposure of the weld joints. This research systematically explored the corrosion behavior and its relationship with the mechanical properties of Al alloy/steel RSW joints. [ABSTRACT FROM AUTHOR]

Steel is the primary shipbuilding material; however, it erodes quickly. Adequate protection requires hard, durable, and adhesive coatings. This study examines how aluminium-graphite pigment and heat treatment affect epoxy-coated SS400 steel plate corrosion, adhesion, and coating resilience. This study used a 1:1 and 3:1 pigment ratio with 100°C and 150°C heat treatment. The coating layer was 250 µm thick and comprised 80% epoxy and 20% aluminum-graphite. The maximum adhesion strength, 19.62 MPa, was achieved with an aluminium-graphite pigment ratio of 1:1 and 100°C heat treatment. The top coating resistance was 6.86 Joules under identical conditions. The lowest corrosion rate, 0.047 mmpy, was at a 3:1 aluminum-graphite ratio and 150°C heat treatment. This discovery has significant consequences for shipbuilding steel corrosion resistance. [ABSTRACT FROM AUTHOR]

Hot‐dip Zn55Al‐coated steel samples have been exposed for up to 6 years at 11 different weathering sites, including marine, marine‐industrial, acid‐rain and dry atmospheres. From the mass loss measurements, Zn55Al metallic coating showed globally long‐term good corrosion resistance in all weathering conditions compared with hot‐dip Zn‐0.2Al‐coated steel (Z). Yet, weaker performance was observed on Zn55Al in high SO2 polluted atmosphere, particularly when combined with seawater aerosols. This is explained by a more acidic surface condition linked to high SO2. Although the extent of corrosion in this phase was different at the different sites, the final corrosion products formed after 6 years were rather similar at all sites. This consists of hydrous aluminium sulphate or hydrous aluminium hydroxy sulphate and, probably also a smaller amount of sulphate‐containing zinc corrosion products or Al/Zn products. [ABSTRACT FROM AUTHOR]

Weathering steel (WS) and high‐performance steel (HPS) have been widely used in bridge engineering. Investigating the corrosion performances of WS and HPS is of great significance to the safety evaluation and maintenance of uncoated WS or HPS bridges, especially aging bridges. This study focused on the correlation between the corrosion performance and composition of the rust layer. Accelerated corrosion tests were conducted on Q345CNH and HPS 70 W to observe their corrosion performance under salt‐spray corrosive environment. Based on the results of corrosion test and the existing corrosion attack evaluation theories, the empirical formulae of uniform corrosion and pitting corrosion were derived. X‐ray diffraction experiments were performed to analyze the composition of the rust layer formed on the surface of steel specimens after various corrosion cycles. The relationship between the composition of the rust layer and the corrosion performance was established. The test corrosive environment was verified to be consistent with the C3 environment. The conclusions of this study could provide guidance for the corrosion evaluation in the following test or practical application. [ABSTRACT FROM AUTHOR]

The study investigated the effect of sebacate as a corrosion inhibitor for acrylic-coated steel. Specifically, it examined its impact on mitigating a frequent case of paint delamination, known as filiform corrosion (FFC), through a chosen weathering test designed to stress the degradation of the produced samples. Sebacate was demonstrated to be an efficient organic molecule for enhancing the corrosion resistance of steel. This efficacy was evaluated through electrochemical characterization based on electrochemical impedance spectroscopy measurements and potentiodynamic polarization curves, including the application of an FFC susceptibility prediction methodology based on measurements obtained in FFC-simulated electrolytes. An inhibition efficiency of 98% was measured in near-neutral saline solutions compared to conditions lacking inhibitor presence. During FFC simulation, the primary effect observed was associated with a reduction in cathodic activity evolution. Furthermore, a significant reduction in corrosion creep evolution of 35% was found. These experimental findings aligned closely with the outcomes projected by the simulated investigations. [ABSTRACT FROM AUTHOR]

Sulfate-reducing bacteria (SRB) is a bacterium that can cause microbial corrosion. SRB often leads to corrosion and perforation of oil and gas pipelines. Cathodic polarization is usually used for pipe external corrosion protection, while cathodic polarization may influence the growth and reproduction of SRB on the pipe wall. Based on 14-day electrochemical experiments and morphological characterization of corrosion product, SRB corrosion on L360N under different cathodic polarization potentials was analyzed. Under the action of cathodic protection potential, − 0.85 VSCE stimulated SRB metabolism and accelerated corrosion due to a large amount of electron supply. At − 0.95 VSCE and below, the SRB adsorption process was interrupted, which could play a protective role. The conclusions of this study could provide basic guidance for the corrosion prevention of L360N steel with SRB corrosion environment and reduce the economic losses caused by microbial corrosion. [ABSTRACT FROM AUTHOR]

In the CCUS project, CO2 utilization had achieved remarkable results in oil displacement. But, at present, one of the main reasons that seriously affected the large-scale application of CCUS projects was that the corrosion behavior of underground environment on pipe string or wellbore was not fully evaluated. It was revealed that the wellbore corrosion behavior in the harsh environment in the process of CO2 flooding was the key to ensure the safe production of oil fields. Therefore, this paper took the corrosion environment with temperature of 81.7°C, pressure of 52.3 MPa and high salinity in the well depth of 4517 m as the research object, to study the corrosion behavior of oil casing N80 steel through corrosion rate, corrosion morphology and electrochemical experiments. The results showed that the corrosion rate increased with the increase of experimental time, behaved by the charge transfer resistance decreased. However, when the experiment increased from 800 h to 1000 h, the pitting corrosion rate increased from 1.47 mm/a to 1.782 mm/a, which was consistent with the ratio of anode/cathode Tafel constants and corrosion density. This was mainly because the relatively dense FeCO3 corrosion product layer generated on the N80 steel surface gradually brook down due to synergistic effect of amorphous CrO3, Fe2+/Ca2+ complex salt and Cl– during the experiment, which promoted the initiation and development of the corrosion pits. Compared with the bare N80 steel, the incomplete corrosion product layer aggravated the rapid development of pitting corrosion. [ABSTRACT FROM AUTHOR]

This research developed and evaluated the corrosion-inhibiting efficiency of a natural inhibitor prepared from a bamboo tree [referred to as bamboo leaf extract (BLE)]. The corrosion behavior of steel in BLE-admixed cementitious systems was examined using dynamic-polarization tests and salt-fog tests. The effect of the addition of BLE on the workability and compressive strength of cementitious systems was studied using flow-table and compression tests on mortars. Increased concentration of BLE and the preimmersion period of steel in BLE-admixed pore solution resulted in the increase of corrosion potentials and the reduction of corrosion currents. Furthermore, the addition of BLE improved the workability and compressive strength of mortars, and the mass loss of steel in BLE-admixed mortar was observed to be less than that in the control (BLE-free) specimens. The inhibitor's adsorption on the steel followed the Langmuir isotherm model, suggesting the formation of a protective layer at the steel–electrolyte interface, and accordingly, a 99% reduction of the corrosion current was achieved by preimmersing the steel in simulated concrete pore solution containing 700 ppm BLE for 7 days. [ABSTRACT FROM AUTHOR]

The corrosion behavior of Q345qDNH steel and Q420qENH steel under the industrial atmosphere containing PM2.5, as well as the effect of PM2.5 on the rust layer were studied by dry–wet alternating accelerated corrosion experiment. The results show that the corrosion rate of Q345qDNH is always less than that of Q420qENH, the Cr content of rust layer is higher than that of Q420qENH steel. After 30 days of corrosion, compared with Q420qENH steel, the self‐corrosion potential of Q345qDNH is larger, the self‐corrosion current density is smaller, and the rust resistance is 1.49 times of Q420qENH steel, the Iα‐FeOOH/Iγ‐FeOOH ratio is 1.29 times of Q420qENH, indicating that the protection of the rust layer of Q345qDNH is better than that of Q420qENH. This is due to the effect of microstructure factors in the early stage of corrosion and alloying elements in the late stage of corrosion. PM2.5 with SiO2 as the main component is easy to deposit at cracks and holes, which becomes the nucleation substrate for corrosion products, promotes the nonuniform nucleation of corrosion products, making the rust layer develop unevenly, leading to an increase in holes in the outer rust layer. [ABSTRACT FROM AUTHOR]

Alkynyl alcohol derivatives (N‐14) were synthesized by 2‐chloromethyl pyridine, propargyl alcohol and bromotetradecane and the structure was confirmed by 1H NMR, 13C NMR, MS and FTIR. The corrosion inhibition performance was evaluated by weight loss, Tafel polarization, EIS measurements and DFT quantum calculations. The results proved that N‐14 effectively inhibited the acid corrosion of N80 steel. The corrosion inhibition of N‐14 increased with its concentration and decreased with increasing temperature. A maximum of 99.56% inhibition efficiency was achieved using 5 × 10−5 mol/l of N‐14 at 60°C. Thermodynamic parameters showed that the adsorption of N‐14 on N80 steel is spontaneous and exothermic, conforming to Langmuir's adsorption. Electrochemical results showed that N‐14 behaved as a mixed‐type inhibitor. In addition, corrosion products produced on N80 steel surface were researched by SEM, XRD, UV and contact angle. At the same time, the corrosion inhibition mechanism was discussed. [ABSTRACT FROM AUTHOR]

The corrosion of steel materials has become a global issue, causing significant socio-economic losses and safety concerns. Hot-dip galvanizing is currently one of the most widely used steel anti-corrosion processes. With the rapid advancement of science and technology and emerging industries, the performance of pure galvanized products struggles to meet the demands of practical applications in various environments. Consequently, researchers have begun introducing various metals into the zinc solution to form high-performance alloy coatings. This article primarily explains the process flow of hot-dip galvanizing and the impact of metal elements such as Al, Mg, Sn, and Bi on the coating, as well as outlining the major issues currently faced by the hot-dip galvanizing process. The objective is to offer a more comprehensive introduction to those new to the field of hot-dip galvanizing and to provide theoretical insights for addressing production issues. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new hydrazone derivative inhibits steel rebar corrosion in chloride-contaminated SCPS. • The tested inhibitor exhibits an excellent corrosion protection for 720 h of immersion. • XPS and other characterization techniques confirm the effective adsorption of inhibitor molecules on steel rebar. • SCC-DFTB simulation reveals the formation of chemical bonds between inhibitor molecules and iron surface. Corrosion-induced deterioration of infrastructure is a growing global concern. The development and application of corrosion inhibitors are one of the most effective approaches to protect steel rebar from corrosion. Hence, this study focuses on a novel hydrazone derivative, (E)-N′-(4-(dimethylamino)benzylidene)-2-(5-methoxy-2-methyl-1H-indol-3-yl)aceto-hydrazide (HIND), and its potential application to mitigate corrosion in steel rebar exposed to chloride-contaminated concrete pore solutions (ClSCPS). The research aims to evaluate the anti-corrosion capabilities of HIND on steel rebar within a simulated corrosive environment, focusing on the mechanisms of its inhibitory effect. The corrosion of steel rebar exposed to the ClSCPS was studied through weight loss and electrochemical methods. The surface morphology of steel rebar surface was characterized by FE-SEM-EDS, AFM; oxidation states of the steel rebar and crystal structures were examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) methods. Further, experimental findings were complemented by theoretical studies using self-consistent-charge density-functional tight-binding (SCC-DFTB) simulations. The performance of HIND was monitored at an optimal concentration over a period of 30 days. The results indicated a significant reduction in steel rebar corrosion upon introducing HIND. The inhibitor molecules adhered to the steel surface, preventing further deterioration and achieving an inhibition efficiency of 88.4% at 0.5 mmol/L concentration. The surface morphology analysis confirmed the positive effect of HIND on the rebar surface, showing a decrease in the surface roughness of the steel rebar from 183.5 in uninhibited to 50 nm in inhibited solutions. Furthermore, SCC-DFTB simulations revealed the presence of coordination between iron atoms and HIND active sites. The findings demonstrate the potential of HIND as an effective anti-corrosion agent in chloride-contaminated environments. Its primary adsorption mechanism involves charge transfer from the inhibitor molecules to iron atoms. Therefore, applying HIND could be an effective strategy to address corrosion-related challenges in reinforced infrastructure. [ABSTRACT FROM AUTHOR]

It takes 3–5 years for the stable rust layer to form when the bridge weathering steel is used in the industrial atmosphere, and the loose rust layer appearing in the early stage will pollute the atmospheric environment. Therefore, a method for the rapid formation of stable rust layer is developed in this paper, and the influence of rust layer stabilizing treatment on corrosion behavior of bridge weathering steel Q345qNH in simulated industrial atmospheric medium is studied. The results showed that in simulated industrial atmospheric medium, the stabilizing treatment shortened the formation time of stable rust layer and significantly reduced the corrosion rate, which is 47.9 % lower than that of bare steel after 480 h of corrosion. During the whole corrosion process, the Iα-FeOOH/Iγ-FeOOH peak intensity ratio of the stabilizing treatment steel was always higher than that of the bare steel, and was 1.26 times that of the bare steel after 480 h corrosion. After the stabilizing treatment, the self-corrosion potential of the rust layer increases, the self-corrosion current density decreases, and the resistance of the rust layer after 480 h corrosion was 1.57 times that of the bare steel sample, and the protection of the rust layer was significantly improved. [ABSTRACT FROM AUTHOR]

Corrosion may cause uniform or localized deterioration to steel bridges, which could gradually diminish carrying capacity as the damage worsens. Carbon fiber reinforced polymer (CFRP) has immense promise due to its low weight and excellent durability, elasticity, and strength. This paper investigates the effectiveness of CFRP as a repair for corroded steel I-girder ends in terms of shear and end-bearing capacities. First, this study presents finite element validation of corrosion and CFRP modeling; based on the result, the setting and analysis process can be implemented in the case study. Then, the simulation of five cases of uniform corrosion involves a range of corrosion damage situations, encompassing corrosion heights, widths, and thickness loss. The stiffener, end web, and inner web simulate the corroded part. Finite element analysis (FEA) uses nonlinearity buckling analysis and assigns the Shell S4R element type steel. The constitutive isotropic elastic model is applied to steel, while CFRP utilizes an orthotropic lamina. The CFRP failure pattern uses the Hashin Damage Criterion model constitutive. Three layers are applied to each side of the model. Analysis shows CFRP in stiffener corroded area significantly increases remaining shear capacity by 0-11.8% for one side and 0-19% for both sides, in bearing capacity by 0-8.4% and 0-17.3%, respectively. Its efficacy in end-bearing is 0-6.3% in the end web, inner web, and combination areas. End web shear capacity increased slightly, while inner and combination web capacity decreased by 0-2% from the health model. [ABSTRACT FROM AUTHOR]

Alloy coatings protect steel from corrosion in various applications. We investigated the effects of Si addition on the microstructure, electrochemical behavior, and corrosion resistance of steel sheets coated with a hot-dip Zn–Mg–Al–Si alloy using a batch-type galvanization process. Microstructural analysis revealed that the Zn–Al–Mg alloy coating layer contained a significant amount of Fe that diffused from the substrate, leading to delamination due to the formation of brittle Fe–Zn intermetallic compounds. However, the introduction of Si resulted in the formation of a stable Fe2Al3Si inhibition layer at the substrate–coating interface; this layer prevented interdiffusion of Fe as well as enhanced the coating adhesion. Additionally, the formation of acicular Mg2Si phases on the coating surface improved the surface roughness. As the Si content increased, the corrosion resistance of the coating improved. Specifically, the Zn–Al–Mg coating layer with 0.5 wt.% Si exhibited excellent anti-corrosion performance, without red rust formation on its surface even after 2600 h, during a salt spray test. [ABSTRACT FROM AUTHOR]

EH36 offshore platform steel, La (0.0031%) steel, Ce (0.0027%) steel, and Pr (0.0001%) steel were selected as the research objects. The corrosion of four groups of steel was simulated by immersion experiments. In the presence of Cl− the effect of rare earth elements (La, Ce, Pr) on corrosion was investigated by the weight loss method. The morphology of the corrosion products and the apparent morphology after the removal of the corrosion products were observed by scanning electron microscopy (SEM); the main components of four steel corrosion products were analyzed by X-ray diffraction (XRD). The electrochemical behavior and the influence of temperature and Cl− concentration on the corrosion of the four kinds of steel were analyzed by an electrochemical polarization curve and Nyquist diagram. The results showed that the addition of trace rare earth elements, La, Ce, and Pr, to EH36 offshore platform steel can reduce the corrosion rate and the corrosion current density (Icorr), and increase the charge transfer resistance during the corrosion process. The Icorr of La steel, Ce steel, and Pr steel is 6.59 × 10−5 A·cm−2, 7.57 × 10−5 A·cm−2, and 9.53 × 10−5 A·cm−2, respectively, which is lower than that of EH36 steel (Icorr = 1.82 × 10−4 A·cm−2). The influence of Cl− concentration and temperature on the four steels showed the same trend; that is, with the increase in Cl− concentration, the corrosion rate first rises and then slows down, and with the increase in temperature, the corrosion rate gradually accelerates. Rare earth elements promote the production of more α-FeOOH in the rust layer, and the compactness of this product plays a certain role in protecting the steel matrix. The addition of trace rare earth elements, La, Ce, and Pr (less than 0.004%), improves the corrosion resistance of EH36 steel. [ABSTRACT FROM AUTHOR]

Aiming at the limitation of section reduction method and multi-scale method to simulate corrosion-induced steel offshore platform, a generalized steel constitutive model was proposed considering the variability, randomness and locality of corrosion. To simulate possible corrosion scenarios, random corrosion treatment with different corrosion degrees was carried out on offshore steel specimens using electrochemical accelerated corrosion, and the relationship between laboratory corrosion specimens and platform corrosion components and the equivalent corrosion life of the specimens were obtained based on a time-varying model of platform corrosion thickness established by regression analysis of corrosion data from the platform. Monotonic tensile tests on specimens with different corrosion degrees were conducted to obtain the time-varying corrosion damage influence law of steel mechanical properties, based on R–O model of linear exponential time-varying corrosion loss, a generalized constitutive model for steel, with the aid of this model to push static pushover analysis of service platform, platform reserve strength and ductility time-varying corrosion influence law of reserves, the simulation of corrosion damage caused by steel offshore platforms in different service periods can be realized. [ABSTRACT FROM AUTHOR]

Organically coated steels are widely used in applications in which they are subjected to the natural environment and therefore require excellent corrosion resistance. Organic clearcoats are typically employed as a barrier that improves the overall corrosion resistance; however, they are typically derived from fossil fuel-based feedstock. A more sustainable alternative could be possible using sol–gel coatings. The application of a simple tetraethoxysilane (TEOS)-based sol–gel was applied to polyurethane-coated steels using a spray coater. The concentration of TEOS was altered to produce coatings containing either 2.5% or 10%. The 10% TEOS resulted in dense, homogeneous coatings that offered a significant improvement in corrosion resistance compared to an uncoated substrate. Whereas the 2.5% TEOS coatings were inhomogeneous and porous, which indicated a limitation of concentration required to produce a uniform coating. The successful demonstration of using a simple TEOS-based coating to improve the corrosion resistance of organically coated steel highlights the potential for further investigation into the use of sol–gels for these applications. [ABSTRACT FROM AUTHOR]

This study evaluates the corrosion inhibition capabilities of two novel hydrazone derivatives, (E)-2-(5-methoxy-2-methyl-1H-indol-3-yl)-N′-(4-methylbenzylidene)acetohydrazide (MeHDZ) and (E)-N′-benzylidene-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HHDZ), on carbon steel in a 15 wt.% HCl solution. A comprehensive suite of analytical techniques, including gravimetric analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM), demonstrates their significant inhibition efficiency. At an optimal concentration of 5 × 10−3 mol/L, MeHDZ and HHDZ achieve remarkable inhibition efficiencies of 98% and 94%, respectively. EIS measurements reveal a dramatic reduction in effective double-layer capacitance (from 236.2 to 52.8 and 75.3 µF/cm2), strongly suggesting inhibitor adsorption on the steel surface. This effect is further corroborated by an increase in polarization resistance and a significant decrease in corrosion current density at optimal concentrations. Moreover, these inhibitors demonstrate sustained corrosion mitigation over extended exposure durations and maintain effectiveness even under elevated temperatures, highlighting their potential for diverse operational conditions. The adsorption process of these inhibitors aligns well with the Langmuir adsorption isotherm, implying physicochemical interactions at the carbon steel surface. Density functional tight-binding (DFTB) calculations and molecular dynamics simulations provide insights into the inhibitor-surface interaction mechanism, further elucidating the potential of these hydrazone derivatives as highly effective corrosion inhibitors in acidic environments. [ABSTRACT FROM AUTHOR]

By the advancement of the oil, electricity, and transportation industries, an increasing number of oil and gas pipelines were buried alongside high‐voltage alternating current (AC) transmission lines and electrified railways. This resulted in a growing issue of AC interference in buried pipelines. Previous studies have shown that the presence of AC interference can result in severe corrosion damage to metallic structures, even when cathodic protection (CP) is available. This paper provides a state‐of‐the‐art review on AC corrosion of cathodically protected pipeline steel. Specifically, attention is paid to research areas including influencing factors in AC corrosion for pipelines under CP, existing AC protection criteria, corrosion risk assessment based on probability of failure, numerical simulation in AC corrosion, and mitigation of AC corrosion. Each area of research is reviewed in detail and the corresponding technical gaps and future research opportunities are identified and discussed. [ABSTRACT FROM AUTHOR]

The rusting of metals brings huge losses to the industry every year, and post-treatment of rusted metals to restore their properties to the initial state is a hot topic of current research. In particular, 20 steel, which is widely used in various structural components such as ships, is prone to oxidation in atmospheric environment. Therefore, in this study, a nanosecond pulsed laser was used to remove the rust layer on the surface of 20 steel. The effects of different energy densities and spot overlap rates on the roughness, surface morphology, chemical composition, microhardness and corrosion resistance of the rust layer were analyzed. The results showed that the best cleaning effect was achieved at an energy density of 4.26 J/cm2 and a spot overlap rate of 75%. Under these conditions, the rust layer was completely removed without damage to the substrate, and it even improved the corrosion resistance of 20 steel. At energy densities of 1.42 J/cm2 and 2.84 J/cm2, the rust layer was not completely removed, while at 5.68 J/cm2, the rust layer was removed but the substrate was damaged. In addition, the mechanism of rust removal and substrate damage is discussed. [ABSTRACT FROM AUTHOR]

The ability to accurately identify fire patterns is the fundamental requirement for fire investigations. The corrosion layers of steel in fire scenes exhibit three distinct characteristics. First, due to steel's nonflammable nature, steel patterns can be preserved better at the fire site than patterns formed on other combustible materials; second, both the high temperature and the smoke during the fire affect the high‐temperature oxidation process; and third, the corrosion layer of steels inevitably undergoes further evolution after the fire because of the subsequent room‐temperature corrosion. This study focuses on investigating Q235 steel because of its extensive use in construction and vehicles. The pattern evolution processes of high‐temperature oxidation at elevated temperatures in air, polyethylene (PE), and polyvinyl‐chloride (PVC) combustion smoke and the corresponding subsequent corrosion at room temperature were systematically investigated from the perspective of macroscopic and microscopic morphology. The results showed that the smoke atmosphere played an important role in the formation of the corrosion layer of Q235 steel. Compared with samples oxidized in air, samples oxidized in PE combustion smoke exhibited a uniform and dense oxide layer on the surface, which inhibited the corrosion at room temperature further. The PVC combustion smoke accelerated the high‐temperature oxidation of the sample, and its influence on the subsequent room‐temperature oxidation process was closely correlated with the temperature of the high‐temperature oxidation. The results of this study provide important references for understanding the formation of the corrosion layer of Q235 steel for fire investigations. [ABSTRACT FROM AUTHOR]

Marked changes in temperature, pH, dissolved oxygen (DO) content, and nutrient content typically occur in marine thermoclines, which are key factors that affect the corrosion of metals. Offshore platforms require marine metals to be exposed to deep-sea environments and thus increase their penetration into the marine thermocline. This study investigates the galvanic corrosion of E690 steel in a marine thermocline using a simulated marine thermocline (SMT). Specifically, the corrosion of E690 steel was analyzed using the wire beam electrode (WBE) technique, linear polarization (LP), corrosion morphology, and weight loss measurement. Results indicated that the SMT had a stable multilayer structure, and the variations in temperature, DO, pH, and nutrient concentration in the SMT were similar to those in the natural marine thermocline. There were two forms of E690 steel corrosion in the SMT: galvanic corrosion and seawater corrosion. The corrosion rate of seawater corrosion was influenced by the DO concentration. Galvanic corrosion occurred after the intrusion of E690 steel into the marine thermocline. The driver of galvanic corrosion was the difference values for Ecorrs of E690 steel at various depths of the marine thermocline. The Ecorr of E690 steel was influenced by the temperature, pH, and DO of the seawater, in the following order: DO >> T > pH. The continuous reduction in Ecorr with depth contributed to large-scale galvanic corrosion, and the oscillation variation in Ecorr with depth was the reason for small-scale galvanic corrosion. The primary anodic regions of galvanic corrosion were located in the area with the fastest temperature variation in the thermocline, and the position of the anodic regions rose with time. The anodic regions gradually expanded with time. The proportion of galvanic corrosion in the average corrosion rate could increase up to approximately 80% in the stable anodic region. There were many hemispherical corrosion pits on the surface of the single electrodes that were at the depths of 75 cm, 105 cm, and 135 cm. These single electrodes comprised a long-term, sustainable anodic region of galvanic corrosion. [ABSTRACT FROM AUTHOR]

Corrosion on the interface between a metal alloy, such as steel, and a wet, permeable non-metallic medium is of considerable practical interest. Examples include the interface between steel and water, the atmosphere or concrete, as for steel reinforcement bars; between metal and soil, as for buried cast iron or steel pipes; deposits of some type, as in under-deposit corrosion; and the interface with insulation, protective coatings, or macro- or micro-biological agents. In all cases, corrosion initiation depends on the characteristics of the interfacial zone, both of the metal and the medium, and the spatial variability. For (near-)homogeneous semi-infinite media with good interfacial contact, the pitting, crevices and general corrosion of the metal will be largely controlled by the metal (micro-)characteristics, including its inclusions, imperfections and surface roughness. In other cases, these may be overshadowed by the macro-characteristics of the medium and the degree of interfacial contact, possibly with severe resulting corrosion. Where the build-up of corrosion products can occur at the interface, they will dominate longer-term corrosion and govern the long-term corrosion rate. For media of finite thickness, diffusion issues and material deterioration may also be involved. The practical implications are outlined. It is argued that with the presence of a suitable medium, it is possible to achieve negligible long-term corrosion but only if certain practical actions are taken. [ABSTRACT FROM AUTHOR]

This work reviews surface modification techniques for improving the wear and corrosion resistance of 42CrMo steel. The advantages and disadvantages of various methods, including thermal spraying, deposition, hardfacing, laser cladding, nitriding, and laser surface treatment, are discussed. The review elaborates on the materials commonly employed in laser cladding technology, including iron-based, cobalt-based, nickel-based, and high-entropy alloys and reinforced composite coatings. Furthermore, the mechanisms and methods of improving the wear and corrosion resistance of 42CrMo steel are summarized. Finally, this review presents research shortcomings and future opportunities of surface modification techniques. This review also provides a theoretical guide for the application of 42CrMo steel. [ABSTRACT FROM AUTHOR]

The corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid was investigated to reveal the corrosion pattern and protective properties of corrosion products in the two environments. Potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), Mott–Schottky tests, and electrochemical noise (EN) tests were used to study the corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid saturated with CO2. Scanning electron microscopy (SEM) combined with Energy-Dispersive Spectrometer (EDS) mapping was used to characterize the corrosion morphology and elemental distribution of P110 casing steel. The results show that the corrosion resistance of P110 casing steel deteriorates with the increasing immersion days in the simulated annulus fluid, the impedance decreases gradually, and the corrosion-product film shows a loose and porous structure. In the simulated concrete liquid, under the condition of containing a low concentration of Cl−, the protection of the corrosion products gradually increases with the extension of immersion days. With the increasing concentration of Cl− and the extension of immersion days, the electrochemical noise resistance and charge transfer resistance of P110 steel decrease gradually, and the protective property of the corrosion-product film decreases, which is capable of forming steady pitting corrosion. [ABSTRACT FROM AUTHOR]

This work investigated the mechanical decay mechanism and high‐temperature corrosion mechanism of high‐strength steel via high‐temperature mechanical experiments, and corrosion and stress corrosion cracking tests were performed in simulated working conditions where water, oil, H2S, and CO2 coexist. The results show that the tensile strength and yield strength of high‐strength steel decrease with increasing temperature; the tensile strength and yield strength at 350°C reduce 11.91% and 19.08%, respectively, compared with 25°C. Moreover, the corrosion rate of high‐strength steel gradually increased from 0.0914 mm/a at 150°C to 1.2288 mm/a at 350°C. In addition, the influence of high temperature on the corrosion mechanism was inferred through thermodynamic calculations, and the reason for the presence of Fe3O4 in the corrosion products at 350°C was analyzed. At 350°C, stress corrosion cracking was observed in high‐strength steels when the applied stress reached 90% of the yield strength. Based on the aforementioned studies, the relevant mechanisms related to the decay of mechanical properties, corrosion, and stress corrosion cracking are also proposed. [ABSTRACT FROM AUTHOR]

In this manuscript, the effect of Mo addition on the corrosion resistance of the low-alloy steel in a simulated tropical marine atmospheric environment has been studied through microstructure characterization, corrosion immersion experiments, electrochemical measurement, and a series of microscopic characterization methods. The results show that Mo has the ability to reduce the corrosion rate of low-alloy steel in a marine atmospheric environment, with a more pronounced reduction effect observed over longer corrosion periods. The addition of Mo enhances the corrosion product film's compactness when coupled with Cr, subsequently improving corrosion resistance. Simultaneously, MoO42−, acting as a slow-release ion, can effectively suppress localized corrosion in low-alloy steel. The research findings can offer data support and a theoretical foundation for the design of low-alloy steels with enhanced corrosion resistance in a tropical marine atmospheric environment. [ABSTRACT FROM AUTHOR]

Chitosan microspheres (CSM) loaded with synthesized Gemini imidazolium‐based ionic liquids ([C2(Bim)2]Cl2@CSM and [C6(Bim)2]Br2@CSM) are constructed as smart corrosion inhibitors to protect N80 steel in hydrochloric acid solution. The optimal inhibition efficiency of [C2(Bim)2]Cl2 and [C6(Bim)2]Br2 at 300 mg L−1 reaches 94.68% and 95.96%, respectively, indicating mixed‐type inhibition behavior. On this basis, the prepared [C2(Bim)2]Cl2@CSM and [C6(Bim)2]Br2@CSM can proactively identify corrosive environments and protect the metal. The microspheres are pH‐responsive owing to the presence of Schiff‐base C═N bonds and the loaded inhibitors can be released rapidly in acidic environment. Released inhibitors are delivered to corroded sites and synergistically interact with decomposed microspheres for enhanced corrosion inhibition effect. [ABSTRACT FROM AUTHOR]

The service performance of FH36 marine steel subjected to ultrasonic surface rolling processing (USRP) in terms of surface integrity, corrosion resistance, and low-temperature impact property was investigated. The results demonstrated that the surface integrity of FH36 steel after USRP was reconstructed with the surface roughness declined to 0.117 μm by 88.7%, the average grain diameter refined to 2.77 µm by 31.8%, the surface hardness improved to 256 HV0.1 by 39.9%, and the compressive residual stress introduced up to − 172 MPa. Due to the reduced surface roughness, introduced work hardening, and compressive residual stress, the FH36 steel after USRP obtained the excellent corrosion resistance with the corrosion current density declined up to 35.3% and the polarization resistance raised up to 34.8%. While the FH36 steel treated by USRP showed a decrease in the low-temperature impact property, as a result of the reduced high angle grain boundaries, improved surface hardness and reduced surface roughness. Meanwhile, the grain refinement and compressive residual stress induced by USRP were favorable to the low-temperature impact property of FH36 steel. [ABSTRACT FROM AUTHOR]

Steel is considered the most widely used metal because of its excellent strength and comparatively low‐production cost. Preventing steel corrosion will be a top priority in industry. This work investigates the influence of an epoxy resin liner to steel filled with different percentages (1, 2, and 3 wt%) of either micro or nanoparticles of alumina (Al2O3) on both bending properties and corrosion resistance. To test for barrier resistance, the coated steel samples were submerged in a citric acid and saline solution. In comparison with pure epoxy coatings, the addition of nano and micro alumina (Al2O3) particles enhanced the corrosion resistance, bending strength, and bending strain under dry and wet conditions. Furthermore, under both dry and wet circumstances, the bending strain rose dramatically with the addition of micro and nano fillers. The 1 wt% of Al2O3 nanoparticles coated steel exhibited the maximum bending strength of 492.81 and 436.9 MPa under wet and dry conditions, respectively. Moreover, the micro filled steel of 1 wt% Al2O3 micro fillers exhibited a 483.7 and 319.08 MPa bending strength under wet and dry circumstances, respectively. Stepwise graded micro/nanocomposite coatings showed good bending and corrosion properties in both dry and wet conditions. Highlights: Coating is an economical means to protect steel structures from deterioration.The coating on the steel on each side is epoxy filled with 1, 2, and 3 wt% micro or nano particles of alumina (Al2O3).Bending and corrosion resistance properties of micro/nanocomposite coated specimens were investigated and compared with pure epoxy coating.The lined steel specimens were tested for corrosion resistance by immersing them in saline solution and citric acid medium.Under dry and wet conditions, the addition of alumina (Al2O3) particles to epoxy coatings enhanced the corrosion resistance, bending strength, and bending strain compared with pure coating. [ABSTRACT FROM AUTHOR]

Various spraying techniques have been used to apply engineered coatings on different industrial parts and components. Enhancing the properties of coated components for particular uses requires a surface treatment of thermally assisted as-sprayed coatings. In this study, we provide a study of various coating techniques and a thorough overview of the complexes in different AISI steels' corrosion, erosion, and wear behaviour. In-depth analysis and discussion are provided on the impact of processing techniques, microstructure, and alloying components on the behaviour of surface deterioration. We emphasize the underlying processes and synergy between the various degradation paths and point out significant information gaps in individual publications. [ABSTRACT FROM AUTHOR]

In the petroleum industry, the casing steel is fixed with a cement sheath to ensure reliable service in demanding conditions characterized by high temperature, high pressure, and exposure to multiple types of media. After the hydration of the cement, a porous material is produced with a highly alkaline solution filling the pores, commonly referred to as the pore solution. The casing will form a protective passive film when in contact with a highly alkaline pore solution. Nevertheless, once the cement sheath cracks, chloride ions in the stratum will pass through the cement sheath to the surface of the casing. When chloride ions accumulate to a certain concentration, the passive film will be destroyed, without exerting a protective influence on the substrate. After chloride ions come into direct contact with the casing, the casing is prone to severe failure due to corrosion perforation. The casing failure can cause a blowout outside the casing and even scrapping of the oil well. Controlling casing corrosion and ensuring casing integrity relies on understanding the critical chloride ion concentration that can cause the degradation of the passive film. Therefore, to assess the electrochemical properties and analyze the damage process of the passive film under varying chloride ion concentrations, several characterization techniques were employed. These included potential–time curves (E-t), polarization curves, electrochemical impedance spectroscopy (EIS), and Mott–Schottky curves. In addition, the composition of the passive film on the surface of the P110 casing steel was qualitatively analyzed using X-ray photoelectron spectroscopy (XPS). To further understand the surface morphology of the P110 casing steel, scanning electron microscopy (SEM) was used. [ABSTRACT FROM AUTHOR]