The requirements of corrosion protection for marine engineering materials are relatively high in the polar marine environments due to its low temperature, strong ultraviolet radiation, freeze-thaw cycles, and complex electrochemical environment. This review paper introduces the current research progress on corrosion and protection of Fe, Al, Cu, Zn, and their alloys in the cold-temperate marine atmosphere and seawater environments. It focuses on analyzing the corrosion mechanism of metallic materials in conditions of low temperature, atmospheric pollutants, ultraviolet radiation, and the effect of cold-temperate marine microorganisms. Moreover, it introduces the research progress in corrosion protection of metallic materials in Antarctic and Arctic regions from three aspects: coating protection technology, sacrificial anode alloy design, and metal surface modification technology. Finally, future research on the corrosion and protection of metals in polar marine environments is proposed based on the problems and development trends encountered in the research on the corrosion and protection of metallic materials in the polar marine environments.

The internal environment of crude oil storage tanks remains complex and harsh over extended periods, leading to frequent failure of conventional protective coatings. As an innovative intelligent protective material, self-healing coatings demonstrate significant application potential for corrosion protection in crude oil storage tanks. This study examines key tank components—including the inner roof, bottom plate, tank wall, and heating coils, and systematically analyzes the performance requirements for coatings in each area, encompassing thermal stability, corrosion resistance, mechanical properties, as well as responsive performance. The paper provides an in-depth evaluation of the advantages, limitations, and applicability of self-healing coatings (both intrinsic and extrinsic) for crude oil storage tank applications. Findings indicate that pH- and ion dual-responsive microcontainers offer superior advantages due to their high self-healing efficiency, excellent corrosion resistance, good thermal stability, strong responsiveness, and cost-effectiveness. However, challenges regarding microcapsule dispersion and matrix compatibility require further optimization.

The key material failure induced by leakage current in the water-cooling system of converter valves troubles the stable and secure operation of voltage source converter-high voltage direct current (VSC-HVDC) systems. From an interdisciplinary perspective integrating electrical engineering and materials science, this study systematically investigates typical failure phenomena encountered in actual operations, including corrosion of metal components, scaling on grading electrodes, and aging of sealing materials. It reveals the corrosion behavior of Al-radiators and stainless-steel pipelines under low-conductivity and high electric field conditions, and clarifies the migration-deposition mechanism of corrosion products leading to scaling. These findings may provide valuable reference for material design and corrosion protection in advanced power equipment.

The steam generator (SG), serving as the critical junction between the primary and secondary circuits in pressurized water reactor (PWR) nuclear power plants, is subjected to long-term exposure to high-temperature, high-pressure, and multiphase flow corrosive environments. Surface corrosion issues in SGs pose a direct threat to the safety and economic viability of nuclear power stations. This paper reviews the latest research progress on the corrosion mechanisms and protection technologies for SG surfaces. It discusses the environmental factors affecting SGs during storage, transportation, and operation, analyzes the causes of surface corrosion, and points out the specialized protection requirements for SG surfaces. The paper also provides a comprehensive overview of the current development status of coating protection technologies, aiming to serve as a reference for addressing corrosion and protection challenges on steam generator surfaces.

Lead-bismuth eutectic (LBE) has emerged as the preferred coolant material for lead-cooled fast reactors owing to its good physical properties and chemical stability. However, many metallic structural materials are prone to degradation in liquid LBE at high temperatures. Among others, alumina-forming austenitic stainless steel (AFA) exhibits excellent corrosion resistance and mechanical properties. Thus, it has been recognized as a promising candidate structural material for lead-cooled fast reactors. This paper presents an overview of AFA stainless steel. The effect of chemical composition, oxygen concentration and pre-oxidation treatment on the corrosion behavior and the mechanical behavior of AFA steel in liquid LBE are summarized. The mechanism underlying liquid metal corrosion and liquid metal induced embrittlement of AFA stainless steel are also discussed. The existing challenges in current research and the future research issues are outlined.

The cathodic polarization behavior of X60 steel bar without and with concrete counterweight layer in static and flowing artificial seawater of different salinities (5‰, 16.8‰, 26.7‰) and real mud, the later was tokened from the Hangzhou bay coastal wetlands, was assessed via steady-state constant potential polarization, electrochemical impedance spectroscopy (EIS), and numerical simulation methods, aiming to understand the effect of concrete counterweight layer on the cathodic protection of submarine pipes in nearshore marine environments. Meanwhile, the resistivity of the concrete weighted layer was also measured, and the cathodic protection potential distribution and sacrificial anode output current of the pipe in the presence of the concrete weighted layer were obtained. The results showed that when the polarization potential was reached -0.85 V (CSE) in static seawater of salinities of 5‰, 16.8‰, and 26.7‰, as well as sea mud, the cathodic polarization current density required for the bare X60 steel was about 3.5-8 times that required for X60 steel with a concrete counterweight layer. In 2 m/s flowing seawater, the difference in cathodic polarization current density required for X60 steel with concrete counterweight layer by the corresponding potential is relatively small compared to that in static seawater. The flow velocity will significantly increase the cathodic polarization current density required for bare X60 steel, which is related to the increased oxygen diffusion and the destruction of calcium deposition layer due to the increased flow velocity. While the concrete counterweight layer hinders this effect of flow velocity. The change in polarization resistance measured by electrochemical impedance spectroscopy is consistent with the change in polarization current density. At the same time, the resistivity of the concrete counterweight layer in seawater is about 70 times that of the corresponding seawater resistivity, and the resistivity of the concrete counterweight layer in marine mud is about 37 times that of the corresponding marine mud resistivity. The numerical simulation results show that the concrete counterweight layer reduces the cathodic polarization current density, resulting in a significant negative shift and small potential attenuation of the cathodic protection potential. The concrete counterweight layer reduces the output current of the sacrificial anode, resulting in a slightly positive shift of the cathodic protection potential. In a word, the concrete weighted layer has a significant effect on the improvement of the cathodic protection effectiveness of submarine pipes.

The so called Hitec molten salt (40%NaNO₂-7%NaNO₃-53%KNO₃, by mass fraction), as an efficient heat transfer and thermal storage medium, plays a crucial role in the flexibility retrofitting of thermal power plants. The dynamic compatibility between this medium and the storage tank structural material, Q345R carbon steel, constitutes a key scientific issue determining the long-term reliability of the system. Addressing the current lack of corrosion data and mechanistic understanding under dynamic conditions, herein, the influence of flow velocity (0-2 m/s) of the salt on the corrosion kinetics and underlying mechanisms of Q345R carbon steel in Hitec molten salt at 400 ℃ for 1000 h was assessed. Quantitative results demonstrate that the average annual corrosion rate of the steel increases significantly with the increasing flow velocity, namely from 18.20 μm/a for static state increases to 20.64 μm/a and 21.82 μm/a for 1 and 2 m/s, corresponding to increment of 13.5% and 19.93%, respectively. Then a quantitative correlation between the corrosion rate and the flow velocity of salt was established for this material system. Microstructural characterization revealed that although the phase composition of the corrosion products was consistent across different flow velocities (namely Fe₂O₃, Fe₃O₄, FeCr₂O₄), however, their formation and evolution mechanisms differ fundamentally. Dynamic flow not only mechanically compromises the integrity of the surface oxide scale, leading to protective function loss and accelerated spallation, but also significantly enhances the inward migration of corrosive species (e.g., oxygen) and the selective dissolution of the key alloying element Cr, synergistically exacerbating the corrosion process. From the perspectives of kinetics and micro-mechanisms, a comprehensive failure model for Q345R carbon steel was also proposed as follows: the initial protective oxide formation, intermediate flow-dominated oxide scale degradation competing with internal oxidation, and late-stage inward migration and depletion-dominated internal corrosion development. In sum, the findings may provide good reference for the design and safety assessment of highly reliable molten salt storage tanks.

Zn-based eutectic alloy coatings with high corrosion resistance and sacrificial anode protection performance are widely used for corrosion protection of steel. During the usage process, galvanized steel plates are often subjected to cutting or shaping operations, which can cause the galvanized coating and/or the steel substrate at the cutting edge to be exposed to environmental corrosion. Then, how the steel substrate at the cutting edge is corroded, and how the adjacent galvanized layer or its corrosion products will affect the corrosion behavior of the steel substrate, are all topics worthy of study. Herein, the corrosion behavior of cut edge of galvanized coatings of pure Zn, Zn-3Mg, Zn-5Al, and Zn-4Al-3Mg/Q235 carbon steel was studied. First the galvanized steels were cut into cylindrical samples, and sealed using epoxy resin, leaving only one cut-edge surface free and polished. The samples were immersed in a 5% (mass fraction) NaCl solution for corrosion testing; meanwhile another part of samples were subjected to salt spray testing. The microstructure of samples, morphology and phase constituents of corrosion products were characterized by means of field emission scanning electron microscope with energy dispersive spectrometer, 3D microscope, X-ray diffractometer. Besides, the micro-area corrosion behavior of the cut edges of different galvanized coatings was characterized by scanning electrochemical microscopy (SECM). Results show that the corrosion products are distributed both on the coating at the cut edge area and on the steel substrate near the coating. The corrosion products on the Zn and Zn-3Mg coatings were mainly simonkolleite, and on the steel substrate were mainly Zn₅(OH)₈Cl₂ and hydrozincite (Zn₅(OH)₆(CO₃)₂). For Zn-5Al and Zn-4Al-3Mg coatings, the main corrosion products were layered double hydroxide (Zn₆Al₂(OH)₁₆CO₃·4H₂O), Zn₅(OH)₈Cl₂, and Zn₅(OH)₆(CO₃)₂·H₂O. Scanning electrochemical microscope measurements revealed that initially, the feedback currents of Zn-Al and Zn-Al-Mg coatings were higher than those of Zn. Over time, the feedback currents of Zn-Al and Zn-Al-Mg coatings decreased to levels below those of Zn. The feedback current on the surface of the coating and the surface of the steel substrate far away from the side of the coating are larger, while the feedback current on the surface of the steel substrate close to the side of the coating is smaller. Overall, both the feedback current and the current depression decreased with the corrosion time. Salt spray corrosion tests showed that the average weight loss rate of cut edges is 1.04 × 10^-2, 9.88 × 10^-3, 5.73 × 10^-3, and 5.21 × 10^-3 g·m^-1·h^-1 for that with coatings of pure Zn, Zn-Mg, Zn-Al, and Zn-Al-Mg respectively. Among others, the corrosion resistance of the cut-edge with Zn-4Al-3Mg coating is the best. The corrosion product layer of Zn-4Al-3Mg coating is compact with higher content of protective products, Zn₅(OH)₈Cl₂ and Zn₆Al₂(OH)₁₆CO₃·4H₂O, provides a synergistic protective effect. The good protective performance of the corrosion products layer makes the Zn-Al-Mg coating show superior long-term corrosion resistance.

Q355 steel, a high-strength low-alloy steel is extensively used in offshore structures and naval vessels. Its service environment is extremely aggressive, characterized by elevated temperature, high humidity, elevated salinity, and intense ultraviolet radiation, which renders Q355 steel highly susceptible to corrosion. Particularly, when coupled with the impingement of seawater and chloride-laden sand, the imposed erosion loads dramatically accelerate the degradation of critical Q355 steel components, potentially leading to catastrophic failure. Clarifying the corrosion mechanism of Q355 steel in realistic service conditions is therefore crucial for guiding corrosion-mitigation strategies and refining metallurgical processes. Nevertheless, the acceleration laws governing erosion-induced corrosion in multi-factor environments remain poorly elucidated. In this study, rust-layer morphology and composition are examined, while potentiodynamic polarization and electrochemical impedance spectroscopy are employed to quantify the corrosion kinetics of the Q355 steel. Acceleration factors are further calculated to assess the erosion contribution. Results demonstrate that erosion markedly accelerates the corrosion of Q355 steel primarily by mechanically damaging the substrate surface, generating defects that deteriorate the rust layer and diminish its self-healing capability. Under the synergistic influence of erosion and multi-factors of the environment, these two factors may alter the rust-layer structure and composition, contributing 49% and 51%, respectively, to the overall corrosion rate. Erosion dynamically modulates the anodic and cathodic reactions, with 28% of the corrosion current density directly governed by the erosion action. Integrating morphological, compositional, and electrochemical data yields an acceleration factor of 1.28 for erosion-induced corrosion of the Q355 steel.

In this study, ingots of NiCrMoNb and NiCoFeCrMoNb alloys were melted and cast using vacuum arc melting method. Then the corrosion behavior and mechanism of these two alloys in molten chloride salts (24.5NaCl-20.55KCl-54.95MgCl₂ (in mass fraction)) in an argon atmosphere at 700 ℃ were comparatively investigated. Results show that the two alloys suffered from significant mass loss in the molten salts. Due to the high oxygen partial pressure in the environment in the initial corrosion stage, scales of discontinuous oxides (including MgNiO₂, MgCr₂O₄, MgNb₂O₆, and Mg₄Nb₂O₉) are formed on the surface of both alloys. In the middle corrosion stage, a continuous and thick MgO scale is developed, which can partially mitigate the corrosion process. In the late corrosion stage, chloride-induced reactions lead to pronounced active dissolution of the alloys, resulting in substantial mass loss. Additionally, the introduction of Co and Fe into the NiCrMoNb alloy results in the coexistence of phases rich in Nb/Mo- and/or in Fe/Co/Ni/Cr within the alloy, which further induce galvanic corrosion. During the entire corrosion process of 200 h, the corrosion behavior of the NiCrMoNb alloy gradually transforms from being controlled by the diffusion rate of charged particles within the oxide scale to being dominated by the diffusion rate of charged particles in the molten salts. In contrast, the corrosion behavior of the NiCoFeCrMoNb alloy remains relatively stable, with its corrosion rate consistently governed solely by the diffusion kinetics of charged particles within the oxide scale throughout the entire corrosion period.

Herein, Moringa leaf extract (MLE) was prepared via an ultrasound-assisted extraction method, and of which the potential chemical functional groups were characterized by means of Fourier transform infrared spectroscopy (FTIR). Next, the corrosion inhibition performance of MLE for cold-rolled steel in 0.5 mol/L H₂SO₄ solution was systematically investigated via weight loss measurements, electrochemical measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) etc. The results demonstrate that with a dosage of 100 mg/L MLE, a corrosion inhibition efficiency of 90.06% may be reached for cold-rolled steel in 0.5 mol/L H₂SO₄ solution at 30 ℃. The adsorption of MLE on the surface of cold rolled steel follows Langmuir and Freundlich isothermal models. The calculated standard adsorption Gibbs free energy (∆G⁰) ranges from -26.12 to -31.86 kJ·mol^-1, indicating that the adsorption is mainly a mixed mode of physical and chemical adsorption, and confirmed that MLE has the best adsorption performance at 30 ℃. Electrochemical analysis also confirmed that MLE acts as a mixed-type inhibitor. Its primary mechanism involves increasing the charge transfer resistance at the steel/acid interface, thereby effectively inhibiting the electrochemical corrosion process. The presence of MLE will reduce the surface roughness and hydrophilicity of steel; Furthermore, XPS analysis further revealed that the key mechanism of MLE's corrosion inhibition was the formation of an adsorption film on steel surface, quantum chemical calculations show that the oxygen-containing groups in MLE serve as active adsorption sites. It provided a new idea for the high value utilization of moringa leaves in industrial anticorrosion.

With the continuous improvement of the tin plating process for cold rolled steel plates, the amount of tin deposition on the tinplate surface has decreased in contrast to the traditional ones. This will directly affect the quality of the surface passivation film formed after the subsequent passivation treatment. Hence, it has been observed currently that corrosion troubles gradually occur during storage and transportation of tin-coated plates. Clearly, changes in the structure and corrosion characteristics of the surface passivation film will determine the corrosion behavior of the tinplate. Herein, the surface structure- and the corrosion performance-evolution of the surface passivation film on the tinplate in neutral NaCl solution and acidic NaCl + Na₂SO₃ solution was assessed by means of electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The results indicate that the as-received surface passivation film presents characteristics of "double-layered structure" with an outer layer rich in Cr and Sn oxides, while the inner layer is rich in Sn oxides. In addition, the EIS response of the tinplate in NaCl solution exhibits two time-constants characteristics, corresponding to the bi-layered structure of the passivation film. But the observed two time-constants locating at the low-frequency domain and high-frequency domain in NaCl + Na₂SO₃ solution are derived from the residual film layer/newly formed corrosion product layer and from the double layer at electrolyte/tinplate interface, respectively. Furthermore, the corrosion resistance of tinplate in NaCl solution is relatively high, and the surface passivation film thickness remains basically unchanged. However, in NaCl + Na₂SO₃ solution, the surface passivation film rapidly dissolves and thus the corrosion resistance decreases sharply. Therefore, the passivation film dissolution in acidic environment is the main reason for its reduced corrosion resistance. It follows that the EIS technique can effectively characterize and elucidate the structure of the passivation film on the tinplate surface and the evolution mechanism of its corrosion.

The effect of the addition of polydopamine modified multi-scale boron nitrides (PDA-BN) on the thermal conductivity and corrosion resistance of epoxy resin composite coatings was assessed, special attention was paid to the influence of the addition of polydopamine modified multi-scale BN with different ratios on the performance of epoxy composite coating, then the optimal ratio for different dopamine modified multi-scale BNs was acquired. The results showed that the addition of the multi-scale PDA-BN can improve the thermal conductivity of epoxy coatings. The optimal ratio of PDA-BN (5-10 μm) to PDA-BN (1-2 μm) is 5:1, and when the total addition amount of PDA-BNs is 10%, the thermal conductivity can reach 0.3748 W·m^-1·K^-1. In addition, the thermal conductivity of the coatings increases with the increase of the amount of multi-scale PDA-BN addition. When the amount is low (5%-20%), the multi-scale PDA-BN are uniformly dispersed, which can improve the protective performance of the epoxy composite coatings. When the addition reaches 30%, aggregations defects appear inside the coatings, and the protective performance of PDA-BN epoxy composite coatings sharply decreases. 15% multi-scale PDA-BN addition in the composite coatings has a higher thermal conductivity (0.4207 W·m^-1·K^-1) and the optimal protective performance (|Z|_{0.01 Hz} of the coatings maintained 1.47 × 10⁹ Ω·cm²) even after immersion in 3.5%NaCl solution for 14 d.

The influence of the particle shape of Al-pigments on the high-temperature degradation behavior of the organic silicone coatings on Ti-6Al-4V alloy was investigated in the precent article. First a coating (0F), as the calibrator was prepared by using TiO₂-particles as the pigment and with a ratio of TiO₂ to organic silicone resin of 3:2 (mass fraction). Then other two silicone composite coatings (2S) and (2F) were prepared by replacing 1/3 of the TiO₂-particles in the (0F) coating by 1% (mass fraction) of spherical Al-powder and 1 mass fraction of flake Al-powder, respectively. Then the variation of the microstructure, fracture morphology, and mechanical properties of the three coatings on Ti-6Al-4V alloy were comparatively examined during the heat exposure testing at 500 ℃, in terms of the effect of the partially replacing TiO₂ particles with spherical Al-particles (2S) and flake Al-particles (2F) on the thermal resistance, mechanical properties, and failure behavior of the organic silicone composite coatings. The results showed that the incorporation of flake-Al particles (2F) could significantly enhance the toughness of coating by inducing multiple crack deflections (namely, 60.89 kJ/m³, 65% higher than 0F coating). At elevated temperatures, their bridging effect could effectively dissipate the thermal mismatch strain energy, suppress the formation of through-cracks, allowing the coating to maintain structural integrity even after 100 h of heat exposure. In contrast, 0F and 2S coatings exhibited severe spalling due to the accumulation of thermal stress and resin degradation. These findings reveal that, the incorporation of flake Al-powder could significantly enhance the toughness of organic silicone coatings at high temperatures through a synergistic toughening mechanism (crack path extension and bridging effects), therewith providing a novel strategy for designing high-performance and heat-resistant coatings through regulating the particle shape of pigments.

The effect of pre-charging hydrogen time (1, 6, 12 and 24 h) on the hydrogen embrittlement susceptibility of two seamless pipe steels X42QS and X65QS with different microstructures in a 10 MPa high-pressure hydrogen environment was studied by means of slow strain rate tensile (SSRT) testing and field emission scanning electron microscope (FE-SEM). The results indicated that the pre-charging hydrogen time significantly affected the hydrogen embrittlement susceptibility and the corresponding fracture mechanism, while the influence extent and mechanism varied depending on the difference in microstructure. The pearlite/ferrite microstructure of X42QS steel is non uniform while contains a large number of inclusions. Its hydrogen embrittlement susceptibility increased rapidly with the increasing pre-charging hydrogen time, reaching 13.70% at 12 h, and then gradually slows down. The hydrogen embrittlement mechanism was dominated by hydrogen-enhanced local plasticity (HELP) for the short-term, transitioning to hydrogen-enhanced decohesion (HEDE) synergistic effect for the long-term; The hydrogen embrittlement susceptibility of X65QS steel with bainite/acicular ferrite microstructure increased gradually as the pre-charging hydrogen time increases, it only rose to 7.0% at 24 h. The mechanism of HELP dominated throughout the entire process, and the fracture always presented a ductile fracture morphology. Considering all the factors, the pre-charging hydrogen time may preferably be 12 h for detecting the influence of hydrogen on the mechanical property of steels.

The atmospheres above polluted ocean may contain corrosive substances such as NaCl, Na₂SO₄, and water vapor etc., which can synergistically corrode the components of aeroengine compressor in service. Hence, the corrosion behavior of Ti60 alloy a candidate material for compressor blade, induced by salt spray composed of Na₂SO₄ and Na₂SO₄-NaCl mixture respectivelyat 600 ℃ was studied via mass change measurement, scanning electron microscopy (SEM), X-ray diffractometer (XRD), and electron probe microanalyzer (EPMA). The results indicated that the corrosion process in the two salts spray environments was controlled by the diffusion process. The corrosion process was promoted by the presence of the mixture NaCl and Na₂SO₄. In the Na₂SO₄ salt spray environment, the corrosion products layer was mainly composed of TiO₂, Ti(SO₄)₂ and Na₂TiO₃. In the 75% (mass fraction) Na₂SO₄ + 25% (mass fraction) NaCl salt spray environment, intergranular corrosion was clearly observed, and the corrosion products layer was composed of Na₂TiO₃ and TiO₂. According to these results, a mechanism of synergistic action of oxidation, chlorination, and sulfidation was proposed for the corrosion of Ti60 alloy in 75%Na₂SO₄ + 25%NaCl salt spray environment.

The inhibition mechanism of rosemary extract (RWE) on cold-rolled steel in 0.10 mol·L^-1 dichloroacetic acid (DCA) solution was studied via gravimetry, potentiodynamic polarization, and surface analysis etc. The results showed that with a dosage of 50 mg·L^-1 RWE an inhibition efficiency of 94.86% at 20 ℃ may be reached. The inhibition performance exhibited a significant positive dependence on the concentration and a negative dependence on temperature. The adsorption of RWE on the steel surface followed a mixed mechanism dominated by physical adsorption. At lower temperatures (20-40 ℃), the process adhered to the Langmuir isotherm model, while at higher temperature (50 ℃), it better conformed to the Temkin isotherm model. The corrosion rate in the inhibited system satisfied both the Arrhenius equation and transition state theory. The apparent activation energy (E_a), pre-exponential factor (A), activation enthalpy (ΔH), and activation entropy (ΔS) all showed increasing trends. Based on potentiodynamic polarization curves, RWE was identified as a mixed-type inhibitor, effectively retarding both anodic metal dissolution and the cathodic hydrogen evolution reaction. XPS analysis confirmed the formation of an organic adsorption layer on the metal surface by RWE molecules, which effectively suppressed corrosion. LC-MS analysis revealed that active components such as rosmarinic acid and sulfonated jasmonates are present in RWE. These constituents contain active functional groups including benzene rings, O/N-heterocycles, and -OH, which facilitate interaction with the steel surface via physical and/or chemical adsorption. RWE demonstrates excellent corrosion inhibition and adsorption properties in DCA solution, serving as a promising environmentally friendly alternative to traditional inhibitors with significant economic and environmental value.

By taking the service conditions of a high salinity reservoir water environment with high temperature, high pressure, high-Ca²⁺ concentration and O₂-CO₂ coexistence in a western oilfield in China into account, the evolution of corrosion products film and corrosion behavior of C110 steel in different oxygen partial pressures (0-0.4 MPa) were investigated using a high-temperature/high-pressure reactor and an electrochemical testing system. The results showed that as the oxygen partial pressure increased, the uniform corrosion rate of the steel significantly rose from 0.59 to 3.56 mm/a, with intensified localized corrosion. In pure CO₂ environment, a highly resistive composite film (inner layer FeCO₃ and outer layer CaCO₃) with protective properties was formed, resulting in low corrosion current density. In conditions of coexisting O₂-CO₂, additional FeO(OH) and Fe₂O₃ appeared in the corrosion products. Notably, under high oxygen partial pressure (P{}_{{\mathrm{O}}_{\mathrm{2}}} = 0.4 MPa), the corrosion product film was composed of a top layer of porous Fe₂O₃, intermediate CaCO₃ layer with dispersed Fe₂O₃ particles, and discontinuous inner layer FeCO₃. This structural evolution drastically reduced the film resistance and increased the corrosion current density. Moreover, Fe₂O₃ promoted the precipitation of CaCO₃. Under the synergistic effect of O₂ and CaCO₃, the protective FeCO₃ film diminished, and CaCO₃ exhibited both inward and outward growth patterns. Additionally, the coupling of Ca²⁺ and Cl^- exacerbated localized corrosion. This study will provide in-depth theoretical insights into the corrosion mechanisms of C110 steel in coditions of high-salinity, high-Ca²⁺ concentration, and O₂-CO₂ coexistence etc., offering important reference for corrosion protection design in harsh production well environments.

Marine environments are rich in carbon-source, nitrogen-source, and vitamins, which promote microbial adhesion and biofilm formation on ship hull steel surfaces, thereby accelerating microbiologically influenced corrosion (MIC). Herein, the corrosion behavior of AH36 high-strength hull steel induced by sulfate-reducing bacteria (SRB), a typical marine bacterium, was systematically investigated by means of mass loss measurements, microscopic morphology analysis, and electrochemical testing. The results show that after 30 d of exposure, the corrosion rate in the SRB-inoculated solution was approximately five times higher than that in the sterile control ones, with FeS deposits observed on the steel surface and evident localized corrosion pits. Electrochemical tests revealed significantly lower low-frequency impedance and polarization resistance values in the SRB containing solution, and a corrosion current density of 5.01 × 10^-5 A·cm^-2, which is about ten times that of the sterile solution. These findings indicate that SRB accelerate the anodic dissolution of the steel by catalyzing sulfate reduction through bio-cathodic activity and promoting the formation of concentration cells under biofilms, thus playing a critical role in the corrosion process in marine environments.

The rapid growth of shale gas production has led to frequent CO₂ corrosion and SRB corrosion during operations. Traditional organic corrosion inhibitors and bactericides are not environmentally friendly. To develop a green dual-functional agent, Eclipta extract was prepared using ultrasonic-assisted ethanol extraction. The corrosion inhibition performance and antibacterial performance of the acquired Eclipta extract were studied by electrochemical test, weight loss measurement, extinction dilution method and surface analysis technology, while its functional groups was characterized by FTIR and XPS. Results showed that the corrosion inhibition efficiency of 20# steel in a real produced water from a gas field in the Southwest China at 35℃ reached 94.31% for a dosage of 5% Eclipta extract (in volume ratio). The antibacterial effect on SRB was enhenced with the increasing Eclipta extract volume ratio. The adsorption on 20# steel surface of Eclipta extract followed the Langmuir adsorption model. Effective components (e.g., quercetin and ecliptasaponin A) adsorbed onto the metal surface to form a dense protective film. Quantum chemical calculations showed that the adsorption properties of quercetin were superior to those of eclipcoside A and stigmasterol. Additionally, flavonoids in the extract could inhibit bacteria by binding and denaturing proteins. Eclipta extract shows good prospect as a green dual-functional agent for corrosion inhibition and bacterial suppression.

In this study, the twin imidazolyl ionic liquid [C₂(Bim)₁₀]Br₂ was successfully prepared through the substitution reaction of 1, 10-dibromodecane with 1-propyl-2-methylimidazole imidazole. The molecular structure was confirmed to be intact, and the thermal stability was good by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and thermogrirmetric analysis. The corrosion inhibition behavior of this ionic liquid on N80 steel in 1 mol/L HCl solution was systematically investigated via static mass loss measurement, electrochemical analysis and surface characterization after corrosion. The results show that when the concentration of the corrosion inhibitor is 50 mg/L, the corrosion inhibition efficiency reaches above 70%. The efficiency gradually increases with the increase of concentration. When it reaches 200 mg/L, it tends to stabilize after reaching 90%. [C₂(Bim)₁₀]Br₂ can act on the reactions both on anode and cathode simultaneously, comprehensively inhibiting the corrosion process and thus belongs to a mixed type of corrosion inhibitor. The corrosion morphology of the steel sheet with the addition of corrosion inhibitors was significantly improved, the contact angle increased, and the characteristic peak of Fe—N bonds appeared in the X-ray photoelectron spectroscopy, revealing the chemical coordination adsorption mechanism between the N atoms of the imidazole ring and Fe on the surface of the steel sheet. Molecular simulation shows that this corrosion inhibitor promotes electron transfer through a narrow energy gap (4.955 eV), preferentially adsorbs parallel to the iron surface (1.79 nm), and forms a stable protective film relying on Van der Waals forces, effectively blocking corrosive media and demonstrating excellent corrosion inhibition performance.

In the article, the corrosion behavior of Zn-plate in saline-alkali soils with different underground seawater contents was assessed via a laboratory simulation where Zn-plates were buried in the designed soils. Then the morphology and phase composition of the corrosion products were characterized by means of SEM + EDS and XRD. Meanwhile the correlation between the acquired corrosion data of Zn in soils with 3.5%NaCl solution and with natural seawater soil was explored by using gray correlation and correlation analysis. The results indicate that when the salt-alkali soil contains various aqueous solutions such as deionized water, 3.5%NaCl solution, and natural seawater respectively while their contents all being less than 20%, the corrosion rate of Zn in the saline-alkali soils increases as the contents of each solution in the soil increase; when their contents are exactly 20%, the corrosion rate of Zn reaches its peak: i.e. 0.121, 1.094 and 1.152 g·cm^-2·a^-1, respectively; when the contents of all the three solutions are higher than 20%, the corrosion rate of Zn decreases as the content of each solution increases. When in soils with contents of 3.5%NaCl solution and natural seawater content ranging respectively from 10% to 50% the generated corrosion products on Zn surface are mainly ZnO, Zn(OH)₂, and Zn₅(OH)₈Cl₂·H₂O, which are loose with poor protectiveness. Besides, in soils with natural seawater, there was also a small amount of ZnS in the corrosion products. In soils contents both NaCl solution and natural seawater, the corrosion morphology of Zn transitions from localized corrosion to general corrosion with the increasing content of the two waters. The corrosion data for Zn in the above two types of soil exhibit high gray correlation coefficients (γ = 0.683-0.869) and strong correlations (R² = 0.989). Therefore, using 3.5%NaCl solution instead of seawater for the infiltration of saline-alkali soil may be a very effective method to simulate and predict the soil induced corrosion behavior of metals in coastal areas.

The test samples of A588 weathering steel were field-exposed in the test site of the Zhongshan Station in Antarctica (69°22'24" S, 76°22'40" E) for 12 months in terms of the corrosion performance of A588 in an extremely cold atmospheric environment. The results show that the annual corrosion rate of the alloy was determined to be 11.0 μm/a using the weight loss method. SEM observations revealed that there existed cracks and pores within the rust layer, while with the corrosion degree on the upward surface being more severe than that on the downward surface of test samples. EDS analysis indicated widespread distribution of Cl element on the corroded surfaces, with more significant Cl^- enrichment on the upward surface. Furthermore, XRD results showed that the corrosion products mainly consisted of β-FeOOH, γ-FeOOH, α-FeOOH, and Fe₃O₄/γ-Fe₂O₃, among which β-FeOOH was predominant, and the α/γ* protection index was relatively low. Raman spectroscopy further revealed that a distinct stratified distribution of phases within rust layer, with α-FeOOH enriched in the inner layer and γ-FeOOH primarily located in the outer layer. These characterization results collectively suggest that the rust layer formed on A588 steel under extremely cold conditions exhibits cracking and phase stratification, which may compromise its long-term protective performance.

This study investigated how ultrasound and polymer corrosion inhibitors affect the rusting of 20# carbon steel in a polyacrylamide solution, focusing on the safety issues related to metal pipeline rust during oil and gas development in a polymer flooding environment. Contemporary research primarily focuses on examining individual factors in polymer flooding or ultrasound. In contrast, the mechanism by which ultrasound and polymer synergistically regulate the corrosion behavior of metals remains ambiguous. The experiment examined the mechanism by which a polymer corrosion inhibitor affects the corrosion behavior of 20# carbon steel in a polyacrylamide medium under ultrasonic modulation. Characterization techniques, including kinetic potential polarization tests, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were employed to analyze the impact of varying ultrasonic power (0%-100%) on the rheological properties of the polyacrylamide solution and the electrochemical corrosion behavior of the metals. The experimental findings indicate that the corrosion inhibition effect is optimal at an ultrasonic power of 25%, resulting in a substantial reduction in corrosion current density. The cavitation effect of ultrasonic diminishes solution viscosity, suppresses the cathodic oxygen reduction reactions, regulates the anodic dissolution of metals, and facilitates the formation of non-conductive corrosion products. This paper proposes innovative technical concepts for the corrosion protection of oil and gas transmission pipelines, which are of great engineering significance for extending their service life.

Eichhornia crassipes extract (ECE) was prepared by reflux extraction, with the invasive aquatic plant Eichhornia crassipes as raw material. The corrosion inhibition performance of ECE, as an eco-friendly corrosion inhibitor, for cold-rolled steel in 0.1 mol·L^-1 Cl₂CHCOOH solution was evaluated by means of electrochemical methods, mass loss measurement, surface morphology characterization, and analysis of solution physicochemical properties. Results showed that with a dosage of 100 mg·L^-1 ECE a maximum inhibition efficiency of 91.8% at 30 ℃ may be reached. The adsorption of ECE on the cold-rolled steel surface followed a mixed physical and chemical adsorption mechanism, consistent with the Langmuir isotherm model. Potentiodynamic polarization curves revealed the simultaneous inhibition of both cathodic and anodic reactions, driven by a "geometric coverage effect". Nyquist plots revealed an increase in the capacitive reactance arc with increasing ECE concentration, while the polarization resistance (R_p) increased by 5-9.5 times. Micromorphological characterization also revealed a significant reduction in corrosion after ECE loading, and surface tension (σ) measurements revealed that the addition of ECE reduced interfacial tension. Theoretical calculation results show that the free volume fraction (FFV) of protonated molecules has an upward trend, which leads to a weakening effect on the adsorption of protonated molecules, revealing the influence of molecular structure on corrosion inhibition performance at the molecular level.

Two build-up welding overlays of NiCrMo-xNb alloys (x = 0/3.6%, mass fraction) were fabricated on 12CrMoVG steel substrate via welding technique with NiCrMo-based alloy wires with and without 3.6%Nb addition as filler material. Then, their microstructure, and corrosion behavior at 800 ℃ in a mixed gas atmosphere N₂-CO₂ (29.8 mg/L)-O₂ (23.4 mg/L)-HCl (3.53 mg/L) were also assessed, the later issue aims to simulate the corrosive atmosphere of municipal solid waste (MSW) incinerators. The assessment focuses on the effect of Nb addition on local alloy parameters related to formation of the overlay layer such as microstructure, melting point, fluidity, as well as corrosion resistance of the nickel-based build-up welding overlay layers. The results demonstrate that the addition of Nb can lower the alloy's melting point, refine the grain structure, and improve the fluidity of molten alloy. However, the Nb-free alloy overlay layer exhibited superior corrosion resistance. The corrosion mass gain for the build-up welding of NiCrMo-0Nb alloy in this oxygen- and chlorine-containing corrosive atmosphere was 0.0143 mg/cm², while that for the NiCrMo-3.6Nb alloy reached 0.0520 mg/cm². Furthermore, reducing the Nb content significantly decreases the production costs. Therefore, for application scenarios demanding high cost-effectiveness, Nb-free nickel-based alloys present a potential cost-efficient candidate material.

Liquid lithium-lead, as a key functional material for nuclear fusion reactor cladding, offers advantages such as high tritium breeding ratio, strong heat transfer and thermal mass capacity, and excellent flow stability. Oxide dispersion strengthened (ODS) steel serves as a candidate structural material for novel liquid cladding in fusion reactors. During decades of service in fusion reactors, corrosion between ODS steel and high-temperature liquid lithium-lead is unavoidable. The resulting degradation of material properties could potentially lead to equipment failure. Therefore, it is essential to conduct research on the corrosion compatibility between ODS steel and high-temperature liquid lithium-lead. This study employed a self-developed liquid metal rotating corrosion apparatus to conduct corrosion tests on powder metallurgy oxide dispersion strengthened steel in molten lithium-lead at 500 ℃. Tests were performed at 2000, 4000, and 6000 h. Changes in microstructure, phase composition, and mechanical properties were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and depth-sensitive indentation (DSI) techniques. The results indicate that the weight loss rate of ODS steel increases with time, while its mechanical properties decline over time. The corrosion process of ODS steel in high-temperature liquid Li-Pb primarily involves the dissolution and diffusion of metallic elements such as Fe and Cr, progressing through three distinct stages: intergranular erosion during the initial latent period, dissolution of the passivation layer in the second stage, and dissolution of the matrix in the third stage. The research findings provide important reference for evaluating the service performance of ODS steel in liquid lithium-lead environments.

The hydrogen evolution characteristics of two typical metal/ethylene-vinyl acetate copolymer (EVA) interfaces for cable joints were investigated by hydrogen evolution test with stepwise increasing current method, especially in term of the hydrogen production current density threshold, hydrogen production rate, and saturated hydrogen concentration, as well as electrochemical properties such as open-circuit potential, electrochemical impedance, and Tafel curves etc. It also elucidates the mechanism by which radicals exacerbate hydrogen evolution corrosion in metal materials. By using radical quenching agents to inhibit hydrogen evolution and conducting electron paramagnetic resonance detection during the hydrogen evolution process, it is established that the main radicals in the electrochemical hydrogen evolution corrosion process are hydrogen radicals (\cdotH) and hydroxyl radicals (\cdotOH). During the hydrogen production process in cable joints, the hydrogen radical is a key intermediate in the generation of hydrogen molecules, directly influencing the rate of hydrogen gas production. The hydroxyl radical is primarily generated through reactions with current and water (H₂O) or hydroxide (OH^-), and it can significantly exacerbate the corrosion process of metals.

The ordinary characteristics of important environmental factors, including seawater temperature, salinity, dissolved oxygen content, and pH value, which are strongly associated with material corrosion in equatorial high-temperature sea areas, polar low-temperature sea areas, and China's coastal sea areas, were systematically compared and analyzed. Based on the corrosion rate data of T2 Cu-alloy and the relevant environmental parameters of seawater, the corrosivity of extreme marine environments and those along the coastal regions of China was assessed using the grey correlation analysis method. Based on the calculated results, a comprehensively comparative study on the corrosivity of seawater in extreme marine environments was performed. The results indicated that among others, the seawater in tropical high-temperature regions exhibited the highest corrosivity, while temperature being the predominant influencing factor.

To investigate the effect of the shape of zinc powder on the cathodic protection performance and mechanism of solvent-based zinc-rich coatings, three acrylic hybrid resin based coatings with zinc powder pigments composed of mixture of spherical zinc with 0%, 20%, and 100% flake zinc, namely replacing partially the spherical zinc of the pigment with the flake zinc, were prepared on Q235 carbon steel plate respectively. Then the corrosion performance of the Q235 steel with coatings was assessed via immersion test in 3.5%NaCl solution with open circuit potential (OCP) measurement and electrochemical impedance spectroscopy (EIS), as well as salt spray test. The results show that among others, the coating with pigment of spherical zinc and 20% flake zinc exhibits the best cathodic protection performance, i.e. the coating may provide significantly enhanced cathodic protectiveness for the steel substrate. It is concluded that the incorporation of flaky zinc powder can enhance the barrier properties of the coating, increase the zinc powder contact efficiency, and augment the number of effective electrical connections within the coating, thus extending its life-time of cathodic protection.