In this paper, the electrochemical impedance spectroscopy (EIS) characteristics of organic coating systems at different failure stages and their corresponding equivalent circuit models were summarized in terms of the theory related with the electrical properties of organic coatings, and a correlation system of “impedance characteristics-failure stages-equivalent circuits” was established. Secondly, based on key parameters such as coating resistance and capacitance obtained by fitting the equivalent circuit model, a relational expression between coating capacitance and the diffusion coefficient of the medium in the organic coating was alsoestablished. A method for calculating coating porosity and a formula for calculating the corrosion area induced by the diffusion of corrosive media to the coating/metal substrate interface were also proposed, enabling the quantitative evaluation of the protective performance of coatings. Meanwhile, a method of using the graphical approach to obtain impedance spectrum characteristic parameters for efficient comparison and ranking of the corrosion resistance of different organic coating systems was introduced. Combined with impedance spectrum fitting parameters, an in-depth analysis of the synergistic mechanism between radiation effect and corrosion during the failure process of organic coating systems was conducted, and an equivalence relationship model between accelerated tests and natural atmospheric exposure was also constructed. Finally, the paper discussed the precautions, limitations, and corresponding solutions for the application of EIS in the research of organic coating systems. The relevant results can provide a reference for applying EIS technology in conducting research related to organic coatings.

In marine environments, moving parts of Al-alloys are simultaneously subjected to wear and corrosion, and the synergistic interaction of these two factors significantly accelerates the rate of damage. External factors such as load, relative motion speed, humidity, applied potential, and solution pH have significant impact on the wear and corrosion behavior of Al-alloys. This review examines the effects of these factors on the wear-corrosion behavior of Al-alloys in marine environments and the relevant mechanisms, and also summarizes the application of protective methods such as alloying, anodizing, coating, and corrosion inhibitors, emphasizing on how these approaches enhance the wear resistance and corrosion resistance of Al-alloys. Finally, the future research directions on the wear-corrosion behavior of Al-alloys and protective strategies are discussed.

Metal-organic framework materials (MOFs) have attracted much attention in recent years because of their unique structure and properties for the field of corrosion protection. However, MOFs still face many problems in practical applications, such as insufficient stability, unclear corrosion inhibition mechanism, and difficulty in large-scale preparation. In this paper, the research progress of MOFs as anti-corrosion material in recent years is reviewed, focusing on their corrosion inhibition performance and preparation methods in different environments, and the key influencing factors related to MOFs in the field of corrosion prevention in the field of anti-corrosion are revealed, including their pore size, surface chemical properties and the selection of metal nodes. As anti-corrosion material, MOFs have shown broad application prospects in prolonging the service life of metallic materials, saving resource, reducing environmental pollution, and bringing significant economic and social benefits etc. Finally, the future research direction of MOFs as anti-corrosion material is prospected, which provides useful reference and guidance for the follow-up research.

This paper focuses on the application of scanning vibration electrode technology (SVET) in the field of corrosion inhibitor research. The basic principle of SVET was expounded, and the progress of SVET application was summarized in aspects such as revealing the mechanism related with the action of corrosion inhibitors, assessing their performance and the developing of new corrosion inhibitors etc. In terms of exploring the mechanism of action, SVET can monitor in real time the ion current distribution and changes on the metal surface under the action of corrosion inhibitors, intuitively demonstrating the inhibition process of corrosion inhibitors on the electrochemical reaction of corrosion. Therefore, it can provide key data support for a deeper understanding of the corrosion inhibition mechanism. In terms of performance evaluation, SVET can quantify corrosion inhibition efficiency and precisely compare the effect of different corrosion inhibitors. In the research and development of new corrosion inhibitors, SVET testing is helpful for screening the effective components of corrosion inhibitors and optimizing their formula. In addition, this paper looks forward to the future development direction and application prospects of SVET, aiming to promote SVET to play a greater role in the research of corrosion inhibitors and further facilitate the innovative development of corrosion protection technologies.

Microbial-induced corrosion (MIC) is a critical factor leading to the damage and failure of oil and gas pipeline materials. Given the wide diversity of microorganisms in the pipeline operating environment, to understand the nature on corrosion occurred in conditions of multiple microorganisms coexisting on the pipeline surface and beneath scales will become an important approach to address pipeline microbial corrosion in the future. Based on a literature survey, this paper summarizes the research progress of MIC research at home and abroad, outlines the corrosion mechanisms of corrosive microorganisms on pipeline surfaces and beneath deposits, analyzes the progress of composite microorganisms when sulfate-reducing bacteria (SRB) coexist with other bacteria, and discusses the key factors influencing microbial corrosion. It also outlines future research directions based on technological development. This paper systematically analyzes the research status and application of corrosion mechanisms of single microorganisms and mixed microorganisms, and discusses the future research directions of MIC from three aspects, aiming to provide a reference for the engineering application of pipeline microbial protection technologies.

Spent nuclear fuel reprocessing equipment is exposed to high-temperature concentrated nitric acid for extended durations, and the Mn²⁺ ions produced during the process may affect the corrosion behavior of key stainless steel structural materials. Herein, the effect of three factors, namely temperature (60 ℃ to boiling point), nitric acid concentration (3-6 mol/L), and Mn²⁺ ion concentration (0.1-10 g/L) of high-temperature concentrated nitric acid solutions, and their interactions on the corrosion behavior of 304L and C25 austenitic stainless steels was investigated via immersion test, electrochemical measurement, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analysis while a predictive model was established based on response surface methodology (RSM). The results show that temperature and nitric acid concentration are the dominant factors governing corrosion behavior, and their increase significantly accelerates the cathodic reaction, leading to an increase in corrosion current density (I_corr) and a decrease in polarization resistance (R_p). Mn²⁺ ions act as a secondary promoting factor, mainly by weakening the stability of the passive film (especially in medium and low acidity environments), thereby intensifying the corrosion. XPS analysis reveals that high concentrations of Mn²⁺ lead to a decrease in Fe content and enrichment of Cr oxides on the surface of 304L stainless steel. By comparing the corrosion characteristics of the two steels, it can be concluded that C25 stainless steel has better corrosion resistance than 304L in all conditions, these may be ascribed to higher Cr and Ni content and lower impurities for the C25 stainless steel. The RSM model successfully quantified the effect of each individual factor and their interactions and confirmed the order of the influence intensity of each factor as: temperature > nitric acid concentration ≫ Mn²⁺ concentration. The findings may provide a significant reference for the material selection and the determination of the safety window of process parameters for reprocessing equipment.

The stress corrosion behavior of cast Ti-6Al-4V alloy, as an important engineering material of key structural components for deep-sea applications, in actual deep-sea conditions still remains unclear. In this study, the effect of hydrostatic pressure on the stress corrosion sensitivity and electrochemical behavior of the cast and forged Ti-6Al-4V alloys was comparatively studied by means of slow strain rate tensile testing and electrochemical testing techniques, scanning electron microscopy with electron backscatter diffraction (EBSD), etc. The results indicate that under the combined influence of high hydrostatic pressure and tensile stress, the transition of passivation films of both cast and forged Ti-alloys could occur from a dense structure gradually to a porous structure, thereby reducing their protectiveness. The coarse β-phase grain boundaries and defects in the cast Ti-alloy act as sites of weakness in the passivation film, which could significantly lower the compactness and corrosion resistance of the passivation film for the cast Ti-alloy. However, this effect was not observed in the forged Ti-alloy. The stress corrosion sensitivity of both types of Ti-6Al-4V alloys increases with hydrostatic pressure. In contrast, by the same hydrostatic pressure, the stress corrosion sensitivity of the cast Ti-6Al-4V alloy is higher than that of the forged Ti-6Al-4V alloy. Under high hydrostatic pressure, brittle fracture occurs for the cast Ti-6Al-4V alloy, and while ductile-brittle fracture for the forged Ti-6Al-4V alloy. Under high hydrostatic pressure, the applied tensile stress can induce dislocation motion, leading to stress concentration at the original β-phasegrain boundaries of the cast Ti-6Al-4V alloy. In fact, the existence of segregation defects can lead to the preferential damage of the passive film at those sites, and the cracks at the dendrites can initiate and propagate along the α/β phase interface in between the layers, and thus, the stress corrosion sensitivity is high. In contrast, the forged Ti-6Al-4V exhibits an equiaxed structure with a relatively dense passivation film, uniform deformation, and a strong ability of equiaxed crystals to resist crack propagation, thereby exhibiting relatively lower sensitivity to stress corrosion cracking.

Sodium acetate trihydrate, as a storage substance is widely employed in water heater thermal storage systems due to its high phase change energy storage density and suitable melting point. However, as a corrosive medium for Cu, the sodium acetate trihydrate may cause corrosion of Cu-tubes in heat exchange systems, leading to reduced service life of heat exchange components. Therefore, investigating the corrosion behavior of Cu-tubes in the presence of phase change substances in service conditions and predicting their service life are essential. Herein, the corrosion behavior, corrosion morphology and corrosion products of Cu-tubes were studied by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). These Cu-tubes, set at different locations within a water heater, were suffered from corrosion induced by simulated operation in actual conditions for varying durations. Meanwhile, the morphology and depth of the corrosion pits were also assessed by confocal laser scanning microscopy. Furthermore, the service life of Cu-tubes set at different locations was predicted by means of a regression model. The corrosion observed on straight Cu-tubes, bent Cu-tubes, and welded joints manifested primarily as localized pitting corrosion. Notably, the bent Cu-tubes exhibited microcracks induced by tensile-compressive stresses, resulting in more severe corrosion compared to the straight tubes; It may be predicted that these tubes will fail due to corrosion perforation after 31 a. For the welded seams of Cu-tubes, there existed thermal cracks due to welding heat input and P element segregation, suffered from the most severe corrosion, while it may be predicted that they will fail due to corrosion perforation after 35 a. This evidence provides significant reference for understanding and mitigating the corrosion of Cu-components within water heaters.

To address the dual challenges of corrosion and microbial fouling faced by equipment during long-term service in the marine environment, a functionalized MoS₂ synergistic epoxy-based composite protective coating was designed and prepared in this study. MoS₂ was surface-functionalized with KH550 to achieve uniform dispersion within the mixed system of epoxy-modified silicone emulsion and acrylic resin. The effect of MoS₂ loading on the coating's morphology, electrochemical performance, and antibacterial activity against sulfate-reducing bacteria (SRB) were systematically investigated. The results demonstrated that an optimal addition of 5‰ functionalized MoS₂ significantly improved the coating's compactness and uniformity, reducing the corrosion current density to 1.74 × 10^-10 A/cm² and the corrosion rate to 2.0167 × 10^-6 mm/a, thereby exhibiting the best corrosion resistance. Meanwhile, the coating achieved an SRB inhibition efficiency of 96.2% through biofilm disruption, which enable the coating sustainable antibacterial performance. These findings indicate that the functionalized MoS₂ can synergistically exert barrier effect and antibacterial activity in composite coatings, providing both theoretical insights and practical guidance for the development of high-performance marine protective materials.

For the known generation IV nuclear power plants, such as high-temperature gas-cooled reactors (HTGRs) and sodium-cooled fast reactors (SFRs), once-through steam generators typically adopt a reducing all-volatile treatment [AVT(R)] as the feedwater chemistry control strategy. However, this water chemistry induces flow-accelerated corrosion (FAC) for the related structural components, which can result in heat-transfer tube fouling and throttling valve blockage. Oxygenated treatment (OT) is an effective approach to mitigate throttling valve deposition. Nevertheless, the potential impact of increased dissolved oxygen on the stress corrosion cracking (SCC) susceptibility of structural materials remains to be clarified. In this study, the SCC behavior of T22 steel, widely used in the evaporator section of once-through steam generators in Generation IV reactors, was systematically evaluated in conditions of AVT(R), AVT(O), and OT respectively by using slow strain rate tensile (SSRT) tests. The results demonstrate that an increased dissolved oxygen concentration does not significantly alter the oxidation behavior of T22 steel. Importantly, the adoption of oxidizing AVT or OT conditions does not increase the SCC susceptibility of T22 steel. This work provides a technical foundation for addressing throttling valve deposition in once-through steam generators and offers valuable guidance for optimizing feedwater chemistry in generation IV nuclear power systems.

The influence of seawater flowing inside the pipeline on the cathodic polarization behavior of carbon steel pipelines was studied viaa home-made closed-loop circulation system with electrochemical tests, meanwhile, the electrochemical behavior of different locations on the inner side of the pipeline by varying polarization potentials was analyzed by computational fluid dynamics simulation. The results show that as the polarization potential varies, the current density trends at elbows and straight sections are consistent; however, the middle region of the elbow is the most susceptible to corrosion, with the outer bend requiring a significantly higher protective current density than the inner bend. The capacitive arc radius at the elbow first increases and then decreases along the flow direction, consistent with the variation in current density. Surface morphology and XPS analyses reveal that at a polarization potential of -1.2 V, a compact Mg(OH)₂ deposit forms, which enhances protection but increases current consumption due to the cathodic reaction shifting toward hydrogen evolution. Numerical simulations further demonstrate that near-wall radial velocity is highly correlated with current density and can serve as a key parameter for evaluating the influence of seawter flow on the cathodic protection effectiveness. Based on this, a relationship model between current density and radial velocity was established, providing valuable reference for the design and assessment of cathodic protection systems in flowing seawater environments.

Incorporating functionalized graphene oxide (GO) composites as fillers can enhance the service life of organic coatings in marine environments. However, their synthesis methods typically involve the use of toxic reagents and high energy consumption, which increase production costs and restrict practical applicability. To address this, a novel composite of GO-CeMOF were prepared via in situ growth of cerium-based metal-organic frameworks (CeMOFs) on GO surface in aqueous solution at ambient temperature. Then particulates of the composite as fillers were blended with epoxy paint to prepare the GO-CeMOF-EP composite coating on carbon steel Q235. It follows that the CeMOFs were uniformly distributed on GO nanosheets, thus of which the agglomeration and stacking could be effectively suppressed. Cross-sectional analysis revealed that the GO-CeMOF particulates were uniformly distributed within the formed GO-CeMOF-EP coating and the coating is compact with optimal interfacial adhesion strength (4.56 MPa) and minimal water adsorption (0.73%). After immersion test in simulated seawater for 60 d, the Z_{f = 0.01 Hz} value of GO-CeMOF-EP coating (1.0 × 10⁹ Ω·cm²) represented 20.8-fold and 10.0-fold improvements corresponding over the plain EP (4.8 × 10⁷ Ω·cm²) and GO-EP (1.0 × 10⁸ Ω·cm²) coatings, respectively. After peeling off the GO-CeMOF-EP coating, no apparent corrosion was observed on the Q235 steel substrate, further verifying the long-term and reliable corrosion protection performance of the coating. Therefore, this innovative, efficient, and simple design strategy is expected to improve the protective performance of coatings and prolong the service life of metallic equipment in harsh marine environments.

The base metal and the weld zone of X65 steel were pre-charged with hydrogen via electrochemical hydrogen charging method. Then the hydrogen-charged steel was immediately placed into a glass tube filled with liquid paraffin, the captured hydrogen amount was measured via collecting the escaping hydrogen from the steel. The influence of hydrogen charging on the mechanical properties and corrosion resistance of the base metal and welds was investigated by slow strain rate tensile testing and electrochemical analysis techniques. The results indicated that both the captured hydrogen amount and the number of hydrogen blisters formed in the base metal and the weld zone increased with the increasing hydrogen charging current density. After hydrogen charging by a current density of 10 A/cm², the welds zone exhibited a higher hydrogen embrittlement sensitivity than the base metal. However, when the current density reached 25 A/cm², the hydrogen embrittlement sensitivity of the base metal was greater than that of the weld zone. Hydrogen exerted a pinning effect on dislocations, and the weld retained a relatively high concentration of hydrogen. The relatively high captured hydrogen amount in the weld zone hindered dislocation movement, thereby enhancing the resistance of the weld zone to plastic deformation. Meanwhile, this effect also increased the density of defects there, consequently reducing the corrosion resistance of the weld zone in comparison to the base metal.

Generally, stimuli-responsive anticorrosion coatings may be given self-repairing function via dispersing specially designed nanocontainers into host coatings, enabling them to have the property of self-repairing after being suffered from corrosion attack. Herein, hollow-structured Co-N-C nanocatalyst was prepared via a silica-protected pyrolysis method, then the acquired nanocatalyst was incorporated into an epoxy coating to develop a novel nanocatalytic anticorrosion coating. The Co-N-C catalyst exhibits an oxygen reduction reaction (ORR) with half-wave potential of up to 0.89 V, demonstrating excellent catalytic activity. After introducing the catalyst into the epoxy coating, the anticorrosion performance of the coating is significantly enhanced. After 60 d of immersion in an oxygen-saturated 3.5% (mass fraction) NaCl solution, the coating/carbon steel remains intact, and the steel substrate shows no obvious signs of corrosion, indicating markedly superior protection compared with the pure epoxy coating. The enhanced performance is mainly attributed to the oxygen-consuming catalytic mechanism for the hollow-structured Co-N-C nanocatalyst, which effectively delays the chemical corrosion process of the steel substrate, thereby significantly extending the its service life. The oxygen-consumption-based anticorrosion strategy proposed in this study provides a new direction for research on inhibiting oxygen diffusion, prolonging coating service life, and enhancing anticorrosion performance.

The corrosion behavior of hot-dip galvanized steel in the tropical marine atmosphere of the Hainan coastal area was investigated through exposure tests in the natural Hainan coastal atmospheric environment and indoor spectrum-accelerated corrosion tests. Meanwhile, a corrosion prediction model was established based on the mass loss measurement results. The corrosion morphology and phase composition of the test steel surface were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical behavior of the hot-dip galvanized steel at different test durations was also examined by electrochemical means. The results indicate that after atmospheric exposure in Hainan for 2 a and spectrum-accelerated testing for 2.5 cycles, no reddish rust products were observed on the galvanized steel surface. The primary form of corrosion was uniform corrosion of the zinc coating. The corrosion kinetics followed a power function model. The corrosion products formed on the galvanized steel by both outdoor exposure and laboratory accelerated tests consisted mainly of ZnO and Zn₅(OH)₈Cl₂·H₂O. The corrosion potential increased with test duration, while the corrosion current density continuously decreased. This demonstrates that the corrosion products formed on the surface of the hot-dip galvanized steel effectively inhibited the corrosion process, thereby providing good protectiveness for the galvanized steel. Based on the comprehensive analysis of indoor and outdoor corrosion kinetics, corrosion product composition, and electrochemical mechanisms, it follows that the results of the environmental spectrum accelerated test designed for the coastal atmospheric environment of Hainan have a good correlation with the actual exposure test results in the coastal atmospheric environment of Wenchang district of Hainan Province.

The B30 heat transfer tubes on the seaward side of the vessel are critical components of the steam-powered support system and are exposed to the risk of seawater corrosion during service. In this study, a laboratory-scale simulated system of circulating seawater for heat transfer tubes was established. By installing zinc and iron sacrificial anodes separately, the effect of these anodes on the corrosion behavior of the heat transfer tubes were investigated. The findings revealed that, compared with the condition without sacrificial anodes, both zinc and iron sacrificial anodes can all slow down the corrosion of the heat transfer tubes, resulting in lower concentrations of dissolved Cu²⁺ ions in the water. Meanwhile, it was discovered that the effectiveness of sacrificial anode protection correlates with spatial distance, whilst the potential fluctuating along the pipeline may result in varying degrees of protection at different distances on the pipeline. The conclusions of this study provide experimental evidence and recommendations for the rational design of ship condenser heat exchanger piping, particularly regarding the selection and installation of sacrificial anodes.

Fly ash particles, generated during the operation of biomass power plant boilers, deposited on the surface of metallic heating components are likely to cause metal thinning or corrosion leakage, which is an important cause for the frequent occurrence of corrosion and tube-bursting accidents of the metallic heating components for the power plant boilers. Herein, the effect of particles of different sizes (< 30, 30-75 and 75-100 μm) and different deposit amount (10, 20, and 30 mg/cm²) of pine wooden chip ash on the surface of 12Cr1MoVG steel, a typical common steel used for boilers of biomass power plants in the country, on the high-temperature corrosion behavior of the steel was investigated via a home-made set of a tube-furnace system to simulate typical boiler flue-gas composed of CO₂, O₂ and N₂ at 600 ℃, as well as per weight change measurement and relevant characterization techniques for corrosion products, in terms of the corrosion mechanism of the boiler tube steel induced by fly ash deposits generated during wooden biomass combustion. The results show that the influence of wooden ash particles on the corrosion of the boiler tube steel surface is determined by the particle size of the fly ash and its deposition amount. Namely, for the cumulative ash deposition amount is 10 mg/cm² and their particles range within 75-100 μm (large particles), due to their relatively small specific surface area, they are not prone to agglomeration, therewith the ash deposits present a loose and pore structure, which may be conductive to the continuous release and migration of certain active substances and promotes the localized corrosion; For the particles of size range within 30-75 μm, and the ash deposit amount of 20 mg/cm², the hierarchical pore structure of the deposit may be conductive to accelerated corrosion, when the cumulative ash amount increases to 30 mg/cm², the appropriate gradation of particles of different sizes leads to a decrease in the porosity of the deposits, thereby acting as a corrosion barrier. It follows that the most serious corrosion occurred for particles range within 75-100 μm while the ash deposit amount of 10 mg/cm², the corrosion degree is the next for particles range within 30-75 μm while the ash deposit amount of 20 mg/cm², in contrast, the corrosion degree was also the most significant when the particle size below 30 μm while the ash deposit amount of 20 mg/cm². The findings can provide a reference for understanding the characteristics and mechanisms of high-temperature corrosion of boiler tubes in biomass power plants induced by of different sized biomass fly ash.

Nickel-based single-crystal superalloys are extensively applied in aero-engines due to their superior high-temperature performance. However, in coastal and marine environments, they are highly susceptible to hot corrosion induced by Na₂SO₄ and NaCl deposits. Previous studies have revealed that mixed salts accelerate the degradation of protective oxide scale and intensify the internal corrosion, thus significantly reducing the service life of alloy components. Nevertheless, systematic investigations on the hot corrosion behavior of low-Re second-generation single-crystal superalloys in different salt environments remain scarce, and the underlying mechanisms require further clarification. Therefore, the hot corrosion behavior of a low-Re second-generation single-crystal superalloy at 900 ℃ beneath deposits of pure Na₂SO₄ and mixed Na₂SO₄/NaCl salts in air was investigated using the discontinuous weight change measurement method. Results show that the Na₂SO₄/NaCl mixed salt exhibits more severe corrosive effect, manifested by intensified oxide scale spallation, increased corrosion products thickness, and aggravated internal corrosion. Beneath the pure Na₂SO₄ salt deposit, a relatively continuous Al₂O₃ protective oxide scale is formed on the alloy surface, whereas beneath the mixed salt, the synergistic action of Cl^- and S^- triggers a chlorination-oxidation cycle and sulfidation reactions, which compromise the oxide scale integrity and accelerate the deterioration of the alloy.

Natural mixed-dimensional attapulgite (mATP) with a high specific surface area was utilized as a nanocontainer to achieve a high loading capacity of the corrosion inhibitor. The prepared nanocontainer was then integrated into polyvinyl butyral (PVB) to form BTA@H-mATP/PVB anticorrosive coating aimed at enhancing the corrosion resistance of zinc substrates. Then the effect of the addition amount of the as received mATP and the acid etched ones (H-mATP) on the anticorrosion performance of the coatings was comparatively evaluated. Additionally, the self-healing mechanism of the BTA@H-mATP/PVB coating was thoroughly investigated. It was found that after acid etching, the specific surface area of H-mATP increased from 66 for the as received ones to 179 m²/g, significantly enhancing BTA loading capacity and resulting in release amounts of 0.93 and 0.90 mmol/L in alkaline and acidic environments, respectively. The |Z|_{0.01 Hz} of the 1%-BTA@H-mATP/PVB coating is 2.54 × 10⁶ Ω·cm², approximately 12 times higher than that of the pure PVB coating. Notably, even after 20 days of immersion in 3.5%NaCl solution, its electrochemical impedance remained as high as 2.05 × 10⁵ Ω·cm², indicating excellent corrosion resistance and long-term durability. The enhanced corrosion protective performance of the coating may be attributed to the synergistic effect between the physical barrier provided by H-mATP and the localized active protection offered by BTA. This work provides novel insights into the functional design and performance optimization of nanocontainers for intelligent anticorrosive coatings.

Herein the tensile properties in atmosphere and corrosion behavior in 3.5%NaCl solution of a trace Er-containing heat-resistant Al-alloy conducting wire (Al-0.08Si-0.05Er-0.05Fe, mass fraction) with a diameter of 10 mm at various temperatures were studied via Instron 3369 electronic universal testing machine, immersion test and electrochemical testing means etc. The results demonstrated that the transverse section of the wire exhibited a microstructure dominated by fine near-equiaxed grains, while the longitudinal section displayed elongated grains with high aspect ratios. In addition, significant intergranular disorientation and a low fraction of recrystallization were observed. Limited secondary phases were found neither in the cross-section nor in the longitudinal section, primarily composed of coarse Al-Fe particles and Al-Fe-Si particles, alongside finer Al-Fe-Si-Er particles. At ambient temperature, the wire demonstrated a yield strength of 113 MPa and an ultimate tensile strength of 133 MPa. Elevated tensile testing temperatures induced progressive degradation of mechanical properties. However, the yield strength loss rate remained notably lower than the theoretically predicted value at temperatures below 150 ℃, which indicates enhanced thermal stability under moderate heating conditions. Immersion tests at different temperatures revealed that pitting corrosion dominated the corrosion morphology. The corrosion behavior of the alloy changed from pitting corrosion to intergranular corrosion, and corrosion resistance declined with the increasing temperature, which may be attributed to the accelerated negative shift of the free corrosion potential of Al-matrix under thermal activation. Crucially, the incorporation of Er effectively refined both the grain structures and the dimensions of Al-Fe/Al-Fe-Si phases, thereby mitigating the localized corrosion susceptibility through microstructural homogenization.

Nuclear power pump shaft, as a crucial load-bearing component experiences corrosion failure due to long-term exposure to cooling water, this corrosion failure is a critical factor limiting its service life. For such corrosion, sodium phosphate, as an important corrosion inhibitor, herein, of which the inhibition performance on the 40Cr steel was studied by using potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometer. The results indicate that the corrosion rate decreases significantly with increasing sodium phosphate (Na₃PO₄) concentration. At lower concentrations (1 × 10^-4 and 1 × 10^-3 mol/L), corrosion still occurs, forming loose and porous corrosion products composed mainly of Fe₃O₄, Fe₂O_3, and γ-FeOOH, which provide poor corrosion protection. At a concentration of 1 × 10^-3 mol/L, a more stable α-FeOOH phase is emerged, with volume fraction ratio of γ-FeOOH to α-FeOOH being 39.65% and 60.35%. The compact corrosion products of α-FeOOH and Fe₃O₄ effectively decelerate the corrosion process and improve the protective properties of the rust layer. When the concentration is increased to 1 × 10^-2 mol/L, a dense and stable passive film forms on the 40Cr steel surface, primarily consisting of FePO₄ and Fe₂O₃, this film effectively isolates the substrate from the corrosive medium, maintaining the steel in a passive state and thereby significantly inhibiting the corrosion process.

The effect of NaHSO₃ addition on the corrosion behavior of 445J2 ferritic stainless steel in NaCl solution was studied by means of potentiodynamic polarization curve measurement, electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), and Motta-Schottky (M-S) testing, combined with X-ray photoelectron spectroscopy (XPS) and corrosion morphology observation. The results showed that after adding 0.05 mol/L NaHSO₃ to a 0.62 mol/L NaCl solution, the corrosion potential measured by polarization curve of 445J2 ferritic stainless steel decreased, the corrosion current density increased, the charge transfer resistance decreased, and the corrosion resistance sharply decreased. At the same time, many low amplitudes long-life current transient appeared in the EN time-domain signal. After adding NaHSO₃, the point defects concentration of the passive film on the surface of 445J2 ferritic stainless steel increased, and the composition also changed, showing a significant Fe²⁺ peak and a decrease in the O^2-/OH^- ratio in XPS detection results. Based on the above results, the influence mechanism of NaHSO₃ addition on the deterioration of passive film and corrosion resistance of 445J2 ferritic stainless steel was discussed from two aspects: the acidification of the solution and the reduction of SO{}_{\mathrm{3}}^{\mathrm{2}-} by the generation of H⁺ and SO{}_{\mathrm{3}}^{\mathrm{2}-} by HSO{}_{\mathrm{3}}^{-} electrolysis.

The corrosion experiment was conducted on the laser additive manufacturing of Ni-Cr-Mo alloy and TP347H stainless steel under simulated conditions of biomass deposition salt (KCl-K₂SO₄) co-firing in a coal-fired boiler at 600 ℃ for 168 h. The corrosion kinetics curves were obtained, and the microstructure, phase composition, and composition of the corrosion products were analyzed using scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). The results indicate that laser additive manufacturing of Ni-Cr-Mo alloy exhibits superior corrosion resistance compared to stainless steel. The corrosion behavior mainly manifests as oxidative corrosion, activated oxidative corrosion, and alkaline melting mechanism. With the increase of K₂SO₄ content in the mixed salt, the corrosion degree of the alloy intensifies. The surface of the cladding layer forms a dense protective oxide layer, mainly composed of Cr₂O₃ and NiO, which effectively hinders the penetration of corrosive media. However, the activation oxidation corrosion process causes pores and cracks in the surface oxide layer, promoting the inward diffusion of the corrosive medium and intensifying the internal sulfurization reaction.

Herewith a new process was proposed for preparing micro-arc oxidation coating on the surface of AZ91D Mg-alloy. The coating is formed in a modified zirconium salt-based electrolyte that incorporates properly polyaniline (PAN) particles. Then its microscopic morphology and crystal structure were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical properties were evaluated through the Shore A scale method and friction-wear tests, while corrosion resistance was assessed via galvanostatic polarization curves, impedance measurements, hydrogen evolution experiments, and salt spray testing. The results show, that when the doping amount of polyaniline particles is 3.0 g, the porosity of the coating is reduced from the 13.16% for the coating prepared in the un-modified electrolyte to 4.81%, the friction coefficient is small, and the adhesion grade is 0; the coating has free-corrosion potential of -1.558 V, free-corrosion current density of 39.3 μA·cm^-2, resistance of 44037.9 Ω·cm², and hydrogen evolution of only 1.7 mL after immersion in 3.5%NaCl solution for 120 h, and a salt spray corrosion grade of 10G after 120 h. In conclusion, the doping of polyaniline particles is beneficial to the formation of a compact micro-arc oxidation coating. As the doping amount increases, the microstructure and corrosion resistance of the coating are significantly improved. Thus, preparing compact micro-arc oxidation coatings through polyaniline particle doping is an effective method to enhance the corrosion resistance of Mg-alloys.

As an emerging technology in the field of radioactive decontamination of nuclear power plants, laser cleaning is in urgent need of systematic research on the corrosion behavior of metal components after cleaning. In this study, with a home-made laser cleaning equipment, 304 stainless steel was subjected to laser cleaning by applied high and low power levels. The surface morphology, roughness, and elemental composition of the steel before and after cleaning were systematically characterized. Then influence of laser cleaning power on the corrosion resistance of stainless steel via a comprehensive suite of corrosion performance testing methods, including electrochemical measurement, pitting corrosion and intergranular corrosion, as well as high-temperature and high-pressure stress corrosion tests. The results show that the oxygen content and roughness of the test steel surface increase with the increase of laser cleaning power. The pitting corrosion resistance of the steel after high power laser cleaning is improved compared with that of the low power cleaned ones. Compared with the uncleaned steel, the high-power laser-cleaned ones exhibit an increased free-corrosion potential, a decreased current density, and increased EIS-related resistances, thus showing the optimal corrosion resistance. The results of intergranular corrosion test show that no corrosion induced defects such as cracks are observed on the steel surface after laser cleaning. Under the synergistic effect of the tensile stress and the strong corrosive high temperature/pressure boric acid medium, the corrosion crack initiation and gradual inward expansion occurred on the surface of the U-shaped bending steel after laser cleaning. These corrosion tests show that laser cleaning has different effects on the corrosion resistance of 304 stainless steel surface even under the same service environment.

Marine microbial corrosion on AH36 shipbuilding steel surface has significant impact on the safe operation of ships, making the prevention of such corrosion particularly important. In this study, the corrosion behavior of AH36 shipbuilding steel induced by sulfate-reducing bacteria (SRB), a major marine corrosive microorganism was investigated in SRB containing solution by means of corrosion weight-loss measurements, microstructural analysis, and electrochemical monitoring. Then the biocidal and anticorrosion performance of different dosage of the D-tyrosine enhanced tetrakis (hydroxymethyl)phosphonium sulfate (THPS) was also evaluated for the AH36 shipbuilding steel in SRB containing solution. Results indicate that a dosage of 40 mg/L THPS alone exhibited limited inhibition for SRB activity and metabolism, while 100 mg/L THPS demonstrated better inhibitory performance. The combination of 40 mg/L THPS with 1 mg/L D-tyrosine exhibited the most effective inhibition effect, achieving a corrosion inhibition efficiency of 75.68% relative to the bare SRB containing solution, with features of the mildest corrosion defects on the substrate, the lowest sulfur content in corrosion products, and no detectable FeS formation. Electrochemical tests further revealed that the low-frequency impedance modulus and polarization resistance of all three bactericidal containing solutions with SRB, i.e. 40 mg/L THPS, 100 mg/L THPS and 40 mg/L THPS + 1 mg/L D -tyrosine were higher than those observed in the bare SRB solution without addition of bactericidal. Among them, the addition of the combination 40 mg/L THPS + 1 mg/L D -tyrosine exhibited the lowest corrosion current density, corresponding to a corrosion inhibition efficiency of 87.97% relative to the bare SRB solution.

An underground natural gas pipeline with three-layered polyethylene anti-corrosion coating operated in conditions of internal pressure 7.28 Mpa, at 61.87 ℃ for 1425 d. Next, steel pipe samples were collected from three typical sections of the pipeline (namely the cathodic protection end, the non-protection end, and the pipeline connection area). Then the effectiveness of protection for these three sections was comparatively assessed by means of tensile tester, hardness tester, characterization of corrosion morphology and corrosion products, as well as analysis of soil extract etc. While the influence of factors related with environment, corrosion products, and the three-layered polyethylene anti-corrosion coating on the corrosion behavior of pipeline steel was also revealed. The test results showed that the tensile strength of the pipe steel on the protection end was 8.51-9.92 MPa, the elongation at break was 396.94%-446.01%, thus, where the anti-corrosion mearsure exhibited the best performance. The Cl^- concentration at the protection end was 2.99 mg/g, which was significantly higher than that at the non-protection end, but the corrosion degree at the protection end remained light, which fully verified the effectiveness of cathodic protection measures. Through the analysis of corrosion products, it is found that corrosion products are formed in oxidizing environment, and the corrosion products composed mainly of iron oxides. Based on the above analysis, it can be concluded that factors such as moisture, Cl^-, temperature, and strength of the anti-corrosion coating may act together to deteriorate the protective performance of the anti-corrosion coating. This study provides meaningful reference for the maintenance and management of the external anti-corrosion coating for pipelines.

In this paper, the salt spray corrosion resistance of DH460 steel for offshore wind power converter stations and the protective effects of ceramic coatings were investigated via neutral salt spray accelerated corrosion tests as a simulation of the realcorrosion environments in service. The tested samples and the formed corrosion products were characterized by means of scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), electrochemical testing, tensile testing, and fatigue testing etc. The results reveal that corrosion-induced intergranular brittle fracture reduces the mechanical properties of the steel. Based on the salt spray-mechanistic coupling test, the fatigue life of DH460 steel after salt spray test was revealed, and a failure model of “synergistic effect of corrosion product expansion stress grain boundary crack” was constructed. By designing and constructing a composite ceramic coating on the surface of DH460 steel, the resistance to salt spray corrosion of the DH460 steel has been significantly improved by the applied composite ceramic coating. Within the laboratory parameter range, no change was observed in the performance and structural integrity of the DH460 steel before and after corrosion test, indicating that the ceramic coating can completely block the entry of corrosive substances upon the steel substrate.

After long-term service in severe working conditions at high-temperature, the occurrence of damages such as surface pits and extensive spalling etc. caused by oxidation and pressures may significantly reduce the service life of the rolls. Herein, the stellite alloy coating was prepared on 21CrMoV steel, which is commonly adopted for making hot rolling rolls, via laser cladding technique aiming to address the shortcomings of the present hot-rolls. Then the microstructure, elemental distribution, and phase structure of the coating were evaluated by scanning electron microscopy, electron probe microanalysis, and X-ray diffraction. The microhardness distribution and high-temperature properties of the coating were also studied, correspondingly, the mechanisms related with strengthening and oxidation of the coating were clarified. The results show that the stellite coating is about 900 μm in thickness and is well bonded to the 21CrMoV substrate, without obvious cracks, pores, and other defects. It is mainly composed of γ-Co together with M₂₃C₆, M₇C₃ carbides. Under the synergistic effect of solution strengthening, dispersion strengthening, and grain refinement, the coating presents an average microhardness of 356.9HV_0.2, about 1.6 times that of the substrate. After oxidation at 1000 ℃ for 100 h, a continuous compact composite oxide scale, composed of an outer portion of MnCr₂O₄, a middle part of Cr₂O₃ and an inner part of SiO₂ was formed on the coating surface, which could effectively suppress the inward migration of oxygen and ensure the high-temperature service performance.

The influence of temperature and NaCl-content on the corrosion behavior of heat-treated U75V rail steel with fine pearlite lamellar microstructure in NaCl solutions was assessed via full-immersion corrosion tests with mass loss measurement, macroscopic morphology observation, scanning electron microscopy,and X-ray diffraction. The results indicate that the increase in solution temperature significantly accelerates the corrosion process, and the corrosion rate is positively correlated with temperature. At 45 ℃, the steel exhibits the highest free-corrosion current density (I_corr) and the lowest charge transfer resistance (R_ct), but the temperature variation does not alter the phase composition of the corrosion products. The effect of NaCl content shows a nonlinear characteristic: when the NaCl content (mass fraction) increases from 2.0% to 3.5%, the surface passivation film is gradually destroyed by Cl^- attack and the anodic dissolution is promoted, leading to increase in I_corr and decrease in R_ct, i.e. the corrosion of U75V steel is intensified. However, when the NaCl content increases to 5.0%, the solution with high ionic strength may promote the formation of protective corrosion product α-FeOOH and significantly inhibit the dissolved oxygen, resulting in decrease in I_corr and n increase in R_ct, thereby, the corrosion rate decreases instead.

In order to gain an in-depth understanding of the oxidation behavior of metallic materials in a fire environment, herein, the influence of pyrolysis products of polyvinyl chloride on the oxidation characteristics of Cu in an ethanol combustion atmosphere was assessed via a home-made fire atmosphere simulation device. Then the microstructure, elemental composition and phase constituents of the oxidation products were examined by means of atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS), while the composition of the combustion atmosphere was analyzed using gas chromatography (GC). The results demonstrate that the decomposition of PVC produces HCl, which reacts with Cu to form CuCl. Owing to the enhanced volatility of CuCl with the increasing temperature, causes the oxide layer to become loose and porous which leads to accelerated oxidation of the inner Cu substrate. Moreover, the hydrogen generated via the thermal decomposition of PVC induces hydrogen embrittlement of the oxide scale and can reduce part of the CuO to Cu₂O, further compromises the protective capability of the oxide scale. These observed oxidation characteristics provide a very meaningful reference for the further fire investigations.

As a protective means sacrificial anode is an effective method of corrosion prevention for seawater pipelines in coastal power plants. However, to monitor its operation parameters, such as the consumption status of sacrificial anodes within seawater pipelines, remaining lifespan, and the intensity of protective current etc. is quite challenging. In this study, a specific section of Q235 steel seawater pipeline equipped with A21E-2 sacrificial anodes was selected to attempt to acquire the relevant output current and remaining capacity of those sacrificial anodes, and to evaluate their remaining service life. For this purpose, a numerical simulation model for the entire process of sacrificial anode cathodic protection is established by using the finite element method and applying appropriate polarization boundary conditions. This model takes into account the real-time changes in the corrosive environment, including temperature and flow velocity, and was optimized using digital twin technology. Compared with the measured data, the prediction accuracy of this model exceeds 80%.