Electrochemical impedance spectroscopy (EIS) is one of the most important methods for studying the electrochemical corrosion behavior and failure mechanisms of metallic materials and their coating systems. With the development of corrosion electrochemistry theory, numerical calculation, and corresponding fitting software, significant progress has been made in the analysis of EIS data. Through data fitting and analysis, key parameters such as the thickness of the passive film, the resistivity distribution of the passive film, and the resistivity distribution of the coating can be obtained. When the passive film breaks down, the expression of the Faraday impedance Z_F can be derived through the kinetic model, correspondingly, the parameters such as the rate constants of each electrode reaction and the thickness of the diffusion layer can be analyzed. Taking passive metals and their organic coating systems as examples, this paper reviews the applications of the electrochemical equivalent circuit model (ECM), the point defect model (PDM), the electrochemical kinetic model, the power-law model (PLM), and the Young model in analyzing the properties of oxide films, the performance of coatings, and the kinetic parameters of electrode processes. Moreover, the advantages and disadvantages of each method are discussed. Finally, the development trends of EIS data analysis and physical models are pointed out.

Different welding processes can affect the microstructure and mechanical properties of weld jionts for the common TC4 Ti-alloy. Laser welding produces fine equiaxed grains, and an appropriate increase in the β phase can enhance toughness and ductility, but too much can reduce strength; MIG welds consist of columnar grains, suitable for continuous welding, but the non-unniform distribution of β phase may increase the risk of cracking; TIG welding has high quality, but the dendritic morphology of the welds can lead to a decrease in strength and ductility; Electron beam welding combines fine equiaxed and columnar grains with improving strength and ductility, but has high requirements for the welding environment. The inhomogeneity of the microstructure in the weld joint can lead to localized corrosion, the content of β phase affects the susceptibility to stress corrosion cracking, weld defects and inhomogeneous regions are prone to initiate fatigue cracks, and fine and uniform microstructure can improve fatigue life. Optimizing the welding process is crucial for improving the quality and performance of titanium alloy welds.

It is known that modification with micro arc oxidation (MAO) technique, the physical defects such as porosities or pinholes may commonly exist in the formed coatings on the Ti-alloy surface, which seriously affects the relevant properties and the service life-time of Ti-alloy parts or facilities, in view of this problem, herein it summarizes the research progress on the addition of binary compounds in the electrolyte to modify the relevant properties of MAO coatings on Ti-alloy in terms of the resistance to abrasion, corrosion and high temperature oxidation, as well as the photocatalytic and antimicrobial properties. Furthermore, the future research direction and ideas to create MAO coatings of peculiar performance for Ti-alloy, the utilizing different binary compounds with various function and particle size, even multiple binary compounds etc. are proposed, hoping to provide reference and reference for future research on titanium alloys.

The corrosion fatigue performance of materials in liquid lead-bismuth eutectic is a key factor for the design of key equipment of lead-cooled fast reactors. This article presents a review of the current researches on fatigue behavior of ferritic/martensitic steels and austenitic stainless steels in liquid lead-bismuth eutectic, with focus on the influence of the material factors (microstructure and surface state), environmental factors (temperature and dissolved oxygen concentration) and load factors (strain amplitude and strain rate). Meanwhile, the effect of liquid metal corrosion and liquid metal embrittlement on the corrosion fatigue damage mechanism of materials is also discussed. Moreover, the problems existing in the current researches are identified and discussed. An outlook of the future research directions is also provided.

Cavitation is the main cause of failure of Al-alloy propellers in seawater environment, and understanding the dissolution mechanism of Al-alloy under cavitation is crucial for suppressing cavitation erosion. Therefore, the electrochemical corrosion behavior of 7050 Al-alloy in conditions of cavitation erosion was studied by means of electrochemical impedance spectroscopy (EIS). Results show that capacitance arc in the high-frequency region is related to the surface oxide film impedance and Faraday impedance, the diffusion impedance arc in the mid frequency region is related to the diffusion process of Al³⁺ ions in the Al(OH)₃ film, and the inductance arc in the low-frequency region is related to the intermediate product Al{}_{\mathrm{a}\mathrm{d}\mathrm{s}}^{+}. Then the expression of Faraday impedance Z_F based on the kinetic model is deduced theoretically. The phase angle in the high-frequency region is not constant, and the impedance response of the oxide film under cavitation conforms to the Young model, indicating that its structure is relatively loose, and the resistivity of the inner layer of the oxide film is about 10¹⁰-10¹¹ Ω·cm. In addition, its thickness is about 0.58-0.96 nm, and gradually decreases with the prolongation of cavitation time.

Herein, a method for predicting the service life-time of epoxy-based organic anti-abrasive coatings was stablished based on the integrative treatment of the acquired characteristics of microstructure images of multiple scales for organic coatings. Namely, the multiple scale microscopic structural images were collected by means of scanning electron microscopy, metallographic microscopy, laser confocal microscopy and other methods. Then the quantitative parameter data were extracted from the images using image recognition technology based on deep learning. A dynamic evolution relationship model of coating defect parameters with service time and a life prediction network model of organic coatings were constructed. The results indicate that the constructed evolutionary relationship curve model and network prediction model can accurately predict the lifespan of organic coatings.

The oxidation behavior of F91, nitrided F91 and F92 steels were performed in supercritical water (SCW) at 600-620 ℃/25 MPa. The oxidation kinetics, microstructure and phase composition of the oxide scale were analyzed using an electronic balance, SEM, XRD and XPS. The results show that the oxidation kinetics of F91, nitrided F91 and F92 steels deviate from the parabolic law. The oxide scale formed on the steels were a typical double-layer structure, consisting of an Fe-rich outer layer Fe₃O₄, Fe₂O₃, and a Cr-rich inner layer. Furthermore, MoO₃, Ni(OH)₂ and Cr₂O₃ were also detected on the surface of the oxide scale. In addition, with the increase of oxidation time and temperature, the oxide scale undergoes severe warping-type peeling. The oxidation and peeling mechanisms of F91, nitrided F91 and F92 steels in supercritical water were also discussed.

Ceramic top coatings of 8%Y₂O₃-stabilized ZrO₂ (YSZ) were deposited on the surface of NiCoCrAlY bond coat on DZ411 Ni-based high temperature alloy via high-velocity oxygen fuel (HVOF) spraying with tow type of spraying processes, namely Metco 9M and Praxair 7700 spraying techniques, respectively. The corrosion behavior of the two YSZ thermal barrier coatings was evaluated beneath NaCl deposits in oxygen flow carrying water vapor at 900 ℃. As indicated by the results, the air plasma spraying process can optimize the microstructure of the YSZ ceramic top coat through a judicious adjustment of the plasma gas flow rate and spraying current, resulting in a uniformly dense and less porous structure. Due to its dense microstructure and low porosity, the compact YSZ ceramic top coat is capable of hindering the inward migration of chlorine and oxygen to a certain extent, thereby suppressing the oxidation rate of the NiCoCrAlY bond coating. It follows that, the YSZ thermal barrier coating prepared by the Praxair 7700 spraying process exhibited excellent thermal stability and corrosion resistance.

(La _0.2 Nd _0.2 Tm _0.2 Yb _0.2 Lu _0.2 )₂Zr₂O₇ high-entropy ceramic powders and bulks were prepared by high-temperature solid reaction and hot-pressed sintering method, respectively. The microstructure of the powder and the bulk were characterized, and the corrosion behavior of the high-entropy ceramic was also investigated beneath deposits of molten CaO-MgO-Al₂O₃-SiO₂ (CMAS) at 1300 ℃. The results indicate that the (La _0.2 Nd _0.2 Tm _0.2 Yb _0.2 Lu _0.2 )₂Zr₂O₇ high-entropy ceramic is composed of 70.15% defective fluorite and 29.85% pyrochlore structure. After molten CMAS corrosion at 1300 ℃, the main corrosion products are rare-earth (RE) elements stabilized zirconia and Ca (RE, Ca)-ZrO₂and apatite type (Ca₂RE₈(SiO₄)₆O₂). The corrosion mechanism of the high-entropy ceramic in molten CMAS is as follows: firstly, the high-entropy ceramic partially dissolve in molten CMAS; then the light rare-earth elements with large ionic radii (La, Nd) combine with Ca and Si in molten CMAS to form apatite type Ca₂RE₈(SiO₄)₆O₂, while the heavy rare-earth elements with small ionic radii (Tm, Yb, Lu) continue to remain in zirconia to form rare earth and Ca stabilized zirconia, namely (RE, Ca)-ZrO₂.

The effect of temperature and concentration of NaOH solution, as well as the roughness of material on the electrochemical properties of a Zr-based metallic glass in NaOH solution were studied by means of mass loss measurement, electrochemical technology and scanning electron microscopy (SEM/EDS). The free corrosion rate of Zr-based metallic glass in 0.1 mol/L NaOH is 1.22 times that in 0.01 mol/L NaOH solution. With the increase of temperature, concentration and roughness, the I_corr of Zr-based metallic glass increases, the impedance and the corrosion resistance decrease. The corrosion products on the surface of Zr-based metallic glass increased, and the product corroded area increased. ZrO₂, TiO₂, NiO, CuO substrate oxides and Be(OH)₂ corrosion products were formed on the surface of Vit1 after corrosion. As the temperature increases, the mobility of molecules and ions increases, making chemical reactions more likely to occur, and accelerating the dissolution and corrosion of metallic glasses. The increase of NaOH concentration and the acceleration of corrosion rate may be due to the fact that hydroxide ions (OH^-) in highly concentrated alkaline solutions can react more effectively with the surface of metallic glasses, thereby accelerating corrosion. With the increase of roughness, the effective area of surface exposure involved in the corrosion reaction increases, and the corrosion reaction rate accelerates. After immersion, corrosion fluids accumulate on the surface of the alloy, resulting in an increase in local concentration differences, which lead to non-uniform corrosion and corrosion scarring.

Mg-xAl (x = 3, 5, 7, 9, 12, mass fraction, %) alloys were prepared using both atmospheric pressure solidification and high-pressure solidification methods. The microstructure and corrosion resistance of the alloys were investigated using electrochemical tests, SEM and XPS. The results indicated that, after high pressure solidification at 4 GPa, the desolvation transition was inhibited for the alloy, and the eutectic composition point and maximum solubility point shifted to the right. Compared to atmospheric pressure solidification, the maximum matrix solid solubility of the high-pressure solidified Mg-Al alloys increased by 0.38%-3.43%, while the content of the eutectic β-Mg₁₇Al₁₂ phase decreased by 0.1%-14.9%. Furthermore, high pressure solidification could effectively improve the morphology and distribution of β-Mg₁₇Al₁₂. As a result, the propensity for galvanic coupling corrosion in the high-pressure solidified alloys decreased, and their corrosion resistance was significantly enhanced. Among the high-pressure solidified alloys with different Al contents, the Mg-5Al and Mg-9Al alloys exhibited the best corrosion resistance, which may be attributed to the better protective effect of their surface corrosion products on the substrate.

The anode of oxides-coated Ti-substrate plays an important role in the electro-chlorination system for biofouling prevention in seawater. The surface condition of Ti-substrate affects the performance of the anode. Herein, the effect of hydrogen pre-charging for the Ti-substrate on the microstructure and electrochemical properties of Ti/RuO₂-IrO₂-TiO₂ anode was studied using surface analysis methods like SEM, XRD, and electrochemical techniques such as CV, EIS, potentiodynamic polarization measurement, and accelerated life test. The results show that a surface layer composed of hydrides of TiH_1.5 and TiH₂ is formed on the surface of Ti-substrate after being charged with hydrogen, which reduces the corrosion resistance of Ti substrate. As the current density for hydrogen charging increases, the oxide anode presents more large cracks while the porosity of the oxide coating increased, which enhances the electrochemically active surface area and electrocatalytic activity of the oxide anode for chlorine evolution reaction, but lowers the electrochemical stability of the anode. When the charging current density rises to 500 mA/cm², on the contrary, the electrochemical activity of the oxide anode is decreased somewhat while the stability of the anode is improved to some extent.

The corrosion behavior of Mg-Gd-Y-Zn-Zr alloy in NaCl and Na₂SO₄ solutions was studied using hydrogen evolution measurement, mass loss measurement, cathodic polarization curve, electrochemical impedance spectroscopy and corrosion morphology observation. The results indicated that the corrosion rate of Mg-Gd-Y-Zn-Zr alloy in 0.6 mol/L NaCl solution was much higher than that in 0.6 mol/L Na₂SO₄ solution. A scale of needle-like oxides rapidly formed on the surface of Mg-Gd-Y-Zn-Zr alloy in NaCl solution. As immersion progressed, the oxide scale thickened and a large number of micro-cracks appeared. In the initial stage of Mg-Gd-Y-Zn-Zr alloy soaking in Na₂SO₄ solution, the oxide scale was relatively thin. With the increasing soaking time, the oxide scale exhibited a flocculent characteristic, and significant sulfur enrichment was observed in the corrosion products scale. The corrosion morphology observation showed that the α-Mg matrix of Mg-Gd-Y-Zn-Zr alloy was preferentially dissolved in NaCl solution with deeper and localized corrosion characteristics. In Na₂SO₄ solution, the second phase preferentially corroded with shallower and relatively uniform corrosion. Based on the above results, the influence mechanism of Cl^- and SO{}_{\mathrm{4}}^{\mathrm{2}-} on corrosion behavior of Mg-Gd-Y-Zn-Zr alloy was discussed from the aspects of oxide scale formation and galvanic corrosion.

High-strength structural steel faces corrosion problems in the marine environment, so it needs to be microalloyed with specific elements to improve its corrosion resistance, but the role of trace alloying elements needs to be further investigated, so in this paper, the differences in the corrosion behavior of Sb-containing and Sb-free high-strength structural steel in the atmospheric environment at the east coast region near Donghai bridge, Lingang new distric, Shanghai are comparatively investigated through field exposure tests, electrochemical tests, and various characterization means to elucidate the effect of the addition of Sb on the corrosion resistance of high-strength structural steel. The research has found that the addition of Sb can optimize the microstructure of the steel with refined grains. At the same time, the addition of Sb can slow down the corrosion rate of steel and reduce the corrosion current density. The corrosion product layers formed on Sb-containing steels have better compactness and protectiveness rather than those on Sb-free steels, which can effectively resist the access of aggressive Cl ions into the matrix. In addition, with the progress of corrosion process, the corrosion pits on the surface of Sb-containing steels become larger in diameter and shallower in depth, and the rate of this change is more obvious than that of Sb-free steels, and this statistical result confirms that the addition of Sb can promote the corrosion pattern toward uniform corrosion.

Herein, as the candidate material of anti-fouling, four Cu-Ti pseudo alloys with different Ti contents (mass fraction) of 0%, 5%, 10%, and 15% were prepared by cold spraying method, and their microstructure and composition were characterized by SEM, EDS, and XRD. Meanwhile their corrosion performance in natural seawater is assessed by means of electrochemical measurements, namely free corrosion potential and potentiodynamic polarization curve, scanning vibration electrode (SVET) micro electrochemical measurement and inductively coupled plasma emission spectrum analyzer. Results indicated that in natural seawater, Cu particles and Ti particles on the surface of the prepared pseudo alloy Cu-Ti anode can naturally form micro galvanic couples. With the increase of Ti mass fraction, the corrosion rate of the prepared pseudo alloy Cu-Ti anode is accelerated due to the increased number of micro galvanic cells composed of Cu and Ti particles. When the Ti mass fraction is 15%, the corrosion rate is the fastest, and the copper ion release rate increases by nearly ten times, reaching 280 μg/(cm²·d). This method can effectively accelerate the release of Cu ions from the Cu-Ti pseudo alloy materials and promote their anti-fouling effect.

With the increasing oil and gas exploration, the number of service pipelines is growing, making the accurate prediction of internal corrosion crucial for pipeline integrity management. To address the limitations of traditional machine learning methods in interpreting and generalizing corrosion rate predictions, the monotonic relationships between temperature, CO₂ partial pressure, and corrosion rate are incorporated into a Physics-Informed Neural Network (PINN). This approach is designed to adhere to mechanistic constraints, avoid overfitting and underfitting, and ensure physical consistency. The PINN model is shown to outperform Support Vector Machines (SVM), Extreme Gradient Boosting (XGBoost), and Artificial Neural Networks (ANN), demonstrating superior accuracy and generalization.

The pitting corrosion resistance and intergranular corrosion (IGC) sensitivity of conventional and selective laser melted (SLM) 316L austenitic stainless steels were comparatively assessed via electrochemical measurements, microstructure analysis, and various characterization methods. The results indicate that both the as received conventional and SLM 316L stainless steel exhibit similar pitting corrosion resistance and low intergranular corrosion sensitivity. However after being subjected to sensitization treatment, the types of 316L stainless steel present varying degrees of reduction in the pitting potential, and with the increasing sensitization time, the SLM 316L stainless steel shows significantly lower pitting corrosion resistance than the conventional 316L stainless steel. Additionally, after sensitization treated, the IGC sensitivity of both types of 316L stainless steel increases, with the conventional 316L stainless steel showing a faster growth rate in IGC sensitivity as the sensitization time extends. Micromorphology and compositional analysis indicate that preferential dissolution occur along inclusions or carbides both intergranularly and within the grains. This shows that the difference in electrochemical properties between the two stainless steels is directly related to their different microstructures.

In the design stage of marine engineering materials, it is easy to ignore the influence of microorganisms when the engineering facilities are in actual service. In fact, the alloying elements of the materials have a great impact on the adhesion of microorganisms and the corrosion performance of the materials. Herein, the effect of Mo addition on the corrosion behavior of EH36 marine steel in aged seawater included with sulfate reducing bacteria (SRB) is assessed via electrochemical measurement, optical microscope, scanning electron microscope and X-ray diffractometer etc. The results show that the introduction of Mo can accelerate the SRB induced corrosion of the EH36 steel, namely the thickness of the corrosion product scale of the Mo containing steel is 20 μm, while that of the steel without Mo is 13 μm, the corrosion increment of the former is as high as 40%; More pitting corrosion occurs on the surface of Mo containing steel. The relevant molecular mechanisms indicated that molybdenum could increase the expression of genes related to the adhesion and sulfate reduction processes in SRB biofilms. A denser biofilm and more hydrogen sulfide production accelerated material corrosion. Therefore, when designing materials in microbial environments, microbial factors should be fully considered.

In this study, the stress corrosion cracking behavior of X65 pipeline steel exposed to a supercritical CO₂ environment with low water content and co-existence of O₂, SO₂, NO₂, and H₂S impurities was studied by means of slow strain rate tensile test, four-point-bending stress corrosion test, electrochemical measurement and surface analysis techniques. The effect of CO₂ pressure change on the susceptibility of X65 pipeline steel to stress corrosion cracking (SCC) was discussed. The results show that X65 pipeline steel has a very low SCC susceptibility within the CO₂ pressure range of 7.5 MPa to 14 MPa when being exposed to supercritical CO₂ environment with low water content and co-existence of multiple impurities. X65 pipeline steel does not crack under the coupling effect of stress and impurity-containing CO₂ streams during the overall test duration. However, X65 pipeline steel suffers from the slight ductility loss due to the corrosion effect, thereby demonstrating a certain SCC susceptibility. The SCC susceptibility of X65 pipeline steel decreases first and then increases as the rise of CO₂ pressure from 7.5 MPa to 14 MPa, which is closely associated with the difference of corrosion degree caused by CO₂ pressure change. When X65 pipeline steel is exposed to supercritical CO₂ environment containing impurities, the content of corrosive substances in the formed aqueous phase and the protectiveness of the corrosion product film formed on the steel surface are changed with the variation of CO₂ pressure. Therefore, under the coupling effect of stress and impurity-containing CO₂ streams, the corrosion rate of X65 steel decreases first and then increases with the increase of CO₂ pressure.

The hot corrosion behavior of brazed joints of single crystal Ni-based DD10 alloy beneath Na₂SO₄ deposits in air at 850 and 900 ℃ was studied. The results indicate that after 200 h exposure at 850 ℃, the corrosion layer thickness of the DD10 alloy and the brazed joint was 12 and 14 μm, respectively, demonstrating their similar corrosion resistance. However, after 200 h exposure at 900 ℃, the corrosion layer thickness increased to 28 μm for the master alloy and 44 μm for the brazed joint, indicating a change in the corrosion mechanism, with the brazed joint exhibiting inferior hot corrosion resistance compared to the master alloy. The corrosion products at both temperatures consist mainly of metal oxides, spinel phases, and sulfides. Notably, at 900 ℃, additional corrosion products, including CrTaO₄, (Ni, Co)Co₂O₄, and Ni₃S₂, were identified, which were absent at 850 ℃. During the welding process, the precipitated phases in the weld zone consume corrosion-resistant elements, increase the phase boundaries, and consequently reduce the hot corrosion resistance of the brazed joint.

The corrosion behavior of HPB235 hot rolled round steel rebar buried in iron tailings-based geopolymers in a simulated saline-alkali environment was investigated via electrochemical impedance spectroscopy, corrosion potential and polarization curve methods, so that to clarify the influence of the formular of geopolymers on the electrochemical parameters of the test blocks and the corrosion rate of steel bar. The results show that during the corrosion process by applied electric current, the resistance of the test block increases first and then decreases, indicating that SO{}_{\mathrm{4}}^{\mathrm{2}-} and Cl^- can increase the compactness of the test block. In conditions with setting solution concentration and applied electric current, the test block with reasonable formular is conducive to the protection and delays the corrosion process of steel bars. The influence of ceramic powder content on the corrosion of steel bars is particularly obvious. By comparing the evolution of the free corrosion potential, corrosion current density I_corr and impedance R_c of the steel bar with test geopolymers block of different formulars, it is found that the test block with low ceramic powder content, high sodium silicate modulus, low alkali content and moderate water binder has better protection effect for the steel bar.

The superamphiphobic surface was prepared on B10 Cu-alloy by etching with (NH₄)₂S₂O₈ and NaOH mixed solution, followed by oxidation at 160 ℃ and fluorosilane modification. The microscopic morphology, chemical composition and electrochemical property of the superamphiphobic surface were characterized by means of Laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical means etc.Results show that the optimal preparation conditions were etching at 40 ℃ for 5 h, oxidation at 160 ℃ for 1 h, and 1.0% fluorosilane modification for 1 h. The superamphiphobic surface presents contact angle of water and ethylene glycol 158.1° and 151.2° and the rolling angle close to 0° and 5°, respectively. The electrochemical test shows that compared with the bare alloy, the free corrosion potential of the superamphiphobic alloy is shifted to -0.204 V versus calomel electrode used as the reference electrode, the corrosion current density decreases from 1.192 × 10^-5 A·cm^-2 to 1.649 × 10^-6 A·cm^-2, the corrosion suppression efficiency is 94.3%, and the corrosion resistance is significantly improved. Self-cleaning performance test indicates that the superamphiphobic surface possess excellent self-cleaning properties, and mechanical wear resistance test shows that the superamphiphobic surface can maintain a certain protective effect on the substrate over a long sliding distance.

The corrosion behavior of low alloy steel P110SS in NaCl and HCOOK solutions in high temperature and high-pressure CO₂ atmospheres is studied via high temperature and high-pressure autoclave. While the corrosion morphology and corrosion type, the composition and phase constituents of corrosion products were characterized by means of scanning electron microscopy (SEM), confocal laser scanning microscope (CLSM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). The results show that when setting the same CO₂ pressure, the corrosion rate of P110SS in HCOOK solution at 150 ℃ is 10.6 times that in NaCl solution and 3.3 times at 180 ℃. There are obvious differences in the corrosion products of P110SS in the two solutions. The final corrosion product formed in NaCl solution is FeCO₃, which has a rhombic block crystal morphology, no clear dominant growth direction, and is densely accumulated on the substrate surface. Therefore, it has a good ability to protect the substrate from further corrosion. The final corrosion product formed in the HCOOK solution is FeCO₃, but the difference is that its crystal morphology is in the shape of a "flower cluster", in which the "flower branches" are evenly distributed from three "pinnae" growing outward along the "pinnae axis", with dominant growth planes of (018), (116), and (0012). However, the corrosion scale has a loose structure, so the protection is poor and the corrosion rate is high.

Ag/AgCl electrode is a core component for monitoring chloride ion in concrete. In order to improve the life of Ag/AgCl electrodes, pulsed current electrodeposition was adopted to prepare Ag/AgCl electrodes. The effect of current density and electrodeposition time on the Nernst response, anti-polarization performance, and life of the Ag/AgCl electrodes were investigated in a simulated concrete pore solution. In addition, the properties of the Ag/AgCl electrodes prepared by pulsed current electrodeposition were compared to those of the counterparts produced by constant current. The results show that the former Ag/AgCl electrode has wider potential response, better anti-polarization performance, and longer life than the latter electrode, under the same current density and charge condition. The performance of Ag/AgCl electrodes decreased with the increase of pulsed current density. Under the condition of low pulsed current density, the performance of Ag/AgCl electrode can be improved by extending electrodeposition time. In general, the best performance was observed on the Ag/AgCl electrodes that prepared by electrodeposition at 0.1 mA/cm² pulse current density for 15 h. In addition, the microstructure and the chemical composition of AgCl film on the electrode surface were characterized, and the mechanism of the improvement of performance for the Ag/AgCl electrode by the pulsed current electrodeposition was also analyzed.

The corrosion behavior of Cu-15Ni-8Sn alloy in 3.5%NaCl solution containing 10 mg/L sulfur ions (S^2-) was assessed by means of immersion tests, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results show that after 30 d of immersion in 3.5%NaCl solution without sulfur ions, a stable passivation film is formed on the surface of Cu-15Ni-8Sn alloy, mainly composed of basic copper chloride Cu₂(OH)₃Cl. The passivation film can effectively prevent the further attack of Cl^-, and the average corrosion rate is 0.02235 g·m^-2·h^-1. In sulfur ion-containing solutions, the sulfides (Cu₂S and CuS) formed in the initial stage provide a certain degree of protection. However, with the extension of time, after the alloy is immersed and corroded for 30 days in the solution containing sulfur ions, the corrosion weight loss rate is 0.03418 g·m^-2·h^-1, which is higher than that in the solution without sulfur ions. the corrosion products are turn into the mixture of basic copper chloride (Cu₂(OH)₃Cl), copper sulfate (CuSO₄), copper sulfide (CuS), nickel hydroxide (Ni(OH)₂), and tin sulfide (SnS₂). This porous corrosion film provides much weaker protection for the alloys, and the deterioration and rupture of the sulfide film further aggravate the corrosion process, making the average corrosion rate of the alloy in the sulfur ion-containing environment higher than that in a sulfur ion-free environment.

The impact of nanosecond laser irradiation on the electrochemical corrosion resistance of 17-4PH stainless steel in 3%NaCl solution was investigated by means of electrochemical impedance analysis, surface corrosion morphology observation, and passivation film valence state testing. The results show that the steel after being subjected to laser irradiation with optimal processing parameters presents pitting potential and impedance higher than those after being passivated in 30%HNO₃ solution i.e. conventional passivation. Among others, the concentration of point defects in the passivation film of the former was the lowest. while its Cr/Fe ratio was the highest. These phenomena may be attributed to that the nanosecond laser irradiation can promote the preferential oxidation of Cr to form chromium oxide through instantaneous high-temperature oxidation, while reducing surface defects and roughness, optimizing the passivation film structure, and significantly improving the pitting resistance of stainless steel, so that effectively improving the corrosion resistance of stainless steel.

Herein, a non-circular elbow is proposed, aiming to reduce the erosion of ordinary elbow. Based on the theory of gas-solid two-phase flow, the flow field of the non-circular elbow was analyzed using Fluent software, and the non-circular elbow with better erosion resistance was optimized and the effect of flow velocity, mass concentration and particle diameter on the erosion of the elbow was studied. The results show that: the non-circular elbows are resistant to erosion when their long half axis 1(b) is located in ranges of 5.0-10.0 and 20.0-37.5, while the best erosion resistance for that with b of 30.0 with an enhancement of 17.71% in contrast to the ordinary elbow. The maximum erosion rate of non-circular elbow and ordinary elbow increases with the increase of three factors, among which the flow rate has the greatest influence. Regardless of the value of the three factors, the maximum erosion rate of non-circular elbow with b equal to 30.0, 22.5, 35.0, 32.5 and 27.5 is always smaller than that of ordinary elbow. The difference between the maximum erosion rate of the ordinary elbow and the non-circular elbow with b equal to 30.0 increases with the increase of the three factors. The results of the study can provide new ideas for the structural design and improvement of the elbow.

An electrochemical noise signal recognition network for corrosion monitoring was proposed in order to realize the automatic and accurate analysis of electrochemical noise signals collected in real time. The maximum pooling operation method was adopted to smooth the signal while the details and trend features of the signal are preserved, and the end-to-end training is realized by using a network module design. Based on residual structures and spatial pyramid pooling structures, a feature extraction module was designed to enhance the network's ability to characterize the key features. The model was trained and tested via 5-fold cross-validation based on the experimentally acquired electrochemical noise signals. The results show that the proposed model achieved an overall accuracy and F1 score of 0.9463 and 0.9282, respectively, demonstrating that neural networks can be used to accurately identify electrochemical noise signals.

The manufacturing of silicon steel mainly relies on a technology of long process, which has a long process flow, many process nodes and high carbon emissions. In order to actively respond to the policy related with “carbon emission peak and carbon neutrality” and help enterprises achieve energy conservation and emission reduction. A new method was proposed for preparing high-silicon silicon steel thin strips by scrap steel-electric furnace-twin roll casting-solid decarburization. Herein, the effect of temperature and partial pressure ratio of P{}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}/P_CO on the evolution of the solid decarburization oxide scale on 3.5% (mass fraction) silicon steel tripe was studied. During the process carbon in the silicon steel will react with oxygen, so that being removal, while the Si reacts with oxygen forming SiO₂ oxide scale. The results show that for a setting reaction time, with the increasing temperature the oxide scale thickens gradually; for a setting temperature, the oxide scale gradually thickens with the extending decarburization time. Increasing P{}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}/P_CO will accelerate the formation of the surface oxide scale, which will hinder the decarburization reaction in the early stage of decarburization. This study provides an important reference for optimizing the decarburization process and controlling the thickness of the oxide scale.

A comprehensive survey on the causes of the leakage of the top air cooler of a hydrogenation-type sour water vapor stripping unit, covering aspects such as the process and equipment in question. The air-coolant of the top cooler of the sour water vapor stripping unit consists of H₂O, NH₃, H₂S, NH₄HS, and other chemical substances. The failed tube bundles were examined by means of macroscopic observation, metallographic microscope, SEM, and XRD in terms of the microstructure and composition of the tube steel, morphology and composition of corrosion products etc. The results indicated that the hydrogenation-type sour water vapor stripping unit contained higher concentrations of NH₃ and H₂S, leading to erosion-corrosion that caused progressive thinning of the inner wall of tubes and exacerbated the issue of corrosion and leakage. Analysis revealed that the main cause of the leakage for the air-cooled system was identified as the formation of solid deposits NH₄HS on the inner wall of the tube bundle due to condensation, which leads to non-uniform flow velocity of the coolant in the tube, thus leading to localized erosion-corrosion. Finally, corresponding counter measures were also proposed.