Polymer coatings are of particular importance in corrosion and fouling protection of metallic materials in transport and infrastructure industries due to their advantages of low cost, easy preparation, convenient operation and rich variety. Among various polymer coatings, polyurethane (PU) coatings are widely used as surface protection materials for metallic facility because of their excellent mechanical property and strong resistance to abrasion, heat and corrosion. However, the presence of hydrophilic components in the formulation of PU coatings leads to a decrease in hydrophobicity, which seriously restricts their industrial application in humid environment. Therefore, many efforts have been made to develop new modification strategies for PU coatings in order to obtain stable hydrophobic coatings. The review aims to provide insight into the recent advances in hydrophobic PU coatings, and methods that have used to modify and design hydrophobic PU coatings are summarized. Also, the challenges and outlook of hydrophobic PU coatings are discussed.

Austenitic stainless steel is the main material for reactor core components. In the service process, under the joint action of neutron irradiation, tensile stress and high-temperature and high-pressure water medium in the primary coolant circuit, the low stress brittle cracking phenomenon, namely irradiation assisted stress corrosion cracking (IASCC) can occur, which will lead to component fracture and failure, thus affecting the structural integrity of reactor core components. This has become one of the key issues affecting the safety and economic operation of nuclear power plants. In this paper, the crack-initiation, crack-growth and cracking-sensitivity of IASCC are summarized. Then the main influence mechanisms of localized deformation, grain boundary oxidation, irradiation hardening, irradiation induced segregation (RIS), irradiation swelling, irradiation creep and irradiation induced phase transformation on IASCC are analyzed. Meanwhile, the application of post-irradiation annealing (PIA) for resolving IASCC is summarized. Finally, the prospect of research on IASCC mechanism is discussed. This review is aimed to provide a reference for understanding the issue of neutron irradiation assisted stress corrosion cracking of austenitic stainless steels.

With the rapid advancement of industrial technology in recent years, there are higher requirements in better surface related performance, such as wear resistance, heat resistance, corrosion resistance etc. for some key industrial equipment components. Extreme high-speed laser material deposition, as an emerging surface treatment technology, it subverts the traditional metal surface treatment process, using high-energy laser as the heat source, alloy powder as the cladding material. It realizes a significant increase in cladding efficiency through the optimal coupling of powder and laser, and improves the surface properties of the workpiece by cladding coating with special properties with high efficiency and excellent surface accuracy, which also provides many advantages for the preparation of corrosion-resistant coatings. This paper firstly summarizes the influence of the chemical composition of coating materials on the corrosion resistance of coatings. Secondly, it summarizes the relation between passivation film, microstructure, dislocations, low-angle grain boundaries, and thermal corrosion kinetics. Thirdly, it reviews the effect of EHLA combined with off-site assisted technology on corrosion resistance. Lastly, it summarizes and outlooks on the enhancement methods of the corrosion resistance of the coatings prepared by ultrahigh-speed laser melting and cladding.

Dissimilar metal weld joints are widely used in oil and gas fields. However, the environmentally assisted cracking is easy to occur in and around the fusion region of weld joints, which may seriously affect the safety of oil and gas transportation and cause huge economic losses. Therefore, it is necessary to deeply study the sulfide stress corrosion cracking (SSCC) behavior of dissimilar metal weld joints in acidic oil and gas environments. In this paper, the research progress on SSCC of dissimilar metal weld joints in oil and gas fields were summarized. Firstly, the types and microstructure of the weld joints are introduced. Secondly, the mechanism of the SSCC of weld joints is discussed briefly. The effect of microstructure of dissimilar metal welded joints, temperature, CO₂ partial pressure, applied stress and post-welding heat treatment on the SSCC of dissimilar metal welded joints were reviewed. In the end, the research progress of the SSCC of dissimilar metal welded joint in oil and gas fields in recent decades is reviewed, and the future research direction is prospected.

With good conductivity, pitting resistance, corrosion stability and low cost, polyaniline can be used as a filler in the field of anti-corrosion coatings for metallic materials. However, as a filler for anti-corrosion coatings, the solubility and dispersibility of polyaniline are poor, and the porous structure of polyaniline has weak adhesion to the metal substrates, resulting in unsatisfactory corrosion resistance of the coating. If it can be modified reasonably and effectively, the above problems can be solved. The synthetic methods of polyaniline, such as solution polymerization, inverse microemulsion polymerization, template polymerization, electrochemical polymerization and enzyme catalyzed polymerization, were briefly introduced in the article. In response to the problems in the application of polyaniline in anti-corrosion coatings, the modification and preparation methods of polyaniline nanocomposites were mainly discussed from three aspects: organic acid doping, substitution modification, and in-situ polymerization etc. The interaction between polyaniline molecular chains can be reduced by modification, thereby its solubility and corrosion resistance can also be improved. Then, the research status of graphene oxide/polyaniline, carbon nanotubes/polyaniline, inorganic/polyaniline, and organic/polyaniline nanocomposites in the field of metal corrosion protection in recent years was introduced. Finally, it is pointed out that the preparation process of polyaniline nanocomposites is complicated, which may be affected by environmental factors, and the anti-corrosion mechanism of polyaniline nanocomposites needs to be further clarified at this stage. While the development of "intelligent" polyaniline nanocomposites with long-term stability and strong corrosion resistance will be the future research direction.

The resistance to high temperature steam sterilization process of tinplate coated with polyester, epoxy-phenolic and epoxy-amino coating respectively was studied by cathodic polarization and electrochemical impedance spectroscopy (EIS), and then the relevant mechanism was also discussed. The results showed that the cathodic polarization current can effectively distinguish the protective properties of coated tinplate for food packaging, and the higher the cathodic polarization current, the worse the protective properties of the coating. The corrosion resistance of epoxy phenolic coating is the best, followed by the epoxy amino paint, and that of polyester coating is the worst. After high temperature steam sterilization at 127^oC for 1 h, the protection performance of the coated tinplate in 3.5%NaCl solution decreased, and the low-frequency impedance modulus decreased, namely the minimum value was 5.4% and the maximum was 69.7%. Overall, the resistance to high temperature steam sterilization of the three coatings was similar. The bonding strength between the coating/ tinplate and the wettability of the coating were the main parameters that affect its resistance to high temperature steam sterilization process. The better the bonding strength and the worse the wettability of the coating, the better the resistance to the high temperature steam sterilization process.

The effect of mill scale on the evolution of the fast-stabilized rust layer and anti-corrosion performance of Q345qDNH weathering steel in industrial atmospheric environment was studied via real atmospheric exposure testing, field emission scanning electron microscope (FE-SEM), field emission electron probe (FE-EPMA), micro-Raman Spectrum and electrochemical technique. The results showed that the presence of Fe₃O₄, Fe₂O₃, a small amount of FeO and FeCr₂O₄ in the oxide scales could improve the compactness of the rust layer, but could not change the types of corrosion products of Q345qDNH weathering steel. The corrosion products of the bare steel and the steel with mill scale were mainly composed of γ-FeOOH, α-FeOOH and Fe₃O₄. In the three types of corrosion products, the propagation of α-FeOOH is an inward growing process. The steels with mill scales present better rust layer stabilization and corrosion resistance due to the existence of Fe₃O₄ in the mill scale could promote the formation of α-FeOOH.

TiO₂ nanotube arrays are decorated with Bi₂S₃ by a successive ionic layer adsorption and reaction (SILAR) method, aiming to enhance the photoelectric conversion ability of TiO₂ and photogenerated cathodic protection performance of TiO₂ nanotube arrays for 304 stainless steel. B-(x)/TiO₂ nanotubes (x = 1,3,5,7) were prepared by changing the number of deposition cycles of Bi₂S₃. The morphology, structure, light response ability and photogenerated carrier separation efficiency of Bi₂S₃/TiO₂ nanocomposites were examined by means of XRD, SEM and XPS. At the same time, the photoelectrochemical properties of Bi₂S₃/TiO₂ nanocomposites were tested under simulated sunlight. In addition, the effect of the number of deposition cycles of Bi₂S₃ on the photocathodic protection performance of TiO₂ nanocomposites was also studied. After Bi₂S₃ modification, the band gap of the composites decreases, and the recombination rate of photogenerated carriers decreases greatly. When a 5 cyclic deposition of Bi₂S₃ is adopted, the photoelectrochemical properties of the prepared nanocomposites are the best. Of which the band gap is reduced to 2.9 eV, and the photocurrent density is increased from 200 μA·cm^-2 to 550 μA·cm^-2 under the condition of turning on light, which is 2.75 times that of the bare TiO₂ nanotube arrays. After coupling the modified nanocomposite with 304 stainless steel, the coupling potential can be reduced to -1.0 V under simulated sunlight, which is about 80 mV lower than the coupling potential before modification, which can further improve the photogenerated cathodic protection effect on 304 stainless steel.

A superamphiphobic surface film with good corrosion protection durability was successfully prepared on B10 Cu-alloy by chemical etching with 1.5 mol/L FeCl₃ solution and then modifying with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The contact angle of water and ethylene glycol on the prepared surface is 158° and 151° respectively. The morphology, chemical composition and corrosion resistance of the superamphiphobic surface film/B10 Cu-alloy were characterized by means of SEM, XRD, EDS and XPS as well as EIS test and Tafel polarization curve and electrochemical test. The results show that compared with the bare B10 Cu-alloy, the corrosion potential of the superamphiphobic surface film/B10 Cu-alloy is positively shifted to -0.248 V, its corrosion current density I_corr = 2.05 × 10^-6 A·cm^-2 decreases by one order of magnitude, and the charge transfer resistance increases by one order of magnitude, showing excellent corrosion resistance. The charge-transfer resistance of the superamphiphobic film/B10 Cu-alloy after immersion in 3.5%NaCl solution for 5 d is still significantly higher than that of the bare Cu-alloy, in other words, it still maintains good corrosion resistance.

The corrosion behavior of two novel Ni-Cr-Mo-V steels (steel A and steel B) in a simulated seawater environment was comparatively investigated by means of immersion test, electrochemical test, and microscopic observation. The results indicate that the cathodic and anodic electrochemical processes in the corrosion process of the two steels are consistent, while the steel B shows a more positive corrosion potential and lower corrosion current density. The main inclusions in steel A is CaS-MgO-Al₂O₃ with sizes ranging from 3 to 5 μm, which act as active sites of localized corrosion initiation; in comparison, the Al₂O₃ inclusions in steel B with sizes ranging from 1 μm to 3 μm, the tendency of localized corrosion induced by which is relatively light. After long-term corrosion for 42 d, the two steels all show uniform corrosion with bilayered corrosion product scale composed of a dense inner rust layer and a loose outer rust layer. However, the thickness of the rust scale of steel A was greater than that of steel B. Besides, there existed longitudinal cracks in the inner rust layer of steel A, which may deteriorate the protective property of the rust scale.

Trial low alloy steels based on Q420 steel were prepared by alloying with a little amount of Cu 0.5%, 1.0%, 1.5% and 2.0%, mass fraction. Then their corrosion behavior was assessed in an artificial solution (i.e. 10%NaCl (mass fraction) solution with pH 0.85) as a simulation of the corrosive environment of the bottom plate of cargo oil tanks were studied by means of immersion tests, SEM, XRD, TEM, and other methods. The results indicate that the low alloy steel with 1.0%Cu of a microstructure of ferrite and pearlite can ensure excellent corrosion resistance at the strength level of Q420 steel. The addition of Cu plays a crucial role in the corrosion resistance of the low alloy steel. As the soaking time prolongs, the corrosion rate of the trial steels with 5 different Cu-content shows an overall downward trend. The trial low alloy steel with 1%Cu presents a corrosion rate of 0.29 mm/a, which is 43% lower than the Q420 benchmark steel. The study proves that the addition of Cu has a positive effect on the uniform corrosion of Q420 in the simulated bottom plate environment of cargo oil tanks.

Atmospheric corrosion of steels is a universal problem. Improving the prediction accuracy of atmospheric corrosion rate of steels in China is of great significance for setting corrosion margin, preventing corrosion failure and reducing the corrosion induced economic loss. For different type of steels in different regions of China, a prediction method of corrosion depth for steels based on machine learning algorithm was proposed, including data acquisition and processing, model training and testing, model evaluation and screening, feature ranking and other steps. The applicability of different algorithms was evaluated and the optimal algorithm of the corrosion prediction for steels was selected. Firstly, the corrosion data, environmental- and materials-features of 10 atmospheric exposure stations in China were collected. The corrosion depth of steels was predicted by using standard formulas and 6 machine learning algorithms. The grades of environmental corrosivity of atmospheric exposure stations were evaluated. Then, the prediction errors were analyzed, the accuracy of environmental corrosivity grade assessment was compared, and the prediction model suitable for steel corrosion was screened. Moreover, the sensitivity of materials- and environmental-features were analyzed, revealing the main factors of environments and materials affecting the atmospheric corrosion of steels. The results show that compared with the standard formula, the accuracy of the prediction models is greatly improved by RF and LSTM algorithms. In addition to the terms such as temperature, humidity, sulfate- and chloride-deposition rates mentioned in standard formulas, the acidity, alkalinity and rainwater corrosive ion concentration of rainwaters have a great impact on the corrosion of steels, which should be considered.

The structure and thermal property of Zr-based amorphous alloys Zr41.2Ti13.8Cu12.5Ni10Be22.5(Vit1) and Zr55Cu30Al10Ni5(Zr55) were determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The electrochemical behavior of two Zr-based amorphous alloys and two traditional metal alloys (304 stainless steel and 6082 Al-alloy) in 3.5%NaCl and simulated seawater solution were comparatively assessed via electrochemical workstation, scanning electron microscope (SEM) and energy dispersive spectroscope (EDS). The results show that the four metallic alloys present pitting corrosion, but the amorphous alloys show higher corrosion resistance. Tacking the polarization curves aquired in 3.5%NaCl solution as comparison, it follows that the polarization curves of amorphous alloys and conventional alloys in the simulated seawater showed negative shift, which was attributed to the large amount of sulfate and chloride dissolved in the simulated seawater. Compared to the traditional metallic alloys, the passive film formed on the surface of amorphous alloys is more stable.

The corrosion performance of marine engineering welded structures is of significance for the offshore engineering's safety, however, for that there is hardly any scientific and systematic evaluation methods. Herein, two kinds of welded structures are designed and made with two solder alloys of different composition. Then the corrosion performance of the two coupons were comparatively evaluated by immersion in an artificial seawater containing corrosive bacteria. It is surprisingly found that macroscopic testing results (such as electrochemical impedance, massless testing, etc.) and microscopic testing results (micro-area electrochemical scanning) did not exactly match each other. Therefore, it is not rigorous to evaluate the corrosion resistance of welded structural parts only via the conventional electrochemical method or massless testing, but the microscopic electrochemical testing method should also be applied. Combined with the macroscopic and microscopic corrosion tests, we can be more accurately matching and selecting the base metal and solder of the welded structure, which will guide us to improve its overall seawater corrosion resistance.

Composite materials with different Al content Fe-Cr-xAl/La₂Zr₂O₇ (x = 4, 8 and 10, mass fraction, %) were prepared by mechanical alloying and spark plasma sintering technique. Then the oxidation behavior of the composite materials in air at 1000^oC is studied via mass change measurement, scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and X-ray diffractometer (XRD). The results show that in the initial oxidation stage, the oxidation rate of the composite materials gradually increases with the increase of Al content. However, in the stable oxidation stage, the oxidation rates of the three composite materials are similar to each other. During the oxidation process, the formed oxide scale on the composite containing 4%Al remains as stable α-Al₂O₃ with slow growth rate. On the composite containing 8%Al, metastable θ-Al₂O₃ with faster growth rate is generated on the surface while FeAl phase is precipitated in the initial oxidation stage, which accelerates the oxidation. The higher the Al content, the more the FeAl phase precipitated and the obvious higher the oxidation acceleration. With the prolonging oxidation time, θ-Al₂O₃ gradually transforms into α-Al₂O₃, and the oxidation behavior of the three composite materials is similar. The results of this study may provide a reliable reference for the development of the perforated head of long-life and high-reliability for making seamless steel pipes.

Spinel coatings Mn_1.5Co_1.5O₄ on steels SUS430 and Crofer22H were prepared via electrophoretic deposition, aiming to improve their high-temperature oxidation resistance and electrical conductivity as SOFC interconnector. Afterwards, their oxidation behavior at 700-800^oC and electrical conductivity after oxidation were characterized by means of intermittent weighing method, X-ray diffraction (XRD), scanning electron microscope (SEM) and 4-wire electrical resistance tester (ASR). The result showed that relatively dense coatings may be acquired by two-step sintering. The oxidation rate of Mn_1.5Co_1.5O₄/SUS430 oxidized at 800^oC for 1000 h is about (1-3) × 10^-14 g²·cm^-4·s^-1, and the oxidation rate constant decreases by 1-2 orders of magnitude as the temperature decreases. Mn_1.5Co_1.5O₄/SUS430 formed a thinner Cr-containing oxide scale due to its own low Cr content, at the same time, the Fe diffused outward from the substrate steel during the oxidation process to further promote the coating densification. Ultimately, after high temperature oxidation, the Mn_1.5Co_1.5O₄/SUS430 showed ASR values lower than those of the Mn_1.5Co_1.5O₄/Crofer22H.

Corrosion behavior of typical connected parts for aeroengines compressor in acid salt spray and humid-heat environment were simulated with CorrosionMaster software, meanwhile, of which the tests by acid salt spray and in humid-heat conditions were carried out according to the national military standards of China (GJB). Finally, the simulation results were verified with the real test results. It follows that the simulation generated corrosion data of the typical connected parts by acid salt spray and in humid-heat environment are consistent with those acquired by the real tests, therefore, the simulation results can provide valuable reference for corrosion risk prediction and evaluation of metal structures.

Three kinds of steel used for photovoltaic pile foundation were buried in a selected site in Xinjiang area for 30 d, whilst the accelerated soil acceleration test was carried out in the laboratory for comparison in terms of their corrosion behavior. Then their corrosion morphology and corrosion products were characterized by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), and the corrosion behavior of different photovoltaic pile steels in Xinjiang soil environment were compared by electrochemical tests. The results show that compared with the other two corrosion-resistant steels, the Q355B carbon steel suffers from the most serious corrosion. The corrosion products are mainly iron compounds composed of α-FeOOH and γ-FeOOH. The three steels exhibit the same corrosion acceleration ratio in the accelerated corrosion tests with the same parameters, and their corrosion mechanism is basically the same as that of the real field corrosion test.

Microchannel heat exchangers of Al-alloy are the important component for air conditioner, of which the primary material is 3003 Al-alloy. In practical applications, the Al-alloy is suffered from corrosion and then results in the heat exchanger failure. This paper firstly introduces the corrosion problems existing in microchannel heat exchangers, then reviews the corrosion causes and influencing factors, such as coolants, micro-galvanic corrosion of the alloy and air pollutants etc., and summarizes corrosion control methods such as inhibitors and surface treatments. Finally elaborates some surface treatment techniques developed for 3003 Al-alloy, including electroless plating, anodizing, chemical conversion, sol-gel treatment etc., which probably provide references for the development and production of corrosion-resistant microchannel heat exchangers of 3003 Al-alloy.

The atmospheric corrosion behavior of Mg-alloys AZ31B and AZ91D at alternating low temperatures was investigated via laboratory simulation i.e. a high/low temperature dry-humid alternating test chamber. The corrosion rate of the two alloys was positively correlated with temperature as the results acquired by the mass loss measurement. The morphology analysis showed that the two alloys exhibited obvious localized corrosion in the low temperature environment. Combined with corrosion rate and morphology observation (SEM, CLSM), it was found that AZ31B Mg-alloy was more seriously corroded than AZ91D Mg-alloy at the same temperature, but AZ91D Mg-alloy showed obvious pitting characteristics. The average pitting density and depth of AZ91D Mg-alloy were larger than that of AZ31B Mg-alloy, but the corresponding average pitting volume was smaller. FTIR and EDS analysis showed that Mg(OH)₂, MgO and carbonates were the main components of the corrosion products formed at 15-25^oC, while the content of MgO^{in the corrosion products was higher at lower alternating temperatures (from -5oC to -15°C and -5oC to -25°C). EDS results suggested that Aland Cl were present in the area where AZ91D Mg-alloy pitting was serious. It was considered that the destruction of the oxide scale by Cl- had an important influence on the pitting corrosion of AZ91D Mg-alloy.}

Ni-based high-temperature alloys (NiCrAlY) are commonly used in the hot sections of aerospace engines. Hot section components such as combustion chambers, guide vanes, and turbine blades require thermal barrier coatings (TBCs) for protection. TBCs consist of an oxidation-resistant metal bond coat (BC) and a ceramic top coat (TC) that provides thermal insulation. The BC material is also NiCrAlY alloy, with Al and Cr content higher than the substrate Ni-based high-temperature alloys, leading to a 53 mV lower corrosion potential for BC compared to the substrate, therefore, resulting in galvanic couple with the BC. Herein, the influence of different Al contents in NiAl alloys on their corrosion behavior in dilute H₂SO₄, simulating the corrosive environment was studied. The result reveals that Ni₉₅Al₅ exhibits the highest corrosion potential and the lowest corrosion current density, while Ni₇₅Al₂₅ has a lower corrosion potential. The research demonstrates that a high Al content in the BC is the primary cause of corrosion in conditions of natural environment.

The cast WE43 Mg-alloy with addition of 0.04%Be (WE43-0.04Be) was prepared by electromagnetic stirring melting and casting process, and then subjected to solid solution treatment at 525^oC for 10 h plus aging treatment at 225^oC for 6, 10 and 14 h, respectively. Afterwards, the microstructure, mechanical property, oxidation behavior and flame-retardant property were assessed for the prepared alloys. The results showed that the WE43-0.04Be alloy aged for 10 h possessed the best comprehensive performance, namely its tensile strength, yield strength and elongation were 253 MPa, 209 MPa and 8.3% respectively, which could meet the mechanical property requirements for high-speed railway structural parts. The WE43-0.04Be alloy will not burn in air when heated up to 850 ^o C in a furnace. A mixed oxide scale composed of compounds of Mg and alloying elements was generated on the surface of the alloy, thus inhibiting the inwards migration of aggressive species approching onto the interface oxide scale/WE43-0.04Be alloy.

The effect of fatigue damage under stress-controlled mode on mechanical properties and corrosion behavior of AA7075-T651 Al-alloy was systematically investigated through the interrupted fatigue test, tensile test, electrochemical measurement and microstructure observation. The results show that the acquired fatigue damages can not only improve the comprehensive mechanical properties of AA7075 Al-alloy, but also increase its corrosion resistance. It follows that the change of microstructure (the increase of dislocation density and secondary phase precipitation) before and after being experienced fatigue damages is the fundamental reason that affects the mechanical properties and corrosion behavior of AA7075 Al-alloy.

TA2 pure-Ti is a new generation of marine pipeline material, and the flowing seawater induced failure of its passivation film can deteriorate the durability of TA2 pure-Ti pipes. Hence the effect of flowing seawater on the corrosion behavior of TA2 pure-Ti being subjected to different surface treatments is of great significance for evaluating the service performance of TA2 pure-Ti pipes. Herein, the corrosion behavior of two surface treated TA2 pure-Ti rings in flowing seawater was comparatively studied in a home-made seawater pipeline integrated simulation set by means of measurements such as dynamic potential polarization, electrochemical impedance, and Mott Schottky analysis, as well as characterization of corrosion morphology and corrosion products. The results showed when the seawater flow rate below 5 m/s, the change in seawater flow rate had a relatively small impact on the corrosion resistance of the passive film on the surface of TA2 pure-Ti. When the potential rises, the passive film on the surface of TA2 showed a transient dissolution in flowing seawater, but it would soon be re-passivated, which did not have a significant impact on the corrosion resistance of the substrate material. Compared to the surface passivation treated ones, the polished TA2 exhibit limited diffusion characteristics of cathodic polarization in flowing seawater. This is mainly due to the presence of a passivation film on the surface of the passivated TA2, which consumes less oxygen than the surface polished ones that have not yet formed a passivation film. The depolarization of the polished TA2, which was controlled by oxygen mass transfer rate develops slowly, resulting in a limit current density that does not vary with the potential. The passivation films on the TA2, after being subjected to two surface treatments only exhibit n-type semiconductor characteristics in seawater, and after polarization testing, the material surface is flat without significant local corrosion.

The effect of the presence of nitrate and galvanic couple on the crevice corrosion behavior of 7075-T651 Al-alloy in 3.5%NaCl solution is investigated by the electrochemical tests and surface analysis techniques. The results indicate that the nitrate as an oxidizing agengt could promote the formation of passive film, so that inhibit the corrosion of the Al-alloy. However, when there is a formed crevice on the Al-alloy in a solution without nitrate, inside the crevice corrosion is hard to occur and develop, in the contrast, in a solution with the presence of nitrate, which could be reduced forming NH₃, the later agent may accumulate inside the crevice and selectively dissolve the copper particles, thereby induced the nucleation of pitting corrosion, afterwards, further promoted the propagation of crevice corrosion. After coupling with 304 stainless steel, a large Galvano-corrosion driving force is generated between the electrodes inside and outside the crevice, which accelerates the metal dissolution and solution deterioration process in the crevice, resulting in much more serious crevice corrosion in the solution with nitrate.

A natural exposure test of 1050A Al-alloy was conducted in the typical atmospheric environments in the regions Qingdao, Dongying, Weihai and Weifang of Shandong Province for a period of 42 months. Afterwards, the corrosion behavior of the alloy was studied by means of macroscopic- and microscopic-morphology observation, corrosion rate measurement, corrosion product analysis and electrochemical test. The results show that 1050A Al-alloy has good atmospheric corrosion resistance, and the corrosion rate decreases with the increasing exposure time. Corrosion products are mainly Al-oxide and -hydroxide. The corrosion rate of 1050A Al-alloy tested at four different test sites may be ranked as following descending order: Dongying>Weihai>Qingdao>Weifang. The corrosion rate decreases with the extension of exposure time, which may be related to the presence of corrosion product scale. The laser confocal microscopic morphology analysis reveals that the corrosion is mainly pitting corrosion. The size of Pits was mainly below 10 μm after 42 months of exposure. The EIS result indicates that there exists a discernible discrepancy in the corrosion extent between the upward- and downward-sides of the test coupons at the initial exposure stage, which then gradually diminishes as the exposure time prolongs.

Micro-arc oxidation (MAO) can improve the corrosion resistance of Mg-alloys, but it has the deficiency of high energy consumption, which restricts its large-scale application on Mg-alloy components. In order to reduce the energy consumption of micro-arc oxidation, micro-arc oxidation coatings were prepared on the surface of AZ31B Mg-alloy in an electrolyte of Na₂SiO₃ 20 g/L, NaOH 2 g/L and NaF 2 g/L by pulsed power supply, and the effects of electrical parameters (frequency, duty cycle and current density) on the unit energy consumption and corrosion resistance of the coatings were studied by means of scanning electron microscopy, electrochemical testing and salt spray test. The results show that the frequency has less effect on the unit energy consumption of the coatings, but the higher the frequency, the better the corrosion resistance of the coatings; the duty cycle has more obvious effect on the energy consumption, with the increase of the duty cycle, the unit energy consumption of the coatings decreases, but the corrosion resistance decreases; the current density also has a significant influence on the energy consumption, the higher the current density, the higher the unit energy consumption of the coatings, but the change of current density has less effect on the corrosion resistance of the coatings.

Mg-alloys, as light-weight high-performance materials, have extensive potential applications in various fields. However, in practical use for metal-air batteries, their electrochemical performance is significantly influenced by the composition and condition of the anode material. Therefore, to develop more efficient Mg-air batteries, it is crucial to study the electrochemical performance of commercial Mg-alloys in the presence of different electrolytes. This study focuses on the corrosion and electrochemical performance of extruded MB1 and cast MB8 Mg-alloys in NaCl solutions of varying concentrations in terms of the anode utilization efficiency, discharge voltage, and grain structures. The results indicate that the electrochemical performance of Mg-alloys was improved significantly as the NaCl electrolyte concentration increases. Specifically, with increasing concentration, the anode utilization efficiency was gradually improved, accompanied by higher discharge voltages. When the discharge current density is 10 mA·cm^-2 in 4 mol/L NaCl electrolyte, the peak anode utilization efficiency for cast MB8 and extruded MB1 Mg-alloys reach 41.8% and 38.8%, respectively. The extruded MB1 alloy, due to its finer grain structure, exhibits higher activity, slightly higher and more stable discharge voltage in comparison with the cast MB8 alloy. Besides, the cast MB8 alloy has relatively coarser grains, but it has a lower self-corrosion rate and higher anode utilization efficiency. In sum, the extruded MB1 alloy shows higher activity, while the cast MB8 alloy exhibits superior corrosion resistance. These findings offer useful guidance for the future development of Mg-air batteries and are expected to further advance the application of Mg-alloys in the field of energy storage.

The corrosion behavior of welded partitions of 3003 Al-alloy, used for radiators of high-speed train, in artificial solution of settling dust, which aims to simulate the synergistic ation of the settling dusts and rains on the partitions in the real service, was studied by means of immersion test, polarization curve measurement, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Meanwhile, the relevant prediction model for the corrosion depth of welded partitions was established. The results show that, the pitting corrosion is dominant at the initial stage of corrosion, and then gradually evolves into intergranular corrosion. The main corrosion products of welded partitions are Al(OH)₃ and AlCl₃. In comparison with those of the as received ones, the corrosion potential of welded partitions after immersion for 180 d decreases by 24.5% and the corrosion current density increases by 156.7%. A prediction model for the maximum corrosion depth of welded partitions was established based on data of the immersion test results and the measured corrosion depth of the very welded partitions after 8 a of live vehicle service.