Marine Atmospheric Environment Research Articles

Study on the Effect of Dry and Wet Cycle Time Ratio on the Corrosion Behavior of 2198 Aluminum–Lithium Alloy

ABSTRACTThe corrosion of 2198 aluminum–lithium alloy in a marine atmospheric environment was simulated using a wet–dry alternating experimental setup. Weight‐loss measurement methods, electrochemical impedance spectroscopy (EIS), scanning electron microscopy/energy‐dispersive spectroscopy (SEM/EDS), macroscopic morphology testing, three‐dimensional morphology testing, and X‐ray photoelectron spectroscopy (XPS) were used to study the wet–dry alternating corrosion behaviors and mechanisms of 2198 aluminum–lithium alloys under simulated marine atmospheric environment. The results indicate that corrosion weight loss increases with decreasing wet‐to‐dry ratios, accompanied by an increase in the corrosion rate. Various data suggest that the primary corrosion products are composed of Al2O3, AlO(OH), and AlCl3. The reduction in the wet‐to‐dry ratio leads to the enrichment of Cl⁻ within the corrosion products, extending the contact time between the substrate and the medium, thereby intensifying the hydrolysis of Al³⁺. This exacerbates the dissolution at pitting sites, which in turn erodes and breaks down the corrosion product film, accelerating the overall corrosion process.

Study on Corrosion Damage Behavior of 300M Ultra-high Strength Steel in Marine Atmospheric Environment

Abstract The marine atmospheric environment exposure test of 300M ultra-high strength steel was carried out at Hainan test station. The corrosion damage behavior of 300M ultra-high strength steel in marine atmospheric environment was studied by macroscopic and microscopic corrosion morphology, tensile properties and stress corrosion. The results show that the comprehensive corrosion behavior of 300M ultra-high strength steel occurred in the marine atmospheric environment. The color of the corrosion products changed from red to reddish brown, dark brown and black, and the maximum corrosion depth in the three years was 400μm. The corrosion had a significant effect on the tensile properties during the test. The tensile strength and elongation of 300M ultra-high strength steel decreased by 13.3 % and 81.8 %, respectively, which indicated that the effect of corrosion on the plasticity of the material was much greater than that on the tensile strength. Corrosion also caused a decrease in fracture toughness, and the fracture toughness of 300M ultra-high strength steel decreased by 26% in 2 years. The results of stress corrosion show that the crack propagation of 300M ultra-high strength steel is very rapid in the initial stage of marine atmospheric environment test, and the crack propagation length reaches 10.836mm in 7 days. The stress corrosion threshold KISCC of 300M ultra-high strength steel is 24.48MPa•m1/2, and the relative index of stress corrosion cracking sensitivity is 0.31, which indicates that 300M ultra-high strength steel is very sensitive to stress corrosion in marine atmospheric environment. The results show that 300M ultra-high strength steel has poor adaptability to the marine environment. Therefore, it is necessary to adopt excellent surface treatment process and spray aging resistant coating to effectively protect 300M ultra-high strength steel to ensure its long-term reliable use in the marine environment.

Variation of Corrosion Characteristics and Tensile Performances of WE43 Alloy Under Marine Atmospheric Environment.

This study aims to examine the variation in corrosion characteristics and tensile properties of WE43 magnesium alloy in an actual marine atmospheric environment by means of outdoor exposure tests. The macroscopic corrosion morphology, microstructure, and tensile properties were analyzed. The results indicated that WE43 alloy will corrode rapidly during exposure under marine atmospheric environmental conditions, resulting in a loose and porous Mg(OH)2 layer on the surface. The Mg matrix was mainly consumed as an anode, leading to the occurrence of corrosion pits. With the increase in exposure time, both the tensile strength and plasticity of WE43 alloy gradually deteriorated. After exposure for six months, the elongation and area reduction were significantly reduced, with a reduction ratio of more than 50%. After 18 months of exposure, the ultimate strength of the alloy decreased from 359 MPa to 300 MPa. According to an analysis of fractures in the alloy, the corrosion pits on the sample surface were the main reason for the decrease in tensile properties.

Study on corrosion behavior and first-principle analysis of M50 steel in lubricating oil contaminated by salt water

The corrosive wear of M50 steel in lubricating oil contaminated with saline is a form of wear that often occurs within the main shaft bearings of aviation engines carried by aircraft working at sea. In the present paper, the corrosion behavior of M50 steel in lubricating oil contaminated with saline was studied. The open-circuit potential, polarization curve and impedance spectrum were analyzed by rotating electrochemical corrosion wear test. A three-layer interface microscopic molecular model was established with Materials Studio to simulate the dynamic corrosion evolution process of M50 steel self-matching pairs and the adsorption energy was calculated. The results show that the corrosion type is pitting corrosion. With the increase of saline concentration, the corrosion area becomes wider and shallower, and the size of the pitting core gradually decreases. The weight loss of M50 steel increases over time, but the trend slows down, which is also shown in the MS simulation results. Electrochemical tests show that the tribocorrosion of M50 steel is related to load, speed. As the load increases, the corrosion rate decreases. And, as the speed increases, the corrosion rate increases. This has practical significance for extending the understanding of tribocorrosion of M50 steel in marine atmospheric environments.

Corrosion Behavior of 700L Automotive Beam Steel in Marine Atmospheric Environment.

The marine atmospheric corrosion behavior of 700L high-strength automotive beam steel exposed for 36 months was investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and electrochemical technology. The corrosion kinetics of 700L steel followed the exponential function: D = 4.85t1.23. The rust layers were mainly composited of γ-FeOOH, α-FeOOH, γ-Fe2O3, and Fe3O4, regardless of the exposure duration. With an extended exposure time, the porosity, cracking, and spalling of the rust layers increased, and the densification and thickness uniformity decreased. Electrochemical measurements displayed that the corrosion resistance of the rusted 700L steel gradually decreased with increasing exposure time. A good correlation was found between rust layer composition, microstructure, and corrosion resistance.

Novel Understanding of the Formation and Protectiveness of Corrosion Product Film on Ca–Sb–Cr Weathering Steel

The addition of Ca and Sb in Cr‐bearing steel presents improved corrosion resistance during the field exposure test in a marine atmosphere environment. Through local hydrolysis reactions, Ca and Sb can form CaO, Sb2O3, and Sb2O5 to prevent the intrusion Cl− into the corrosion product film, which improves the protectiveness of the corrosion product film and reduces the corrosion rate. The formation of CaCl2 decreases the relative content of β‐FeOOH and makes the corrosion product film more stable. Due to the inhibition of Sb on the local acidification of corrosion product film, Ca and Cr are able to bond with more hydroxide for generating the corresponding oxides and improving the corrosion resistance of Cr‐bearing steel.

Study of corrosion and failure mechanism of the galvanized steel pipes of meteorological tower serviced in the South China Sea

Corrosion issues of steel in the natural tropical marine atmospheric environment widely exist, and they can easily cause the failure of engineering equipment. However, the related studies are poor. Therefore, a deep analysis of the corrosion behavior and failure mechanism of steel materials in natural environments is urgent and important. In this work, the corrosion and failure mechanisms of galvanized steel pipes of a meteorological tower in the South China Sea were deeply studied. Results demonstrated that galvanized steel pipes at a low height happen a serious uniform and localized corrosion, while the bottom surface of each pipe facing the ground is severely corroded. The damage to the galvanized layer and the subsequent steel corrosion in high temperature and humidity conditions are mainly caused by bacteria and Cl−. Some bacteria with high corrosivity, such as Desulfovibrionales, Seminibacterium, Acinetobacter, Ralstonia, Proteobacteria Streptococcus, and Lactobacillus, are found beneath the rust layer, and they can significantly accelerate steel corrosion. The maximum localized corrosion rate is 0.20 mm/y.

Research on the Optimal Protection Parameters of Graphene Composite Conductive Coatings Combined with Impressed Current Cathodic Protection Technology in Marine Atmospheric Environments

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating combined with ICCP technology in a marine atmospheric environment, the effects of the coating damage area (A), impressed voltage (B), and distance from the contact point (C) on the protective performance of the coating were investigated via orthogonal experiments. The optimal protection voltage and effective protection distance were verified by super-depth-of-field morphology observations and electrochemical tests. The orthogonal experimental results show that the primary and secondary orders affecting the protective performance of the conductive graphene composite coating are as follows: applied voltage (B) > coating damage area (A) > distance from the point of contact (C). The optimal protective parameters of the coating in the marine atmospheric environment are an applied voltage of 0.7 V, a damage rate of ≤1%, and a distance from the point of contact of 190 mm. The experimental results show that the corrosion potential of the sample is the highest under an applied voltage of 0.7 V, and the corrosion products do not diffuse to the surface of the coating. When the polarization resistance (Rp) values at 110 mm and 190 mm from the negative electrode at the point of contact are greater, the corrosion rate is lower, and the coating protection performance is better.

Investigation of the Corrosion–Wear Interaction Behavior of 8Cr4Mo4V Bearing Steel at Various Corrosion Intervals

The corrosion–wear coupling damage failure of 8Cr4Mo4V bearing steel under marine atmospheric conditions significantly limits aeroengine bearing applications. The present work aims to investigate the evolution of the corrosion–wear properties of 8Cr4Mo4V bearing steel at varied corrosion intervals and estimate the corrosion–wear interaction (CWI) effect. Neutral salt spray tests combined with tribological experiments were employed to explore the effect of corrosion on wear and the influence of wear on corrosion, and a quantitative characterization method of corrosion–wear interactions was proposed by establishing the component relationships of material losses in the corrosion–wear process. The results indicate that the corrosion rates initially increase and then decrease, ultimately resulting in a pattern characterized by predominant total corrosion and nested localized corrosion. The corroded surfaces tremendously influence the friction coefficient curves at the third stage, and a synergistic acceleration effect exists in the CWI behavior of 8Cr4Mo4V bearing steel under the action of corrosion and wear. A sample corroded for 6 h displayed the significant facilitative effect of corrosion on wear, exhibiting the highest CWI ratio and a greater total mass loss primarily attributed to corrosion. This study offers a significant reference for the quantitative assessment of the tribo-corrosion properties of bearings in a marine atmospheric environment.

Model construction of corrosion resistance of alloying elements for low alloy steel in marine atmospheric corrosive environment based on machine learning

Model construction of corrosion resistance of alloying elements for low alloy steel in marine atmospheric corrosive environment based on machine learning

Recent Progress on Atmospheric Corrosion of Field-Exposed Magnesium Alloys

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior of magnesium alloys in typical atmospheric environments (including the marine atmosphere, industrial atmosphere, etc.) in recent years. According to the literature review, it was found that there are significant regional differences in the atmospheric corrosion behavior of magnesium alloys, which is the result of the coupling of multiple factors in the atmospheric environment. By investigating the corrosion rate and corrosion products of different types of magnesium alloys in different environments, the corrosion mechanism of magnesium alloys in different environments was summarized. Specifically, environmental parameters such as atmospheric temperature, relative humidity, CO2, and chloride ion deposition rates in the marine atmospheric environment can affect the corrosion behavior of magnesium alloys. The corrosion of magnesium alloys in different industrial atmospheric environments is mainly affected by atmospheric temperature and relative humidity, as well as atmospheric pollutants (such as SO2, CO2, NO2) and dust. This review provides assistance to the development of new corrosion-resistant magnesium alloys.

Corrosion behavior and mechanism of 921 A high-strength low-alloy steel in harsh marine atmospheric environments

High-strength low-alloy 921 A steel faces significant corrosion challenges in harsh marine atmospheric conditions, threatening marine and energy industry safety. This study investigates the corrosion behavior of 921 A steel through accelerated tests in a specially developed multi-factor coupled corrosion chamber. Combining the multi-factor coupling cyclic corrosion test method with finite element numerical simulation, the long-term corrosion behavior can be accurately predicted, and the power function relationship between the corrosion rate and time of the test steel is obtained, which is expressed as C=0.2259 t–0.5182. Analysis identified α-FeOOH, Fe3O4, γ-FeOOH, Cl—, and Cr in corrosion layers. First-principles calculations and XPS analysis showed Cr oxidation inhibits Cl— adsorption and diffusion, highlighting the steel’s corrosion resistance. Finite element analysis and outdoor corrosion data confirmed the corrosion rate and time correlation, proving simulation reliability. This research provides crucial insights into 921 A steel’s corrosion resistance in marine environments, benefiting marine engineering.

Modeling Silver Corrosion Mechanisms in Marine Atmospheric Environments

Measures that can assess the severity of the local environment are an important tool for combating atmospheric corrosion. One approach for determining the environmental severity employs electrochemical analysis alongside surface characterization on silver coupons exposed to the environment for varying durations. However, despite the long use of silver as an environmental severity monitor, the underlying reaction mechanisms that give rise to the observed corrosion products are not well understood. In addition, the measured ratios of silver corrosion products appear to be unique to the location where the silver coupons were exposed.The goal of this work is to develop models of silver oxidation reactions that can explore pathways for the formation of silver corrosion products. We use density functional theory (DFT) calculations in nudged elastic band (NEB) approximations to determine electrochemical and chemical reaction along with surface diffusion energy barriers. An example reaction is shown in Figure 1a and b, in which an O2 molecule is adsorbed on an ‘on-top’ site on a relaxed Ag (100) crystal structure with periodic boundary conditions in the x and y-planes. The O2 molecule then dissociates into individual O atoms. The reaction pathway is approximated using the NEB approach to determine the dissociation energy barrier in Figure 1c. These reaction energy barriers are incorporated into a kinetic Monte Carlo (KMC) model of silver reactions to estimate the corrosion products present in marine atmospheric environments for comparison with experimental data. Figure 1

Using DPF to Control Particulate Matter Emissions from Ships to Ensure the Sustainable Development of the Shipping Industry

PM (particulate matter) emissions from ships are the main sources of marine atmosphere pollution. Controlling the emissions of particulate matter from ships is related to the sustainable development of the shipping industry. To reduce PM emissions from marine four-stroke diesel engines, DPFs are effective. Our results show that DPF had more than 90% capturing efficiency for both the number and mass emissions of PM, and the capturing efficiency for the accumulation mode was higher than that of the nuclear mode. DPF can also significantly reduce the chemical components of PM in marine diesel exhaust gas. The removal efficiencies for OC and EC were 89.7–91.6% and 84.8–92.8%, respectively, with each particle size range showing over 80% efficiency. SO42− was the ion with the highest content, followed by NH4+, NO3−, Na+, NO2−, and Cl−, with their reduced proportions remaining consistent with the removal efficiency of particulate matter. DPF can also effectively reduce PAH content and toxicity. The use of DPF can greatly improve the impact of ship emissions on the marine atmospheric environment. The appropriate DPF with the best performance can be selected according to the exhaust parameters and particle size distributions with different characteristics.

Research on accelerated corrosion of 0Cr18Ni9 stainless steel in marine atmospheric environment of the South China Sea

Research on accelerated corrosion of 0Cr18Ni9 stainless steel in marine atmospheric environment of the South China Sea

Influence of impurity content on corrosion behavior of Al-Zn-Mg-Cu alloys in a tropical marine atmospheric environment

The influence of impurity content on the corrosion behavior of Al-Zn-Mg-Cu alloys in a tropical marine atmospheric environment was systematically investigated. Combined with experimental measurements and theoretical calculations, it has been elaborated that the Volta potential difference is the main reason for the localized corrosion. The composition-property correlation has been established between the impurity contents, the type, size, and quantity of precipitates, and the corrosion behavior. The effects of impurity contents on the volume fraction of precipitates and corrosion parameters such as corrosion rate and average pit depth have been quantified, offering quantitative guidance to develop novel Al-Zn-Mg-Cu alloys.

Durability and thermal insulation properties of glazed hollow bead concrete with nanoparticles in marine atmospheric environment

Industrial and civil buildings in coastal areas have been in the marine atmosphere for a long time and are especially susceptible to the combined effects of carbonation and salt spray, which accelerate the deterioration of concrete durability and the reduction of thermal insulation performance. This paper focused on the effect of nano-SiO2 and nano-Al2O3 on the durability and thermal insulation of glazed hollow bead concrete (GC) under a salt spray carbonation environment, and analyzed the mechanism of nanoparticles on the improvement of durability and thermal insulation of GC by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) microscopic tests. The results showed that both nano-SiO2 and nano-Al2O3 incorporation could improve the durability and thermal insulation of GC to a certain extent. The optimal amount of both nanoparticles was 2 %, and nano-SiO2 had a stronger beneficial effect than nano-Al2O3. In comparison to GC, the free Cl− content in the surface layer of GCNS20 and GCNA20 after 56 cycles was decreased by 33.33 % and 27.22 %, respectively. Furthermore, the carbonation depths of GCNS20 and GCNA20 were decreased by 42.83 % and 36.38 %, respectively. The thermal conductivity of GCNS20 and GCNA20 decreased by 24.86 % and 17.34 %, respectively, while the thermal diffusion coefficients were reduced by 33.22 % and 23.73 %, respectively. The incorporation of nanoparticles effectively reduced the microcracks and pores in GC, improved its internal structure, and reduced the possibility of thermal bridge formation. In addition, the incorporation of nanoparticles significantly reduced the production of erosion products such as CaCO3 and Friedel's salt in GC.

Corrosion resistance of zinc-magnesium-aluminium alloy coated steel in marine atmospheric environments

In this study, a salt-spray accelerated experiment was conducted as a simulated corrosion test of hot-dip galvanised zinc-magnesium-aluminium-coated alloy steel under a simulated marine atmospheric environment. In addition, scanning electron microscopy, confocal microscopy, X-ray diffraction, and electrochemical workstations were used to conduct analyses on the macro-morphology, microstructure, corrosion product composition, etc. after the corrosion test. Furthermore, the role of Mg in the corrosion resistance of zinc-magnesium-aluminium alloy steel sheets was determined. The research results indicated that in a marine atmospheric environment, zinc-aluminium-magnesium alloy steel has excellent corrosion resistance, and its external coating provides protection to the substrate. In a marine atmospheric environment, the corrosion products of zinc-magnesium-aluminium alloy steel mainly include Al2O3, AlOOH, zinc hydroxychloride (Zn5(OH)8Cl2·H2O), layered bimetallic hydroxides (Mg6Al2(OH)16CO3·4H2O), ZnO, and MgCO3·H2O. The addition of magnesium to galvanised sheets facilitates the formation of insoluble corrosion products, which protect the iron substrate.

Study on seawater corrosion resistance of copper alloy

Abstract The Marine environment is a very complex and corrosive environment. Marine corrosion environment can be generally divided into Marine atmospheric environment and seawater environment. Because the seawater is rich in a variety of free ions mixed with corrosive media, the main component is sodium chloride, in addition to containing magnesium, potassium, iodine, bromine, and other elements of salt, which has strong corrosion to metal materials, if serious, it will cause safety accidents. Therefore, ensuring the effectiveness of the anticorrosion system is very important for the safe and reliable operation of the offshore platform. pulse plating is used and the metal nickel coating and metal nickel-chromium coating are prepared to analyze the microstructure and corrosion resistance of each film layer. From the macroscopic, it can be found that three coatings have more or less corrosion phenomenon, there is obviously no nickel-chromium and nickel layer on the surface of nickel-chromium corrosion defects, and through scanning electron microscopic observation, microscopic level nickel chromium corrosion after corrosion phenomenon is the least of three layers, which suggests that nickel chromium seawater corrosion resistance is strong. The three layers are then electrochemical corroded to study the corrosion resistance of the three layers. The results show that the corrosion resistance of the nickel-plated layer, nickel-chromium coating, and nickel-iron chromium coating prepared in the copper substrate is improved successively, which shows the influence of different membrane elements on the corrosion resistance of copper substrate against seawater medium. Although the composition parameters of the various membrane layers vary, they experience the same corrosion mechanism-pitting; Nickel chromium and chromium, iron and other atoms are present in the nickel matrix in the form of solid solution and finally form the solid solution alloy coating. For nickel-chromium coating, the content of iron and chromium in the surface layer has a certain influence on the corrosion resistance of the metal coating. The electrochemical parameters of nickel plating are studied separately, and the comparison with the nickel-chromium alloy coating and the coating is conducted. The equivalent circuit is fitted and determines the largest impedance value and the largest phase Angle among the three membrane layers, which finally has the strongest seawater corrosion resistance.

Modeling electrochemical chloride extraction in surface carbonated concrete

This paper investigated the Electrochemical Chloride Extraction (ECE) process in concrete with carbonated surface layers. First, the ECE model for surface carbonated concrete was proposed based on pore size distribution function. Subsequently, to validate the model, concrete cube specimens exposed to natural coastal environments were modified and designed for ECE tests. Based on the validated ECE model, parametric studies were conducted. Parametric studies show that increasing the thickness of the surface carbonation layer up to 20 mm leads to a 57% increase in extraction duration, whereas the thickness of the partially carbonated zone has a relatively minor impact on the ECE process. The parametric study shows that the surface carbonated zone will pose hindrances to the extraction of chloride ions. Due to the simultaneous presence of concrete carbonation and chloride ion ingress in the actual marine atmospheric environment, considering the actual carbonation depth is of significant importance for predicting chloride ion migration during Electrochemical Chloride Extraction.