Marine Atmospheric Environment Research Articles

Study of the Passivation Film on S32750 Super-Duplex Stainless Steel Exposed in a Simulated Marine Atmosphere

The corrosion behavior and passivation mechanism of S32750 super-duplex stainless steel exposed in a simulated marine atmosphere were studied using electrochemical methods, XPS and SEM. Passivation and local corrosion occurred on the metal surface when S32750 SDSS was exposed in the simulated marine atmospheric environment. The passivation film is composed of two chromium-enriched layers. The outer layer is a very thin film at the metal/atmosphere interface of the specimen surface with higher chromium content, whereas the chromium in the inner layer seems a little depleted. The outer and inner layers had similar Fe components, and Fe3+ oxide/hydroxide was the primary oxide in the film. The outer layer contains CrO3, whereas the inner layer has Cr3+ as its primary oxide. Pitting occurred when exposure time exceeded 24 d, and the Cr content of the specimen decreased. Therefore, S32750 SDSS exposed for 24 d exhibited the best corrosion resistance.

Influence of alloying elements on the pitting corrosion of dispersion-strengthened-high-strength steel in the marine atmospheric environment

The effect of alloying elements in dispersion-strengthened-high-strength (DSHS) steel on the pitting corrosion in the marine atmospheric environment was investigated. The results showed that Cr, Ni and Mo showed a degree of bias in the rust layer with increasing exposure time, repairing defects in the rust layer and spreading to the interior of the rust layer. The generation of the protective product α-FeOOH was promoted, slowing down the corrosion reaction. The alloying elements made the rust layer cation-selective and the enhanced protective effect of the rust layer inhibits the vertical development of pitting corrosion at 25 °C. However, the vertical development of pitting corrosion in the late stages of corrosion at 65 °C with 3.5 wt.% NaCl was slightly increased.

Corrosion failure process of organic conductive coating on Mg-RE alloy with PEO in the simulated Xisha atmospheric solution

Organic conductive coating/plasma electrolytic oxidation (PEO) coating/Mg-RE alloy is a simple way to meet the functional requirements and service safety of electronic equipment. In this work, the Macro electrochemistry, micro electrochemistry and mechanical test were performed to study the corrosion failure process of organic conductive coatings and PEO coating on the surface of Mg-RE alloy under the harsh marine atmospheric environment. Organic conductive coatings have protective effect on Mg-RE with PEO coating (the impedance modulus remain higher than 106 at low frequencies during 21d immersion, and the characteristics of EIS remained constant). But local failure of bonding between organic conductive coating and PEO coating were occurred after being immersed in Xisha simulation solution and it weakened the long-term protection ability of organic conductive coating/PEO coating/Mg-RE alloy system, which limited long-term corrosion resistance.

All-organic superhydrophobic coating with anti-corrosion, anti-icing capabilities and prospective marine atmospheric salt-deliquesce self-coalesce protective mechanism

Water-repellent and interfacial non-wetting superhydrophobicity has great potential to address corrosion/icing-induced material-deterioration problems. Herein, an all-organic superhydrophobic coating was constructed using facile and substrate-independent spray-coating method based on PTFE and PDMS. FE-SEM, EDS, and XPS techniques were used to analyze the surface topographies and chemical compositions. The coating exhibits superior anti-fouling and self-cleaning properties against various liquid and solid contaminants due to the synergic effect of low surface energy and hierarchical structures. The EIS and potentiodynamic polarization results show improved charge transfer resistance (Rct), positive shifted corrosion potential (Ecorr), and decreased corrosion current density (Icorr), implying significantly enhanced anti-corrosion performance with 99.83 % inhibition efficiency. Besides, the delay rate of ice-freezing time of the coating is 232 % at −5°C, 137 % at −10 °C and 204 % at −15 °C compared with uncoated Q235 substrate respectively. The ice adhesion strength of the coating accounts for only 6.55 % at −5°C, 7.03 % at −10 °C and 9.35 % at −15 °C than that of the bare Q235 carbon steel, demonstrating ultra-low ice adhesion force and anti-icing capabilities. The hygroscopic and deliquesce behaviors of NaCl salt particles reveal an intriguing salt-deliquescence self-coalescence phenomenon and prospective anti-corrosion mechanism for superhydrophobic materials in high-humidity marine atmospheric environments.

Corrosion inhibition behavior of cerium salt sealing on the scratch of aluminum alloy anode oxide film in a simulated marine atmospheric environment

The anodic oxide film of aluminum alloy was sealed by cerium salt, and the scratch test was used to simulate the damage of the oxide film. The repair and corrosion inhibition effects of cerium in the oxide film on the simulated damaged site were studied by means of alternate immersion accelerated corrosion test, combined with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. The results show that cerium in the undamaged oxide film diffused to the scratch and existed in the form of Ce (III) and Ce (IV), and formed the hydroxide with the cathode reaction product OH− in the scratch. It was only when enough corrosion products were produced on the aluminum matrix in the scratch, both the corrosion products and the hydroxide of cerium would have a synergistic effect on inhibiting the cathode reaction, thus, cerium salt could play the role of corrosion inhibition.

Effect of Different Sealing Treatments of Oxide Films on Corrosion Resistance of Anodized ZL101A Aluminum Alloy in Simulated Marine Atmospheric Environment

Effect of Different Sealing Treatments of Oxide Films on Corrosion Resistance of Anodized ZL101A Aluminum Alloy in Simulated Marine Atmospheric Environment

Development of superhydrophobic and corrosion resistant coatings on carbon steel by hydrothermal treatment and fluoroalkyl silane self-assembly

Superhydrophobic polysiloxane coatings was prepared on the surface of carbon steel by combining the hydrothermal method and self-assembly. The results show that when the hydrothermal reaction time is 6 h, the temperature is 140 °C, and the ethylenediamine concentration is 3.00 mol L−1, the surface achieves super-hydrophobicity with a water contact angle of 152°. The rough regular octahedral and flower-like structures were formulated on the hydrothermal treat surface. The fluorosilane molecules are bonded to the surface of the carbon steel through Fe–O–Si bonds. The superhydrophobic coating with the thickness of 15–17 μm is dense and uniform. During the first 4 h of corrosion test in the simulated marine atmospheric environment, the superhydrophobic coating hindered the diffusion and migration of the corrosive medium on the metal interface, thus decreased the standard deviation of the current noise by 40%, increased the noise resistance by 5 times, showing a good corrosion resistance.

Failure probability analysis of corroded RC structures considering the effect of spatial variability

A reasonable assessment of the probability of structural failure is essential to ensure the safe performance of corroded reinforced concrete (RC) structures. In this paper, a novel cross-sectional area loss model of corroded steel bars is proposed and the scale of fluctuation of some key parameters is estimated using the semi-variogram function method. A stochastic resistance deterioration model considering the effect of unbalanced corrosion and spatial variability and a time-dependent reliability assessment method of corroded concrete structures (CCSs) are then presented. A simple case analysis of a CCS is used to illustrate the application of the proposed method. The case analysis results show that the cumulative failure probability (CFP) is overestimated using the popular pit area model, while it is underestimated without considering the spatial variability of calculation parameters. Random field parameter analysis shows that an appropriate choice of the element size is very important for the safety evaluation of RC structures. Additionally, compared with a marine atmospheric environment, the CFP of a case study structure in tidal and splash environments was found to be increased by 20.15% and 70.40%, respectively, due to the gradual increase of corrosion current density. Of the three service environments, the splash environment thus has the greatest impact on structural failure probability.

Corrosion behaviour of zinc exposed to an extreme tropical marine atmospheric environment for 3 years

ABSTRACT Corrosion behaviour of Zn exposed in the coastal zone of the Nansha Islands for nearly 3 years was studied through gravimetric, and morphological observations, component analysis, and electrochemical measurements. The kinetics of the corrosion process is linear, indicating that the corrosion products have no significant protective effect on the substrate. The average corrosion rate (V d) fluctuated with time, which was attributed to the different morphologies of corroded product film formed on the skyward and field-ward sides. Corrosion products formed on the skyward side had a three-layer structure in which Zn5(OH)8Cl2·H2O was enriched in both the outer and inner layer, NaZn4Cl(OH)6SO4·6H2O was enriched in the intermediate layer. Simultaneously, corrosion products formed on the field-ward side had a double-layer structure, in which Zn5(OH)8Cl2·H2O was concentrated in the inner layer and NaZn4Cl(OH)6SO4·6H2O was enriched in the outer layer. The degrees of corrosion on both sides at different exposure periods were also discussed.

Microplastics and nanoplastics in the marine-atmosphere environment

The discovery of atmospheric micro(nano)plastic transport and ocean–atmosphere exchange points to a highly complex marine plastic cycle, with negative implications for human and ecosystem health. Yet, observations are currently limited. In this Perspective, we quantify the processes and fluxes of the marine-atmospheric micro(nano)plastic cycle, with the aim of highlighting the remaining unknowns in atmospheric micro(nano)plastic transport. Between 0.013 and 25 million metric tons per year of micro(nano)plastics are potentially being transported within the marine atmosphere and deposited in the oceans. However, the high uncertainty in these marine-atmospheric fluxes is related to data limitations and a lack of study intercomparability. To address the uncertainties and remaining knowledge gaps in the marine-atmospheric micro(nano)plastic cycle, we propose a future global marine-atmospheric micro(nano)plastic observation strategy, incorporating novel sampling methods and the creation of a comparable, harmonized and global data set. Together with long-term observations and intensive investigations, this strategy will help to define the trends in marine-atmospheric pollution and any responses to future policy and management actions.

The corrosion characteristic and mechanism of Mg-5Y-1.5Nd-xZn-0.5Zr (x = 0, 2, 4, 6 wt.%) alloys in marine atmospheric environment

The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-xZn-0.5Zr (x = 0, 2, 4, 6 wt.%) alloys were investigated by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry and X-ray Diffraction. The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment. The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-xZn-0.5Zr (x = 0, 2, 4, 6 wt.%) alloys were analyzed by weight loss rate, corrosion depth, corrosion products and corrosion morphologies. The electrochemical corrosion tests were also measured in the natural seawater. The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment. That depended on the microstructure, type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy. Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.

Study on vapor phase corrosion inhibitor for E36 ship steel in marine atmospheric environment

PurposeThis study aims to investigate the effect of vapor phase corrosion inhibitor (VCI) imidazoline, quinoline and urea on E36 ship steel in simulated marine atmospheric environment.Design/methodology/approachThe inhibitive effect was investigated by weight loss, potentiodynamic polarization, electrochemical impedance and Raman spectroscopy.FindingsThe corrosion process was inhibited by adsorption of the three VCIs on the surface of ship steel. The corrosion inhibition mechanism is the adsorption film type. The corrosion inhibitor adsorbs on the metal surface to prevent Cl- from reaching the surface of the substrate, so as to achieve the corrosion inhibition effect.Originality/valueTo the best of the authors’ knowledge, the work described was original research that has not been published previously and not under consideration for publication elsewhere, in whole or in part.

Corrosion Behavior of 7A52 Aluminum Alloy Plasma Arc Welding Joint in Simulated Marine Atmosphere Environment

Corrosion behavior of 7A52 aluminum alloy plasma arc welding (PAW) joint was investigated in simulation of marine atmosphere environment with salt water spray test. The surface morphologies were observed by scanning electron microscopy (SEM), and the effect of corrosion time on corrosion behavior was discussed. The depth of spot corrosion, the corrosion dynamic characteristics, and the distribution of element of 7A52 aluminum alloy welding joint were analyzed by 3D and XRD Microscope. Results show that pitting corrosion is main morphology in heat effect zone at initial stage, pitting corrosion appears in matrix and welding joint with time. The main component compounds existing in the film include Al and O. The depth of pitting corrosion in the heat effect region is the maximum (3.008μm). The law of power function is followed in both phases of the corrosion weight increasing curve, and the corrosion rate decreases with time.

The corrosion behavior of EW75 magnesium alloy in the research vessel KEXUE during the ocean voyage

The corrosion behavior of EW75 magnesium alloy in the Research Vessel KEXUE (RV KEXUE) during the ocean voyage was researched. The weight loss, corrosion depths, corrosion morphologies, and corrosion products were all analyzed. The mean weight loss rate of EW75 alloy Extrusion Surface was 0.0672 mg cm−2 y−1 (0.0903 mm y−1) after exposure corrosion tests, whereas that of Cross-section Surface was 0.0938 mg cm−2 y−1 (0.1537 mm y−1). Both extrusion direction and transverse direction of magnesium alloy samples occurred the brittle fracture in the harsh marine environment, and the mechanical strength fell precipitously after the exposure tests. The corrosion resistance of EW75 magnesium alloys obviously showed the anisotropy, which was due to the texture of the magnesium alloy in the microstructure. High salinity and high humidity environment led to a severe corrosion of EW75 magnesium alloys during exposure in the RV KEXUE during the ocean voyage. This study will provide the effective data for the service of magnesium alloys in typical marine atmospheric environment.

Multi-factor sensitivity analysis of chloride ingression: A case study for Hangzhou Bay Bridge

The transport of chloride into concrete is affected by many factors, including temperature, relative humidity, load cracks, and material properties. The purpose of this paper is to analyze the influence of various factors on the chloride ingression process through a case study for Hangzhou Bay Bridge located in marine environment. Firstly, based on the concentration of free chloride in pore solution, a porous media diffusion model is derived, considering the chloride adsorption term. Then, chloride adsorption isotherm, time-varying diffusion coefficient, temperature, relative humidity, and macroscopic cracks are simulated respectively by the porous media diffusion model. The main conclusions are as follows: (1) The chloride adsorption effect and time-varying diffusion coefficient have a great influence on the numerical results, which cannot be ignored in any case. (2) The natural temperature and relative humidity conditions of the case have a small effect on the simulation results. (3) Under the marine atmospheric environment, the macroscopic load cracks have a small influence on chloride ingression in the long term.

Dry passivation of austenitic SUS 301L stainless steel against pitting corrosion in marine atmospheric environment

Dry passivation of austenitic SUS 301L stainless steel against pitting corrosion in marine atmospheric environment

Environmental Damage Behavior of 2A12 Aluminum Alloy under Coupling Action of Marine Atmospheric Environment and Tensile-Compressive Load

The coupling test of marine atmospheric environment and tensile-compressive fatigue load for 2A12 aluminum alloy was carried out in outdoor environment of Hainan station by coupling test equipment of mechanical load. The coupling effect of marine atmospheric environment corrosion and tensile-compressive fatigue load on the environmental damage behavior of 2A12 aluminum alloy was discussed from the aspects of corrosion morphology, tensile properties and fracture morphology. The results show that the corrosion characteristics of 2A12 aluminum alloy in coupling test and static exposure test are consistent. The corrosion depths of the static exposure test for 6 months and the coupling test for 35 days are 71 μm and 121 μm, respectively. The results of tensile properties show that the decrease rate of tensile properties of 2A12 aluminum alloy are accelerated by the coupling effect. And the accelerated ratio of the coupling test was more than 10 times that of the static exposure test. The fracture morphology shows that the coupling fracture crack of 2A12 aluminum alloy starts from the corrosion surface, and the crack source and propagation zone are quasi-cleavage fatigue crack propagation characteristics. The coupling test results are closer to the actual situation of equipment, which has important reference value for the design and material selection of bearing structure.

Corrosion Behavior and Mechanical Properties of 30CrMnSiA High-Strength Steel under an Indoor Accelerated Harsh Marine Atmospheric Environment.

In this work, the corrosion behavior and mechanical properties of 30CrMnSiA high-strength steel under a harsh marine atmosphere environment were systematically studied using accelerated test technology, along with corrosion kinetic analysis, microstructure and phase composition analysis, electrochemical measurements, and mechanical property tests. The influence of corrosion time on corrosion kinetics was characterized by the weight loss method. The corrosion layer and its product evolution were analyzed by SEM, EDS, XRD, and XPS. The corrosion behavior of steel was studied by a potentiodynamic polarization curve and EIS. Finally, the influence of corrosion on mechanical properties was studied by tensile and fatigue tests. The results show that 30CrMnSiA high strength steel has good corrosion resistance in a harsh marine atmosphere environment. Its corrosion behavior is cyclical: the outer rust layer exfoliated, the inner rust layer became the outer rust layer, and the matrix became inner rust due to the attack by the corrosive medium. The rust layer had a great protective effect on the matrix. The mechanical properties of 30CrMnSiA high-strength steel were reduced under the corrosive environment, and corrosion had a significant effect on its fatigue resistance.

Unraveling the Effect of Chloride Ion on the Corrosion Product Film of Cr-Ni- Containing Steel in Tropical Marine Atmospheric Environment

Unraveling the Effect of Chloride Ion on the Corrosion Product Film of Cr-Ni- Containing Steel in Tropical Marine Atmospheric Environment

On How Microstructure Optimization Enhanced Initial Corrosion Resistance of Ni-Mo Low Alloy Steel in the Simulated Tropical Marine Atmospheric Environment

On How Microstructure Optimization Enhanced Initial Corrosion Resistance of Ni-Mo Low Alloy Steel in the Simulated Tropical Marine Atmospheric Environment