Marine Corrosion Research Articles

An ecofriendly coaxial antibacterial and anticorrosion nanofiber pullulan-ethyl cellulose embedded with carvacrol coating for protection against marine corrosion

Coaxial electrospun coatings with antibacterial and anticorrosion properties have a marked potential to protect against corrosion in marine environments. Ethyl cellulose is a promising biopolymer for corrosion caused by microorganisms owing to its high mechanical strength, nontoxicity, and biodegradability. In this study, a coaxial electrospun coating loaded with antibacterial carvacrol (CV) in the core and anticorrosion pullulan (Pu) and ethyl cellulose (EC) as a shell layer was successfully fabricated. The formation of core–shell structure was confirmed using transmission electron microscopy. Pu-EC@CV coaxial nanofiber had small diameters, uniform distribution, smooth surface, strong hydrophobicity, and no fractures. Electrochemical impedance spectroscopy was used to analyze corrosion of the electrospun coating surface in a medium containing bacterial solution. The results indicated significant corrosion resistance of the coating surface. In addition, the antibacterial activity and mechanism of coaxial electrospun were studied. The Pu-EC@CV nanofiber coating exhibited excellent antibacterial properties by effectively increasing the permeability of cell membranes and killing bacteria, as determined by plate counts, scanning electron microscopy, cell membrane permeability, and the activity of alkaline phosphatase. In summary, the coaxial electrospun pullulan-ethyl cellulose embedded with CV coating can be used as antibacterial and anticorrosion materials and may have potential applications in the field of marine corrosion.

Mechanistic Insight into the Inhibitory Activity of Elasnin-Based Coating against Early Marine Biofilms.

Marine biofilms are multispecies microbial communities on surfaces that are crucial to the marine environment. They cause marine corrosion, biofouling, and transmission of marine pathogens and thus pose a great threat to public health and the maritime industry. To control marine biofilms, effective and environmentally friendly antibiofilm compounds are highly needed. Elasnin is a potent antibiofilm compound that exhibits high efficiency in inhibiting marine biofilms and biofouling, but its mode of action remains unclear. In the present study, multiomic analysis combined with quorum-sensing assays and in silico study revealed that elasnin acted as a signaling molecule in the microbial community. Elasnin promoted the growth of dominant species in the biofilm but deprived their ability of sensing and responding to environmental changes by disturbing their regulations of the two-component system, i.e., the ATP-binding cassette transport system and the bacterial secretion system. Consequently, biofilm maturation and subsequent biofouler settlement were inhibited. Elasnin also exhibited higher antibiofilm efficiency than dichlorooctylisothiazolinone and had low toxicity potential on the embryos and adults of marine medaka fish. Overall, this study provided molecular and ecological insights into elasnin's mode of action, highlighting its application potential in controlling marine biofilms and the feasibility and advantages of using signal molecules to develop eco-friendly technologies.

Guided Waves in Ship Structural Health Monitoring – A Feasibility Study

Abstract Ships and offshore structures operate in a severe corrosion degradation environment and face difficulty in providing long-lasting corrosion protection. The Classification Societies recommend regular thickness measurements leading to structural component replacements, to ensure structural integrity during service life. The measurements are usually performed using ultrasonic thickness gauges and such an approach requires multiple measurements of the corroded structural components. Otherwise, the collected data are insufficient to precisely assess the corrosion degradation level. This study aims to perform numerical and experimental analyses to verify the use of guided ultrasonic waves in defining the corrosion degradation level of the corroded structural components of a ship. The study incorporates the fundamental antisymmetric Lamb mode, excited by piezoelectric transducers attached at the pre-selected points on stiffened panels, representing typical structural ship components. The specimens are exposed to accelerated marine corrosion degradation, the influence of the degree of degradation on the wave time of flight being analysed. The study indicates that guided waves are a promising approach for diagnosing corroded structural components. The signals characterised by a high signal-to-noise ratio have been captured, even for relatively long distances between the transducers. This proves that the proposed approach can be suitable for monitoring more extensive areas of ship structures by employing a single measurement.

Prevention of marine corrosion with graphene-based polymer coatings

Prevention of marine corrosion with graphene-based polymer coatings

Behavior of a 2.66%C-17.9%Ni gray cast iron with an austenitic matrix under simulated marine corrosion.

Behavior of a 2.66%C-17.9%Ni gray cast iron with an austenitic matrix under simulated marine corrosion.

Green Inhibition of Corrosion of Aluminium Alloy 5083 by Artemisia annua L. Extract in Artificial Seawater

Plant extracts are increasingly being examined in the corrosion inhibition of metal and alloys in various environments due to their potent antioxidant properties. The use of Artemisia annua L. aqueous extract (AAE) as an aluminium alloy 5083 (ALA) corrosion inhibitor in artificial seawater (ASW) was investigated using electrochemical tests and spectroscopy tools, while the active biocompounds found in AAE were analyzed using high-performance liquid chromatography (HPLC). Electrochemical results showed that AAE acts as an anodic inhibitor through the physisorption (ΔG ≈ -16.33 kJ mol-1) of extract molecules on the ALA surface, thus reducing the active sites for the dissolution of the alloy in ASW. Fourier-transform infrared spectra confirmed that phenolic acids found in AAE formed the surface layer that protects ALA against the corrosive marine environment, while HPLC analysis confirmed that the main phytoconstituents of AAE were chlorogenic acid and caffeic acid. The inhibition action of phenolic acids and their derivatives found in the AAE was based on the physisorption of caffeic acid on the ALA surface, which improved physicochemical properties of the barrier film and/or conversion of Al3+ to elemental aluminium by phenolic acids as reducens, which slowed down the diffusion rate of Al3+ to or from the ALA surfaces. The protective effect of the surface layer formed in the presence of AAE against ASW was also confirmed by inductively coupled plasma-optical emission spectrometry (ICP-OES) whereby the measured concentration of Al ions after 1 h of immersion of ALA in the pure ASW was 15.30 μg L-1 cm-2, while after the addition of 1 g L-1 AAE, the concentration was 3.09 μg L-1 cm-2.

Corrosion-induced deceleration-to-acceleration of fatigue crack growth for deep-sea Ti6Al4V ELI titanium alloy

The Ti6Al4V ELI titanium alloy is a promising structural material for deep-sea equipment due to the advanced mechanical properties. The damage evolution of the Ti6Al4V ELI induced by cyclic loading accompanying with marine corrosion should be quantified to achieve structural integrity design for deep-sea equipment. However, synchronous acceleration testing for fatigue and corrosion is still challenging, due to the lack of equivalent acceleration ratio between fatigue and corrosion. Here we propose a calculation algorithm to determine the corrosion acceleration ratio based on the electric charge transmission during the corrosion process. Accordingly, we design a testing equipment with controllable current through corrosive solution. The corrosive acceleration ratio is modified by controlling current intensity. Then we observe for the first time that a deceleration-to-acceleration tendency for corrosion-fatigue testing for the Ti6Al4V ELI specimens. In addition, we reveal that this inconspicuous phenomenon is attributed to the competition between the corrosion-induced crack tip blunting and the material volume degradation. These findings provide insights for assessing the Ti6Al4V ELI, thereby designing for the deep-sea equipment.

Monitoring and quantification of non-uniform corrosion induced mass loss of steel piles with distributed optical fiber sensors

Steel piles are used in foundation structures to support offshore wind power system, but they suffer from serious non-uniform corrosion in the marine environment, which can threaten the stability and safety of the overall wind tower infrastructure. Thus, real-time and in-situ monitoring of steel pile corrosion is of great significance to provide timely warning and guidance for maintenance. This study deployed a distributed optical fiber sensor beneath the simulated anti-corrosion wrapping system to monitor non-uniform corrosion of steel pile in the four marine corrosion zones: atmospheric zone, water level fluctuation zone, immersion zone, and sub-mud zone. The sensor was applied to measure corrosion products induced strain variation and analyze non-uniform corrosion influenced by different environmental factors. Two analytical models considering build-ups and run-offs of corrosion products were established to quantify non-uniform corrosion induced mass loss at any location on the surface of steel pile. Functions of volume expansion and reduction coefficients of corroded steel pile were proposed, and sensitivity of mass loss measurement with the distributed optical fiber sensor was investigated. Finally, visualization through color cloud map was applied to illustrate the severity of non-uniform corrosion on the pile surface.

Graphene-based polymer coatings for preventing marine corrosion: a review

Graphene-based polymer coatings for preventing marine corrosion: a review

Application of Artificial Intelligence in Marine Corrosion Prediction and Detection

One of the biggest problems the maritime industry is currently experiencing is corrosion, resulting in short and long-term damages. Early prediction and proper corrosion monitoring can reduce economic losses. Traditional approaches used in corrosion prediction and detection are time-consuming and challenging to execute in inaccessible areas. Due to these reasons, artificial intelligence-based algorithms have become the most popular tools for researchers. This study discusses state-of-the-art artificial intelligence (AI) methods for marine-related corrosion prediction and detection: (1) predictive maintenance approaches and (2) computer vision and image processing approaches. Furthermore, a brief description of AI is described. The outcomes of this review will bring forward new knowledge about AI and the development of prediction models which can avoid unexpected failures during corrosion detection and maintenance. Moreover, it will expand the understanding of computer vision and image processing approaches for accurately detecting corrosion in images and videos.

3D nanothorn cluster-like Zn-Bi2S3 sensitized WO3/ZnO multijunction with electron-storage characteristic and adjustable energy band for improving sustained photoinduced cathodic protection application

Solar energy-driven photoinduced cathodic protection (PICP) technology utilizes solar energy to protect marine metallic structures against severe marine corrosion. To enhance the solar energy utilization and strengthen dark-state application for realizing long-term protection, herein, a 3D nanothorn cluster-like WO3/ZnO/Zn-Bi2S3 multijunction with electron-storage characteristic and adjustable energy band was constructed. It exhibited an enhanced continuous release of photogenerated electron and sustained cathodic protection in dark conditions. Exposed to only 100 s of simulated sunlight irradiation, the WO3/ZnO/Zn-Bi2S3could store 5.27×10−2 C electrons and provide up to 5460 s of sustained CP for the coupled metal after light stops, which was 10.8 and 3.5 times higher than those of WO3/ZnO (4.89×10−3 C) and WO3/Zn-Bi2S3 (1.51×10−2 C), respectively. The WO3 nanothorn cluster-like substrate with reversible valence transformation of W6+/W5+ together with the large surface area and one-dimensional transmission path can store photogenerated electrons under illumination and release photogenerated electrons after light stops efficiently. Notably, the tri-phase heterojunction with introduction of intermediate “Carrier Springboard” ZnO between WO3 and Zn-Bi2S3 contributed to the building of well-matched energy band gradient to strengthen the directional backward transfer of photogenerated electrons and holes. The energy band of Bi2S3 sensitizer was adjusted towards negative direction by doping with zinc element to boost PICP application performance. The reversible valence transformation of Bi3+/Bi5+ could promote the consumption of photogenerated holes. These synergistically enhanced the sustained PICP performance of the WO3/ZnO/Zn-Bi2S3 photoelectrode both in dark and light conditions. This design shed light on energy-storage photoelectrodes for long-term PICP of metallic materials.

An innovative method of assessing yield strength of floater hull for semi-submersible floating wind turbine in whole life period

The concepts of external and internal corrosion damage of materials have been proposed, and the improved corrosion damage models considering marine corrosion zone have been established. Then, a new method of assessing yield strength of floater hull for semi-submersible floating wind turbine considering the effect of corrosion damage in whole life period is proposed based on the equivalent design wave and structural quasi-static analysis method. Taking the OC4 floating wind turbine foundation for example, this new assessment method has been conducted. The results show that the stresses and displacements of structures will be increased under the influence of corrosion damage in whole life period and the risk of structural failure is also increased due to the corrosion damage. The structures which locate in the high stress level region will up to the yield failure critical point (yield strength margin is close to zero) by the end of service period if just considering the external corrosion damage, and these structures may fail due to yield after 18–22 years of service if considering the external and internal corrosion damage simultaneously. Therefore, the corrosion damages (especially the internal corrosion damage) have produced an important effect on the structural yield strength. In addition, the value of material factor γm = 1.1 (given by DNVGL-ST-0119) is small, and the suggested value is 1.25–1.3 for the structures in high stress level region.

Minimization of corrosion in aquatic environment – a review

Corrosion is the gradual deterioration of a material through an electro-chemical reaction with its environment. Electrochemical conditions can be created at the film’s base by bacterial film and salt water of marine environment acts as electrolyte according to the marine science. While corroding, dissolved oxygen and other species as well as the metal surfaces pH can be impact electrochemical process on the metal, which in turn affects. To overcome this problem, there are several methods of preventing a material from corroding. Among them, cathodic protection (CP) and coatings are very popular and effective methods for marine corrosion protection that can provide very good protection over a long period of time. Developing anticorrosive additives that are more effective than the conventional inorganic pigments currently used in paint, may have adverse impacts on environment and human health. In this study, we have focused on cathodic protection (CP) and coatings and the combination of them for providing good protection over a long period.

Preparation of Gallic Acid Intercalated Layered Double Hydroxide for Enhanced Corrosion Protection of Epoxy Coatings

In the field of corrosion protection coatings, layered double hydroxide (LDH) has gained wide attention as a novel controlled-release nanocontainer. In this paper, by using a co-precipitation to store corrosion inhibitors in layered double hydroxide with barrier properties, an environmentally friendly gallic acid (GA) intercalated layered double hydroxide corrosion protection filler (GA-LDH) was prepared. The epoxy coating was then modified with GA-LDH to improve its corrosion protection performance. The structure, composition, and release behavior of GA-LDH were investigated by a series of characterizations, such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectrophotometry (UV-vis). Electrochemical impedance spectroscopy (EIS) and a neutral salt spray test (NSS) were performed to evaluate the effect of EP coating containing GA-LDH on corrosion protection for Q235 steel. The results show that GA-LDH added to an epoxy coating can achieve excellent corrosion protection performance and is expected to be widely used in marine corrosion protection contexts.

Microbe-induced pitting of Fe-based amorphous coating

It is well known that Fe-based amorphous coatings demonstrate excellent performance against marine corrosion, but the corrosion resistance is significantly reduced in the presence of ocean-microbes. However, the mechanism of microbe-induced corrosion, named as microbiologically influenced corrosion (MIC), has yet to be understood. In this paper, the MIC mechanism of an Fe-based amorphous coating (with the composition of Fe43.7Co7.3Cr14.7Mo12.6C15.5B4.3Y1.9) in the presence of Pseudomonas aeruginosa (one of the typical ocean-microbes) was elaborately investigated by electrochemical impedance spectroscopy (EIS), electrochemical noise analysis (EN), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The electrochemical results show that P. aeruginosa reduced the corrosion resistance of the amorphous coating, manifested by the lower impedance values and higher metastable pitting initiation rate compared to those in a sterile medium. XPS analysis indicates the enrichment of soluble high-valent metal oxides in the passive film formed in the P. aeruginosa medium. In addition, TEM observation reveals pitting initiated exactly beneath P. aeruginosa cells, rather than defect regions (i.e., intersplat) as expected. In the pitting region, a thick biofilm was formed, which resulted in thinning of the underlying passive film. Based on these results, an MIC mechanism based on the inward extracellular electron transfer (EET) effect was proposed, and a potential strategy to relieve MIC was examined.

Unexpected higher corrosion in the gas phase region of metals caused by calcium and magnesium ions compared to sodium ions.

In the marine environment, Na+ ions have been the focus of attention owing to their high content, which is one of the important factors causing marine corrosion. With reference to the content of macro ions in seawater, circular iron samples were semi-immersed in 0.04 M MgCl2 and 0.6 M NaCl solutions containing different proportions of ethanol. Unexpectedly, we observed more severe corrosion effects in the gas phase region and at the gas-liquid interface of metal samples semi-immersed in the MgCl2 solution. Although the concentration of the MgCl2 solution was only 1/15 of that of the NaCl solution, the iron corrosion induced by MgCl2 was significantly more severe than that caused by NaCl when the ethanol content was increased. Mg2+ ions outperform Na+ ions in metal gas phase corrosion. Especially in the oxygen content of the gas phase corrosion product, MgCl2 caused an increase by up to 52.7%, while NaCl only resulted in a 10.3% increase. Ethanol is normally regarded as a corrosion inhibitor and exists in the liquid phase. Interestingly, in the gas phase and at the gas-liquid interface, ethanol aggravated rather than reducing iron corrosion, particularly in the presence of Mg2+ ions. In addition, we observed that Ca2+ ions produced more severe corrosion effects.

Understanding of low-carbon steel marine corrosion through simulation in artificial seawater

<abstract> <p>The current laboratory experiments investigated the corrosion resistance of carbon steel in artificial seawater (ASW) using the steel coupons hanging on a closed glass reactor of ASW with volume-to-specimen area ratios ranging from 0.20 to 0.40 mL/mm<sup>2</sup>. These coupons were immersed in ASW for varying time durations (7 and 14 d) at room temperature without agitation. Further, the corrosion rates based on the weight loss and electrochemical analytical method were determined. Following exposure to carbon steel for 7 and 14 d, corrosion rates were 0.2780 <italic>mmpy</italic> and 0.3092 <italic>mmpy</italic>, respectively. The surfaces appeared to be not protected by oxides based on this result. The electrochemical impedance spectrometer in potentiostatic/galvanostatic mode, in conjunction with EDX analysis, predicted the evolution of oxygen reduction. The 7th-day immersion sample had a higher oxygen content, and the 14th-day immersion sample had a slightly lower oxygen content. Methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterized the surface morphology and composition of their corrosion product. Corrosion products derived from rust minerals hematite, lepidocrocite and magnetite appeared to cover the carbon steel surface after exposure. This result can get insight into the corrosion behavior of low-carbon steel used in marine environments.</p> </abstract>

Effect of rare earth addition on corrosion sensitivity of GCr15 bearing steel in marine environment

Recent study demonstrates that only under very low-oxygen conditions can rare earth (RE) play a vital role in improving the performance of RE steels. In this work, the effect of RE addition on marine corrosion of the low-oxygen GCr15 bearing steel has been investigated with the involved mechanisms having been explored. The results indicate that the low-oxygen GCr15 bearing steel exhibits rather low sensitivity to marine corrosion, and the substantially decreased number and size in the inclusions modified by RE addition are responsible for the remarkable performance of the steel. Besides, RE addition has no obvious impact on the structure of GCr15 bearing steel, and the corrosion pits initiate and proceed following the galvanic corrosion mechanism.

The non-crystalline metal-organic framework for corrosion inhibitor behavior in sodium chloride solution

The metal-organic frameworks (MOFs), namely ZIF-62, have the ligand of imidazole and benzimidazole, which are effective corrosion inhibitors. In this context, ZIF-62 is an ideal candidate in marine corrosion protection. However, it is not reported till present. Here, the non-crystalline ZIF-62 ( g -ZIF-62), a novel corrosion inhibitor carrier, is developed by melting the ZIF-62 crystal ( c -ZIF-62) and its corrosion inhibition performance on AZ91 Mg alloy is investigated by electrochemical measurement. The results show that ZIF-62 could effectively inhibit the Mg alloy from corrosion. More significantly, g -ZIF-62 shows a better corrosion inhibition effect, and the corrosion inhibition efficiency ( η ) is up to 83.6%. The glassy grain boundaries of g -ZIF-62 disappear when melting the c -ZIF-62, which hinders the invasion of corrosive media, e.g. H 2 O molecules, Na + and Cl − , to improve the stability in seawater. More importantly, the molar ratio of imidazole to benzimidazole is adjusted by the reaction time ( T m ). Given the significant steric hindrance, the much content of benzimidazole in g -ZIF-62(48 h) have high viscosity under T m , leading to the formation of a pyknotic glass for the corrosion inhibitors. Thus, this study not only highlights the potential of ZIF-62 as a corrosion inhibitor, but also provides fresh insights for the application of non-crystalline MOF in harsh seawater corrosion. • Corrosion inhibitor for metal–organic frameworks is reported. • The stability of MOFs in sodium chloride solution was improved by amorphous method. • The effect of synthesis time and corrosion mechanism were investigated. • ZIF-62 is used for the first time as corrosion inhibitor on the surface of AZ91 Mg alloy.

Numerical simulation study of corrosion behavior of Ni-P coating under multiple working conditions

The research on marine corrosion protection is very important in modern naval warfare. In this paper, combined with the working environment and usage requirements of underwater equipment, a 3D modeling is carried out based on a certain type of underwater equipment, and the model was divided into regions according to the difference between the base material, and the electrochemical corrosion protection was established through the finite element simulation software COMSOL Multiphysics. The simulation model was used to simulate and analyze the corrosion laws of various parts of the equipment under three different working conditions. According to the simulation results, the corrosion rate of the equipment under the protection of Ni-P chemical coating is much lower than the natural corrosion rate and the corrosion rate in seawater with a 30% concentration of Na2SO3 corrosion inhibitor, and the Ni-P chemical coating has a good anti-corrosion effect. This paper puts forward suggestions for the follow-up improvement and development of the corrosion protection research of this type of underwater equipment and provides a reference for the research on the corrosion behavior of other metals.