Marine Corrosion Research Articles

Characterisation and evaluation of paint-coated marine corrosion in carbon steel based on pulsed eddy current thermography and BEMD noise-reducing method

ABSTRACT Eddy current pulsed thermography (ECPT) technique has been investigated for steel corrosion detection and evaluation. However, the random interference was not considered and disposed adequately, which bedims the original thermal images and reconstructed feature ones. This paper applied bidimensional empirical mode decomposition (BEMD) method which used to denoise the thermal image sequences, and the contrast between corroded and uncorroded regions in the skewness reconstructed images of 6-months and 12-months samples was improved by 19% and 28%, respectively. By this means, the skewness of the temperature response curve of each pixel was extracted to reconstruct the feature image. Furthermore, the differential skewness and the contrast of reconstructed skewness image are utilised for distinguishing the early corrosion and the moderate corrosion. The results demonstrate that the method provides higher sensitivity and accuracy in corrosion detection with ECPT.

Progress in Corrosion and Protection Research in Offshore Petroleum Engineering

This paper summarizes the latest research progress on the corrosion of concrete structures in marine engineering and its protection technology. The article firstly emphasizes the influence of seawater on the performance of concrete engineering, and then discusses the application of composite corrosion inhibitors in the marine environment. The composite corrosion inhibitor significantly reduces the corrosion rate by simultaneously inhibiting the anodic and cathodic reactions and forming a protective hydrophobic film on the metal surface. The article describes in detail the classification of corrosion inhibitors, including adsorption or film-forming inhibitors with polar hydrophobic groups such as N, S, and -OH, as well as migratory corrosion inhibitors (MCIs) that diffuse through the pores of the concrete to the surface of the reinforcement bar to form a protective film. The article also discusses the performance evaluation criteria of corrosion inhibitors, including the electrochemical performance of saltwater impregnation, the performance of dry-wet cold-heat cycles, and the performance of resistance to Cl- penetration, etc., and lists the relevant national standards and test methods. Through a comprehensive analysis of relevant literature at home and abroad in recent years, the article points out that composite corrosion inhibitors show great potential in improving the durability of marine concrete structures, but the long-term stability and compatibility with different concrete types still need to be further studied. Future research should focus on developing more efficient and environmentally friendly corrosion inhibitors and expanding their application in marine engineering to meet the increasingly severe challenges of marine corrosion. At the same time, a comprehensive evaluation of the longevity, economy and environmental friendliness of corrosion inhibitors is also an important direction for future research.

Nano Material Innovation in Enhancing Corrosion Resistance of Offshore Structures

Offshore structures are constantly exposed to the corrosive marine environment, causing significant material degradation and potentially jeopardizing structural integrity. This research explores recent innovations in nanomaterial technology to improve the corrosion resistance of offshore structures. The main focus is given to the development of nano-composite coatings incorporating metal oxide nanoparticles and carbon nanotubes. An electrophoretic deposition method was used to apply the coatings on steel substrates, followed by characterization using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Results showed a significant improvement in corrosion resistance, with the nano-composite coatings exhibiting a reduction in corrosion rate of up to 85% compared to conventional coatings. In addition, these coatings exhibited superior adhesion and abrasion resistance in simulated extreme marine conditions. These findings highlight the great potential of nanomaterials in extending the service life and improving the reliability of offshore structures, with important implications for the oil and gas and offshore renewable energy industries.

Enhancing compressive behaviour of seawater sea sand concrete filled hybrid carbon-glass FRP tubes exposed to seawater: Effect of thickness

This study presents a novel investigation into the impact of tube thickness on the residual compressive strength of sea water sea sand concrete (SWSSC) filled filament wound hybrid fibre-reinforced polymer (HFRP) tubes, positioning them as innovative alternatives to traditional concrete-filled steel tubes in corrosive marine environments. The research explores tube thicknesses of 2 mm, 3 mm, and 4 mm, employing a unique hybrid configuration of 50 % carbon fibre reinforced polymer (CFRP) internal layers and 50 % glass fibre reinforced polymer (GFRP) external layers. This study examines the effect of these configurations on compressive mechanical properties, microstructural characteristics, and damage progression under alkaline and seawater conditions. Additionally, the research evaluates cross-ply and hoop orientations as variables in filament winding fibre orientation. A comprehensive set of 108 hybrid tubes were filled with an alkaline solution to simulate the SWSSC environment and exposed to seawater at varying temperatures and durations. Accelerated aging experiments were conducted in the laboratory to assess the long-term compressive performance of SWSSC-filled HFRP tubes exposed to seawater. Long-term compressive strength predictions were made using the Arrhenius theory, based on short-term accelerated aging data. The accelerated test data revealed maximum compressive strength reductions of 33 %, 15 %, and 17 % for 2 mm, 3 mm, and 4 mm cross-ply HFRP tubes, respectively, after 150 days of exposure at 60 °C. For hoop HFRP tubes, the corresponding reductions were 19 %, 18 %, and 17 %. Thicker tubes (3 mm and 4 mm) with sufficient internal CFRP layers protect external GFRP layers from alkaline damage, akin to pure CFRP tubes. Thinner tubes (2 mm) exhibit similar performance to GFRP tubes as alkaline damage spreads from their less substantial internal CFRP layers to the outer GFRP layers. For cross-ply tubes, the recommended strength reduction factors are 0.6 for 2 mm, 0.8 for 3 mm, and 0.8 for 4 mm thicknesses. For hoop tubes, the suggested factors are 0.7 for 2 mm, 0.7 for 3 mm, and 0.8 for 4 mm thicknesses. This study shows the innovative potential of tailored hybrid HFRP tubes in enhancing the durability and performance of marine infrastructure.

Surface Modification of Composite Coating for Marine Application: A Short Review

Corrosion is one of the phenomena that affects the deterioration of materials in offshore applications. Marine corrosion is particularly aggressive, due to the high salt content and low electrical resistivity of seawater. Corrosion cannot be stopped completely, but the reaction can be slowed down. Applying coating is an effective and widely used method to protect metal surfaces from corrosion. Coatings act as a barrier between the metal and its environment, preventing or slowing down the corrosive processes. Pursuant to ISO 12944, the most commonly used generics for coating systems in marine service are alkyd, acrylic, ethyl silicate, epoxy, vinyl ester, polyurethane, polyaspartic, and polysiloxane. The latest innovations in marine coatings still use a layer-by-layer coating method (e.g. primer coats, intermediate coats, and top coats) depending on thickness. Marine structures exposed to the atmospheric zones are usually coated with one or two coats of epoxy. A slightly more costly system of one coat of zinc-rich primer, one coat of epoxy, and one coat of aliphatic polyurethane may provide better performance. Coating systems for the atmospheric zones are frequently used in the intertidal and splash zones. Immersion zones of marine structures are commonly coated with one or two coats of 100% solid epoxy or three coats of solvent-borne epoxy. A single polymer as a generic coating have limitations. Adding fillers is a common method to improve the properties of polymers to become a composite. In marine coatings, fillers are still limited to glass flakes and powder. Poor dispersion and agglomeration might reduce the effectiveness of fillers in the matrix, which decreases the adhesion properties. The fillers must be surface modification before the application. This review provides a comprehensive and critical review of the current research status of composite coatings that serve as candidates to be used in marine coating.

2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives (Adv. Mater. 37/2024)

2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives (Adv. Mater. 37/2024)

(La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 High-entropy ceramic-glass composite coating with a high corrosion resistance

In this work, a new type of high-entropy ceramic powder (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 was synthesized by sol-gel method and high-temperature sintering (1000 °C) method. Combing (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 and glass powder to prepare high-entropy ceramic-glass composite coating. The composite coating exhibits excellent seawater corrosion resistance and high-temperature resistance performance. The impedance values of composite coating are 2.36 × 106 Ω cm2 in 3.5 % NaCl solution for 24 h. The high-entropy ceramic-glass composite coating could withstand the high temperature of 600 °C for 30 days and remains tight and intact with stainless steel without falling out. This work shows that the (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7-glass composite coating can provide long-term high-temperature and seawater corrosion protection for stainless steel and has good application prospects in the field of marine corrosion protection.

Corrosion evolution and quantitative corrosion monitoring of Q355 steel for offshore wind turbines in multiple marine corrosion zones

Offshore wind turbines operating in harsh marine environments are at risk of corrosion. Thickness loss and perforation caused by corrosion can lead to component failure or structure collapse. An environmental test setup was constructed to simulate various marine corrosion zones. Several experimental studies were conducted on Q355 steel, commonly used in offshore wind turbines. The mass loss and electrochemical properties of the steel specimens were analyzed, including electrochemical impedance spectra and polarization curves. The results indicate that corrosion remains stable in the immersion and tidal zones, whereas corrosion in the splash zone is the most severe, with a corrosion rate as high as 0.70 mm/a. A significant macroscopic corrosion cell effect was observed on the vertical steel strip, accelerating corrosion in the splash zone and at the low tide line. The corrosion product compositions and corrosion morphology of each corrosion zone were characterized and analyzed. Furthermore, a corrosion monitoring sensor based on electromechanical impedance was proposed. A prediction model for the mass loss rate of vertical steel strips was developed based on the conductance peak frequency. This study elucidates the corrosion evolution of wind turbine structural steel and proposes a comprehensive steel corrosion monitoring solution.

A self-healing polyurethane/imidazole-modified carboxylated graphene oxide composite coating for antifouling and anticorrosion applications

Marine corrosion and biofouling present significant challenges to maintaining maritime vessels and oceanic infrastructure. Developing coatings that integrate anti-fouling, anti-corrosion, and self-healing properties remains a critical issue. This study introduces imidazolium-modified carboxylated graphene (FCGO) into polyurethane coatings (F-PUSS) containing disulfide bonds to address this challenge. The incorporation of FCGO significantly enhances the mechanical properties of the coating, improving tensile stress by 40 % to 20.97 MPa. The barrier properties of FCGO also provide strong corrosion resistance, with |Z|0.01Hz values an order of magnitude higher than the original samples, even after 15 days of immersion in sodium chloride (3.5 wt%). Additionally, F-PUSS retains corrosion resistance after repairs. The synergistic action of imidazole groups and graphene provides excellent antifouling performance with nearly to an alga rate of 100 % and an antimicrobial rate of 96 %. F-PUSS demonstrates remarkable self-healing capabilities, with a healing efficiency of 78 % after 48 h at 60 °C. This study provides valuable insights for designing multifunctional polymer materials with anti-fouling, anti-corrosion, and self-healing functions.

Mechanical-robust and polymer-based superhydrophobic coating toward self-cleaning and anti-corrosion

The corrosion of reinforced concrete materials severely threatens cross-sea bridges, buildings and marine ships. The unique air layer on the superhydrophobic coating surface can effectively minimize the reinforced concrete corrosion, which not only extends the long-term usability of concrete but also reduces economic losses and environmental pollution. It is necessary to design a superhydrophobic coating on substrate surfaces to accommodate the requirement for corrosion prevention due to their anti-corrosion and self-cleaning properties. Despite gradually developing superhydrophobic coatings to meet diverse needs, they still encounter limitations in engineering preparation and applications. For example, the rough micro-/nano structure of the superhydrophobic surface is easily damaged by mechanical impact or physicochemical damage, which could affect the antiseptic properties. Moreover, designing and preparing all polymer-based superhydrophobic micro-/nano structures using amorphous elastomer materials is vital for enduringly industrial applications, yet it remains a challenge. Here, we design and fabricate a mechanical-robust superhydrophobic coating composed of amorphous polyurethane (PU) and epoxy resin modified with amino-terminated polysiloxane (APT-PDMS) via a scalable atomization spraying method. A quartz sands impact abrasion test evaluates the mechanical durability of the PU superhydrophobic coating (PU-SC). The superficial PU particles can form elastic micro-protuberances, absorbing impact and preventing fracture through elastic deformation during friction. Furthermore, the as-prepared PU-SC can also resist some chemical mechanical damage, including acids/bases/salts solution corrosion, UV radiation, knife scraping treatment, 3M tape-stripping, water flow impact, outside sunlight shining treatment and temperature treatment. Notably, the robust PU-SC can be efficiently produced on a large scale and applied to prevent electrochemical corrosion in a simulated seawater environment. The corrosion protection efficiency (PE) can reach 98.1%. We believe that the design and development of a mechanical-robust and polymer-based superhydrophobic coating has the prospect of actual application on marine corrosion.

Behaviour of eccentrically loaded concrete-filled rectangular ferritic stainless steel tubular slender columns: Numerical modelling and design

Ferritic stainless steel achieves a lower and steady price level due to low nickel content compared to duplex and austenitic stainless steels. Accordingly, the combination of ferritic stainless steel tube and concrete will have better application prospects in corrosive marine environments. However, the structural application of concrete-filled ferritic stainless steel tube (CFFSST) members is still limited due to the absence of performance data and design guidelines. Accordingly, this paper aims to comprehensively investigate the behaviour of eccentrically loaded concrete-filled rectangular ferritic stainless steel tubular (CFRFSST) slender columns using the nonlinear finite element (FE) method, and develop a suitable design method. Two different material models were introduced to simulate corner and flat regions of rectangular ferritic stainless steel tube. Good consistency was found between the simulation and experimental results against the failure mode, ultimate load and moment, and axial load versus mid-height deflection curves for eccentrically loaded CFRFSST slender columns. This is followed by the mechanism analysis and parameter study of the studied CFRFSST columns, which revealed that the longitudinal stress and Mises stress show significant changes perpendicular to the loading line direction, while there is almost no change along the loading line direction. In addition, the initial stiffness and ultimate load increased by increasing the cross-sectional aspect ratio, yield stress and concrete strength, while they decreased as the eccentricity ratio, slenderness ratio and width-to-thickness ratio increased. The outputs of the FE analysis and existing experimental results were used to examine the applicability of current design codes for designing the studied CFRFSST columns. The results demonstrated an unexpected deviation generated in the design predictions. At the end, a new design method for eccentrically loaded CFRFSST slender columns was proposed which achieved better predictive consistency.

Experimental insights on biofouling growth in marine renewable structures.

Marine biofouling is a threat to industries working in the marine environment, representing significant costs associated with equipment impairment and loss of performance. In the Marine Renewable Energy (MRE) and other maritime sectors which operate at sea for long periods, an important aspect of biofouling is related to the type and frequency of inspections and biofouling removal procedures. This study investigated important parameters of macrofouling ( e.g. composition, including the presence of non-indigenous species, thickness, and weight) from communities growing on samples that emulate tubular components of marine renewable devices. The trials were performed during short periods of submersion (one to eight weeks) in the seasons when the colonisation process should be most intensive (spring, summer, and autumn). Furthermore, the frictional resistance forces generated during the scraping of biofouling from those components were investigated. Overall, results provide insights on the growth rates and removal requirements of biofouling in marine components. The results show that, while biofouling growth in early colonization stages might not present great detrimental effects to wave energy components, the consequent marine corrosion (fostered by biofouling) and the settlement of non-indigenous species (NIS) should be factors of concern. Performing biofouling-related maintenance activities after the peak of maximum growth and reproduction (during the warmer seasons in temperate to cold environments) is suggested to reduce the number and frequency of activities. NIS can be detected at very early stages in the colonization process, highlighting the importance of biofouling monitoring and the implementation of biosecurity risk assessment plans early in the operational stage of MRE projects.

Experimental Study on Durability and Bond Properties of GFRP Resin Bolts.

Glass fiber-reinforced polymer (GFRP) anchor bolts are a new type of high-performance nonmetallic anchor with significantly higher tensile strength, a lighter weight, better corrosion resistance, and a lower cost than steel bars. Therefore, exploring the durability and bonding performance of GFRP anchor systems is of great importance for the structural design of protective engineering, especially in coastal environments. However, insufficient research has been conducted on the durability of GFRP resin bolts in seawater conditions, with no universal standard on the pullout testing of GFRP bolts. To study the durability and bonding performance of GFRP resin bolts, durability experiments were conducted in this work using artificial seawater, and the pullout tests were conducted using a large-scale concrete platform with different compressive strengths (21.2, 40.8, and 61.3 MPa). The results of the durability experiments indicated that the strength variations of the GFRP rods and epoxy resin materials in artificial seawater environments were less than 5%. Subsequently, indoor pullout tests using steel tubes filled with epoxy resin were conducted, and the test results indicated a critical anchor length value. Pullout tests of the GFRP resin bolts embedded in large-scale concrete blocks were also conducted with different strengths. According to the test results, all GFRP resin bolts embedded in the three concrete blocks with different compressive strengths exhibited rod fracture failure. The failure mode was not controlled via the compressive strength of the concrete blocks due to the high bonding strength between the resin and the rod, as well as between the resin and the concrete. Therefore, this GFRP resin anchor system could fully utilize the tensile strength of GFRP rods. This research offers significant practical value in verifying the safety and reliability of GFRP resin bolts in corrosive marine service environments, and it contributes to the application and development of GFRP materials in the engineering field, serving as a valuable reference for the structural design and further study of GFRP bolts.

Stability analysis and design methods of steel pipe piles under non-uniform corrosion

Steel pipe piles (SPPs) are commonly applied for marine platform foundations due to high bearing capacity. However, for SPPs in corrosive marine environments, the corrosion on the steel tube is severe and shows a non-uniform distribution along the height direction, resulting in the significantdecrease of the stability bearing capacity. To investigate the stability performance of SPPs in marine corrosive environments, the corroded SPPs are simplified into five-segment stepped columns, and the equilibrium differential equations are established to obtain the rotational stiffness relationship. The analytical solutions of the critical buckling loads of five-segment stepped columns under arbitrary boundary conditions are obtained by iterative methods. Besides, considering the material and geometrical nonlinearity, the finite element (FE) model of corroded SPPs is established and then verified based on existing test results. The effects of the number of segments and stiffness ratios among different segments on the bearing capacity are analysed. Furthermore, considering the interactions among different segments, the calculation methods for the stability bearing capacity of stepped columns under axial compression and combined compression-bending are proposed respectively. The comparison between calculated and FE results indicates that the proposed calculation methods have good prediction accuracy and can be available for practical engineering reference.

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.

2D materials for marine corrosion protection: A review

The pervasive issue of metal corrosion in various industrial environments, especially in marine settings, incurs significant economic costs and hazardous failures. Traditional protection methods, although diverse, fall short in durability and environmental adaptability, necessitating advanced solutions, such as two-dimensional (2D) materials, including graphene, layered double hydroxides, boron nitride, MXenes, and MoS2. These materials offer exceptional barrier properties against corrosive agents due to their high surface area and minimal thickness, enhancing the lifespan and reliability of metal assets under harsh conditions. Innovations such as self-repairing coatings and advanced application techniques, such as automated spraying and rapid photocuring, further augment their effectiveness. In this Review, recent advancements in the development and application of 2D material-enhanced coatings are reviewed, underscoring their potential in revolutionizing marine corrosion protection through improved performance metrics and sustainability. The challenges and prospects of these novel materials are also discussed, highlighting the need for further research to overcome application hurdles and realize their full potential in industrial uses.

Design and realization of versatile durable fluorine-free anti-corrosive coating with robust superhydrophobicity

Bio-inspired superhydrophobic coatings are of increasing interest in marine corrosion protection due to their superior barrier and shielding effects. However, some difficult problems like weak mechanical strength, the use of costly and toxic reagents, and intricate preparation processes have long hindered the practical application of the superhydrophobic coatings. Herein, a durable, self-cleaning and anti-corrosion superhydrophobic coating based on epoxy resin matrix was successfully fabricated, avoiding the use of fluorine materials. The prepared coating possessed excellent superhydrophobicity and was applicable to a variety of substrates, which was ascribed to the effect of modified kaolin particles on lowering surface energy. Through SEM and LSCM, the superhydrophobic coatings manifested the morphology feature of "hills+mountain", which could store air to reduce solid-liquid contact. The prepared coating had been proven to have greater impedance modulus and charge transfer resistance by EIS test, and displayed outstanding durability in salt spray environment compared with pure epoxy coating. In addition, the sandpaper abrasion, standard cross-cut tape and self-cleaning tests indicated that the superhydrophobic coatings satisfied robust mechanical stability and excellent resistance to contaminants, laying the foundation for the application of superhydrophobic coating in practical environment.

Durability life evaluation of marine infrastructures built by using carbonated recycled coarse aggregate concrete due to the chloride corrosive environment

Due to the harsh marine environment of chloride ion invasion and corrosion, the issues of long-term chloride transport and durability life evaluation for marine infrastructures constructed/maintained by recycled aggregate concrete (RAC) after enhancement remain poorly understood. For our studies, an accelerated carbonation modification method for recycled coarse aggregate (RCA) was adopted to prepare carbonated recycled coarse aggregate (CRCA) samples, and the macroproperties, i.e., apparent density and water absorption, of CRCA were enhanced by approximately 1.40-3.97% and 16.3-21.8%, respectively, compared with those of RCA. An in-door experiment for chloride transport into concrete specimens subjected to a simulated marine environment of alternating drying-wetting cycles was conducted. The chloride profiles and transport characteristics of carbonated recycled coarse aggregate concrete (CRCAC), recycled coarse aggregate concrete (RCAC), and natural coarse aggregate concrete (NCAC) were analysed and compared. The results indicated that the chloride penetration depths and concentrations of CRCAC were approximately 52.6-96.2% of those of RCAC, which highlighted the better chloride resistance of CRCAC. A chloride transport model for marine concrete structures with various coarse aggregate types in a corrosive marine environment was established. Taking a certain harbour wharf as an example, the durability life of this case considering the application of the CRCAC was evaluated based on the chloride transport model, and the durability life of the CRCAC structure was improved by approximately 28.10% compared with that of the RCAC. The CRCAC developed in this paper has improved mechanical performance and durability than those of RCAC, and it has the potential to replace the NCAC and further support the construction and maintenance of marine infrastructures.

Introducing Unmanned Aerial Vehicles to multi-criteria performance assessment of inspection techniques for port concrete infrastructure

Port infrastructure plays an important role in the economic and social activities of the regions they serve. Pressures induced by the corrosive marine environment and weather conditions, unexpected events associated with climate change, the usually high freight and vehicle loading conditions, the dynamic load of the equipment, and insufficient maintenance and rehabilitation measures that sometimes are not enough to repair an in-service facility, increase the susceptibility of port structures to rapid aging and deterioration. To ensure port infrastructure safety and reliability, and to maintain operational efficiency, port managers are tasked with forming successful inspection schemes for structural condition monitoring. Within this context, identifying the capabilities and prioritizing existing inspection techniques allow for optimizing resources (cost, time, personnel). The issue of performance assessment for commonly used Non-Destructive Testing techniques has received significant research interest. However, state-of-the-art Unmanned Aerial Vehicle techniques have not been previously involved in studies that assess the performance of various inspection techniques. Hence, the present research seeks to introduce Unmanned Aerial Vehicles techniques into multi-criteria performance assessment practices of inspection techniques for port concrete infrastructure. Three Non-Destructive Techniques: a) Infrared Thermography, b) Ground Penetrating Radar, and c) Impact-Echo, are compared to camera-based Unmanned Aerial Vehicle techniques linked to Close Range Photogrammetry applications. A qualitative approach, including a literature review and expert judgment, is applied to acquire data required for Multi-Criteria Decision Analysis practices with the Preference Ranking Organization METHod for Enrichment Evaluation methodology. The ranking output of the applied model is validated with other multi-criteria methods to ensure the robustness of the results. The obtained results for the specific set of criteria will assist decision-makers in selecting the most suitable technique for inspecting surface or sub-surface defects in port concrete infrastructure. Highlights The integration of UAV-driven techniques into current practices for assessing the performance of inspection techniques affects the ranking order The prioritization of the inspection techniques is conducted qualitatively (expert judgment and literature survey) by implementing the PROMETHEE method A camera-based UAV technique improves the practical part of inspections and provides flexibility A camera-based UAV technique is the optimal inspection technique for detecting surface defects, while Impact Echo is preferred for sub-surface defects

The Positive impact of biomineralization for marine corrosion protection of AA5083 alloy

This paper investigates, using surface characterisation techniques (SEM, XPS and ToF-SIMS), the impact of marine biological activity on AA5083 corrosion behaviour during seawater immersion. Different solar exposure (light vs. dark) results in distinct marine fouling development, influencing surface modifications. On the dark side, an Al/Mg oxide/hydroxide layer forms, allowing Cl- penetration. Pitting attack is observed after immersion. For the light side, a dual layer structure forms, with a hydrated Mg rich outer layer, showing barrier effect to Cl- penetration. No localized corrosion occurs. A comparison with abiotic conditions demonstrates the corrosion-inhibiting effect of marine biological activity on AA5083.