Search Results (176)

Offshore wind turbine blades are chronically exposed to complex marine environments with high humidity, salt spray, strong wind, waves, and intense radiation. Under such conditions, blade defects often exhibit small sizes, weak visual features, and heterogeneous visible infrared manifestations. Conventional single-sensor monitoring and empirically weighted fusion methods are insufficient for reliable defect diagnosis and risk grading. To address this problem, this paper proposes a cross-sensor consistency-guided dual-spectrum fusion framework, termed CG-DSF, for offshore wind turbine blade defect diagnosis and risk assessment. First, visible-light images and infrared thermal images are acquired by UAV-mounted imaging sensors, and sensor-specific branches are constructed to extract surface structural features and thermal anomaly responses. Second, visible and infrared features are aligned at the feature token level, and cross-sensor evidence is evaluated for spatial consistency, diagnostic semantic consistency, and anomaly consistency. A reliability-aware fusion strategy is then used to suppress low-quality or conflicting observations and construct a unified defect representation. Finally, a series of representative simulation case studies are carried out to comprehensively assess the overall performance and practical applicability of the constructed model. Experimental results reveal that the proposed framework possesses evident advantages in blade defect identification for offshore wind turbines, offering a feasible solution for advancing proactive and intelligent condition-based operation and maintenance of offshore wind assets in complex marine environments. Full article

Neutral salt spray tests were conducted on assemblies comprising H59 brass and either electrogalvanized or hot-dip galvanized bolts. The polarization curves, electrochemical impedance spectroscopy (EIS), corrosion morphology, elemental distribution, and corrosion product composition of the H59 brass were systematically characterized. The results demonstrated that upon coupling with galvanized bolts, the formation of a protective Cu₂O film on the H59 brass is significantly weakened, leading to accelerated corrosion. After coupling with electrogalvanized bolts, the i_corr reached a maximum value of 0.21 mA/cm². A corrosion layer predominantly composed of ZnO formed on the sample surface with a thickness of approximately 13 μm, and no penetration or enrichment of Cl was observed in the matrix. More seriously, when the brass was assembled with hot-dip galvanized bolts, the i_corr never dropped below 0.2 mA/cm². A porous and complex Zn-Cu-O-Cl mixed corrosion layer developed on its surface. This loose structure allows Cl⁻ to reach a depth of 55 μm into the matrix and continue causing corrosion. The mechanisms underlying the different corrosion behaviors of H59 brass caused by different galvanizing bolt processes require further investigation. Full article

Thermal shock resistance is a critical parameter for evaluating the long-term service reliability of protective coatings in high-temperature molten-salt environments. In this study, Al₂O₃–Y₂O₃ composite coatings containing 0, 2, 5, and 8 wt.% Y₂O₃ were fabricated on 316L stainless-steel substrates by atmospheric plasma spraying (APS). Their phase constitution, microstructure, mechanical properties, and thermal shock resistance were systematically investigated. The results showed that, with increasing Y₂O₃ content, the relative content of α-Al₂O₃ gradually increased, whereas the coating densification, microhardness, and fracture toughness first increased and then decreased. After 200 thermal shock cycles, the thermal shock resistance of the Al₂O₃–Y₂O₃ composite coatings followed the order of 5 wt.% Y₂O₃ > 2 wt.% Y₂O₃ > 8 wt.% Y₂O₃ > 0 wt.% Y₂O₃, indicating that the addition of an appropriate amount of Y₂O₃ significantly improves the thermal shock resistance of the coatings. Analysis of the failure mechanism further revealed that the addition of an appropriate amount of Y₂O₃ enhanced phase stability and optimized the coating microstructure, thereby improving the crack-propagation resistance and ultimately enhancing the thermal shock resistance. In contrast, excessive Y₂O₃ weakens this beneficial effect because of increased microstructural heterogeneity and a higher defect density. Full article

The self-formed rust layer is significant for weathering steels because their corrosion resistance in a marine atmospheric environment mainly relies on the stability, uniformity and compactness of the rust layer. However, the initial stage of rust formation is vulnerable and prone to being disturbed by the external environment, compromising the protectiveness of the rust layer at a later stage. Therefore, weathering steel often requires the application of rust stabilization techniques. This study has developed a waterborne polyurethane (WPU)-based coating incorporated with mesoporous/hollow SiO₂ nanoparticles, acting as the primary components for the construction of pathways for gaseous H₂O and O₂, as well as for Cl⁻ dissolved in moisture, while blocking liquid water. Salt spray was applied to accelerate the rust formation process, and rust can form beneath the coating, which provides shelter for rust formation against the external environment. Hexamethyldisilazane (HMDS) was applied to further hydrophobize the nanoparticles, and a hydrophobic surface with self-cleaning properties was achieved. The hydrophobized and non-hydrophobized coatings with different thicknesses (10–80 µm) were systematically compared: the morphology of the rust layer and coating surface after salt spray was investigated, the ability of the rust layer to inhibit chloride ingress was compared, and the electrochemical behaviors were analyzed. This study presents a new strategy for weathering steel rust stabilization that features maneuverability, environmental friendliness and low cost. Full article

In this study, C/N-containing Fe₃O₄ oxide films over an inner nitride layer were fabricated on 45# steel by oxynitriding to improve corrosion resistance in chloride-containing environments. The films exhibited a dense polyhedral structure, with nanoscale Fe₃O₄ precipitates at grain boundaries. Nitrogen and carbon were uniformly distributed within the oxide grains, inducing lattice expansion and modifying the Fe-O bonding environment. First-principles calculations based on C/N substitution models suggested that C/N incorporation may increase the unit cell volume, strengthen lattice bonding, and enhance the theoretical hardness of Fe₃O₄. The optimally doped films exhibited outstanding corrosion resistance, with a corrosion potential of 0.115 V_SCE, a corrosion current density of 3.16 × 10⁻¹⁰ A/cm² in 3.5 wt.% NaCl solution, and a corrosion-free lifetime of up to 3600 h in neutral salt spray testing. This superior performance is attributed to the synergistic effects of the compact single-phase magnetite layer, grain boundary precipitates, and modified electronic structure, which collectively inhibit chloride ingress and convert localized electrochemical attack into uniform corrosion. The experimental results are consistent with first-principles predictions, which clarified the mechanism of nitrogen doping in material corrosion protection from a mechanistic perspective. Full article

This study investigated the degradation behavior of a polyurethane acrylate coating/Q345B steel system under the coastal atmospheric conditions of Wenchang, Hainan, and evaluated the correlation between indoor accelerated tests and outdoor exposure. Outdoor exposure tests, single-factor accelerated tests (UV irradiation and neutral salt spray), and a multi-factor cyclic accelerated test combining UV, salt spray, humidity, and thermal cycling were conducted. Coating degradation was characterized by morphological observation, gloss measurement, adhesion testing, and electrochemical impedance spectroscopy. The results showed that after 8 months of outdoor exposure, localized rust spots, blistering, and under-film corrosion appeared on the coating surface. The gloss loss rate reached 15.72% after 3 months, while adhesion decreased from 5.83 MPa to 2.39 MPa during prolonged exposure. UV irradiation mainly affected gloss degradation, whereas corrosive media penetration played a dominant role in adhesion loss and electrochemical deterioration. Compared with single-factor tests, the multi-factor cyclic accelerated test exhibited the highest correlation with outdoor exposure. The corresponding correlation coefficients for gloss loss, adhesion, and low-frequency impedance modulus were 0.9764, 0.9988, and 0.9929, respectively, while the gray relational coefficients reached 0.8334, 0.8467, and 0.7977. These results demonstrate that the multi-factor cyclic accelerated test more accurately reproduces the degradation behavior and failure characteristics observed in the coastal atmosphere of Hainan. The proposed method provides a practical approach for indoor–outdoor correlation analysis and durability evaluation of protective coatings in marine atmospheric environments. Full article

A comparative investigation of the corrosion behavior evolution of 15%SiCp/Al-Cu-Mg aluminum matrix composites (AMC) subjected to different heat treatments in a salt spray environment containing 5wt% NaCl was performed. Metallographic microscopy was used to observe the surface morphology of the corroded materials. Field-emission transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for microstructural evaluation and elemental analysis of the samples. Polarization curves and electrochemical impedance spectroscopy (EIS) were also employed to investigate the corrosion performance of the particle-reinforced aluminum matrix composites under different heat treatments. The test results indicate that, in addition to the influence of various grain boundary precipitates and electrochemical inhomogeneities between the precipitate-free zone (PFZ) and the aluminum matrix, differences in electrochemical properties between the SiC reinforcement particles and the aluminum alloy matrix are also a primary factor contributing to the corrosion of the aluminum-based composites in a 5wt% NaCl salt spray environment. Microstructural observations and electrochemical testing of AMC specimens at different corrosion stages indicate that under-aged samples exhibit relatively higher intergranular corrosion susceptibility. Under prolonged exposure to a salt spray environment, the over-aged specimen exhibited more pronounced galvanic corrosion phenomena, specifically, a significant decrease in Charge transfer resistance (R_ct) values and an increase in CPE values. R_ct results indicate that naturally aged AMC exhibits higher corrosion resistance than artificially aged AMC. With increased salt spray corrosion time, varying degrees of crevice corrosion occurred at the Al–SiC interface in all heat-treated samples. Full article

To investigate the mechanical property degradation laws of 6061-T6 aluminum alloy under the synergistic effect of coastal corrosive environments and cyclic loading, the effects of various corrosion durations (0 h, 600 h, 900 h, and 1200 h) on the static performance, hysteretic characteristics, and energy dissipation capacity of the material were studied through indoor accelerated salt spray corrosion tests, monotonic tensile tests, and multi-regime cyclic loading tests. The results indicate that after 1200 h of corrosion, the yield strength and ultimate strength decreased by an average of 2.28% and 5.16%, respectively, with the peak stress point shifting significantly forward. Corrosion significantly inhibits the cyclic hardening effect and accelerates the loss of ductility, with the ductility loss of 1200 h specimens reaching up to 44.0%. Strain is the key factor in activating the energy dissipation potential of the material; when the loading amplitude exceeds 4%, the energy dissipation coefficient stabilizes between 3.0 and 3.3. However, the combination of corrosion and random loading exacerbates the decay of energy dissipation capacity. This study aims to provide a theoretical foundation for the performance assessment and safety assurance of aluminum alloy structures in coastal engineering. Full article

The use of shotcrete is a critical support technique in ocean engineering structures. However, it often exhibits low chloride and salt erosion resistance under ocean environmental conditions and poor long-term durability. This study employed polypropylene fiber (PF) and basalt fiber (BF) to optimize the shotcrete mix design. Laboratory immersion and salt spray tests simulated chloride ion corrosion environments in the ocean’s underwater and atmospheric zones. The effects of different corrosion mechanisms and varying fiber volume fractions on shotcrete strength and durability were then analyzed. The results indicate that shotcrete demonstrates strong resistance to chloride-induced corrosion in both ocean underwater and atmospheric zones when the volume fractions of PF and BF are 0.2% and 0.1%, respectively. Based on test results from 3D digital microscopy (3D-DM), X-ray diffraction (XRD), and scanning electron microscopy (SEM), the chloride-induced degradation mechanism of hybrid fiber-reinforced shotcrete was analyzed from both mesoscopic and microscopic perspectives. This study offers theoretical support for applying hybrid fiber-reinforced shotcrete in ocean engineering environments. Full article

The anti-aging performance of stay cables in complex marine environments is directly related to the long-term service safety of sea-crossing cable-stayed bridge structures, and it has been recognized as one of the key issues for the priority evaluation of the structural performance of sea-crossing cable-stayed bridges with Basalt Fiber Reinforced Polymer (BFRP) cables. In this paper, the coupled aging effects of ultraviolet radiation, salt spray, temperature and humidity, and prestress on BFRP cables were taken into consideration. Accelerated aging tests involving the coupling of light, heat, water, salt, and prestress were carried out to simulate the actual marine service environment. The anti-aging performance of BFRP cables was investigated by combining the analysis of macro mechanical properties with the characterization of micro structural morphology. The results of the study were as follows: (1) With the increase in aging duration, the tensile strength and ultimate fracture strain of BFRP cables decreased gradually. The degradation rates of tensile strength and ultimate fracture strain of BFRP cables exhibited a decreasing trend, characterized by an initial rapid phase followed by a gradual slowdown under the coupled aging effects of light, heat, water, salt, and prestress. (2) Compared with the significant decrease in tensile strength, the elastic modulus of BFRP cables showed an insignificant decrease. The elastic modulus of BFRP cables was observed to exhibit a trend of initial decrease, subsequent increase, and another decrease, with an overall reduction. (3) Temperature and prestress were verified to exert a considerable influence on the anti-aging performance of BFRP cables. The influence of temperature on the degradation of aging performance of BFRP cables was found to be greater than that of prestress. (4) The degradation in the anti-aging performance of BFRP cables under coupled aging effects was confirmed to originate from the initiation and propagation of microcracks in the resin matrix, which were caused by the combined actions of prestress, photochemistry, and hydrolysis. Meanwhile, the damage to the fiber–resin interface was accelerated by chloride ions in seawater under high-temperature conditions, which ultimately led to a reduction in the anti-aging performance of BFRP cables. Full article

Zn-Fe-Cr coatings were successfully deposited on sintered Nd-Fe-B matrix through the addition of the complexing agent etidronic acid (HEDP) to the plating solution; the electrodeposited process of the metal elements and the corrosion behavior of the coatings were also investigated. Through cyclic voltammetry (CV) tests, it was observed that the reduction potential difference between the metal elements was reduced by the addition of HEDP, which contributed to a more feasible electrodeposited process. The surface of Zn-Fe-Cr coating was covered by a chromate conversion film, and its microstructure was identified as the solid solution of Fe and Cr in Zn matrix. Compared with Zn and Zn-Fe coatings, the corrosion current density (J_corr) of Zn-Fe-Cr coating was decreased to 0.28 × 10⁻⁶ A·cm⁻², and the corrosion potential (E_corr) was increased to −1.01 V. Compared with the Zn and Zn-Fe coatings, the corrosion rate of the Zn-Fe-Cr coating has decreased by 90% and 98%, respectively. The corrosion resistance of coatings was further analyzed by neutral salt spray tests (NSS), and the analysis results showed that a composite oxide layer, composed of ZnO and Cr₂O₃, was formed in the corroded area of Zn-Fe-Cr coating during the corrosion process, which is capable of effectively inhibiting the expansion of the corrosion area. This research provides a promising strategy for ensuring the long-term service integrity of sintered Nd-Fe-B materials in marine environments. Full article

Coastal wind turbines operate under severe salt spray, high humidity, and wind-driven erosion, which accelerate coating degradation and corrosion-induced cracking. In such environments, corrosion defects exhibit blurred boundaries, weak textures, and significant scale variations, challenging object detectors in small-target localization and precise boundary regression. To address these limitations, this study proposes CoastCor-Net, an enhanced YOLOv11-based framework that improves spatial–semantic alignment, boundary representation, and channel–spatial dependency modeling. The architecture integrates three complementary modules to enhance boundary sensitivity, spatial–semantic consistency, and cross-channel interaction: a Decoding-Driven Enhancement Block, a Complementary Feature Alignment Module, and a Channel-Transposed Coordinate Attention module. Extensive experiments on the Wind Turbine Blade Damage Dataset show that CoastCor-Net achieves 84.7% mAP@0.5 and 54.1% mAP@0.5:0.95, surpassing YOLOv13n by 3.2 percentage points in mAP@0.5 and improving AP_damage by 5.2 percentage points. The framework also demonstrates strong robustness under composite coastal perturbations. These findings highlight the practical effectiveness of structured multi-level feature enhancement for reliable and high-precision blade inspection in complex coastal environments. Full article

Sliding contact wear at the pantograph–catenary interface directly impacts the current collection performance and power supply reliability of electrified railways. Addressing the challenges in multi-environmental wear studies—namely, fragmented modeling chains, inconsistent parameter calibrations, and prohibitive computational costs that hinder horizontal comparisons—this study develops an equivalent parameterized modeling framework tailored for engineering assessment. The framework encapsulates environmental effects as equivalent load increments and interface coefficient corrections, facilitating efficient multi-scenario parameter scanning within a 3D contact model. Findings reveal that environmental factors drive wear through a distinct “pressure-wear” nonlinear decoupling mechanism. In sandy environments, abrasive-mediated micro-cutting dominates, leading to a monotonic surge in wear depth as sand concentration increases, despite a buffered contact pressure response. In icing conditions, the synergy of low-temperature brittleness and geometric impact renders hotspot wear highly sensitive to temperature fluctuations. For salt spray conditions, the environmental impact is represented via equivalent corrections to the interfacial parameters; within this equivalent framework, the results suggest that salt spray intensity has a more pronounced effect on wear accumulation than humidity alone. This work reveals the divergence of dominant damage pathways across environments, offering a quantitative basis for the differentiated maintenance and remaining life estimation of pantograph–catenary systems in extreme climates. Full article

This paper presents an investigation of chloride-induced corrosion in steel fiber-reinforced cementitious composites (SFRCCs) under uncracked and pre-cracked conditions. The study focuses on a single SFRCC mixture and evaluates the impact of chloride exposure on the mechanical strength of the material using a 3-point bending test, with a particular focus on the chloride exposure period and the role of crack width in the corrosion process. The specimens were categorized into three groups: reference (unexposed), uncracked, and pre-cracked (with initial crack widths of 0.4 mm and 0.9 mm). They were exposed to salt spray cycles in a controlled chamber, simulating severe chloride environments, and tested after various exposure durations (28, 56, and 112 cycles). The results showed that in the uncracked samples, there was an increase in $f_{R1}$ with longer exposure time to the aggressive environment, reaching a 15.45% increase after 112 days compared to the reference. Overall, uncracked specimens maintained their residual tensile strength despite extended chloride exposure, supporting previous findings that corrosion in uncracked SFRCC does not significantly compromise durability. In the cracked samples, increases in $f_{R2}$, $f_{R3}$, and $f_{R4}$ were observed at early exposure stages (28 and 56 cycles) for specimens with a 0.9 mm crack width. After prolonged exposure (112 cycles), the residual tensile strengths converged toward reference values. For pre-cracked specimens, initial corrosion enhanced residual tensile strength in those with larger pre-cracks. However, after prolonged exposure, deterioration of the fiber–matrix bond became apparent. Full article

Crust Ash Triad Clay (CATC) is a traditional construction material commonly used for jointing coastal stone masonry in Southeast China. Its surface is prone to blackening in coastal environments. This study focused on traditional stone masonry residences within the protection area of Quanzhou Shihu Ancient Wharf. A systematic detection and analysis were conducted using combined technologies: XRD, Raman, SEM-EDS, and 16S rRNA sequencing. The results revealed that the CATC substrate is mainly composed of quartz and feldspar minerals, with calcite and other substances as binding components. The black coating on the surface is a loose material attached to the substrate, retaining some of the original minerals. The core mechanism of blackening lies in the coastal environment’s abundance of salt spray and humidity. The sulfate substances carried by rainwater react synergistically with metal ions such as Cu, Fe, and Mn in the substrate under the metabolic action of anaerobic bacteria, producing metal sulfide minerals. Photoautotrophic bacteria generate oxygen through photosynthesis, promoting the oxidation and acidification of metal sulfide. This process directly triggers the chain deterioration of the CATC substrate. Based on the principle of “minimal intervention”, physical waterproofing or laser stain removal can be implemented. This study provides scientific support for optimizing the durability and achieving precise protection of traditional building materials in coastal stone structure heritage. Full article