Search Results (213)

This study examines how the Alkali–Silica Reaction (ASR) modifies chloride transport and chloride-induced corrosion (CIC) in reinforced concrete beams. Non-reactive and reactive concrete beams were cast with blue metal and dacite aggregates and subjected to a two-stage exposure: (i) alkali-rich immersion at 38 °C to induce ASR, and (ii) impressed-current CIC and NT BUILD 492 chloride migration testing. Microstructural changes were characterized using SEM–EDS and TGA. The reactive specimens developed extensive surface cracking, but after one year of ASR exposure, exhibited 47–53% lower non-steady-state migration coefficients (Dnssm: 7.03–8.02 × 10⁻¹² m²/s) than the non-reactive beam (15.09 × 10⁻¹² m²/s). After two years, Dnssm was reduced by approximately 37–56% (4.78–6.93 vs. 10.92 × 10⁻¹² m²/s). Crack mapping confirmed higher crack density and width in reactive beams, while SEM–EDS and TGA evidenced Ca depletion and the formation of C–(N,K)–S–H gels, which fill cracks and refine the pore structure. Electrical resistance monitoring showed earlier corrosion initiation in ASR-damaged beams but less pronounced resistance loss during the propagation phase. Overall, the results indicate that ASR can initially accelerate corrosion initiation through microcracking and reduced resistivity, but long-term gel deposition can partially seal transport paths and lower chloride migration under the specific conditions of this study. Full article

This study established a marine atmospheric corrosion prediction model by comparing the corrosion behavior of 7075 aluminum alloy in neutral salt spray tests and outdoor exposure tests conducted in the coastal atmosphere of Hainan. The results show that severe rusting occurred after 96 h of neutral salt spray testing, with loose white cluster-like corrosion products mainly composed of Al(OH)₃ and Al₂O₃. The thickening of the corrosion product layer slowed down the corrosion process, following a nonlinear power-law kinetic relationship. In the later stage, potential dropped sharply due to product layer spallation, and recovered as new corrosion products formed, confirming that the stability of the product layer is critical for protection. Under coastal atmospheric exposure, the composition of corrosion products was similar to that observed in the salt spray test, but the actual corrosion rate was affected by environmental dynamic equilibrium. The acceleration factor of the neutral salt spray test corresponding to the same corrosion amount in the Hainan marine atmosphere exhibited a declining trend, reflecting that differences in the protective nature of the corrosion product layer were influenced by environmental factors. Electrochemical analysis indicated that both tests showed similar current–potential synergistic variation mechanisms dominated by product layer stability. In summary, while the neutral salt spray test effectively simulates the chloride-induced corrosion mechanism in marine atmospheres, its kinetic model cannot directly predict real corrosion behavior through a simple acceleration factor, as environmental complexity must be considered. Full article

This paper presents a validated, data-driven framework for the sustainable rehabilitation of corrosion-damaged marine infrastructure, demonstrated through a comprehensive study on a historic coastal structure. The implemented three-phase methodology—integrating advanced condition assessment, evidence-based intervention design, and rigorous performance validation—successfully addressed severe chloride-induced deterioration. Diagnostic quantification revealed that 30% of the primary substructure was severely compromised, with chloride concentrations reaching 1.94% by weight (970% above the corrosion threshold) and half-cell potential mapping confirming a >90% probability of active corrosion in critical elements. Guided by this data, a synergistic intervention combining galvanic cathodic protection, high-performance coatings, and structural strengthening was deployed. Post-repair validation confirmed exceptional outcomes: a complete electrochemical repassivation (potential shift from −385 mV to −185 mV), a 97.3% reduction in chloride diffusion rates, a 250% increase in surface resistivity, and the restoration of structural capacity to 115% of design specifications. The framework achieved a 65% reduction in projected lifecycle costs while establishing a new paradigm for preserving marine infrastructure through evidence-based, multi-mechanism strategies that ensure long-term durability and economic viability. Full article

Dehumidification plays a vital role across industrial, commercial, and residential settings, where controlling moisture is essential for maintaining air quality, protecting materials, and ensuring comfort. Calcium chloride (CaCl₂) is a widely used, low-cost desiccant, but it suffers from a critical drawback: under humid conditions, particles tend to agglomerate, which reduces their ability to absorb water. In addition, when the salt dissolves in hydration water, its contact surface with moist air decreases, and corrosive liquid leakage can occur. Embedding CaCl₂ into hydrophilic porous matrices offers a solution by dispersing particles more effectively, preventing agglomeration, increasing the contact area, and retaining liquid within the pore network to suppress leakage. In this study, we introduce a novel approach for fabricating carbon-based foams impregnated with CaCl₂, produced through the thermal decomposition of glucose under self-induced pressure. These foams exhibit a composite architecture that integrates CaCl₂ and calcium carbonate, enabling controlled porosity through selective dissolution. Importantly, the in situ transformation of CaCl₂ into calcite refines the internal structure, improving both stability and acids absorption performance. FTIR confirmed the strong hydrophilicity of the foam walls, which enhances water vapor uptake while preventing leakage of saturated salt solutions. The carbon matrix further suppresses salt particle agglomeration during moisture absorption, resulting in high efficiency. These multifunctional foams not only capture water vapor and volatile acids but also show potential as phase change materials. Mechanical testing revealed tunable behavior among the fabricated foams, ranging from high-stiffness structures with superior energy absorption (e.g., C2) to more compliant foams with extended strain capacity (e.g., A2), illustrating their versatility for practical applications. Full article

Carbon dots (CDs) have recently emerged as a novel class of eco-friendly and multifunctional corrosion inhibitors owing to their nanoscale dimensions, tunable surface functionalities, and sustainable synthesis pathways. This review summarizes the latest progress in CD-based inhibitors, focusing on synthesis methods, applications, and inhibition mechanisms. Various strategies—including hydrothermal/solvothermal treatment, microwave irradiation, pyrolysis, electrochemical synthesis, and chemical oxidation—have been employed to obtain CDs with tailored size, heteroatom doping, and surface groups, thereby enhancing their inhibition efficiency. CDs have demonstrated remarkable applicability across diverse corrosive environments, including acidic, neutral chloride, CO₂-saturated, microbiologically influenced, and alkaline systems, often achieving inhibition efficiencies exceeding 90%. Mechanistically, their performance arises from strong adsorption and compact film formation, heteroatom-induced electronic modulation, suppression of anodic and cathodic reactions, and synergistic effects of particle size and structural configuration. Compared with conventional inhibitors, CDs offer higher efficiency, environmental compatibility, and multifunctionality. Despite significant progress, challenges remain regarding precise structural control, scalability of synthesis, and deeper mechanistic understanding. The effectiveness of CDs inhibitors is highly dependent on factors such as pH, temperature, inhibitor concentration, and exposure time, which should be tailored for specific applications to maximize performance. Future research should focus on integrating sustainable synthesis with rational heteroatom engineering and advanced characterization to achieve long-term, cost-effective, and environmentally benign corrosion protection solutions. Compared to earlier reviews, this review discusses the emerging trends in the field of CDs as corrosion inhibitors. Full article

Corrosion of steel structures remains a persistent challenge in construction, particularly in coastal and industrial environments where chloride-induced degradation accelerates structural failure. This study presents an eco-friendly approach to improve the corrosion protection of the steel by incorporating Lawsonia inermis (henna) leaf extract into zinc–aluminum silicate coatings. The henna extract was added at varying concentrations (0–12 wt%) to evaluate its influence on structure, adhesion, and electrochemical performance of the coating. Physicochemical characterizations including FTIR, XRD, XRF, and SEM revealed that a 5 wt% addition optimized pigment dispersion, resulting in a denser and more homogeneous coating microstructure. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 35 days of immersion in 3.5 wt% NaCl solution demonstrated that this formulation achieved the highest impedance and polarization resistance, confirming enhanced corrosion resistance. The improvement was attributed to the dual action of the henna extract: (i) as a dispersant, promoting uniform Zn–Al pigment distribution and reducing porosity, and (ii) as a green corrosion inhibitor, forming an adsorbed protective film on the steel surface. This work highlights the potential of bio-derived additives to enhance the long-term durability of steel infrastructure and supports the development of sustainable protective materials for construction applications. Full article

This paper presents the results of corrosion resistance tests of materials (Fe40Al5Cr0.2ZrB alloy and X18CrN28 steel) in a 5% NaCl solution at room temperature using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, complemented by confocal/AFM topography and SEM/EDS analysis. Confocal/AFM mapping showed pronounced roughening and localized features on Fe40Al5Cr0.2ZrB alloy (e.g., S_a rising locally to ~1.63 μm), consistent with heterogeneous chloride-induced attack, whereas X18CrN28 steel exhibited only minor roughness changes (S_a ~ 13–19 nm). SEM/EDS of Fe40Al5Cr0.2ZrB alloy revealed mixed oxides with detectable chlorine at corroded sites, while the steel retained a thin, Cr-rich passive layer with negligible Cl signal. Overall, X18CrN28 steel demonstrates significantly higher resistance to localized corrosion in neutral chloride media than Fe40Al5Cr0.2ZrB alloy, aligning electrochemical metrics with surface and chemical analyses. Full article

A prediction methodology for the mid-span deflection of fatigue-damaged RC beams subjected to chloride-induced corrosion is proposed, incorporating the coupled effects of fatigue stress levels and localized pitting corrosion in steel reinforcement. The reliability of the methodology is validated through experimental comparisons. The effects of fatigue stress are quantified via two mechanisms: degradation of the concrete elastic modulus and the development of fatigue-induced cracks in the steel reinforcement, which reduces its effective cross-sectional area. Pitting corrosion is simplified as equivalent surface cracks. To determine the chloride concentration within the concrete cover for predicting steel pit depth, a 3D meso-scale model is developed to simulate chloride ingress in fatigue-damaged concrete. The concrete is treated as a three-phase composite composed of coarse aggregate, mortar matrix, and the interfacial transition zone (ITZ), and each phase has its own diffusion coefficient. Based on previous chloride concentration tests, the effect of fatigue loading is considered by the accelerated and depth-dependent diffusion coefficients. Based on the meso-scale simulation results, mid-span deflections of fatigue-damaged RC beams under varying chloride exposure durations are predicted. The findings conclusively demonstrate that, under prolonged chloride erosion, the mechanical stress state remains the predominant factor governing structural deformation, overshadowing time-dependent corrosion effects. Full article

The aluminum casting alloy AlSi7Mg0.6 (A357) is extensively used in the automotive industry due to its favorable balance of mechanical properties, castability, lightweight characteristics, and corrosion resistance. Castings made from this alloy are often subjected to harsh service environments, where surface degradation and microstructural variability can significantly impact fatigue performance. This study investigates the combined effects of surface corrosion damage and higher Fe content on the fatigue life of the AlSi7Mg0.6 alloy, using a rotating bending fatigue test under simultaneous corrosion exposure in a 3.5 wt. % NaCl solution. The effect of corrosion and Fe content on fatigue life was then investigated and analyzed using Wöhler curves and scanning electron microscopy (SEM). The results demonstrate that the corrosion-fatigue interaction accelerated the kinetics of the fatigue process, while the fracture mechanism and crack initiation places are not fundamentally altered compared to alloys in the state without corrosion damage. A comparison of the fatigue lifetime of samples in an air environment and a corrosive environment shows that the corrosive environment (3.5% NaCl) reduces the fatigue lifetime of alloys without T6 by an average of 7.5 MPa and alloys after T6 by 6 MPa. The results are probably due to the penetration of chloride ions into casting defects located on the surface of the samples. Surface pits formed during corrosion act as stress concentrators, increasing the likelihood of stress-induced failure. Microstructural feature morphology, especially Fe-rich intermetallic phases, influences crack propagation mechanisms. Full article

This study investigates the torrefaction of polyvinyl chloride (PVC) and cellulose, two major constituents of agricultural waste, with the aim of improving chlorine removal and enhancing the energy quality of the resulting solid products. Thermodynamic simulations using HSC Chemistry 9.0 were first conducted to predict equilibrium compositions, particularly chlorine-containing species. Thermogravimetric analysis (TGA) and coupled TGA-FTIR were employed to monitor mass loss and identify gaseous chlorine compounds. Based on these preliminary results, torrefaction experiments were carried out at temperatures of 250–300 °C and durations of 30–90 min. The results demonstrate a significant synergistic effect between cellulose and PVC during co-torrefaction, achieving 97% chlorine removal under optimal conditions (9:1 cellulose-to-PVC ratio, 250 °C, 30 min). This effective dechlorination helps mitigate Cl-induced corrosion and reduces the risk of dioxin formation in industrial applications, enabling the sustainable upcycling of PVC-contaminated biomass into clean solid fuels. Torrefaction temperature exerted a stronger influence than time on mass loss, yielding approximately 40% solid residue at 300 °C. While both solid and energy yields decreased with increasing temperature and time, the O/C and H/C atomic ratios decreased by 56% and 48%, respectively, indicating a substantial improvement in fuel properties. The observed synergy is attributed to cellulose-derived hydroxyl radicals promoting PVC dehydrochlorination. This process offers a scalable and economically viable pretreatment route for PVC-containing biomass, potentially reducing boiler corrosion and hazardous emissions. Full article

With the increasing demand for sustainable building materials, it is essential to investigate the durability of recycled fine aggregate concrete (RFAC) under corrosive environmental conditions. This study systematically assessed the performance of RFAC with three compressive strengths after dry–wet cycles in chloride and sulfate environments, respectively. The experimental program encompassed measurements of compressive strength, mass variation, porosity, ion penetration depth, and free ion content, complemented by comprehensive microstructural characterization. Results show that under sulfate exposure, 20 MPa and 40 MPa RFAC suffered significant strength losses of 60.1% and 18.0% after 70 cycles, while 60 MPa RFAC gained 2.5% strength. In chloride environments, 20 MPa and 40 MPa RFAC experienced strength reductions of 30.7% and 6.9%, whereas 60 MPa RFAC increased in strength by 6.6%. Compared to sulfate exposure, all groups exhibited slight mass increases or porosity reduction under chloride exposure, with high-strength RFAC showing the most noticeable densification. The chloride penetration depth in RFAC of 60 MPa was measured at 14.65 mm, representing a 41.0% reduction compared to RFAC of 20 MPa; sulfate penetration depth was 17.84 mm, which is 44.6% lower than that of the 20 MPa counterpart. Microstructural analysis revealed that sulfate-induced ettringite and gypsum formation triggered crack propagation, while chloride mainly affected pore structure through crystallization and filling, and the formation of C-S-H in high-strength RFAC inhibits pore expansion and mitigates deterioration. Full article

This study examined the combined effects of chloride ions and stray DC on reinforced concrete (RC) using electromigration and impressed-current methods under varying current densities (0.5, 3.0, 5.0 mA/cm²) and chloride concentrations (50, 1350, 5500 mg/kg). Chloride was identified as the dominant deterioration factor. At 3.0 mA/cm², cracking times in moderate and severe chloride environments decreased by 48.75% and 52.62%, respectively, compared to mild conditions. At 0.5 mA/cm² in severe conditions, the corrosion rate reached 1.317% after 20, 2.75 times that in moderate conditions. Electromigration specimens showed delayed cracking but deeper chloride penetration, while impressed-current specimens exhibited pronounced strip-shaped pitting corrosion. A quadratic polynomial model predicting cracking time based on current density and chloride concentration achieved high accuracy (R² = 0.95, mean relative error = 7.%). Actual corrosion mass loss was lower than theoretical Faraday values, with current efficiency increasing from 0.3–0.8% to 16.5–18.1% as current density and chloride content rose. These findings highlight the synergistic effect of stray current and chloride attack, emphasizing chloride concentration’s greater impact on service life. The model provides a scientific basis for RC durability design in urban rail transit and coastal engineering. Full article

Chloride-ion (Cl⁻)-induced corrosion of steel bars is a major threat to the durability of marine concrete structures. To address this, a type of calcined CaFeAl-layered double oxide (LDO-CFA) with different calcination temperatures was used to enhanced the Cl⁻ adsorption, compressive strength, and corrosion resistance of sulphate-resistant Portland cement (SRPC)-based materials. Experimental results demonstrated that LDO-CFA exhibited high Cl⁻ adsorption capacity in both CPSs and cement-based materials. Specifically, LDO-750-CFA reached 1.98 mmol/g in CPSs—60.1% higher than LDHs-CFA—and followed the Langmuir model, indicating monolayer adsorption. It also reduced the free Cl⁻ content of SRPC paste to 0.255–0.293% after 28 days, confirming its sustained adsorption over extended curing. Furthermore, LDO-CFA positively influenced the compressive strength at all curing ages. At an optimal dosage of 0.8 wt.%, LDO-750-CFA paste significantly improved the compressive strength, increasing it by 22.1% at 7 days and 15.6% at 28 days compared to the control. Electrochemical analysis confirmed the superior corrosion resistance of the LDO-750-CFA system. The property enhancement originated from LDO-750-CFA’s synergistic effects, which included pore refinement, increased tortuosity, Cl⁻ adsorption by structural memory, a PVP-induced passive film, and PVP-improved dispersion. Overall, this work provides a framework for developing LDO-750-CFA-based composites, paving the way for more durable marine concrete. Full article

Due to the presence of stray current in the subway environment, the durability issues of subway structures differ from those of general structures. This study simulates the combined effects of chloride ions and stray current in the subway environment through electrochemical corrosion experiments, thereby analyzing the corrosion morphology and mechanical property degradation of steel strands and the corrosion-induced cracking of concrete. The experimental results indicate that stray current affects the strength and ductility of steel strands as well as the cracking of concrete. The corrosion difference coefficient μ_c at different positions is greater than 1.6 and the average corrosion degree η_ave is less than 7%. The corrosion morphology gradually changes from non-uniform to uniform corrosion until the η_ave is greater than 12%. The concrete crack width under a stray current of 60 mA is 10.67 times that of cracks under 20 mA after 42 days, which is approximately linearly related to the current intensity. Based on the experimental results, a corrosion-induced crack prediction model for prestressed concrete under stray current is proposed, with the main influencing factors being current intensity, concrete tensile strength, and protective layer thickness. These findings can provide valuable references for the durability analysis of subway structures. Full article

To ensure the highest safety standards in modern automobiles, the industry is constantly adopting zero-defect frameworks, such as AEC-Q100, which aims for defective-parts-per-billion (DPPB) or grade-0 level reliability standards in automotive integrated-circuit (IC) packages. Most contemporary wire-bonded packages use either pure copper (Cu) or palladium (Pd)-coated copper (PCC) wires bonded to aluminum (Al) bond pads as interconnections. This choice is made due to their lower cost and superior electrical and mechanical performance, compared to traditional gold wire-based devices. However, these Cu–Al wire-bonded interconnections are prone to ion-induced lift-off/open-circuit corrosion failures when exposed to even trace amounts (<20 ppm) of extrinsic and/or intrinsic halide (Cl⁻ and Br⁻) contaminants, decreasing device longevity. This study investigates corrosion failure mechanisms in Cu and PCC wire-based devices by subjecting non-encapsulated devices to a highly accelerated aqueous-immersion screening test containing 100 ppm chloride (Cl⁻), 100 ppm bromide (Br⁻), and a mixed-ion solution (MX: Cl⁻ + Br⁻). The screening results indicate that even control PCC-Al devices with a Pd overlayer can be susceptible to Cl⁻ and Br⁻ induced corrosion, with 21 ± 1.6% lift-off failures in MX-solution. In contrast, applying a novel Cu-selective passivation reduced lift-off to 3.3 ± 0.6% and introducing phosphonic-acid-based inhibitor into the MX solution eliminated lift-off failures, demonstrating markedly improved reliability. Full article