Search Results (134)

Graphene is considered one of the most promising flexible transparent electrode materials as it has high charge carrier mobility, high electrical conductivity, low optical absorption, excellent mechanical strength, and good bendability. However, graphene-based flexible transparent electrodes face a critical challenge in balancing electrical conductivity and optical transmittance. Here, we present a green and scalable direct ink writing (DIW) strategy to fabricate graphene grid patterns by optimizing ink formulation with sodium dodecyl sulfate (SDS) and ethanol. SDS eliminates the coffee ring effect via Marangoni flow, while ethanol enhances graphene flake alignment during hot-pressing, achieving a high conductivity of 5.22 × 10⁵ S m⁻¹. The grid-patterned graphene-based flexible transparent electrodes exhibit a low sheet resistance of 21.3 Ω/sq with 68.5% transmittance as well as a high stability in high-temperature and corrosive environments, surpassing most metal/graphene composites. This method avoids toxic solvents and high-temperature treatments, demonstrating excellent stability in harsh environments. Full article

This study systematically investigated the corrosion evolution and protective mechanisms of X80 pipeline steel in Xinjiang’s saline soil environments under freeze–thaw cycling conditions. Combining regional soil characterization with laboratory-constructed corrosion systems, we employed electrochemical impedance spectroscopy, potentiodynamic polarization, and surface analytical techniques to quantify temporal–spatial corrosion behavior across 30 freeze–thaw cycles. Experimental results revealed a distinctive corrosion resistance pattern: initial improvement (cycles 1–10) attributed to protective oxide layer formation, followed by accelerated degradation (cycles 10–30) due to microcrack propagation and chloride accumulation. Synchrotron X-ray diffraction analyses identified sulfate–chloride ion synergism as the primary driver of localized corrosion disparities in heterogeneous soil matrices. A comparative evaluation of asphalt-coated specimens demonstrated a 62%–89% corrosion rate reduction, with effectiveness directly correlating with coating integrity and thickness (200–500 μm range). Molecular dynamics simulations using Materials Studio revealed atomic-scale ion transport dynamics at coating–substrate interfaces, showing preferential Cl⁻ permeation through coating defects. These multiscale findings establish quantitative relationships between environmental stressors, coating parameters, and corrosion kinetics, providing a mechanistic framework for optimizing protective coatings in cold-region pipeline applications. Full article

Eco-friendly mortars have been manufactured with hybrid binders made of blast furnace slag and a reduced amount of clinker. The objective is to explore new formulations suitable for reinforced structures. Previous studies are mainly focused on activation with sulfates, a salt that is corrosive to reinforcing steel. Sodium nitrate and sodium carbonate, easily implementable in construction, have been used as activators in two different concentrations that involve similar Na content. A Type II PC mortar is used as reference. The dimensional stability of the mortars during curing (at 99% RH) and subsequent drying at 40% RH, has been evaluated, as well as their porosity and mechanical properties. Böhme tests revealed that studied hybrid binders have lower wear resistance than PC mortar. Activation with Na₂CO₃ allows the obtention of mortars with reduced porosity and good compression resistance, but generates microcracking that favors chloride diffusion. Activation with nitrates favors precipitation of AFm phases identified through differential thermal analysis. Nitrates in moderate amounts (4% w/w) allow manufacturing hybrid mortars with good resistance to chloride penetration and reasonably good mechanical properties. Hence, this binder can be a promising option for reinforced structures. Higher amounts of nitrates (8%) for activation give rise to more porous mortars. Full article

Considering the harsh marine environment characterized by dry–wet cycles, freeze–thaw action, chloride penetration, and sulfate attack, four optimized ultra-high-performance concrete (UHPC) mix designs were developed. Durability was assessed via electric flux, dry–wet cycles, and rapid freeze–thaw tests to evaluate the effects of curing methods, aggregate types, and mineral admixtures on key durability indicators, including chloride ion permeability, compressive strength loss, and mass loss. Scanning electron microscopy (SEM) examined microstructural changes under various conditions. Results showed that curing method significantly affected chloride ion permeability and sulfate resistance. High-temperature curing (70 ± 2 °C) reduced 28-day chloride ion electric flux by about 50%, and the compressive strength loss rate of specimens subjected to sulfate attack decreased by 2.7% to 45.7% compared to standard curing. Aggregate type had minimal impact on corrosion resistance, while mineral admixtures improved durability more effectively. Frost resistance was excellent, with mass loss below 0.87% after 500 freeze–thaw cycles. SEM analysis revealed that high-temperature curing decreased free cement particles, and mineral admixtures refined pore structure, enhancing matrix compactness. Among all mixtures, Mix Proportion 4 demonstrated the best overall durability. This study offers valuable insights for UHPC design in aggressive marine conditions. Full article

To investigate the influence of the water–cement ratio and erosion patterns on the deterioration of concrete in a sulfate corrosion environment, concrete specimens with different water–cement ratios were immersed in Na₂SO₄ solutions of varying concentrations (0%, 5%, and 8%). The immersion times were set at 0 days, 30 days, 60 days, and 90 days. Macro-scale compressive strength tests and micro-scale performance tests were conducted to obtain the damage morphology, micro-scale elastic modulus, and hardness of eroded concrete. Additionally, K-means clustering analysis was used to analyze the micro-mineral phases of the specimens, and SEM and XRD were employed to reveal the degradation mechanisms of sulfate erosion on the microstructure of concrete. The results indicated that the erosion products of calcium aluminate and gypsum in concrete gradually increased with the increase in Na₂SO₄ solution concentration and immersion time. In the early stages of erosion, the compressive strength and corrosion resistance coefficient of concrete showed a temporary upward trend, which then decreased as the erosion depth increased. From a microstructural perspective, erosion had a significant impact on the internal structure of concrete, while the elastic modulus and hardness of hydrated calcium silicate and calcium hydroxide under erosion showed relatively minor changes, both exhibiting a gradual decrease. The volume fraction of microporous pores gradually increased, further exacerbating the depth and extent of erosion. Full article

This study demonstrates that effervescent denture cleansers can influence the electrochemical behavior of cobalt–chromium (Co-Cr) alloys, with a particular focus on their corrosion resistance. The findings underscore the importance for dental professionals of selecting cleansers compatible with Co-Cr prostheses to minimize material degradation and enhance clinical durability. Corrosion resistance was evaluated using open-circuit potential (OCP), corrosion current density (i_corr), and passivation current density (i_pass). Surface morphology and elemental composition were analyzed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Forty specimens (n = 5 per group) were individually immersed in one of ten test solutions: distilled water (DW), artificial saliva (AS), and eight commercial denture cleansers—Polident 3 minutes™ (P3M), Steradent™ (St), Polident for Partials™ (PP), Efferdent™ (Ef), Corega Tabs™ (CT), NitrAdine™ (Ni), Fixodent™ (Fi), and Kukident™ (Ku). Each specimen was exposed a single solution to avoid cross-contamination. Results showed St, Ef, and Ku had higher OCP values than DW and Ni (p < 0.05), indicating better corrosion resistance. AS exhibited lower OCP values compared to St (p = 0.034), Ku (p = 0.023), and P3M (p = 0.050). DW had higher i_corr than PP (p = 0.030), CT (p = 0.005), and P3M (p = 0.003). For i_pass, DW had lower values than Ef (p = 0.025) and Ku (p = 0.016). SEM and EDS revealed no significant surface alterations. Understanding the underlying corrosion mechanisms in different solutions provides valuable insights into optimizing material performance and ensuring durability in clinical applications. The corrosion resistance of Co-Cr depends on the stability of the passive oxide layer, which can be degraded by chloride ions, reinforced by sulfate ions, and influenced by active ingredients in denture cleansers. Overall, the Co-Cr alloy demonstrated acceptable corrosion resistance, underscoring the importance of selecting suitable cleansers for prosthesis longevity. Full article

The preparation of low-cost and high-durability cement-based material systems using seawater mixing has become an urgent task in marine engineering construction. The requirements have addressed key challenges, including high transportation costs for fresh water and raw materials, poor structural durability, and difficulty in meeting actual construction schedules. Sulfatealuminate cement (CSA) has become an ideal material for marine engineering due to its high corrosion resistance, rapid early strength, which is 35–40 MPa of 3-day compressive strength and is 1.5–2 times compared ordinary Portland cement (OPC), and low-carbon characteristics, reduced production energy consumption by 35–50%, and CO₂ emissions of 0.35–0.45 tons/ton. The Cl⁻ and SO₄²⁻ in seawater can accelerate the hydration of CSA, promote the formation of ettringite (AFt), and generate Friedel’s salt fixed chloride ions, significantly enhancing its resistance to chloride corrosion. Its low alkalinity (pH ≈ 10.6) and dense structure further optimize its resistance to sulfate corrosion. In terms of environmental benefits, CSA-mixed seawater can save 15–20% fresh water. And the use of solid waste preparation can reduce environmental burden by 38.62%. In the future, it is necessary to combine multi-scale simulation to predict long-term performance, develop self-healing materials and intelligent control technologies, and promote their large-scale application in sustainable marine infrastructure. Full article

To investigate the sulfate resistance of recycled concrete with composite admixtures under dry–wet cycling, a single-factor experimental design was first conducted to study the deterioration patterns of recycled concrete with single and composite admixtures (ground granulated blast furnace slag (GGBS) and fly ash) under sulfate attack. Based on the single-factor test results, orthogonal experiments were designed with composite admixtures as one influencing factor. Quantitative analysis was performed to determine the impact magnitude and significance of various factors on the sulfate resistance of recycled concrete at different corrosion ages. A damage model for recycled concrete under sulfate dry–wet cycling was established for preliminary service life prediction. The experimental results indicated that the sulfate resistance performance followed the sequence of composite admixtures > single slag admixture > single fly ash admixture. When uncycled (0 cycles), the influence ranking of factors was B (water–binder ratio) > A (recycled coarse aggregate replacement rate) > C (GGBS + fly ash content). After 60 and 120 cycles, the ranking became B > C > A. For the compressive strength regression model, the measured values deviated significantly from the calculated values (−6.88% to 16.66%), while the dynamic elastic modulus model showed good agreement between the measured and calculated values (−2.86% to 4.87%). A three-indicator lifespan prediction equation was established. Using practical engineering parameters (30% recycled aggregate replacement, 0.4 water–binder ratio, 20% fly ash and 20% slag content), the predicted service life of this recycled concrete project was T = 117 years. Therefore, incorporating fly ash and slag can effectively improve weak zones in recycled concrete and enhance its durability. Full article

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries. Full article

To address the protective demands of marine engineering equipment in complex corrosive environments, this study proposes an environmentally friendly composite coating based on carboxylated graphene oxide (CGO)-modified water-based epoxy organosilicon resin. By incorporating varying mass fractions (0.05–0.25%) of CGO into the resin matrix via mechanical blending, the microstructure, corrosion resistance, and long-term corrosion kinetics of the coatings were systematically investigated. The results demonstrate that the coating with 0.15 wt.% CGO (designated as KCG15) exhibited optimal comprehensive performance: its corrosion current density (I_corr = 4.37 × 10⁻⁸ A/cm²) was two orders of magnitude lower than that of the pure resin coating, while its low-frequency impedance modulus (∣Z∣_0.1Hz = 4.99 × 10⁶ Ω⋅cm²) is significantly enhanced, accompanied by improved surface compactness. The coating achieved a 97% inhibition rate against sulfate-reducing bacteria (SRB) through synergistic physical disruption and electrostatic repulsion mechanisms. Long-term corrosion kinetics analysis via 60-day seawater immersion identified three degradation phases—permeation (0–1 day), blockage (1–4 days), and failure (7–60 days)—with structural evolution from microcrack networks to foam-like blistering ultimately reducing by 97.8%. Furthermore, a 180-day atmospheric exposure test confirms the superior weatherability and adhesion of the KCG15 coating, with only minor discoloration observed due to its hydrophobic surface. This work provides theoretical and technical foundations for developing marine anti-corrosion coatings that synergize environmental sustainability with long-term protective performance. Full article

Microbially influenced corrosion (MIC) in anaerobic environments accounts for many severe failures and losses in different industries. Sulfate-reducing bacteria (SRB) represent a typical class of corrosive microorganisms capable of acquiring electrons from steel through extracellular electron transfer processes, thereby inducing severe electrical microbially influenced corrosion (EMIC). Although prior research has underscored the significance of extracellular electron transfer, the contribution of EMIC to the whole MIC has not been comprehensively studied. In this study, Q235 steel coupons were employed in an H-shaped electrochemical cell to conduct electrochemical and coupon immersion experiments, aiming to determine the contribution of EMIC to the overall MIC. The experiments were conducted under two distinct carbon source conditions: 100% carbon source (CS) and 1% CS environments. It was observed that the biotic electrodes exhibited significantly higher cathodic currents, with the most pronounced biological cathodic activity detected in the 100% CS biotic medium. The voltammetric responses of the electrodes before and after changes in the medium confirmed the biocatalytic capability of the attached biofilm in stimulating the cathodic reaction. The proportion of EMIC in MIC was calculated using linear polarization resistance, revealing a trend over time. Additionally, weight loss tests indicated that the contribution of EMIC to the total MIC was approximately 27.69%. Furthermore, the results demonstrated that while the overall corrosion rate was lower in the 1% CS environment, the proportion of EMIC in MIC increased to approximately 37.68%. Full article

Concrete coating technology is a key measure that enhances the durability of concrete structures. This paper systematically studies the performance, applicability, and impact of different types of anti-corrosion coatings on concrete durability, focusing on their resistance to chloride ion penetration, freeze–thaw cycles, carbonation, and sulfate corrosion. The applicability of existing testing methods and standard systems is also evaluated. This study shows that surface-film-forming coatings can create a dense barrier, reducing chloride ion diffusion coefficients by more than 50%, making them suitable for humid and high-chloride environments. Pore-sealing coatings fill capillary pores, improving the concrete’s impermeability and making them ideal for highly corrosive environments. Penetrating hydrophobic coatings form a water-repellent layer, reducing water absorption by over 75%, which is particularly beneficial for coastal and underwater concrete structures. Additionally, composite coating technology is becoming a key approach to addressing multi-environment adaptability challenges. Experimental results have indicated that combining penetrating hydrophobic coatings with surface-film-forming coatings can enhance concrete’s resistance to chloride ion penetration while ensuring weather resistance and wear resistance. However, this study also reveals that there are several challenges in the standardization, engineering application, and long-term performance assessment of coating technology. The lack of globally unified testing standards leads to difficulties in comparing the results obtained from different test methods, affecting the practical application of these coatings in engineering. Moreover, construction quality control and long-term service performance monitoring remain weak points in their use in engineering applications. Some engineering case studies indicate that coating failures are often related to an insufficient coating thickness, improper interface treatment, or lack of maintenance. To further improve the effectiveness and long-term durability of coatings, future research should focus on the following aspects: (1) developing intelligent coating materials with self-healing, high-temperature resistance, and chemical corrosion resistance capabilities; (2) optimizing multilayer composite coating system designs to enhance the synergistic protective capabilities of different coatings; and (3) promoting the creation of global concrete coating testing standards and establishing adaptability testing methods for various environments. This study provides theoretical support for the optimization and standardization of concrete coating technology, contributing to the durability and long-term service safety of infrastructure. Full article

In this study, cellulose nanocrystals (CNs) were utilized to enhance the mechanical properties and sulfate corrosion resistance of engineered cementitious composites (ECCs). The results of compressive strength and uniaxial tensile tests demonstrated that the incorporation of CNs significantly improved the compressive strength, strain rate, tensile strength, and sulfate corrosion resistance of ECC specimens. Scanning electron microscopy (SEM) observations revealed that the addition of CNs facilitated the formation of increased amounts of ettringite and calcium silicate hydrate (C-S-H) in the matrix, enhancing the hydration degree of the cementitious system and increasing the overall density of the ECC structure. Molecular dynamics simulations were employed to investigate the interactions between CN, C-S-H, water molecules, and sulfate ions (SO₄²⁻) while also calculating the kinetic parameters of atoms at the interface. These simulations provided insights into the microstructural strengthening mechanism of CNs in improving the sulfate corrosion resistance of ECCs. The results indicated that CNs adsorb onto C-S-H via Ca-O and H-O coordination, forming a protective layer that inhibits the penetration of SO₄²⁻ and water molecules into the C-S-H structure. Additionally, CNs form hydrogen bonds with SO₄²⁻ and water molecules, which restricts their diffusion and reduces their coordination with the C-S-H interface and the dissolution of SO₄²⁻ and water to the hydration product, thereby enhancing the sulfate corrosion resistance of ECCs. Full article

In this study, the behavior of sodium silicate (Na₂SiO₃), manganese sulfate monohydrate (MnSO₄·H₂O), and ammonium metavanadate (NH₄VO₃) as corrosion inhibitors for AA6061 aluminum alloy (Al) was investigated. The polarization resistance (R_p) of the Al substrate immersed in 0.1 M NaCl solution was found to be 13 kΩ·cm². In comparison, the R_p of the Al substrate immersed in 0.1 M NaCl in the presence of Na₂SiO₃, Na₂SiO₃/MnSO₄·H₂O, and Na₂SiO₃/NH₄VO₃ inhibitors was found to be 100, 133, and 679 kΩ·cm², respectively. The best inhibition result was obtained when the mixture of the inhibitors was used with R_p of 722 kΩ·cm². The maximum percentage of the corroded area calculated from the scanning electron microscopy (SEM) images was found to be 5.7% for Al substrate immersed in 0.1 M NaCl, which decreased to 0.06% when the mixture of the inhibitors was used. The synergetic effects between the three inhibitors were studied, and the results illustrated that the combination of Na₂SiO₃, MnSO₄·H₂O, and NH₄VO₃ provided the best corrosion inhibition properties for Al in aqueous NaCl environments. Full article

Higher demands on extreme pressure lubrication performance are posed by stringent working conditions. In this study, the synergistic tribological properties of phosphate ammonium salt in combination with active sulfurized olefin (S1) and non-active sulfurized fatty acids (S2) were investigated to meet the needs under stringent working conditions. The anti-wear mechanisms were further explored using scanning electron microscopy (SEM) with EDS, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), and focused ion beam microscopy. The experimental results indicate that P-S2 demonstrates superior friction reduction and wear resistance under low loads, potentially attributable to its higher polarity, whereas P-S1 exhibits better wear resistance under high loads. P-S1 also shows superior extreme pressure performance attributed to its higher active sulfur content and stronger film-forming ability, evidenced by a thicker friction film (82.62 nm vs. 24.28 nm for P-S2). The study highlights that the variations in the synergistic tribological performance of phosphorus- and sulfur-based additives may link to differences in molecular structure, active sulfur content, polarity, and corrosiveness, with P-S1 demonstrating enhanced extreme pressure performance possibly through the formation of a multi-layered friction film of polyphosphate, sulfide, oligophosphate, and sulfate layers. Full article