ABSTRACT Ginkgo biloba leaf extract was evaluated as a natural corrosion inhibitor for carbon steel in a simulated concrete pore solution containing 3.5 wt% NaCl and saturated Ca(OH)2 at pH 13.5. Open-circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarisation were used to clarify concentration-dependent interfacial evolution. The extract showed a distinct concentration effect. During early exposure, all extract-containing systems exhibited lower impedance than the blank, indicating initial disturbance of natural passivation. With prolonged immersion, the systems gradually diverged. In the 100-500 mg/L range, the adsorbed layer showed limited coverage and stabilisation, and the 300 and 500 mg/L systems were more prone to form loose, defect-rich composite films. The 700 and 1000 mg/L systems developed more stable inhibitor-passive composite films after interfacial rearrangement. Among them, 1000 mg/L showed the highest impedance, the highest film and total electrode-process resistances, the lowest equivalent film capacitance, and the best overall long-term inhibition performance.

This paper investigates the structural performance of carbon steel and hybrid stainless steel–carbon steel semi-rigid beam-to-column connections under both ambient and elevated temperature conditions. Stainless steel exhibits superior strength retention, stiffness and ductility at high temperatures, making it an attractive material for enhancing fire resilience in steel-framed structures. To leverage these benefits, a nonlinear finite element model of a semi-rigid flush endplate connection is developed in ABAQUS and validated against experimental tests at ambient and elevated temperatures. A comprehensive parametric study is then conducted to examine the influence of endplate thickness, material grade, bolt size and temperature. The results demonstrate that hybrid connections where stainless steel is selectively used in critical components offer improved moment resistance and rotational capacity, particularly under fire conditions. A component-based approach is subsequently proposed, extending the Eurocode framework to elevated temperatures. The method predicts initial stiffness, design moment resistance and ultimate moment resistance, and is shown to be both safe and accurate through comparison with numerical results for both carbon steel and hybrid stainless steel–carbon steel configurations. • Parametric analyses explore behaviour of hybrid steel joints at high temperatures. • Hybrid joints exhibit higher resistance and deformation capacity than carbon steel. • EN 1993-1-8 is extended to address joint behaviour at elevated temperatures. • New design approach estimates rotation limits and ultimate moment resistance. • The design methods provide safe, accurate stiffness and moment estimates.

Graphene layers on metals: A disruptive approach to durable corrosion resistance.

Long-term stiffness trends of concrete beams with carbon fiber and steel reinforcement: Experimental and analytical evaluation after retrofitting, repeated loading, and environmental exposure

Structural health monitoring often involves temperature measurement. However, traditional sensors cannot measure subsurface temperature non-invasively, making them unsuitable for monitoring temperature-driven damage mechanisms such as high-cycle thermal fatigue. This limitation arises, in part, due to effective thermal low-pass filtering caused by material properties. A previous feasibility study demonstrated that subsurface temperature can be inferred non-invasively in mild steel subjected to uniform heating. This was achieved using the ultrasonic-based inverse thermal modelling (ITM) method, which assumes the temperature of a component can be described by a 1D system. This study investigated the behaviour of ITM under non-uniform heating applied to the 'inaccessible' surface of a stainless steel sample through experiments and simulations. The experimental results show that ITM over-predicts temperature by as much as 120% when the heated region is small compared with the 10mm ultrasonic beam size. In simulation, the overestimation was reduced as the size of the heating source increased, effectively making the temperature distribution more uniform across the volume through which the ultrasonic wave travels. Despite the overestimation under non-uniform heating, ITM overcomes the thermal low-pass filtering, allowing the detection of thermal transients compared with a thermocouple mounted on the 'accessible' surface of a component.

Synthesis of ethanol extract of rose petal and its coating on mild steel for corrosion prevention in sodium chloride solutions

Effect of ultrasonic amplitude on morphology and wetting behavior of mild steel deposition layer in direct energy deposition-Arc.

Three-point bending performance of carbon steel with random pitting corrosion in marine environments

Isapa leaf extract in tri-blends acid solution for corrosion control of carbon steel (API: 5LX70) in oil and gas industries and its process optimization

Assessing the potential of electrochemical techniques for monitoring pitting corrosion in carbon steel for offshore structures

Corrosion severely affects marine metallic infrastructures. Organic coatings offer a low-cost, effective solution, but their solvent-rich processing reduces sustainability. For polymer nanocomposite coatings, additional chemical modification of fillers is typically required to improve dispersibility. Herein, we report the synthesis of waterborne polymer/reduced graphene oxide (rGO) nanocomposites via a miniemulsion polymerization as an anticorrosion coating for Q235 steel. Using a vinyl copolymer based on styrene and n-butyl acrylate, we successfully formulated kinetically stable latexes with inherent film-forming ability at room temperature. The thermally annealed polymer/rGO coatings formed a uniform, defect-free layer on the steel surface without rGO agglomeration and delamination. These polymer/rGO coatings, particularly at pH 10 demonstrated electrical conductivity, mechanical robustness, and highly effective anticorrosion performance. Polymer/rGO coating of pH 10 exhibited enhanced corrosion protection after 168 h exposure to 3.5 wt.% NaCl solution ((Icorr = 0.01µAcm-2, P.E of 99%), outperforming the corresponding pH 2, neat polymer coating, and bare metal, validated by post-immersion analysis and marine field testing. This organic solvent-free type of protective coating, comprising vinyl polymer and unmodified rGO represents a novel approach towards the development of advanced anticorrosion coating for critical metals.

Corrosion and icing pose critical challenges to material durability and operational safety across various industries, yet conventional protective strategies often rely on energy-intensive or environmentally harmful approaches. Herein, we introduce a photothermal superhydrophobic coating as an integrated solution for anti-icing, deicing, and corrosion protection. The coating is fabricated on Q235 carbon steel using a scalable spray-coating approach that relies on fluorine-free components, namely carbon black (CB) and polydimethylsiloxane (PDMS). The optimized coating achieves a water contact angle (WCA) and a sliding angle (SA) of 154.2 ± 2.1° and 0.9 ± 0.1° respectively, enabling excellent nonwetting and self-cleaning properties. Upon exposure to 1-sun illumination, the coating rapidly attains a temperature of 106.4 ± 2.4 °C, demonstrating excellent photothermal conversion capability and cycling stability. At -10 °C, the coating delays water freezing to 676 s (compared to 135 s on bare steel) and completely melts frozen droplets within 327 s. The ice adhesion strength measures as low as 17.3 ± 0.1 kPa, which remains 86.1 ± 3.6 kPa even after ten cycles. Electrochemical impedance spectroscopy (EIS) shows 4 orders of magnitude rise in the impedance modulus at the lowest frequency (|Z|0.01Hz), corresponding to a calculated corrosion inhibition efficiency of 99.99%. Additionally, the prepared coating retains its superhydrophobicity after 55 tape-peeling cycles and 240 cm of sandpaper abrasion, and proves applicable to various substrates (metal mesh, glass, wood, and aluminum alloy), achieving steady-state photothermal temperatures between 75.2 and 102.5 °C. This fluorine-free, dual-functional coating offers a promising route toward sustainable anti-icing and anticorrosion applications.

An eco-friendly corrosion inhibitor, Panax notoginseng leaf extract (PNLE), was systematically studied via electrochemical experiments, surface analysis, and first-principles calculations. Electrochemical measurements show that PNLE exhibits remarkable inhibition performance toward mild steel in 1 M HCl medium, with a peak inhibition efficiency of 99.1% at 400 mg L-1. Theoretical calculations corroborate the generation of Fe-O, Fe-N, and Fe-C bonds at the PNLE-steel interface, which furnishes unambiguous evidence for chemisorption. Overall, PNLE exhibits outstanding corrosion inhibition performance and has a wide range of raw material acquisition pathways and simple extraction process operations. It is a corrosion inhibitor of high development value in the industrial field.

The hydrogen-natural gas blending is proving to be a viable route toward the decarbonization of the city gas distribution (CGD) network in India. In this research work, a full-scale experimental testbed is introduced that has high-pressure hydrogen storage, a programmable logic controller, mass flow controllers, a static gas-mixing manifold, hydrocarbon filtration, and a moisture absorber, as well as multimaterial pipelines (galvanized iron, medium-density polyethylene pipe, and carbon steel) used in the Indian CGD infrastructure. To study the flame structure, thermal efficiency, heat flux, gas consumption, and stability of operation in the CGD simulated conditions. The experiments were performed using 0-30% hydrogen mixtures in methane. Gradual increase in hydrogen enrichment changed the flame from a typical blue flame of methane to a bluish-purple high-temperature profile, and the flame remained stable with the enrichment of the hydrogen up to 25% without flashback or instability, and at 30%, minor instability was observed. Maximum values of the highest heat flux (22,489-22,763 W/m2) were obtained at 18-25% blends of hydrogen, which implied shorter heating time and faster combustion rates. The analysis of emissions indicated a consistent decrease in carbon monoxide (CO), from 112 to 38 ppm, and in carbon dioxide (CO2), from 8.9% to 6.1%. Additionally, with a 0-30% enrichment of hydrogen (H2), there was an increased formation of nitrogen oxides (NO x ) due to higher temperatures. The 25% hydrogen mixture exhibited the best combination of high heat flux, uniform flame geometry, and low gas consumption, while also achieveing the highest (12.6%). These findings illustrate that 18-25% hydrogen is the best blending range of domestic burners in the CGD system, which has better combustion efficiency, less emission intensity, and can blend with available confirmation of the hydrogen-enriched natural gas as a short-term decarbonizing measure of the CGD infrastructure in India.

Corrosion of metallic materials in acidic environments remains a critical economic and safety concern in industries such as petroleum refining, acid pickling, chemical cleaning, and descaling. This review critically summarizes recent advances in corrosion inhibition strategies for mild steel and other industrial metals exposed to aggressive acidic media, with emphasis on organic, inorganic, polymeric, and environmentally friendly inhibitors. Organic and polymeric inhibitors predominantly function through adsorption-driven mechanisms involving heteroatoms, π-electron systems, and functional groups, forming protective interfacial films through physisorption, chemisorption, or mixed adsorption processes. In contrast, inorganic inhibitors mitigate corrosion through surface passivation and formation of stable oxide layers. Increasing environmental regulations have accelerated the transition from toxic chromate and phosphate-based inhibitors toward sustainable green alternative derived from plant extracts, biopolymers, pharmaceuticals, and biobased resources. Comparative evaluation reveals inhibition efficiencies frequently validated by electrochemical impedance techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy, complemented by surface characterization using SEM, AFM, and XPS. Despite promising laboratory-scale performance, challenges persist, including thermal instability, long-term durability, limited industrial scalability, and insufficient structure-property correlations. Future developments are expected to focus on bioderived polymers, ionic liquids, nanocomposite inhibitors, and machine-learning-assisted molecular design, offering pathways toward high-performance and environmentally sustainable corrosion protection systems.

ABSTRACT This work investigates the corrosion inhibition performance of two newly synthesised quinazolinone derivatives, 2-(4-methoxyphenyl)-3-phenyl-2,3-dihydroquinazolin-4(1H)-one (DHQ-4-OMe) and 2-(4-nitrophenyl)-3-phenyl-2,3-dihydroquinazolin-4(1H)-one (DHQ-4-NO2), for mild steel in 1.0 M HCl solution. The molecular structures were confirmed by nuclear magnetic resonance (NMR) spectroscopy, while electrochemical techniques, including potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS), were employed to evaluate their protective efficiency. Both compounds exhibited remarkable inhibitory activity, with efficiencies reaching 90.9% for DHQ-4-OMe and 91.4% for DHQ-4-NO2 at an optimal concentration of 10−3 M. Potentiodynamic polarisation results indicated that both inhibitors behave as mixed-type compounds, effectively suppressing both anodic metal dissolution and cathodic hydrogen evolution reactions. Adsorption followed the Langmuir isotherm model, and thermodynamic data ( Δ G ads ∘ ≈ − 41 kJ . mo l − 1 ) indicated spontaneous and predominantly chemisorptive interactions between the inhibitor molecules and the steel surface. Surface analyses using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) revealed the formation of a compact protective film, while density functional theory (DFT) calculations supported experimental observations, showing stronger adsorption and higher stability for DHQ-4-NO2 due to its electron-withdrawing substituent. These findings confirm that DHQ-4-NO2 and DHQ-4-OMe are highly effective corrosion inhibitors, providing valuable insights for designing advanced organic molecules for sustainable industrial corrosion protection.

The corrosion inhibition performance of N-(1-methylpyrrolidin-2-ylidene) benzo[d]thiazol-2-amine (MPBA) for carbon steel in 1.0M HCl solution was systematically investigated using chemical and electrochemical techniques. The corrosion rate decreased markedly with increasing MPBA concentration. Inhibition efficiency increased progressively with inhibitor concentration, reaching values exceeding 97.0% at 5 mM and 298K. The inhibition mechanism was primarily governed by the adsorption of MPBA molecules onto the carbon steel surface and was well described by the Langmuir adsorption isotherm. The negative values of the standard Gibbs free energy of adsorption (ΔGads) confirm the spontaneous nature of the adsorption process. Depending on temperature, ΔG°ads values ranged from - 37.75 to - 36.20kJ mol⁻¹, indicating a mixed physisorption-chemisorption mechanism. The observed decrease in the adsorption equilibrium constant (Kads) with increasing temperature can be attributed to the partial desorption of MPBA molecules from the carbon steel surface. Density functional theory (DFT) calculations combined with the conductor-like polarizable continuum model (CPCM), along with Monte Carlo and molecular dynamics simulations, further confirmed the strong adsorption affinity of MPBA toward the steel surface, thereby supporting its excellent corrosion inhibition performance.

ABSTRACT A new piperidinyl-acetamide derivative, N-(4-fluorophenyl)-2-(piperidin-1-yl)acetamide (IM4), was synthesised and characterised using FT-IR, NMR and mass spectrometry. This corrosion inhibition performance of carbon steel in 1M HCl was investigated by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), surface analyses (SEM-EDS, AFM and contact angle measurements), density functional theory (DFT) and molecular dynamics simulation (MDS). In silico antimicrobial activity and molecular docking studies were also carried out using Escherichia coli (1T9U), Pseudomonas aeruginosa PAO1 (2UV0) and Aspergillus niger phytase (3K4P). Electrochemical results showed that the excellent inhibition efficiencies obtained were 95.8% (EIS) and 95.2% (PDP) at 10−3 M. The charge-transfer resistance increased from 21.57 to 512.6 Ω cm−2 while the corrosion current density decreased from 1104.1 to 35.1 μA/cm−2. By using PDP measurements, it was found that IM4 is a mixed-type inhibitor. The adsorption was of Langmuirian type and mostly chemisorptive. The results of the surface characterisation verified the presence of a protecting film on the steel surface and DFT and MDS calculations corroborated the experimental results. In addition, SEM-EDS and AFM showed that the surface of the materials is smoother and more hydrophobic when IM4 is present. The docking results indicated good interactions between IM4 and the targeted microorganisms.

Repurposing expired vancomycin drug as an effective corrosion inhibitor for API 5L X60 carbon steel (X60-CS) in 1M hydrochloric acid (HCl). The pharmaceutical drugs that have expired are included in this category; they are a waste type that is usually burned rather than recycled. It's interesting to note that certain drug compounds exhibit characteristics that prevent corrosion in a variety of metals and corrosive liquids. This study aimed to comprehensively evaluate vancomycin based on concentration on X60-CS in acidic environments. A variety of techniques were employed to assess the corrosion-mitigating properties of vancomycin. To assess vancomycin's remarkable performance, we used extensive procedures, including weight loss (WL) and sophisticated electrochemical methods such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). By increasing vancomycin concentration, the inhibition efficiency will increase. The outcomes are remarkable: 94.2% (weight loss), 92.3% (polarization), and 95.3% (EIS) were the best inhibitory efficiencies attained at 298K. With a good fit, vancomycin follows the Langmuir isotherm. The data obtained for activation energy increased from (50.82-80.35kJ mol⁻¹), providing physical adsorption mechanisms in the interaction of the vancomycin inhibitor with the X60-CS surface. PDP results indicate that the corrosion current density (Icorr) decreases from 244 to 54 µA cm⁻² at inhibitor concentrations of 20 and 100 ppm, respectively. Along with weight-loss studies, surface analysis was carried out using Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Energy Dispersive X-Ray (EDX), and Scanning Electron Microscopy (SEM), and vancomycin adsorption on the X60-CS surface was evidenced. The quantum chemical parameters (ELUMO, EHOMO, and [Formula: see text]E) have a strong relationship with the protection efficiency of the investigated drug. The vancomycin inhibitor conformational adsorption modification on the iron surface was also predicted using molecular dynamics (MD) simulations. Results gained for all techniques used are in good agreement.

Unveiling the corrosion inhibition mechanism of titanium nitride composite carbon dots in saline-alkali environments: An experimental and theoretical study.