Purpose This study aims to investigate the corrosion inhibition performance of the benzimidazolic derivative OSMBZ for C38 steel in 1 M HCl and to clarify its inhibition mechanism through combined experimental and theoretical approaches. Design/methodology/approach OSMBZ was synthesized and characterized by proton and carbon nuclear magnetic resonance spectroscopy. Its inhibition performance was evaluated using weight-loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy, SEM/EDX surface analysis, adsorption isotherm analysis, temperature-dependent measurements, density functional theory calculations and molecular dynamics adsorption simulations on the Fe(110) surface. Findings The inhibition efficiency increased with OSMBZ concentration, reaching 95.22% at 3 × 10–4 M and 298 K. Electrochemical results showed that OSMBZ acts as a mixed-type inhibitor with predominant cathodic influence. The adsorption process followed the Langmuir isotherm and involved both physical and chemical contributions. SEM/EDX observations confirmed the formation of a protective adsorbed layer, while theoretical calculations supported the role of molecular planarity, heteroatom-rich adsorption centers, p-conjugation and favorable interaction with the Fe(110) surface. Originality/value This work provides an integrated mechanistic assessment of a benzimidazolic derivative as an efficient corrosion inhibitor by correlating gravimetric, electrochemical, surface, thermodynamic, DFT and molecular dynamics results.

Purpose This study aims to clarify the effect of cerium (Ce) content on passive film stability and localized corrosion behavior of a Cr-containing alloy in hypersaline seawater, with particular emphasis on the differences between aerated and deaerated conditions. Design/methodology/approach Alloys with different Ce contents were prepared and exposed to NaCl solutions with chloride concentrations up to 50,000 ppm under aerated and deaerated environments. Microstructural evolution and precipitation behavior were characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy-dispersive spectroscopy. Corrosion behavior was evaluated using open-circuit potential, electrochemical impedance spectroscopy, potentiodynamic polarization, surface morphology analysis and X-ray photoelectron spectroscopy characterization of passive films. Findings Moderate Ce addition (0.5 Wt.%) significantly refines the microstructure, suppresses harmful precipitates and promotes the formation of compact, Cr-rich passive films, resulting in enhanced corrosion resistance under both aerated and deaerated conditions. Excessive Ce addition induces Ce-rich and Cr/Mo-rich precipitates, increasing electrochemical heterogeneity and accelerating pitting corrosion, especially in oxygen-deficient environments. Deaerated conditions markedly weaken passive film stability and facilitate chloride penetration, leading to more severe localized corrosion. Originality/value This work provides a systematic comparison of Ce-regulated corrosion mechanisms under aerated and deaerated conditions in hypersaline seawater, revealing the synergistic roles of microstructure, precipitation evolution and passive film chemistry in governing localized corrosion resistance.

Purpose The interfacial performance of epoxy coatings strongly influences their long-term corrosion protection on metallic substrates. This study aims to elucidate how cerium-based conversion coatings affect epoxy/metal interfacial interactions and adhesion mechanisms. Design/methodology/approach Electrochemical impedance spectroscopy (EIS) and pull-off tests were used to assess interfacial stability and adhesion on differently pretreated substrates. A surface-energy-based thermodynamic model was implemented to predict interfacial bonding strength. In addition, density functional theory (DFT) calculations and molecular dynamics (MD) simulations were conducted to probe atomic-scale interactions and dynamic adsorption behavior at the epoxy/CeO2 interface. Findings Cerium conversion coated substrates exhibited superior interfacial stability and adhesion compared to other pretreatments, as indicated by higher impedance values and cohesive failure within the coating. Thermodynamic predictions of interfacial bonding strength were consistent with EIS and adhesion results. DFT results revealed enhanced electronic interactions and charge transfer at the epoxy/CeO2 interface, while MD simulations demonstrated stable adsorption and resistance to interfacial disruption under realistic conditions. Originality/value This work integrates experimental electrochemical and adhesion characterization with thermodynamic and atomistic simulations to provide a predictive understanding of corrosion-resistant coating interfaces, offering a rational basis for interface design beyond conventional trial-and-error approaches.

Purpose The Al-Ce alloys have attracted considerable attention for thermal exchangers and automotive applications owing to their remarkable thermal stability; however, their corrosion behavior remains insufficiently understood. This study aims to investigate the mechanical properties and corrosion behavior of Al-Ce-8Mg alloys with varying Ce contents. Design/methodology/approach The mechanical and corrosion properties of Al-Ce-8Mg alloys with different Ce content were analyzed based on Thermo-Calc calculations, tensile testing, electrochemical impedance spectroscopy and scanning kelvin probe force microscopy. Findings There are three phases in the Al-Ce-8Mg alloys, which are the a-Al(Mg) matrix phase, the primary and the eutectic Al11Ce3 phase. As the Ce content decreases from 9 Wt.% to 5 Wt.%, the hard and brittle primary phase is progressively reduced and eventually eliminated, leading to an improvement in mechanical strength, with an ultimate tensile strength of 251.9 MPa and an elongation of 4.45%. In addition, the overall corrosion resistance of the alloys is improved due to the reduced potential difference between the matrix and the eutectic phase, compared to the difference observed with the primary phase. Originality/value Although Ce is beneficial for improving the performance of Al alloys at high temperatures, the addition of excessive Ce does not improve the corrosion resistance and mechanical properties of the alloy at room temperature. It is determined that the eutectic Al-Ce phase has superior potential in aerospace and heat-exchanger applications.

Purpose The study aims to enhance the corrosion resistance of mild steel by developing advanced nanocomposite coatings based on poly(3,4-ethylenedioxythiophene) (PEDOT) reinforced with nanoscale fillers that improve both barrier and electroactive protective mechanisms. Design/methodology/approach α-Fe2O3 and γ-Al2O3 nanoparticles were synthesized via co-precipitation and characterized by X-ray powder diffraction, revealing crystallite sizes of 8.4 nm and 6.4 nm, respectively. PEDOT and its nanocomposites were electrodeposited onto steel substrates through electrochemical polymerization. Corrosion performance was systematically evaluated using open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy in 0.05 M H2SO4. Complementary analyses, including atomic absorption spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, provided insights into morphology, elemental composition and passive film formation. Findings The incorporated nanoparticles enhanced the electropolymerization of EDOT and improved the protection efficiency (PE) of the resulting polymer coatings. Electrochemical measurements showed PE values of 56.9% and 77.2% for the PEDOT/ γ-Al2O3 and PEDOT/ α-Fe2O3 coatings, respectively. Atomic absorption spectroscopy analysis further confirmed that the PE increased upon aging in the solution, reaching 88.77%, 90.32% and 92.53% for the PEDOT, PEDOT/ α-Fe2O3 and PEDOT/ γ-Al2O3 coatings after six days, respectively. Thick, compact deposits of iron oxides and oxides of minor elements were observed to accumulate beneath the coating. Originality/value This study establishes PEDOT/metal oxide nanocomposites as eco-friendly, high-performance coatings that combine barrier reinforcement with redox-driven self-passivation. The synergistic role of α-Fe2O3 and γ-Al2O3 highlights a sustainable pathway for developing long-term corrosion protection strategies for steel in aggressive environments.

Purpose The purpose of this paper is to present the synthesis, characterization and corrosion inhibition performance of a novel MgO@MnO2@graphite hybrid nanocomposite for carbon steel protection in acidic media. The study demonstrates its high inhibition efficiency (up to 98.86% at 300 ppm) through electrochemical and surface analyses. The work also explores the underlying adsorption mechanism using thermodynamic and kinetic evaluations. These findings highlight the potential of MgO@MnO2@graphite as an effective, low-cost and environmentally friendly corrosion inhibitor, aligning with current research interests in advanced materials for industrial corrosion control. Design/methodology/approach This study used a sol–gel synthesis approach to prepare MgO and MnO2 nanoparticles, which were subsequently integrated with graphite via ultrasonication to form a MgO@MnO2@graphite nanocomposite. Comprehensive characterization was performed using X-ray diffraction, Fourier transform infrared, scanning electron microscopy-energy-dispersive X-ray, transmission electron microscopy, ultraviolet–visible, atomic force microscopy and X-ray photoelectron spectroscopy to confirm structure and morphology. The corrosion inhibition performance of the nanocomposite on carbon steel in 1 M HCl was evaluated using weight loss analysis, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation. Surface analysis further supported the protective film formation mechanism. All tests were conducted under standardized conditions and validated through repeat measurements. Findings The MgO@MnO2@graphite nanocomposite exhibited remarkable corrosion inhibition performance for carbon steel in 1 M HCl. Weight loss, electrochemical and surface analyses confirmed a concentration-dependent inhibition efficiency, reaching 98.86% at 300 ppm. Potentiodynamic polarization and EIS studies indicated mixed-type inhibition, enhanced charge transfer resistance and reduced corrosion rates. Surface analyses (AFM and XPS) verified protective layer formation. Thermodynamic and kinetic evaluations revealed a spontaneous, exothermic adsorption process involving both physisorption and chemisorption. Adsorption followed Frumkin isotherm behavior. These comprehensive findings highlight the nanocomposite’s potential as a highly efficient and stable corrosion inhibitor in aggressive acidic environments. Originality/value This study introduces a novel MgO@MnO2@graphite nanocomposite synthesized via a simple sol–gel and ultrasonication route for corrosion protection of carbon steel in acidic media. The originality lies in the synergistic integration of MgO and MnO2 with graphite, offering enhanced inhibition efficiency through a mixed physisorption-chemisorption mechanism. Comprehensive evaluation using electrochemical, surface and thermodynamic analyses demonstrated superior protection efficiency (up to 98.86%) and long-term stability. The findings provide valuable insight into designing multifunctional nanocomposites as environmentally friendly, low-cost alternatives for corrosion mitigation in industrial applications, particularly where aggressive acidic conditions are encountered.

Purpose The purpose of this study is to investigate the susceptibility of L80, and other steels with 1% Cr, 3% Cr and 9% Cr, to stress corrosion cracking (SCC), pitting, crevice and stress concentration effect at the existing conditions of an oil reservoir. Design/methodology/approach The 4-points bent beam specimens were employed in the experimental works. The experimental works were performed at 82°C in a simulated environment that contains CO2 and Cl−. The effect of stress concentration on corrosion rate was confirmed by the novel circumferential notched tensile (CNT) specimen approach. Findings The results indicate that these steel grades are not susceptible to SCC in the given condition, and are promising materials for the application. The L80, 1% Cr and 3% Cr steels were attacked by pitting and crevice corrosion, while the 9% Cr steel was insignificantly affected, presumably due to its higher Cr, Mo and Ni contents. The local corrosion concentrated on sites that have high stress concentration. The CNT specimens confirmed the effect of stress concentration on promoting the local corrosion. Originality/value The study provides an essential insight into the susceptibility of downhole tubular to SCC for L80, 1% Cr, 3% Cr and 9% Cr steels in simulated reservoirs environment that contains CO2 and Cl−. A novel fracture mechanics approach using the CNT specimen method was introduced in investigating the effect of stress intensity on corrosion rate.

Purpose The purpose of this study is to develop an organic coating to mitigate the corrosion of exhaust gas fans in acid regeneration processes. Design/methodology/approach In this research, a composite modified epoxy resin (F-GF/EP-PU) coating was prepared using epoxy resin (EP) as the base material, polyurethane prepolymer (PU) as the modifier and functionalized glass flake (F-GF) as the filler. The modification effect, thermal stability and mechanical properties of F-GF/EP-PU composites were evaluated by Fourier transform infrared, thermogravimetric analysis and tensile testing, respectively. The corrosion resistance of F-GF/EP-PU coating was evaluated by electrochemical impedance spectroscopy. Findings The combination of PU and F-GF enhances the mechanical properties, thermal stability and acid corrosion resistance of the F-GF/EP-PU coating. After 21 days of immersion in an 80°C solution containing 1 Wt.% HCl and 3.5 Wt.% NaCl, the low-frequency impedance of the coating remains above 10¹° O·cm2, indicating its excellent protective capabilities. Originality/value This study simulates harsh conditions in actual working environments, and the coating exhibits excellent protective capabilities in harsh environments.

Purpose This paper aims to clarify the corrosion inhibition effects of biocides NaClO, ClO2 and C17H30ClN on carbon steel pipelines at different service stages. Design/methodology/approach The corrosion behavior of new service pipelines and in-service pipelines with corrosion nodulations after biocide application was compared using microbial counting, surface analysis and electrochemical tests. Findings The results of this study show that for the new service pipelines, the corrosion rate increases in the NaClO and ClO2 systems and decreases in the C17H30ClN system. Therefore, C17H30ClN exhibits the best corrosion inhibition efficiency for new service pipelines. For the in-service pipelines with corrosion nodulations, ClO2 and NaClO can accelerate the sample corrosion, while C17H30ClN cannot fully remove the existing corrosion nodulations. So the application of a single biocide is insufficient to reduce the risk of corrosion. The synergistic use of C17H30ClN and ClO2 is beneficial for removing the existing nodulations, thereby minimizing the risk of local corrosion during long-term service. Originality/value This study provides guidance for corrosion control of pipelines at different service stages.

Purpose This paper aims to investigate the impact of high-frequency dry-wet alternation on the corrosion behavior of 921A steel in the marine splash zone. Design/methodology/approach This study used a multifactor coupled comprehensive testing apparatus to conduct an eight-day accelerated simulated corrosion test by regulating the dry-wet ratio and splash frequency. The corrosion characteristics of the material and its underlying mechanism were evaluated using methods including corrosion weight loss testing, surface and cross-sectional morphology observation, phase analysis of corrosion products and electrochemical testing. Findings The results show that under the condition of the same splash frequency, the corrosion rate first increases and then decreases with the increase of the dry-wet ratio; while when the dry-wet ratio is fixed, the corrosion process intensifies as the splash frequency increases. A moderate dry-wet ratio (4:1) combined with high-frequency splashing tends to form a typical gas/liquid/liquid film three-phase interface, which enhances cathodic reactions and induces the formation of corrosion peaks. In contrast, excessively high or low dry-wet ratios and low-frequency conditions are conducive to the formation of a denser and more continuous rust layer structure. Electrochemical test results indicate that the variation trend of corrosion current density is positively correlated with the corrosion rate. Originality/value Using a self-developed multi-factor coupled corrosion testing device, this study systematically investigated the synergistic effects of dry/wet cycles and splash frequency on the rust-layer evolution, electrochemical corrosion processes and corrosion-region distribution patterns of 921A steel under simulated marine splash-zone conditions. The results are of great scientific significance for revealing the dominant corrosion mechanisms under multifactor coupled interactions in the marine splash zone.