Synergistic anodic dissolution and hydrogen embrittlement in stress corrosion cracking of high-strength steels: Mechanisms and multiscale dynamics

The efficacy of expired dapagliflozin (DAP) as a sustainable and cost-effective corrosion inhibitor for copper (Cu) in 1.0M HNO₃ was investigated using a combination of experimental and theoretical approaches. Chemical and electrochemical methods were applied to assess the anticorrosion efficacy over a range of concentrations and temperatures. The results demonstrated that the anticorrosion efficiency of expired DAP is significant and increases with increasing inhibitor concentration but decreases as the temperature rises. This indicates that the inhibition process is primarily governed by the physical adsorption of expired DAP molecules onto the Cu surface. However, the observed change in βₐ suggests that the adsorption is not purely physical in nature but rather involves a mixed physical and chemical adsorption mechanism. Potentiodynamic polarization (PDP) results indicate that expired DAP functions as a mixed-type inhibitor, effectively suppressing both anodic metal dissolution and cathodic reduction reactions. Moreover, a pronounced positive shift in the pitting potential (Eₚiₜₜ) was observed, indicating a significant enhancement in resistance to pitting corrosion. The thermodynamic parameters associated with both activation and adsorption processes were evaluated and analyzed, offering deeper insight into the corrosion inhibition mechanism. The inhibition effect of expired DAP is attributed to the formation of a stable complex between DAP molecules and Cu²⁺ ions adsorbed on the metal surface. Conductometric titration indicates a 1:1 stoichiometric ratio for the Cu²⁺-DAP complex. The adsorption of this complex reduces the corrosion rate and enhances inhibition efficiency. Theoretical calculations further confirm that DAP exhibits a strong tendency to absorb onto the Cu surface, reflecting its remarkable inhibitory potential. Good agreement between the theoretical predictions and the experimental results highlights the consistency of the applied approaches and strengthens confidence in the reported results.

• Corrosion of Monel 400 assessed in HF, HCl, and mixed HF-HCl environments. • Vapor-phase HF-HCl exposure greatly accelerates material degradation • O 2 , Cu 2+ , and Fe 3+ ions intensify anodic dissolution and localized corrosion. • SEM/EDS revealed dealloying, fluoride–chloride deposits, and severe surface damage. • Industrial validation confirmed rapid corrosion in acidic condensates of Monel 400. This study assesses Monel 400′s corrosion behavior in liquid and vapor phases in hydrofluoric (HF), hydrochloric (HCl), and mixed HF-HCl acid environments. Through mass loss testing and electrochemical measurements, the alloy’s degradation was evaluated under varying acid concentrations, temperatures, gas atmospheres (N 2 , O 2 ), and metal ion contaminants (Cu2 + , Fe3 + ). Electrochemical measurements (ASTM G59/G102) and mass loss (ASTM G31/G1) were used for corrosion testing. The findings demonstrate that corrosion rates are considerably increased by vapor-phase exposure, especially in combined HF-HCl vapors (up to 0.8 mm·y −1 ), because of combined fluoride and chloride chemical attack. Improved anodic dissolution and decreased passivation are confirmed by electrochemical data, particularly when oxidizing conditions (O 2 ) and Cu2 + and Fe3 + ions are present. Significant surface deterioration, dealloying, and the development of corrosion products rich in fluoride and chloride were discovered by SEM/EDS investigations. The addition of CuCl 2 and FeCl 3 changed the surface chemistry and increased localized corrosion. Similar degradation trends were shown by industrial validation in a condensing heat exchange unit employing Monel 400, where concentrated acidic condensates promoted rapid material loss and corrosion deposits consisting of chlorides. The findings emphasize the limitations of Monel 400 in HF-HCl systems, notably under vapor-phase and oxidizing conditions, and propose mitigation measures such as alternate Ni-Cr-Mo alloys, protective coatings, and oxygen exclusion to improve durability in harsh fluorinated environments.

The integration of metal-organic framework (MOF) thin films into functional devices is currently hindered by high temperatures, prolonged processing times, and complex additives required by conventional fabrication methods. We demonstrated a plasma-assisted strategy to directly synthesize crystalline MOF films on metal substrates under ambient conditions and overcome these kinetic and processing limitations. We used a HKUST-1 on a copper substrate as a model system and demonstrated that continuous crystalline films are formed within minutes in an ethylene glycol solution without the need for thermal annealing or external metal precursors. The mechanistic investigation revealed that the plasma-liquid-solid interface functions as a unique reaction field providing a dual driving force. The plasma treatment induced a reaction by functioning as an electrochemical driver for anodic metal dissolution while simultaneously assisting in ligand deprotonation through the generation of reactive species such as hydroxyl and superoxide ions. This process is governed by a kinetic balance, where a specific processing window defined by the metal electrode potential and the ligand acidity distinguishes copper from other metals. These results indicate that atmospheric pressure plasma serves as a potent tool for interfacial coordination chemistry, provided that the electrochemical ion supply and acid-base kinetics are synchronized. This work establishes a design principle for the rapid and additive-free fabrication of MOF films, thus offering a foundation for the streamlined integration of functional porous layers into next-generation devices.

This study investigated the correlation between mechanical strengthening and electrochemical corrosion behavior in 18Ni300 maraging steel fabricated via laser powder bed fusion (LPBF). To evaluate the impact of post-processing, specimens were analyzed under four conditions: solution treated (S), solution peened (SP), solution aged (SA), and solution aged peened (SAP). The aging treatment (490 °C for 6 h) effectively enhanced the corrosion resistance by homogenizing the martensitic matrix and promoting the formation of a stable passive film, resulting in the lowest corrosion current density (icorr of 1.716 × 10-6 A/cm2). In contrast, the application of shot peening after aging (SAP) significantly degraded the corrosion resistance, characterized by the most negative corrosion potential (Ecorr of -0.374 V and a 2.4 times increase in icorr compared to the SA condition. Quantitative analysis revealed that the 1250 MPa of compressive residual stress induced by peening increased the thermodynamic instability of the surface through extreme lattice distortion, thereby lowering the activation energy for anodic dissolution. Furthermore, the increased surface roughness (60.68 µm) expanded the effective electrochemical reaction area, acting as a kinetic accelerator for corrosion. The results demonstrate that while the SA process provides an optimal balance between microstructural stability and corrosion resistance, additional shot peening (SAP) imposes a significant corrosion penalty despite its mechanical benefits. This study concludes that for 18Ni300 maraging steel, the trade-off between mechanical reinforcement and electrochemical stability must be carefully managed, emphasizing the need for surface stabilization when high-intensity peening is applied in corrosive environments.

Titanium alloys are widely used in aerospace and other industries owing to their low density, high strength, and excellent corrosion resistance, yet their machinability remains challenging. Electrochemical machining (ECM) is a promising non-contact approach; however, the formation of a stable passive film on titanium alloys often suppresses anodic dissolution in scanning ECM. In this study, we propose laser-assisted scanning ECM using an electrolyte suction tool, in which nanosecond laser irradiation locally disrupts the passive film and activates electrochemical dissolution. Parametric experiments identified conditions that produced a V-shaped groove along the laser path even when ECM alone was ineffective. The optimized parameters were an applied voltage of 9.0V, a laser fluence of 0.5J/cm2, a scanning speed of 0.25mm/s, and a 2.0s irradiation followed by a 2.0s interval. In addition, extending the voltage application time to 12.0s after laser irradiation improved groove uniformity. High-speed observation of the electrolyte film during scanning indicated that vigorous bubble generation at higher laser fluences disturbed the current distrubusion, whereas stable machining was achieved by using a lower laser fluence and a slower scanning speed. These results demonstrate that controlling laser activation and post-irradiation voltage duration enables localized pattern machining of Ti-6Al-4V.

Under the conditions of laser power of 1500 W, scanning speed of 5 mm/s, spot diameter of 3.5 mm, and powder feeding rate of 10 r/min, this study systematically investigated the influence of different tempering temperatures (200 °C and 600 °C) on the microstructure, friction and wear properties, and corrosion resistance of laser cladding Ni25 coatings, as well as the underlying mechanisms. The phase composition, microstructure, chemical composition, wear resistance, and corrosion resistance of the coatings were characterized and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), pin-on-disk friction and wear tests, and electrochemical workstations. The results showed that the as-clad coating was composed of γ-Ni supersaturated solid solution and various metastable borides/carbides (such as Cr3B4), presenting fine-grained and non-equilibrium features. Tempering at 200 °C mainly achieved stress relaxation, enhancing and shifting the diffraction peaks to the left without changing the phase composition, while tempering at 600 °C drove significant diffusion-type phase transformation, leading to the decomposition of metastable Cr3B4 and the precipitation of stable phases such as Ni2Si, accompanied by grain growth and microstructure coarsening. Friction tests indicated that the coating tempered at 600 °C exhibited the lowest average friction coefficient (0.679) and wear volume (0.0582 mm3) due to stable microstructure and hard phase strengthening, demonstrating the best wear resistance. However, electrochemical tests revealed a “trade-off” effect: the fine-grained microstructure of the as-clad coating, with its uniform composition, had the lowest corrosion current density (8.10 × 10−5 A/cm2) in 3.5% NaCl solution, showing the best resistance to uniform corrosion, while tempering, especially at 600 °C, caused grain growth, coarsening of the second phase, and micro-galvanic effects, slightly reducing the anodic dissolution resistance and increasing the corrosion current. This study clarified that heat treatment can significantly enhance the mechanical and tribological properties of Ni25 coatings by regulating their transformation from metastable to stable states, but at the potential cost of some corrosion resistance, providing a theoretical basis for optimizing post-treatment processes for different service conditions (wear resistance or corrosion resistance).

Evaluating the influence of silicon on phase formation, hardness and corrosion in Al–6.5% Mg alloy

With the continued downscaling of microelectronic components, electrochemical migration (ECM) has become an increasingly significant reliability concern. This phenomenon promotes the formation and growth of metallic dendrites, which can eventually cause short circuit failures. In response to these challenges, this study presents a comprehensive 2D numerical model that simulates the ECM process of Cu under a contaminant-free electrolyte environment and an applied bias voltage of 10 V. The model employs deterministic formulations to describe both anodic dissolution and ionic transport mechanisms. In contrast, dendritic growth is modeled using a stochastic approach to capture the inherent randomness and variability of dendrite growth. Focusing specifically on dendrite growth, the present work systematically investigates three distinct algorithmic strategies designed to reproduce the characteristic tree-like morphology observed in Cu dendrites. These algorithms also aim to accurately predict the time to failure (TTF) of test samples under the specified conditions. Experimental validation was conducted through water-drop (WD) tests. The model demonstrates strong agreement with experimental TTF data, as confirmed by Weibull statistical analysis. Furthermore, the model successfully replicated the complex tree-like dendritic structures and captured variations in fractal dimensions, underscoring their effectiveness in representing the nuanced morphological features of ECM-induced Cu dendrites. Our modeling framework thus offers valuable insights for predicting ECM-related failures in microelectronic systems.

The efficacy of plasma electrolytic nitrocarburizing (PENC) in enhancing the surface hardness and wear resistance of the surface of Ti6Al4V alloy additively manufactured by selective laser melting (SLM) and electron beam melting (EBM) was assessed in comparison with the surface of the alloy obtained by the traditional method (TM) of vacuum casting and subsequent hot rolling. The surface of TM, SLM and EBM samples after PENC without pre-treatment have the same structural-phase composition and consist of TiN nitride and TiC, Ti8C5 titanium carbides in a martensitic matrix with an oxide layer on the surface. Such a structure leads to an increase in microhardness to 1170 ± 180 HV for SLM samples, 1050 ± 40 HV for TM samples and 1025 ± 130 HV for EBM samples. Significant differences in the morphological features of the surface are associated with the presence of unmelted and semi-melted particles of raw materials after additive manufacturing, which causes predominant anodic dissolution along the contours of these particles and high-temperature oxidation of depressions during plasma electrolytic treatment. The most significant increase in wear resistance (a factor of 14.4) was observed in EBM samples, concomitant with a change in the dominant friction mechanism from microcutting to plastic displacement. For SLM samples, fatigue wear was observed both before and after treatment. Nitrocarburizing increased the wear resistance of these samples by a factor of 5.2. For TM samples, the treatment increased wear resistance by a factor of 3.2. The reduction in weight wear of the samples following PENC is attributed to the combined effect of increased titanium surface microhardness, oxidation, an increased bearing capacity of the rough profile (Kragelsky-Kombalov criterion), and a softer friction condition. For industrial application, a significant simplification of post-processing is the primary technological effect of plasma electrolytic processing of the additively manufactured titanium. • PENC can be effectively applied to additively manufactured parts. • Structure and composition of surface is similar to traditionally manufactured parts. • The granule contours dissolve and the depressions oxidize with PENC. • Microhardness of SLM and EBM surfaces after PENC increases to 1170 and 1025 HV. • Wear of SLM and EBM samples after PENC is reduced by 5.2 and 14.4 times.

The article is devoted to studying issues of electrochemical machining. It is shown that during high-speed anodic dissolution of nickel, chromium, and alloys XH78T and XH77TYuPU in solutions of NaCl, NH4Cl, NaNO3, NH4NO3, NaClO3, the main factors determining the logarithmic dispersion index are the change in the effective electrical conductivity of the electrolyte with the change in the interelectrode gap and the change in current efficiency with current density.

Achieving a balanced combination of mechanical performance and corrosion resistance remains a critical challenge restricting the broader application of Al-Zn-Mg-Cu alloys in aerospace, marine, and transportation industries. In this investigation, the addition of Si significantly enhances the mechanical properties of the alloy. Among them, the alloy containing 0.35Si has the best corrosion resistance, which is closely related to the transformation of precipitates. A non-monotonic relationship between Si content and corrosion resistance was observed. At low Si levels, the simultaneous precipitation of η, T, and GPB-II phases leads to a large electrochemical potential difference among these phases, which promotes micro-galvanic corrosion. With increasing Si content, the microstructure evolves toward the dominance of GPB-II precipitates, thereby reducing the internal potential difference and improving corrosion resistance. However, excessive addition of Si will lower the equilibrium solid phase temperature, resulting in overburning during the solid solution treatment process and a significant decrease in corrosion resistance. In addition, lowering the solution treatment temperature effectively improves corrosion resistance by suppressing the formation of remelted spheres and low-melting-point brittle phases along grain boundaries. These phases can form strong micro-galvanic couples with the matrix, accelerating anodic dissolution. Therefore, by adding an appropriate amount of Si and optimizing the solid solution temperature, a corrosion-resistant high-strength Al-Zn-Mg-Cu-Si alloy can be obtained. This strategy also provides a broader compositional and heat-treatment design window, which could be further expanded through the incorporation of rare-earth (RE) elements.

Aluminum–air batteries have attracted considerable interest as alternative electrochemical energy systems owing to their high theoretical energy density, abundant aluminum resources, and inherent safety. These attributes make them promising candidates for cost-effective and long-duration energy conversion and storage applications. However, practical implementation remains limited by several challenges, including parasitic corrosion and uneven dissolution of aluminum anodes, insufficient activity and durability of air cathodes, electrolyte-related degradation, and system-level issues such as water management and cell configuration. Addressing these limitations requires integrated improvements not only at the material and component levels but also in cell and system design. This review summarizes recent research trends in aluminum–air batteries, with a focus on aluminum anodes, air cathodes, electrolytes, and cell and system designs, and discusses future prospects toward practical applications.

ABSTRACT In this study, polyacrylonitrile (PAN) nanofiber membranes were fabricated via electrospinning and subsequently carbonized at 2200°C to produce freestanding carbon nanofiber (CNF) substrates. The CNF membrane served as the working electrode in a three‐electrode electrochemical system, with a copper sheet counter electrode and Ag/AgCl reference electrode. Copper nanoparticles supported on CNFs (Cu‐NPs/CNFs) were synthesized through cyclic voltammetry (CV), where anodic dissolution of the Cu counter electrode generated Cu 2+ ions, followed by electrochemical reduction and deposition onto CNFs. Crucially, the number of CV scanning cycles (10‐15 cycles) was optimized to achieve highly active catalysts. The Cu‐NPs/CNFs demonstrated superior catalytic performance in the Ullmann coupling of iodobenzene compared to commercial Cu nanopowder, yielding biphenyl at 85%–89% versus 76.12% for the nanopowder. Material characterization revealed that increasing scan cycles enlarged both the particle density and size of Cu nanoparticles; catalysts prepared with 10‐15 cycles exhibited uniform particles with diameters of 30–80 nm. Furthermore, the Cu‐NPs/CNFs catalyst maintained structural integrity after 5 reaction cycles, retaining 78% biphenyl yield and demonstrating excellent reusability. This work establishes a controllable electrochemical route for fabricating efficient, separable, and durable carbon‐supported metal catalysts.

The temperature-dependent corrosion behaviour and through-plane conductivity of nano-thin carbon/titanium/stainless steel (C/Ti/SS316L) composite coatings in a DOE-specified simulated PEMFC cathode environment (0.1 ppm HF, pH 3) were investigated. Elevated temperatures accelerated mass transfer, reducing corrosion resistance via negative corrosion potential shifts, increased corrosion current density, and lower impedance modulus. Under 0.67 V polarisation, coatings maintained low corrosion current density (<0.5 μA cm −2 ) and ICR (<2 mΩ cm 2 ) even at 90°C, meeting DOE targets. Conversely, polarisation at 1.43 V and high temperatures triggered preferential carbon corrosion, Ti interlayer exposure/dissolution, and Ti-oxide formation/dissolution, degrading through-plane conductivity. A temperature-dependent anodic dissolution transition is proposed: Ti-interlayer-controlled dissolution at moderate temperatures shifts to synergistic Ti dissolution and carbon corrosion at high temperatures. These findings define a safe operating temperature window for C/Ti-coated bipolar plates, supporting their practical PEMFC applications.

Influence of the nature of metal M on the anodic dissolution of PdM electrolytic alloys (M = non-noble metal)

Efficient wastewater treatment is essential for environmental protection and sustainable water resource management, particularly when dealing with complex wastewater streams. Hybrid processes that combine electrochemical and physicochemical methods are increasingly explored due to their potential to enhance pollutant removal efficiency and reduce operating costs. This study evaluates the performance of hybrid treatment methods for complex compost wastewater by integrating electrocoagulation (EC), zeolite and magnetic assistance using aluminium (Al) and iron (Fe) electrodes. The influence of different electrode materials on magnetically assisted hybrid treatment process was assessed with respect to key treatment indicators, including chemical oxygen demand (COD) and turbidity reduction, as well as electrode mass loss, surface morphology, suspension settling, and EC sludge amount. Energy consumption and electrode usage were also considered to evaluate process economics. The results show that the application of a magnetic field in Al electrode systems slightly improves COD and turbidity removal, enhances anodic dissolution, and contributes to a more homogeneous surface morphology. In contrast, Fe electrodes exhibit a partially opposite response – the magnetic field accelerates floc settling and increases EC sludge production but reduces pollutant removal efficiency due to decreased dissolution intensity. Ferromagnetic Fe electrodes respond more strongly to the magnetic field, promoting aggregation and compaction of Fe-hydroxide flocs and partial surface stabilisation, which leads to lower anode mass. Weakly paramagnetic Al electrodes, on the other hand, are not directly affected by the magnetic field, but experience an indirect influence through magnetohydrodynamic (MHD)-induced micro-mixing and improved mass transfer. This leads to more uniform and intensive dissolution and a slightly higher pollutant removal efficiency. These findings provide a deeper understanding of the interactions between electrochemical and magnetic effects in hybrid electrocoagulation and offer guidance for optimising electrode material selection and magnetic field parameters to achieve more efficient and sustainable treatment of complex wastewater.

This paper investigates the influence of electrochemical processes in drinking water on the transport of microparticles and the formation of precipitates under a DC electric field generated by two copper electrodes. Experiments were performed in a 1 L electrolytic cell: the applied voltage was varied from 0 to 29 V, and the interelectrode distance from 5 to 50 mm. Gas evolution was observed at both electrodes (water electrolysis), along with the formation of a loose copper “coat” around the anode and comparatively weak fouling of the cathode. It was found that, under a number of operating regimes, the deposit mass exceeds the measured anode mass loss, indicating the incorporation of water components into the solid products. To account for the initial mineralization, X-ray fluorescence analysis of dissolved impurities was carried out. A physicochemical interpretation of the effect is proposed: anodic copper dissolution (Cu → Cu2+ + 2e−) occurs simultaneously with cathodic water reduction producing OH− and H2, which generates pH gradients in the near-electrode regions; migration of Cu2+ and transport of OH− lead to precipitation of Cu(OH)2 followed by transformation to CuO. The experimental dependences of deposit mass on the interelectrode distance and electric-field strength are presented graphically and approximated by simple analytical expressions, including a generalized model m(d,E), suitable for optimizing electroprecipitation regimes and estimating parameters of water-treatment processes. It is noted that a similar mass imbalance is also observed for silver electrodes, supporting the universality of the mechanism. The results can be applied to the design of compact electrophysical units for selective metal extraction and for controlling secondary water contamination under real operating conditions.

Corrosion inhibition evaluation of sulphur-doped pomegranate peel waste-derived carbon dots for carbon steel in acidic environment

Green synthesis of biogenic ZrO2 nanoparticles using Ficus pumila leaf extract: A sustainable approach to corrosion inhibition and antioxidant enhancement