Corrosion Process Research Articles

The Role of the Bactericidal Mechanism of Copper Elements and Its Effect on the Corrosion Resistance of Steel

In this paper, two kinds of copper-containing steels with copper contents of 2.31 and 6.01 wt.% were designed. By comparing with commercial Q355, the bactericidal properties of copper in seawater containing sulfate-reducing bacteria (SRB) and its influence on the corrosion process of steel were revealed. The corrosion rate, morphology of products, and bactericidal action of copper were tracked by scanning electron microscopy, X-ray diffraction, confocal microscopy, and electrochemical analysis techniques. It was found that the resistance of copper-containing steel to bacterial corrosion was obviously better than that of non-copper-containing steel. At 28 days, the weight loss rates in the SRB environment for 0Ni2Cu6 samples increased by merely 5.43%, which was nearly half that of Q355 of 9.75%. Cu-containing steels exhibited potent antibacterial action, with the ε-Cu phase altering the corrosion byproduct composition from brittle flakes to robust particles and inhibiting the production of H2S. The killed bacteria adhered to the surface of the steel and slowed down the corrosion of the steel. The confocal laser scanning microscope and electrochemical experiments showed that a dense CuFeO4 film formed on the substrate, impeding corrosive ion penetration, and an upsurge in Cu content markedly enhanced the material’s anti-corrosion and antimicrobial attributes.

Three-Dimensional Model of Ionic Species Concentration and Flux During Localised Corrosion of Steel in Marine Environment

Localized corrosion, exemplified by pitting and crevice corrosion, presents a significant challenge in industrial and marine settings due to the presence of chloride ions in seawater, brines and industrial fluids. It initiates and spreads at specific points on metal surfaces and its hidden rapid metal degradation beneath intact surface layers complicates detection and monitoring, increasing the risk of unforeseen structural failures and jeopardizing critical infrastructure integrity. Factors influencing its severity include chloride concentration, pH levels, temperature variations and aggressive ion presence, which degrade protective oxide layers and expose metal to accelerated corrosion. This study aims to enhance predictive capabilities to effectively manage corrosion in chloride-rich environments. Using COMSOL Multiphysics software, this study models a microscale geometry representing a micropit and simulates chloride-induced localized corrosion in steel, by integrating Nernst-Planck equations to incorporate electrochemical reactions, ion transport dynamics and three-dimensional geometrical features. Key parameters such as chloride concentration, pH and material properties are crucial in the modelling approach to simulate the formation and growth of corrosion sites. For 0 to 800 seconds simulation, the model displays the flux of ionic species into and out of the pit. At 800 second, the results demonstrate a peak of Fe2+ concentration of approximately 2.53×103 mol/m3 at the deepest section, the Cl- of 7×103 mol/m3 and an increase in H+ inside the pit, reducing the pH from 8 to about 4.9. These concentration changes indicate substantial metal dissolution is actively occurring inside the pit, making COMSOL Multiphysics software a versatile platform for coupling multiphysical phenomena, enabling comprehensive analysis and 3D visualization of corrosion processes.

A new sample preparation approach based on microwave-induced combustion in disposable vessels for Ni and V determination by ICP-MS in crude oil

The presence of Ni and V in crude oil is associated with pollutant emissions, corrosive processes and low-quality products. Nevertheless, the knowledge of the concentration of these elements, helps to predict geochemical characteristics and to bring information about the crude oil source. Moreover, Ni and V can cause problems during the crude oil refining process. Therefore, the development of alternative, low-cost and rapid approaches for Ni and V determination in crude oil is still welcomed and was the aim of this work. The proposed microwave-induced combustion in disposable vessels (MIC-DV) system allows the use cheap and/or reusable materials, combined to the possibility of sample combustion under atmospheric pressure and using a domestic microwave. The parameters evaluated during MIC-DV optimization were, sample mass (5 to 20 mg) and volume (1 to 10 mL) and concentration (0.5 to 7 mol L-1 HNO3) of absorbing solution. MIC-DV was applied for the digestion of ten crude oil and the results were compared with those obtained after microwave-assisted digestion (MAD) and Ni and V determination by inductively couple plasma mass spectrometry (ICP-MS). The agreement values achieved ranged from 92 to 103% for Ni and from 93 to 106% for V. The limits of quantification after MIC-DV/ICP-MS were 0.28 and 0.15 μg g-1 for Ni and V, respectively. The developed MIC-DV method, can be considered environmentally friendly since it uses low-cost materials and instrumentation, requires reduced handling (based on the single vessel principle), avoids the use of additional dilution steps and minimizes the digest contamination.

Eco-friendly corrosion inhibition of steel using phenolic compounds from Cynara syriaca

This study evaluates the corrosion inhibition performance of the n-butanol (n-BuOH) fraction derived from Cynara syriaca on mild steel in acidic environments. The n-BuOH fraction achieved up to 94 % inhibition at 500 ppm, as assessed through gravimetric analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Key phenolic compounds, including kaempferol, naringenin, myricetin, chlorogenic acid, and quercetin, were identified by UPLC-MS/MS. These compounds form stable flavonoid-metal complexes, as confirmed by UV–Vis spectroscopy. FT-IR and SEM-EDS analyses revealed the formation of protective coatings and interactions with the steel surface. Polarization curves indicate that the n-BuOH fraction acts as a mixed-type inhibitor, predominantly affecting the anodic reaction. The inhibition efficiency decreased from 93.89 % to 73.43 % with increasing temperatures. Thermodynamic analysis showed an increase in activation energy (Ea = 58.20 kJ/ mol) and a positive ΔH value of 56.17 kJ/mol, which can be attributed to the increased thickness of the double layer, enhancing the activation energy of the corrosion process. A Gibbs free energy (ΔG0ads) value of −25.48 kJ/mol confirms that the adsorption process is spontaneous and involves both physisorption and chemisorption. pKa analysis identified specific adsorption sites. This research underscores the potential of the n-BuOH fraction as a novel, eco-friendly corrosion inhibitor, offering valuable insights for sustainable corrosion control strategies.

Investigating chloride-induced corrosion in reinforced concrete structures using Laser-Induced Breakdown Spectroscopy

Reinforced concrete structures face significant annual expenditures in combating rebar corrosion, with chloride penetration identified as a major contributor. This study employs laser-induced breakdown spectroscopy (LIBS) to quantitatively predict the chloride-induced corrosion rate in such structures. Eighty samples, characterized by known chloride content (ranging from 0% to 1.0%), underwent controlled corrosion processes with predetermined degrees measured as bar weight loss. The investigation included two cement types, Type I and Type V, along with samples incorporating pozzolanic materials (FA, SF, and GGBFS,) in addition to plain OPC samples. LIBS was subsequently employed to detect chlorine presence in each concrete sample, recording the corresponding intensity of the chlorine line. After the initial data acquisition, peak analysis was performed to identify the dominant spectral peaks, ensuring that the most relevant signals were isolated. Following this, the intensity of the chloride emission line from the LIBS spectrum was recorded and correlated with its corresponding chloride signal, establishing a quantitative relationship between the LIBS output and chloride presence. A model was then developed to link the LIBS signal intensity to its corresponding chloride concentration in the sample. In parallel, the corrosion rate associated with each specific chloride concentration was measured and then linked to the LIBS-derived chloride concentrations, creating a framework that ties the LIBS output to the actual rebar degradation within the concrete. Comparisons with previous studies demonstrated superior conformity of the developed models. The study also presents optimized parameters for the LIBS setup. Notably, results indicated a high correlation between LIBS intensity and chloride concentration, with the developed model accurately predicting the degree of corrosion.

Terminalia bellirica fruit shell extract by microwave assisted extraction as a green inhibitor for mild steel acid corrosion: insight from chemical, electrochemical and computational studies

In the current study, the corrosion protection role of ethanol extract of Terminalia bellirica fruit shell on Mild Steel (MS) in 0.5 M HCl solution was studied by using weight loss, Tafel plot, AC impedance and surface techniques. The existence of functional groups in the plant extract was confirmed with the aid of FT-IR spectroscopy technique. The presence of 31.12% of gallic acid in the Terminalia bellirica fruit shell extract was complemented with HPLC and LCMS results. The surface coverage and protection efficiency of Terminalia bellirica fruit shell extract were enhanced with its concentration and declined with solution temperature. The activation parameters such as activation enthalpy, entropy and change in Gibb’s free energy are related to adsorption process were calculated and discussed. The adsorption of Terminalia bellirica fruit shell extract was found to obey the Langmuir adsorption model. The process of adsorption of inhibitor molecules on the metal surface can be verified by using UV–Visible spectroscopy technique. The potentiodynamic polarization and impedance results suggest that, Terminalia bellirica fruit shell extract functioned by adsorption at metal (MS)-Corrodent (0.5 M HCl) interface, which blocks the both cathodic and anodic half reactions of the MS corrosion process. Theoretical approach by Monte Carlo (MC) simulations and quantum chemical study support the experimental findings and adsorption of extract of Terminalia bellirica fruit shell molecules on MS surface.

Mechanical damage coefficients of corroding reinforcement of an old building based on the residual “effective” area

AbstractCorrosion decreases the metal mass of the rebar, which reduces its bearing section in addition to developing the risk of hydrogen embrittlement of the bars due to the acidity created during active corrosion. To evaluate the residual strength of corroding bars, a framework was proposed in a previous paper to categorize the alternative modes of failure (ductile or brittle), emphasizing the need to calculate first what was named “the effective residual” area to further calculate tensile parameters characterizing the stress–strain curve: yield and tensile strength, modulus of elasticity, and ultimate strain. Using the effective residual area, it is possible to deduce some damage coefficients of each mechanical property by calculating the ratio of corroded/uncorroded condition and deducing if the uncorroded properties of the steel remain or have been degraded by the corrosion process. In the present paper, such an approach has been applied to bars obtained from a historical building around 100 years old. First, stress–strain tests were performed on quasi‐uncorroded and on corroded bars and thereafter, effective residual area is deduced in this case from the weight loss of the bars. With this effective residual area, we then recalculate the mechanical parameters in corrosion conditions and the corresponding damage coefficients.

Influence of rare earth second phases on the salt spray corrosion and electrochemical corrosion properties of FeCrAl-Gd-Sc alloys

FeCrAl alloys have excellent oxidation and corrosion resistance and have been widely used in cladding materials and structural components. In this study, Fe-21Cr-4Al-xGd-xSc (x=0, 0.5, 1, 2 wt%) alloys were prepared by the vacuum hot press sintering method. The corrosion properties of the Fe-21Cr-4Al-xSc-xGd alloy have been investigated by salt spray and electrochemical corrosion methods. The results show that Sc and Gd doped FeCrAl alloys form nanoscale cubic phase ScAlO3, Gd monomer and intermetallic compounds between Gd and Fe as the second phase. The Sc and Gd doped FeCrAl alloy forms a corrosion film on the surface during the corrosion process. It can effectively hinder the erosion of corrosive ions on the alloy, thus improving the corrosion resistance of the FeCrAl alloy. The second phase (Gd monomer, Fe5Gd, Fe9Gd, ScAlO3) effectively prevents micro galvanic corrosion of inclusions when the addition of Sc and Gd is less than 1 wt%. When the content of Sc and Gd reaches 2 wt%, the role of the second phase tends to accelerate the corrosion of the alloy by acting as the cathode of micro galvanic corrosion. Therefore, FeCrAl-1wt%Sc-1wt%Gd alloy has a better corrosion resistance, and the corrosion rate is only 1.37 mm/year.

A multi-physics dual-phase field model for chloride-induced localized corrosion process and cracking in reinforced concrete

Corrosion-induced deterioration poses a significant threat to the serviceability of reinforced concrete (RC) structures. This study develops a comprehensive mesoscale model utilizing dual-phase field methods to capture the entire time-dependent chloride-induced corrosion and cracking mechanisms, incorporating interactive multi-physics. The model accurately delineates the evolution of corrosion morphology and cracking patterns, focusing on their interdependent interactions within localized areas through detailed electro-chemo-mechanical processes, from steel dissolution to precipitation. The robustness of the proposed numerical method is confirmed through alignment with previously reported experimental results. Extensive parametric studies investigate the impacts of various geometric and material characteristics on corrosion processes. Furthermore, the model’s applicability to RC configurations with multiple reinforcements is also demonstrated. These findings offer pivotal insights into the substantial correlations between rebar corrosion and concrete cracking across multi-physics fields, with their coupling driven by the variable corrosion current density.

Molecular-scale insights into the electrical double layer at oxide-electrolyte interfaces

The electrical double layer (EDL) at metal oxide-electrolyte interfaces critically affects fundamental processes in water splitting, batteries, and corrosion. However, limitations in the microscopic-level understanding of the EDL have been a major bottleneck in controlling these interfacial processes. Herein, we use ab initio-based machine learning potential simulations incorporating long-range electrostatics to unravel the molecular-scale picture of the EDL at the prototypical anatase TiO2-electrolyte interface under various pH conditions. Our large-scale simulations, capable of capturing interfacial water dissociation/recombination reactions and electrolytic proton transport, provide unprecedented insights into the detailed structure of the EDL. Moreover, the larger capacitance of the EDL under basic relative to acidic conditions, originating from the higher affinity of the cations for the oxide surface, is found to give rise to distinct charging mechanisms on negative and positive surfaces. Our results are validated by the agreement between the computed EDL capacitance and experimental data.

Inspired corrosion resistance of copper mediated by multiple ethoxy units linker included indazole based bis-Schiff base dyes in NaCl solution

In this study, hydrophilic multiple ethoxy units linkage chain included bis-Schiff base dyes (SBs 1–3) were designed and synthesized for strengthening corrosion resistance of copper in NaCl solution. The corrosion resistance and corrosion inhibition mechanism of the target dyes for copper were investigated in 3.0 wt% NaCl solution. The adsorption of these dyes on copper surface was revealed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) revealed the adsorption of these dyes containing CN double bonds on copper surface, achieving excellent corrosion inhibition efficiency. The electrochemistry shows that the dyes were able to inhibit the corrosion of copper in sodium chloride solution, and the corrosion inhibition efficiency reached the peak value at a concentration of 1.00 mM. It is noted that the corrosion inhibition efficiency increased with the number increase of ethoxy units. The kinetic potential polarization curves indicate that the dyes were anodic corrosion inhibitors, which could inhibit the anodic reaction process of corrosion. The adsorption of corrosion inhibitor these dyes on copper surface followed Langmuir isothermal adsorption model.

Formation mechanisms of product film on high corrosion resistant EW75 Mg alloy: The effect of corrosive media

Compact and uniform product films with the similar microstructure as magnesium substrate are formed on EW75 alloy in both NaCl and Na2SO4 solution, and the film growth rate in Na2SO4 was even faster than that in the higher corrosive NaCl. This special phenomenon was investigated by electrochemical measurements, transmission electron microscopy (TEM) observation and X-ray diffraction (XRD) analysis, experimental design of corrosive media with different conductivity and concentration was used, and the corrosion process of Mg matrix and Mg-RE precipitates was explored, respectively. The results show that compared with Cl-, SO42- exhibits the stronger binding trend with Mg2+/RE3+, resulting in the faster charge transfer of the anodic metal in SO42- containing solution. And the higher dissolution rate of Mg substrate in Na2SO4 solution promotes the formation of the product film.

Kinetic and Thermodynamic Aspects of the Degradation of Ferritic Steels Immersed in Solar Salt

The study and improvement of the corrosion resistance of materials used in concentrated solar power plants is a permanent field of research. This involves determining their chemical stability when in contact with heat transfer fluids, such as molten nitrate salts. Various studies indicate an improvement in the corrosion resistance of iron-based alloys with the incorporation of elements that show high reactivity and solubility in molten nitrate salts, such as Cr and Mo. This study analyzes the kinetic and thermodynamic aspects of the beginning of the corrosion process of ferritic steels immersed in Solar Salt at 400, 500, and 600 °C. The analysis of the kinetic data using the Arrhenius equation and the Transition State Theory shows that an increase in the Cr/Mo ratio reduces the activation energy, the standard formation enthalpy, and the standard formation entropy. This indicates that its incorporation favors the degradation of steel; however, the results show a reduction in the corrosion rate. This effect is possible due to a synergistic effect by the formation of insoluble Fe-oxide layers that favor the formation of a Cr oxide layer at the Fe-oxide-metal interface, which limits the subsequent oxidation of Fe.

Effect of temperature on the electrochemical corrosion behavior of X52 pipeline steel in NS4 simulated solution

In this study, the electrochemical corrosion performance of both the base material and welded joint of X52 pipeline steel was analyzed at various temperatures (room temperature-RT, 30 °C, 50 °C, and 80 °C) using microscopic characterization techniques and electrochemical methods in a simulated soil solution (NS4). Additionally, the influence of temperatures on the electrochemical corrosion behavior of the X52 pipeline steel base material and welded joint was examined. The findings indicate that the open circuit potential (Eocp) of the base material and welded joint shifts in the negative direction with increasing temperature. The corrosion current density increased from 30.7 to 110.2 μA∕cm2 and from 19.5 to 100.2 μA∕cm2, respectively, while the polarization resistance dropped from 637.3 to 272.6 Ω•cm2 and from 961.3 to 360.7 Ω•cm2. Notably, anodic dissolution controls the corrosion process of the base material and welded joint of X52 pipeline steel at room temperature. Furthermore, the charge transfer resistance (Rt) of the base material and welded joint gradually decreases with increasing temperature, and the corrosion process transforms into cathodic diffusion control. Additionally, the welded joint of X52 pipeline steel exhibits superior corrosion resistance to that of the base material at the same temperature.

Plasmachemical Processes of Iron Corrosion in a Moist Air Medium Exposed To Ionizing Radiation of Radioactive Decay

Plasmachemical Processes of Iron Corrosion in a Moist Air Medium Exposed To Ionizing Radiation of Radioactive Decay

Molecular insights into the effect of adsorption and reaction of H2O-O2-Cl- on initial electrochemical corrosion of steel

A deeper understanding of the effect of chloride on the process of iron initial corrosion could reveal the detailed mechanism of the Cl--induced acceleration corrosion of steel. In light of the difficulty to unravel the intricacies of H2O-O2-Cl- interactions in experiments, this study conducted the molecular study on the effect of H2O, O2 and Cl- coadsorption and interactions on the electrochemical corrosion process of Fe (100) surface by DFT method, and the electron-correlation functional is GGA-PW91. It is discovered that the adsorption of H2O, O2 and Cl- all promote the electrochemical corrosion of iron. The electrochemical corrosion rate of iron surface rises as the Cl-/H2O concentration ratio increasing, while decrease with the Cl-/O2 concentration ratio increasing. The transition state search found that the presence of Cl- assists the dissociation of H2O on the iron surface, while the interaction between Cl- and O2 could be ignored. Moreover, the successive reaction of Cl-, H2O and O2 with iron surface were further investigated. When the Cl- reacts with H2O ahead of O2, the Cl- promotes the iron oxidation via promoting the dissociation of H2O. While O2 and Cl- firstly coadsorb on iron surface, Cl- accelerates iron oxidation by exacerbating the iron surface losing electrons. These findings could facilitate the development of anti-corrosion techniques for steel in chloride environment.

Epoxy nanocomposites with dual filler system: Improving surface protection against wear and thermocyclic corrosion

This investigation explores the influence of dual nanofillers - multi-walled carbon nanotubes (MWCNT) and silicon nitride nanoparticles (SiN) - on the properties of epoxy (EP). Analyses of tribological characteristics show hybrid nanocomposite of 0.25/ 0.75 wt% of SiN/MWCNT filler system improves the wear resistance by 96 % compared to EP. Raman spectroscopy reveals a novel curing mechanism induced by SiN nanoparticles when incorporated into epoxy at room temperature, while DSC thermograms show SiN's role in enhancing the crosslinking density. Creep studies indicate that EP/SiN nanocomposites at 0.5 wt% loading reduced the creep rate by 99 % compared to EP over a 10-min duration at 60 °C. Dynamic mechanical analysis (DMA) illustrates a significant increase in storage modulus and a 13 °C increment in the glass transition temperature (Tg) for 0.5 wt% EP/SiN nanocomposites. High-resolution transmission electron microscopy (HR-TEM) ascertained the homogeneous dispersion of nanofillers in hybrid nanocomposites, suggesting improved and uniform stress transfer. SiN-based composites are more effective than MWCNT-based composites in protecting mild steel from corrosion with a coating efficiency of 87 %. The potential of SiN to reduce free amine groups responsible for the corrosion process is presented, while physisorption tests are conducted to evaluate pore size and volume in the corroded samples. Field emission scanning electron microscopy (FE-SEM) is employed to analyze worn-out and corroded surfaces comprehensively. In EMI shielding, SiN reduces reflectivity without affecting the absorptive capacity of MWCNTs, making them suitable for coatings in stealth applications.

Enhancing turbine blade durability: Evaluating protective ceramic coatings for Ti6Al4V alloy

Ti64 turbine blades face extreme conditions during solid particle erosion, accelerating the erosive and corrosive processes. Hard-coating materials such as DLC, AlTiN, TiSiN, AlCrN, and AlTiCN have been introduced through physical vapor deposition to enhance the turbine blade characteristics and increase the component lifespan. The results showed preferential orientations of (002) and (022) in coating crystallization with DLC exhibiting the highest compressive residual stress. DLC and AlTiCN coatings demonstrated fewer macroparticles and white spots, correlating with a lower coefficient of friction (COF) and surface roughness. The wear analysis revealed that DLC had the lowest COF and wear rate, followed by AlTiCN. Electrochemical tests indicated DLC's superior corrosion resistance of DLC. Although the properties of AlTiCN are comparable, DLC has emerged as the most promising coating material for achieving high erosion particle resistance in Ti64 turbine blades.

Numerical investigation on chloride-induced macro-cell corrosion of steel fiber reinforced concrete

Steel corrosion is a significant deterioration issue of reinforced concrete structures in marine environments. Steel Fiber Reinforced Concrete (SFRC) is widely accepted to have better corrosion resistance than reinforced concrete (RC). Moreover, fibers in the cover inhibit corrosion of the reinforcement inside. However, the mechanism for SFRC corrosion has not been clarified yet, and the effective period of corrosion inhibition cannot be predicted. This paper proposes a space-averaged modeling method (including discrete and smeared models) for the macro-cell corrosion of SFRC. The method accurately reproduces the corrosion processes and rust distribution observed in previous pseudo-concrete experiments. Due to the chloride ion concentration difference, steel fibers dispersed in concrete solutions form a global macro-cell circuit. Thus, the corrosion of internal reinforcement is inhibited due to the cathodic protection. Additionally, using real chloride supplies in marine environments and concrete pore structures, fibers provides a more substantial corrosion inhibition duration ( > 10 years). This method can be used as a reliable reference for evaluating the corrosion of SFRC structures.

Laboratory and synchrotron x‐ray micro–computed tomography to shed light on degradation features of corroded Roman glass

AbstractThis study explores the three‐dimensional structure of Roman glass through the combined use of laboratory and phase‐contrast synchrotron x‐ray micro–computed tomography. This original approach validates a noninvasive analytical procedure designed to enhance the understanding of glass degradation mechanisms, crucial for the preservation of historical artefacts. The high‐resolution images obtained reveal the intricate internal structure and morphology of various forms of glass deterioration, including cracking, pitting, and the formation of multilayered iridescent patinas. The research provides compelling evidence of corrosion processes and interaction mechanisms with burial soil, shedding light on the chemical and physical interactions that occur over centuries. By characterizing and examining the long‐term alteration of ancient glass, this work contributes to the field of archaeometry, offering insights into how different types of glass withstand the test of time in diverse environmental conditions. The findings have important implications for conservation strategies, enabling better preservation techniques for glass artefacts.