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In this study, we report an eco-friendly and facile process for the synthesis of biochar, BC, and a cobalt-biochar nanocomposite, Co-BC, using rice straw biomass. We constructed two superhydrophobic coatings on steel substrates using potentiostatic electrodeposition of nickel-modified biochar, Ni@BC, and nickel modified by cobalt-biochar nanocomposite, Ni@Co-BC, then, these coatings were soaked in an ethanolic stearic acid solution. Fourier transform infrared spectroscopy showed that the stearic acid-grafted Ni@BC coating, Ni@BC@SA, and the stearic acid-grafted Ni@Co-BC composite, Ni@Co-BC@SA, were well grafted on the steel surface. Scanning electron microscopy revealed that the superhydrophobic coatings have nanoscale features. Atomic force microscopy results showed that the Ni@Co-BC@SA coat had higher roughness than Ni@BC@SA, resulting in higher superhydrophobicity. The water contact angles for Ni@BC@SA and Ni@Co-BC@SA coatings were 161° and 165°, respectively, while the values of water sliding angles for both coatings were 3.0° and 1.0°, respectively. Quantitative estimation of the scale inhibition efficiency revealed that the Ni@Co-BC@SA coating exhibited greater efficiency compared to the Ni@BC@SA coating. Additionally, the Ni@Co-BC@SA coating demonstrated improved corrosion resistance, UV resistance, mechanical abrasion resistance, and chemical stability compared to the Ni@BC@SA coating. These results highlight the superior performance of the Ni@Co-BC@SA coating and its potential as a highly effective and durable superhydrophobic coating for steel substrates. [ABSTRACT FROM AUTHOR]

Mathematical modelling and software simulation nowadays are very effective tools for both understanding and predicting corrosion processes and the protection of metallic components. COMSOL Multiphysics 5.6 software provides validated mathematical models that can be used, for a given geometry, as a tool to predict and prevent corrosion of components. The corrosion of zinc-coated steel sheets has been studied in this work by comparing results of the simulations with laboratory tests carried out in a salt spray. Results of both the mathematical modelling and empirical tests give the possibility to estimate the stability of the protective zinc layer over time. The examination of the discrepancies between two analytical methods for the investigation of corrosion phenomena leads to possible modifications in the model in order to reach as much as possible coherence with experimental data. As a final result, a computational model of corrosion phenomena in an automotive component has been reached, allowing in the future to partially substitute laboratory tests, usually being highly time consuming and expensive. [ABSTRACT FROM AUTHOR]

In the chloride-rich environment, reinforced concrete (RC) structures may suffer from different types of non-uniform rebar corrosion (NURC). The effect of different types of non-uniform rebar corrosion on the cyclic behavior of RC beams under axial load has been studied here by experimental and numerical study. The structural behavior of three RC beams with the same dimensions and reinforcement configuration was examined under reversed cyclic loading. Two RC beams were subjected to different types of non-uniform rebar corrosion, and another beam was used as a sound specimen. The specimens were subjected to an axial load equivalent to 5% of the axial capacity. The obtained results revealed that cross-sectional non-uniformity leads to a notable difference in the yield strength, maximum strength, and stiffness in the positive and negative loading cycles. Nevertheless, interestingly the presence of corrosion pit did not affect the ductility of the RC beams. To predict the structural response of RC beams with different kinds of non-uniform corrosion and axial load, a numerical model was developed by extending the author's previous numerical model for RC beams. Thereafter, the numerical model was verified with the results obtained from the experiment. The obtained results revealed that the axial loading improves the displacement capacity and load-carrying capacity of the non-uniformly corroded RC beams significantly. Finally, a parametric study was carried out to examine the effect of different crucial factors on the cyclic behavior of RC beams subjected to various non-uniform corrosion and axial load. [ABSTRACT FROM AUTHOR]

This work evaluates the anticorrosion behavior of a new epoxy resin, i.e., Triglycidyl Ether Ethylamine (TGEEA) for C38 steel in 1.0 M HCl was explored via performing both the modeling and experimental evaluations. According to the electrochemical data, the TGEEA at a concentration of 5 mM is characterized by a high protection effectiveness reaching a maximum of 95.09% at 293 K. Further, the results of the potentiodynamic polarization showed that TGEEA functions as a mixed-type inhibitor, and its adsorption procedure followed the Langmuir isotherm type. In addition, TGEEA exhibits high inhibitory efficiency over a wide temperature range between 293 and 323 K. Regarding the morphological examination of the surface (SEM/EDX), it was demonstrated that the corrosion barrier is created by the TGEEA material adhering to the C38 steel/1.0 M HCl interface. Finally, the theoretical approach (i.e., Density Functional Theory, Molecular Dynamics, and Monte Carlo) established an association between the TGEEA molecular structure and its anti-corrosive capacity. Theoretical investigations and experimental findings are well-concordant. [ABSTRACT FROM AUTHOR]

In the production of shale gas, solid particles such as gravel and clay can adhere to the pipe wall surface and generate under-deposit corrosion (UDC). Meanwhile, the adhesion of sulfate reducing bacteria (SRB) film can further aggravate the local corrosion problem, which would easily result in the failure of pipe lines. Therefore, understanding the corrosion of the steels when SRB film and deposit layer are co-existed is of highly significance. In this work, UDC in SRB-containing shale gas flowback water was studied by means of wire beam electrode, scanning electron microscope, energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that SRB can adhere to bare steel to form biofilm and then corrosion occurs. For deposit-covered steel, SRB cannot directly contact the metal matrix due to the barrier effect of the artificial deposit layer, therefore no SRB corrosion was observed. Bare steel and deposit-covered steel can form a galvanic couple, where the deposit-covered steel serves as the anode and the bare steel as the cathode. However, SRB could accelerate the corrosion of bare steel and enhance the cathodic reaction, thus promoting the anodic reaction under the deposit-covered steel. [ABSTRACT FROM AUTHOR]

Available chlorine is known to play a significant role in metal corrosion due to its oxidising properties. In this paper, the effect of available chlorine concentration on corrosion behaviour of the low alloy marine steel was investigated by electrochemical and immersion tests. Experimental results show that the corrosion rate of low alloy marine steel is accelerated with the increase of available chlorine concentration in seawater. The localised electrochemical dissolution of the steel is more active with the concentration of available chlorine increasing. Energy dispersive spectroscopy (EDS) was performed to understand the composition of the corrosion products that the large enrichment of Cl element occurred for the high available chlorine concentration (100 ppm) after 720 h exposure to seawater. The influence of available chlorine concentration on mechanical property of low alloy marine steel indicatesthe less impact on the tensile and yield strength of the low alloy marine steel. [ABSTRACT FROM AUTHOR]

The study investigates the anticorrosion potentials of Zingiber officinale (ZO) on mild steel induced in 1.0 M HCl and 0.5 M H2SO4 acid solution respectively using structural characterization (gas chromatography-mass spectroscopy, GC-MS and Fourier transform infrared spectroscopy, FTIR) and electrochemical (electrochemical impedance spectroscopy, EIS and potentiodynamic polarization, PDP) techniques respectively and theoretical simulations. The structural characterization was performed to identify chemical constituents and functional groups present in the plant extract whereas electrochemical techniques and theoretical computations were used to examine the anticorrosion potentials of the extract and validate the experimental results. The GC-MS result revealed the presence of twenty-three (23) compounds within the extract and out of which three (1-(1,5-dimethyl-4-hexenyl)-4-methyl-, dodecanoic acid and 9-Octadecenoic acid (Z)-2-hydroxy-1-(hydroxymethyl)ethyl ester) were selected for computational simulation and the results of FTIR revealed the presence of the following functional groups (O-H, C=C, C=O, C-C and C-H) in the ZO extract. The results of EIS revealed that extract of ZO exhibited corrosion inhibition efficieny of 82.7% and 93.6 % for mild steel in 1 M HCl and 0.5 M H2SO4 solution respectively at maximum inhibitor concentration of 1000 mg/L for mild steel. Also, PDP results revealed that ZO extract functioned as mixed inhibitor because both the anodic and cathodic reaction process was altered. The quantum chemical calculation results revealed that 9- Octadecenoic acid (Z)-2-hydroxy-1-(hydroxymethyl) ethyl ester had a good energy gap (ΔE) compared to other two compounds, indicating its better adsorption interaction with the metal surface in sulfuric acid environment. This was further confirmed by its good adsorption energy of -355.55 Kcal/mol with mild steel surface in H2SO4 environment compared with -167.81Kcal/mol in HCl environment from the molecular dynamic simulation. [ABSTRACT FROM AUTHOR]

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As one of the most common forms of corrosion in the marine environment, pitting corrosion can have a detrimental impact on the ultimate strength of steel columns. Pitting pits are usually covered by corrosion products, and the detection of pitting is very difficult, so how to effectively identify random pitting corrosion on steel columns has become a very vital issue. In this paper, a deep-learning-based pitting damage determination method for steel columns is investigated by combining numerical simulation and theoretical analysis, which was validated by experimental results. First, a multi-parameter localized pitting corrosion model was proposed that considered the pitting corrosion randomness in time and space distribution. Second, the relationship between the ultimate strength and corrosion rate of steel columns was analyzed. Finally, a steel column damage determination framework was constructed based on the convolutional neural network. Results showed that the ultimate strength and corrosion rate developed different trends in various corrosion regions, and a damage determination accuracy of 90.2% could be achieved by the neural network after training, which satisfied the practical engineering requirements. This study lays the groundwork for further application of deep learning to the research on the pitting damage to steel structures. [ABSTRACT FROM AUTHOR]

Corrosion prevention studies show a predominant trend in the recent era. Especially mild steel material was used in many industrial sectors because it has specific properties like malleability and ductility. Corrosion inhibition action of a novel synthesized N-(1,3-benzothiazol-2-yl)-2-[4-furan-2-carbonyl)piperazin-2-yl]acetamide (1,3BFCPA) compound was performed on MS-mild steel material in 1 N HCl and 1 N H2SO4 medium. Using the mass loss data, the inhibitor efficiency has been evaluated on both the acidic and alkaline mediums. The inhibitor shows a maximum inhibitor efficiency on both acidic mediums, but when comparing 1N sulfuric acid, it shows a better efficiency of 90%. Based on surface coverage analysis (q) from mass loss data, adsorption isotherms were interpreted to fit the behavior of the inhibitor over the surface of MS material, which shows a Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

Materials decay naturally through a process called corrosion in which they react with their surroundings. It is possible to prevent mild steel from corroding in hydrochloric acid (HCl) by applying a variety of corrosion inhibitors. In this work, the novel mononuclear manganese coordination complex [Mn(Hbpz)2(NCS)2] showed promising properties that make it suitable for corrosion prevention applications. In this experiment, different experimental methods were used to evaluate its inhibitory potential. For example, weight loss (WL) showed a 96% reduction in corrosion rate at higher concentrations. EIS was evidence that the concentration effect increases Rct and reduces Cdl. Moreover, the polarization examination demonstrated that C3 is a mixed-type inhibitor. In addition, quantum mechanical and statistical methods were also used, and the effect of temperature was also determined. Besides, thermodynamic equations were used and calculated. The adsorption follows the Langmuir isothermal model and the simulation method confirmed the spontaneous adsorption nature of the complex, which improves the surface characterization results. [ABSTRACT FROM AUTHOR]

AlCrSiN coatings are promising protective candidates for cutting and forming tools. During the coating deposition process, the microstructure and properties of the coatings were dramatically affected by bias voltages. To further optimize and enhance the AlCrSiN coating, a series of coatings were deposited at different pulse bias voltages using arc ion plating technology. By virtue of scanning electron microscopy, X-ray diffraction, scratch method, OCP, EIS, and other analytical methods, the effects of the pulse bias voltage on the crystal structure, microstructure, and mechanical, tribological, and electrochemical properties of the AlCrSiN coatings were analyzed. The study revealed that the pulse bias voltage exerted a slight influence on the aluminum and nitrogen content of the coatings. As the pulse bias voltage increased, the hardness, critical load, and tribological performance of the AlCrSiN coatings first increased gradually, and then were impaired slightly. When the pulse bias voltage was −100 V, the resulting AlCrSiN coating exhibited the densest structure, the highest hardness, the strongest adhesion, and the best wear resistance. In this case, the coating hardness and critical load reached 2668 HV and 72.7 N, respectively. The friction coefficient and wear rate were 0.35 and 1.02 × 10−3 μm3/N·μm, respectively. Simultaneously, the AlCrSiN coating demonstrated exceptional corrosion resistance in 3.5 wt.% NaCl solutions, surpassing uncoated 304 steel by 3~4 times. [ABSTRACT FROM AUTHOR]

Stainless steel is one of the most commonly used structural materials in industry for the transportation of liquids such as water, acids, and organic compounds. Corrosion is a major concern in industry due to the use of strong mineral acids, feedstock contamination, flow, aqueous environments, and high temperatures. Stainless steel is the most commonly used material in the petrochemical industry because of its characteristics of self-protectiveness, offered by thin passive oxides, and its metallurgical composition. However, chlorides and mineral acids attack the stainless steel continuously, consequently breaking down the passivation film, causing a continuous challenge from corrosion. The corrosion in stainless steel is influenced by many factors including flow rate, temperature, pressure, ethanol concentration, and chloride ion content. This review describes the impact of organic compounds and organic acids on the degradation behavior of stainless steel. The review also summarizes the commonly used organic compounds and their applications. It has been demonstrated that organic acid concentration, temperature, and halide impurities have significant effects on susceptibility to pitting corrosion by damaging the passivation film. The phenomenon of corrosion in stainless steel is quite different in immersion tests and electrochemical potentiodynamic polarization. This review article discusses the importance of organic compounds and their corrosion behavior on steel. The article also puts emphasis on the roles of corrosion inhibitors, monitoring methods, corrosion management, and forms of corrosion. [ABSTRACT FROM AUTHOR]

The atmospheric corrosion of high-strength steels can lead to hydrogen absorption directly linked to hydrogen embrittlement or delayed fracture phenomena. A scanning Kelvin probe (SKP) and electrochemical permeation technique (EPT) were applied to correlate the potential of an oxidized surface with the flux of hydrogen across a thin steel membrane. The side of the membrane opposite the corroding or electrochemically charged area was analyzed. The potential drop in the oxide was calibrated in terms of surface hydrogen activity, and SKP can be applied in situ for the mapping of hydrogen distribution in the corroding metal. A very low flux of hydrogen can be characterized and quantified by SKP, which is typically observed under atmospheric corrosion conditions. Therefore, hydrogen localization that drives steel durability under atmospheric corrosion conditions can be evaluated. [ABSTRACT FROM AUTHOR]

The paper focuses on the experimental investigation and mathematical modeling of the corrosion of steel when a film of water flows over its surface. The experimental monitoring of corrosion dynamics in the flowing film was carried out using a laboratory pilot model, exploited in such a way as to obtain data necessary to identify some characteristic parameters of the mathematical model of this problem. The mathematical model of the case takes into account the transfer of oxygen through the liquid film flowing on the surface of the corroding plate where the chemical surface processes characteristic of corrosion occur (dissolution of Fe, oxidation of Fe2+ to Fe3+, formation of surface deposit, etc.). Experimental measurements were used to identify the parameters of the mathematical model, especially the reaction constant of the Fe dissolution rate and the surface oxidation yield of Fe2+ to Fe3+. Calculation of the correlation coefficients for the apparent constant surface reaction rate and process factors showed that they correlate strongly and non-linearly with the Reynolds number (Re) of the film flow, with the cumulative flow duration, and with the cumulative standby time of the experiments. Using the dynamics of the resistance to the transfer of oxygen through the rust film and the dynamics of its thickness resulting from the specific flow of rust deposition, the apparent oxygen diffusion coefficient through the rust film formed on the plate was expressed. [ABSTRACT FROM AUTHOR]

Composite coatings prepared by mixing 5 wt.% polyaniline with commercial alkyd-based paints were applied on carbon steel. The polyaniline emeraldine chloride salt was prepared by procedure recommended by IUPAC, including deprotonation by ammonia hydroxide, and reprotonation with sulfamic, succinic, citric, and acetic acids with different doping degrees or oxidation states. The steel samples with base and composite coatings were immersed in 3% NaCl and the corrosion current density was determined after 96 h in situ using the ASTM 1,10-phenanthroline method. The samples were also inspected by optical microscopy. It was shown that the composite coatings reduced the possibility of blister formations and delamination. The corrosion current density and the appearance of the corrosion products, whose area was determined by ImageJ software, closely followed the initial oxidation state of the polyaniline. It was also shown that damaged composite coatings with higher degrees of oxidized (doped) polyaniline were more prone to formation of corrosion products. The role of the initial state of the polyaniline is discussed. It is suggested that such behavior could be connected to the oxygen reduction reaction mechanism that proceeds mainly via two electron paths on the polyaniline particles, releasing a much smaller amount of hydroxyl ions, which is responsible for the delamination and blister formation of the commercial coatings. [ABSTRACT FROM AUTHOR]

This study investigates effect of heat treatment on fatigue and corrosion fatigue resistance of 17-4PH stainless steel at two thermal cycles, which consisted of 30 min solution annealing at 1050 C and 240 min ageing at 620 C as an overaged thermal cycle, and heat treatment at 464 C for 129 min as an optimized aged thermal cycle. Microstructural characteristics, tensile and hardness properties, corrosion performance, Hydrogen permeation, fatigue and corrosion fatigue resistance of these samples were then compared. Results showed that corrosion resistance and fatigue resistance of aged 17-4PH stainless steel was superior. Despite this, the corrosion fatigue resistance of the heat-treated steels was a function of applied loads and their exposure time to the corrosive environment. In fact, for the lower applied loads/longer exposure times, the overaged steel with higher corrosion rate, and less susceptibility to hydrogen damage had better corrosion fatigue performance, than the aged 17-4PH stainless steel. [ABSTRACT FROM AUTHOR]

Steel is an indispensable material in the modern construction industry. The economic loss and safety threats caused by steel corrosion are very serious each year. Some traditional measures, such as surface coating and corrosion inhibitors, have been implemented to mitigate steel degradation. These methods are typically environmentally unfriendly and uneconomical. Therefore, a novel, promising and "green" approach was investigated in this study for the protection of steel corrosion through the formation of organic-inorganic hybrid biofilms composed of calcite minerals and microbial extracellular polymeric substances in the presence of the biomineralized bacterium Paenibacillus. The surface morphologies and electrochemical tests revealed that the hybrid biofilm was dense and compact, providing a strong protective barrier for the steel. In addition, the mechanism by which bacteria inhibited steel corrosion was discussed carefully in this study. Hence, this study introduces a new perspective and an alternative for inhibiting steel corrosion. [ABSTRACT FROM AUTHOR]

In this paper, the corrosion performance of galvanized steel was investigated in a simulated marine environment, under UV irradiation coupling with an alternating wet and dry cycle in a NaCl solution. The surface morphology, composition, and corrosion performance of galvanized steel before and after different alternating wet and dry corrosion under UV irradiation were investigated. The results show that the corrosion current density gradually increases and the corrosion resistance decreases as a function of the alternating wet and dry corrosion cycles. Meanwhile, UV irradiation accelerates the increase in the corrosion current density and the decrease in the corrosion resistance. In addition, the corrosion product ZnO shows a semiconductor property, and the photo-induced electrons and holes produced under UV can participate in the corrosion reaction and promote the formation of loose corrosion products Zn(OH)2, Zn5(OH)8Cl2, and Al2Cl3(OH)5·4H2O, thus accelerating the corrosion of galvanized steel in the atmosphere environment. [ABSTRACT FROM AUTHOR]

The purpose of this research is to characterize and evaluate the corrosion behavior of zinc coatings used for corrosion protection, with a special focus on the S235 steel material. The introduction highlights the need for corrosion protection in industrial settings, as well as the importance of understanding corrosion processes and the development of corrosion products to develop more effective solutions. The study's goals are to undertake an extensive analysis of corrosion products formed on the zinc coating's surface, to evaluate the performance of these coatings under atmospheric circumstances, and to investigate the effect of deposition parameters on coating quality. The essential message provided to readers is the critical significance of knowing corrosion product formation mechanisms and zinc coating corrosion behavior in developing long-lasting and effective protection measures. The study methodology includes cycle testing, morphological and chemical examination of corrosion products, as well as optical and electron microscopy and energy-dispersive spectroscopy. Corrosion resistance is assessed using accurate measurements. The results show that zinc coatings have exceptional corrosion resistance under air settings, with the produced corrosion products offering further protection to the underlying material. Furthermore, the study demonstrates that the surface roughness of S235 steel has a substantial impact on the quality and corrosion behavior of hot-dip galvanized coatings. The findings emphasize the necessity of detailed characterization of corrosion products, the effect of depositional factors on zinc coating performance, and the need for novel corrosion protection methods. These discoveries have significant implications for the corrosion protection sector, providing the potential to improve the longevity and efficiency of protective systems used in industrial applications. [ABSTRACT FROM AUTHOR]

Laser cladding technology is a surface modification technology emerging in recent years, and it is widely used in the marine engineering field. Since the structural steels used in marine engineering are mostly carbon steels, their wear resistance and corrosion resistance are poor. In this paper, 316 L stainless steel/TiC composite coatings with different Y2O3 addition amounts were fabricated on Q355B steel surface using the laser cladding technology, and the phase composition, microstructure, microhardness, wear resistance, and corrosion resistance of the coatings were investigated with an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a digital microhardness tester, a friction and wear tester, and an electrochemical workstation. When Y2O3 is added, the crystals in the bottom part of the coating are basically broken and the organisation becomes more dense. When the Y2O3 addition amount is 2%, the hardness is highest, the frictional coefficient curve of the coating exhibits a stable descending trend, and the coating mass loss is the lowest. When Y2O3 is added at 1%, the dynamic potential polarisation curve shows high corrosion potential and low corrosion current density and exhibited the best performance in EIS. The added Y2O3 evidently improves the wear resistance and corrosion resistance of 316 L stainless steel/TiC composite coatings, and this provides a new possibility that a composite coating modified with rare earth oxide is used for repair of marine engineering structures. [ABSTRACT FROM AUTHOR]

Hot galvanization on steel surfaces can isolate the steel from corrosive environments and alleviate the stress corrosion cracking caused by the anodic dissolution mechanism. However, the cathodic protection potential of the coating is excessively negative, which may aggravate the hydrogen embrittlement problem. The effect of a coating on the stress corrosion performance of bridge cable wire was studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), a thermal desorption analysis (TDA), an electrochemical workstation, and an FIP test. The results show that hot-dip ZnAl and ZnAlMg alloy coatings can significantly prolong the stress corrosion fracture time of steel wire substrates. From a macroscopic perspective, the stress corrosion cracking fracture is a brittle fracture caused by hydrogen embrittlement. Moreover, the coating type has little effect on the fracture morphology of bridge cable wire. In NH4SCN solution (50 °C, 20 wt.%), a corrosion product layer composed of ZnS and Al2O3 was formed on the surface of the coated steel wire. The electrochemical analysis showed that the corrosion resistance of the ZnAlMg coating was better than that of the ZnAl coating, which was the main reason for the improvement of the stress corrosion performance. [ABSTRACT FROM AUTHOR]

In order to achieve the goal of green and sustainable development, solid waste of sludge, straw and steel slag were used as raw materials for the preparation of in-situ magnetic activated carbon (MAC) by chemical activation and co-pyrolysis, and was then used to remove methylene blue (MB). The MAC with the highest specific surface area (359 m²/g) was obtained at 750°C, and the in-situ magnetization was achieved by reducing the iron oxides in steel slag to Fe3O4 and Fe0, resulting in a saturated magnetization of 8.69 emu/g, this allowed for easy separation using a magnet. Batch adsorption of MB onto MAC was studied, indicating the removal efficiency of methylene blue was higher than 95% under room temperature at pH = 8 while the dosage of MAC was 1 g/L. Adsorption kinetic and isotherm studies indicated the adsorption of methylene blue onto MAC involved multilayer physisorption with intraparticle diffusion and chemisorption as the ratelimiting steps. The maximum calculated adsorption capacity of MB was 283 mg/g; thermodynamic analysis showed the adsorption was spontaneous and endothermic. The adsorption mechanism of methylene blue onto MAC involved electrostatic attraction, formation of hydrogen bonds and the interaction of π electron system. [ABSTRACT FROM AUTHOR]

An appropriate hybrid form of steel and fiber-reinforced polymer (FRP) bars in reinforced concrete members can prevent steel corrosion and ensure capacity and ductility. To investigate the impact resistance of concrete beams reinforced with hybrid steel and basalt FRP (BFRP) bars, a three-dimensional numerical model was developed that takes into account the strain-rate strengthening effect. The validity of the numerical model was first verified. Subsequently, drop hammer impacts were simulated on 10 concrete beams reinforced with hybrid steel–BFRP bars to determine the influence of the BFRP bar proportion and position on their impact resistance. The results indicated that the level of concrete damage in the hybrid bar–RC beams is between those of the concrete beams with steel bars and concrete beams with BFRP bars. As the proportion of BFRP bars increased from 0 to 1, the peak impact force and internal force of the beams linearly decreased by 20%, the reaction force linearly declined by 50%, while the peak midspan displacement linearly increased by 20%. Except for the midspan deflection, the comparable degree of damage among beams with four different bar configurations indicates the equivalent impact resistance of the beams. The change in the frequency of the hybrid bar–RC beams before and after impact loading can reflect their impact resistance. [ABSTRACT FROM AUTHOR]

The well-known limitations of modal system identification methods have led to a broad exploration of alternative solutions for operational monitoring and damage diagnosis of structures. This study presents a time-domain Bayesian finite element model updating approach to jointly identify the vehicular loads and finite element modeling parameters of bridges using the vibration data and the location of vehicles traversing the bridge as input. A Bayesian model updating is devised and verified through a series of case studies based on numerically simulated data from a prestressed reinforced concrete box-girder bridge model. Damage states are defined for concrete degradation and delamination, steel corrosion, and loss of prestressing force. Ten different damage scenarios, encompassing the range from minor localized to major distributed damage, are examined. The responses of the damaged bridge are simulated under random traffic scenarios. The acceleration responses, along with the location of the vehicles on the bridge, are used for jointly estimating the model parameters and vehicular loads. The estimated model parameters are then used to infer the location and extent of damage within the bridge. The results show the successful performance of the proposed approach in a numerically simulated environment. [ABSTRACT FROM AUTHOR]

One application of organic compounds is to utilize them as corrosion inhibitors in acidic environments to diminish steel corrosion. These inhibitors do not show very good inhibition properties in saline (NaCl) environments. There have been many studies on boosting these inhibitors' performance in such environments (especially Cl− containing media). One of the ways that have been proposed is the use of organic and inorganic inhibitors, simultaneously. The synergistic effect of these inhibitors has shown promising results in reducing steel corrosion. In this study, cerium(III) nitrate and tri-sodium phosphate (TSP) was used as organic and inorganic inhibitors to control the corrosion of steel in a 3.5 wt.% NaCl environment. The corrosion measurements were conducted in the 3.5 wt.% NaCl environment by EIS and polarization methods. Surface studies were done by SEM, Raman, GIXRD, and EDS methods. Corrosion studies (EIS and polarization) have revealed that when 500 ppm of Ce(NO3)3 and 500 ppm of TSP are added to the 3.5 wt.% NaCl medium, the highest synergism index (1.27) and inhibition efficiency (73.7%) are achieved. Also, by adding 500Ce-500TPS to the solution, icorr and Rct of steel decreased by about 80% and increased approximately 4-fold, respectively. This improvement in the steel performance against corrosion in the presence of an equal ratio of Ce(NO3)3 and TSP is the outcome of the formation of a hydrophobic dense film (consisting of Ce(OH)3, Ce/Fe-phosphate complexes) on the metal surface. This claim has been proven by SEM/EDS, contact angel, FT-IR, and XRD analysis. [ABSTRACT FROM AUTHOR]

Evaluating the physical degradation behavior and estimating the lifetime of engineering systems and structures is crucial to ensure their safe and reliable operation. However, measuring lifetime through actual operating conditions can be a difficult and slow process. While valuable and quick in measuring lifetimes, accelerated life testing is often oversimplified and does not provide accurate simulations of the exact operating environment. This paper proposes a data-driven framework for time-efficient modeling of field degradation using sensor measurements from short-term actual operating conditions degradation tests. The framework consists of two neural networks: a physics discovery neural network and a predictive neural network. The former models the underlying physics of degradation, while the latter makes probabilistic predictions for degradation intensity. The physics discovery neural network guides the predictive neural network for better life estimations. The proposed framework addresses two main challenges associated with applying neural networks for lifetime estimation: incorporating the underlying physics of degradation and requirements for extensive training data. This paper demonstrates the effectiveness of the proposed approach through a case study of atmospheric corrosion of steel test samples in a marine environment. The results show the proposed framework's effectiveness, where the mean absolute error of the predictions is lower by up to 76% compared to a standard neural network. By employing the proposed data-driven framework for lifetime prediction, systems safety and reliability can be evaluated efficiently, and maintenance activities can be optimized. [ABSTRACT FROM AUTHOR]

To investigate the flexural behavioural characteristics of recycled concrete beams under the combined action of steel corrosion and static pre-loading, 12 recycled concrete beam specimens, encompassing a combination of three recycled coarse aggregate (RCA) replacement ratios (0, 50 and 100%) and four static pre-load levels expressed as ratio of the ultimate moment capacity (0, 0.2, 0.4 and 0.6), were prepared for accelerated corrosion test and four-point bending test. The test results indicated that under a given RCA replacement ratio of the beams, the maximum width of corrosion-induced longitudinal cracks exhibited a linear relationship with the corresponding corrosion depth of longitudinal tension reinforcement. For the beams with 50% RCA replacement ratio, when the applied static pre-load level increased from 0 to 0.6, the ultimate load and ultimate deflection reduced by 10.4% and 21.2%, respectively, whereas for the beams with 100% RCA replacement ratio, the corresponding reduction in ultimate load and ultimate deflection were respectively 8.9% and 35.5%. Theoretical degradation models for the ultimate moment capacity and yield moment capacity of corroded beams were proposed, whereby the analytical values were in good agreement with the experimental values. This study provides useful reference for practical analysis of recycled concrete beams, which promote sustainable concrete construction. [ABSTRACT FROM AUTHOR]

Through our present study, three novel Gemini-fluorinated cationic surfactants bearing different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity of the as-prepared surfactants was examined. The inhibiting influence of FSG6 molecules on the X60 steel corrosion in the pickling solution (HCl) was examined by diverse methods comprising electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and X-ray photoelectron spectroscopy (XPS) experimentations, and computational calculations. The inhibition effectiveness of FSG6 surfactants followed the order of 93.37% (FSG6-2) < 96.74% (FSG6-4) < 98.37% (FSG6-6) at 2.0 × 10−4 M. The FSG6 surfactants function as mixed-type inhibitors, according to PDP investigations. The H2O molecules that adsorbed on the steel interface were substituted with surfactant molecules, and the surfactant's inhibitory activity is likely caused by the improvement in an adsorptive layer on the steel substrate, as specified by the EIS results. The Langmuir isotherm describes the absorption of FSG6 molecules on the metal surface. The XPS investigations validate the steel interface's extremely protective nature. The mechanism of interaction between FSG6 molecules with an X60-steel employing the DFT calculations and MC simulations methods was also examined and discussed. [ABSTRACT FROM AUTHOR]

Reinforcing steel (RS) is mainly used in building construction and many industries, but it suffers from corrosion problems, especially in acidic environments. Biopolymers are characterized by their unique chemical composition, as they contain a variety of functional groups that are capable of binding strongly to the metal surface and forming a protective layer on it. Herewith, two biopolymers, viz. dextrin (Dex) and inulin (Inu), were tested as eco-friendly inhibitors for the corrosion of RS in 1.0 M HCl medium at different temperatures. Various experimental tools were utilized in this research. The inhibition efficiencies (% IEs) of the tested polymeric compounds were improved by increasing their doses while reducing with rising temperature. The % IEs of Dex and Inu at a dose of 500 mg/L reached 85% and 93%, respectively. The examined biopolymers displayed cathodic/anodic behavior (mixed type) with a foremost anodic one. The acquired higher % IEs were demonstrated by intense adsorption of Dex and Inu on the RS surface fitting the Langmuir isotherm. The influence of rising temperature in the range of 288–318 K on the corrosion behavior was examined, and the evaluated thermodynamic and kinetic parameters sustained the mechanism of physical adsorption of the polymeric inhibitors. Additionally, the kinetics of corrosion, as well as its inhibition by Dex and Inu, were also investigated. The SEM micrographs of the RS surfaces were accorded with all utilized experimental tools. The results gained from all used tools were discovered to be in good agreement with each other. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel GO-Ti 3 C 2 T x nanohybrid was synthesized. • GO-Ti 3 C 2 T x strongly improved adhesion strength of epoxy coating. • GO-Ti 3 C 2 T x endowed epoxy coating with active anti-corrosion property. MXene flakes shows the great potential in corrosion protection area owing to their lamellar structure and remarkable mechanical features. However, these flakes are highly susceptible to oxidation, which results in their structure degradation and restrict their application in anti-corrosion field. Herein, graphene oxide (GO) was used to functionalize Ti 3 C 2 T x MXene through Ti O C bonding to fabricate GO-Ti 3 C 2 T x nanosheets, which proved by Raman, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR). GO-Ti 3 C 2 T x nanosheet inclusion into the epoxy coating and their corrosion performance in 3.5 wt.% NaCl solution with 5 MPa pressure was evaluated through electrochemical techniques including open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) along with salt spray. Results indicated that GO-Ti 3 C 2 T x /EP presented superior anti-corrosion capability, the impedance modulus at low frequency (|Z| 0.01 Hz) was above 108 Ω cm2 after 8 days' immersion in 5 MPa environment, which was 2 orders of magnitude higher than that of the pure epoxy coating. Scanning electron microscope (SEM) and salt spray images demonstrated that the epoxy coating loaded with GO-Ti 3 C 2 T x nanosheet could provide robust corrosion protection for Q235 steel via the physical barrier effect. [ABSTRACT FROM AUTHOR]

In this work, SiO2 nanoparticles-based corrosion-resistant superhydrophobic coating for mild steel has been developed. A wire electrical discharge machine (EDM) was used to cut micro-patterned mild steel followed by chemical etching via Piranha solution. The etched metal was coated with triethoxyoctylsilane-modified SiO2 nanoparticles via the solution method to generate the hierarchical micro-nano roughness with low surface energy. The developed coating exhibited micro-nano hierarchical roughness due to SiO2 nanoparticles and their clusters, verified by atomic force microscope (AFM) and field-emission scanning electron microscope (FESEM) analysis. The maximum water contact angle (CA) of 153 ± 2° with a sliding angle (SA) of 5 ± 2° was obtained for the coated mild steel. The electrochemical impedance spectroscopy (EIS) plots confirmed the noteworthy corrosion resistance performance of coated metal over the uncoated one. Thus, the modified SiO2 nanoparticles-based superhydrophobic coating could be a good option for inhibiting the corrosion of mild steel. [ABSTRACT FROM AUTHOR]

Corrosion has caused significant annual costs for building construction and civil architectural designs. In this study, Monosodium glutamate (GLU) was proposed as a potential candidate for long-lasting corrosion inhibition to slow down the rate of corrosion in the concrete pore environment. In this regard, the electrochemical and morphological properties of the various GLU concentrated systems between 1 to 5 wt% in the simulated concrete pore solution media were investigated. According to the EIS results, adding 4 wt% of GLU could reduce the mild steel corrosion process by 86% through a mixed inhibition mechanism. Also, the polarization records represented that the samples' corrosion current density was diminished to 0.169 µA cm−2 after the addition of 4 wt% GLU into the harsh environment. Using the FE-SEM method, the growth of the GLU layer over the metal substrate was demonstrated. The results of spectroscopic methods, i.e., Raman and GIXRD, demonstrated that GLU molecules were successfully adsorbed over the surface of the metal. Contact angle test outcomes showed that by increasing the GLU concentration to its optimum level (4 wt%), the surface hydrophobicity was dramatically raised to 62°. [ABSTRACT FROM AUTHOR]

In this work, six groups of non-toxic compounds were tested as inhibitors for mild steel in 1 M HCl solution: glycine (Gly), glutamic acid (Glu), cysteine (Cys), a mixture of three amino acids glycine, glutamic acid, and cysteine (Gly + Glu + Cys); a mixture of dipeptide composed of glycine and glutamic acid with amino acid cysteine (Gly-Glu + Cys); and a tripeptide composed of glycine, cysteine and glutamic acid which is called glutathione (Glt). The inhibition performances of inhibitor systems for steel corrosion were investigated by electrochemical tests (polarization measurements and electrochemical impedance spectroscopy) and surface analyses (atomic force microscopy-AFM, optical microscope, and photoelectron spectroscopy-XPS). Experimental results showed that all six groups of inhibitors affect the reduction of steel corrosion rate, with Glt having the highest efficiency during 4-h immersion (97.3%). Atomic force microscopy and optical microscope showed that the inhibitors are able to protect the metal surface and reduce the extent of corrosion. The existence of the Glt inhibitory film on the steel surface was confirmed by the XPS method. DFT calculations provided useful insights into adsorption of the corrosion inhibitors. [ABSTRACT FROM AUTHOR]

Corrosion protection efficiency of gum exudates of Astragalus genus (AG) on mild steel surface in 1N HCl medium was investigated using potentiodynamic polarization and electrochemical impedance spectroscopic measurements. The results show that AG acts as an effective green inhibitor for mild steel corrosion in 1N HCl and their inhibition efficiency increases with increasing concentration. Tafel's measurements showed that AG behaves as a mixed-type inhibitor with a predominant cathodic character. The impedance parameters confirm that AG is adsorbed in the form of a protective film on the mild steel surface. The DFT theory at the B3LYP/6-31G (d) basis set level was also performed for the identification of active constituents of AG to investigate the correlation between their molecular structure and corrosion protection efficiency. [ABSTRACT FROM AUTHOR]

The corrosion of 10Cr18Ni10Ti and 10Cr17Ni13Mo2Ti austenitic constructional steels in 5% hydrochloric acid containing an inhibitor based on aqueous extracts of aspen (ABE), spruce (SBE), and pine (PBE) bark was studied by gravimetric and electrochemical methods. Such solutions are used for washing and chemical cleaning of cooking and heat-exchange equipment. The influence of temperature and composition of inhibitors on the process was examined. New data on the kinetics of the acid corrosion of the steels were obtained and analyzed. At equal concentration of 1 g L–1, the inhibiting effect of water-extractable substances (WESs) of wood bark on the acid corrosion of steels increases in the order PBE < SBE < ABE. The inhibiting effect also increases with an increase in the WES concentration to 3.8 g L–1 and in the temperature from 20 to 50°С, on mixing extracts of different kinds of bark, and to a still greater extent on introducing a synergistic agent, hexamethylenetetramine or potassium iodide, into the extracts. [ABSTRACT FROM AUTHOR]

The 2.3-diaryl-4.5-dihydro-imidazo[1.2-a]quinolinium-3 bromides were tested as biocides and inhibitors of microbial corrosion of low-carbon steel induced by bacteria of Desulfovibrio sp. M-4.1 strain. The degree of metal protection against corrosion induced by sulfate-reducing Desulfovibrio sp. M-4.1 bacteria was 84.6–92.4%. 2-(para-tolyl)-3-(41-methoxyphenyl)-4.5-dihydro-imidazo[1.2-a]quinolinium bromide demonstrated the best protective effect. It was established that sulphate-reducing bacteria of Desulfovibrio sp. M-4.1 strain were sensitive to 2.3-diaryl-4.5-dihydro-imidazo[1.2-a]quinolinium-3 bromides. Under the influence of imidazoquinolinium quaternary salts, the inhibition zones of bacterial growth have the diameters of 24.7–45.5 mm. Quaternary salts of imidazoquinolinium completely suppress the growth of sulfate-reducing Desulfovibrio sp. M-4.1 bacteria in plankton and significantly influence the formation of biofilm (the number of cells decreases by 6–8 orders compared to the control sample) under conditions of microbial corrosion. Suppression of the sulfate-reducing activity of Desulfovibrio sp. M-4.1 bacteria by quaternary salts of imidazoquinolinium (by 88.8–91.6%) was proven. The effectiveness of the quaternary salts was discussed with the account of molecular descriptors. [ABSTRACT FROM AUTHOR]

Hyperbaric oxygen-accelerated corrosion testing (HOACT) is a newly developed method to study in the labor the corrosion behavior of steel bars in concrete. This work aimed to intensively investigate the mechanical properties and microstructures of HOACT-generated corrosion products by means of nano-indentation tests, Raman micro-spectrometry, and scanning electron microscopy. The local elastic modulus and nanohardness varied over wide ranges of 6.8–75.2 GPa and 0.38–4.44 GPa, respectively. Goethite, lepidocrocite, maghemite, magnetite, and akageneite phases were identified in the corrosion products. Most regions of the rust layer were composed of a complex and heterogeneous mix of different phases, while some regions were composed of maghemite or akageneite only. The relationship between the micromechanical properties and typical microstructural features is finally discussed at the micro-scale level. It was found that the porosity of corrosion products can significantly influence their micromechanical properties. [ABSTRACT FROM AUTHOR]

Q235 steel components have poor corrosion resistance and are susceptible to erosion by corrosive media, so they are generally passivated before being put into service. This paper investigates the corrosion behaviour and corrosion mechanism of passivated Q235 steel in atmospheric environments through macro and micro morphological characterisation and electrochemical simulation analysis. [ABSTRACT FROM AUTHOR]

Marine reinforced concrete structures have a significant risk of corrosion, and embedded sacrificial anodes can provide effective protection for the steel bars. In order to reveal the protection law and practical application effect of sacrificial anodes and to guide their engineering application, a systematic application research has been conducted. The performance requirements of embedded sacrificial anodes are analyzed and summarized, and laboratory and field tests with self -made sacrificial anodes as the research object were conducted. Laboratory simulation tests reveals the protection law of sacrificial anode in marine reinforced concrete and clarifies its protection parameters. At the same time, based on the obtained protection parameters, field application tests were carried out to verify its application effect under actual working conditions. The results show that the embedded sacrificial anode has good working performance and can provide effective protection for marine reinforced concrete structures. The sacrificial anode protection parameters are suitable for field application scenarios. [ABSTRACT FROM AUTHOR]

Theoretical aspects of low-carbon steel corrosion in H3PO4 solutions containing FePO4 are considered. In the system under study, reactions of iron with the acid solution and Fe(III) salt are thermodynamically allowed. The oxidizing power of this medium, characterized by the Fe(III)/Fe(II) couple redox potential, is mainly determined by its anionic composition. Phosphate anions of a corrosive medium bind Fe(III) cations into complex compounds, reducing their oxidizing ability. In H3PO4 solutions containing FePO4 and Fe3(PO4)2, the dependence of the system's redox potential on the Fe(III) and Fe(II) cation relative content is poorly described by the Nernst equation, which is due to the nonequivalent complex formation of these cations with phosphate anions. Analysis of the effect of the studied media convection on the low-carbon steel electrode reactions allowed revealing some of their features. In a FePO4-containing H3PO4 solution, kinetically controlled partial reactions of iron anodic ionization and H+ cathodic reduction, as well as diffusion-controlled Fe(III) cation cathodic reduction, occur on the steel. The FePO4 accelerating effect on the steel corrosion in H3PO4 solution is due only to the Fe(III) reduction but does not affect the H+ reduction and the iron ionization. The value of the Fe(III)-cation diffusion coefficient in the studied corrosive medium was experimentally determined from the data of cyclic voltammetry of the Pt electrode therein and the results of the studying of the cathodic reaction of a steel disk electrode at different rotation velocities. The data on the low-carbon steel corrosion in the flow of the studied media, obtained from the metal samples mass loss, are in full agreement with the results of the study of the electrode partial reactions. An accelerating effect of FePO4 on the steel corrosion in H3PO4 solutions is observed. In this environment, steel corrosion is determined by the convective factor, which is typical of processes with diffusion control. The empirical dependence of the steel corrosion rate on the medium flow intensity is described by the linear dependence k = kst + λw1/2, where kst is the steel corrosion rate in a static medium, w is the rotation velocity of the propeller stirrer that creates the medium flow, λ is the empirical coefficient. [ABSTRACT FROM AUTHOR]

The corrosion behaviour of coated stainless steel as bipolar plate material in PEM fuel cell applications and its improvement through the surface modifications was investigated. A commercial SS316L stainless steel grade was deposited with thin multi-layer coatings, consisting of a carbon top layer and a chromium interlayer of two different thicknesses. Interfacial contact resistance measurements revealed that the applied Cr/C coatings are highly conductive and surpass the ICR criteria, suggested by the U.S. Department of Energy. Corrosion resistance was thoroughly analysed by potentiodynamic polarisation and cyclic voltammetry in 0.5 M H 2 SO 4 at room temperature and 80 °C, respectively, combined with numerical modelling. Electrochemical results agree well with numerical modelling, including the dissolution of metallic species, local pH-shifts and changes of electrolyte conductivity. Furthermore, the study shows that the application of a Cr/C coating significantly reduces the current density in the passive region during potentiodynamic polarisation and lowering the corrosion rate of the steel substrate by at least a factor of two. [ABSTRACT FROM AUTHOR]

The fungal biomass of cocoa bean shell (FBCS) obtained by solid-state fermentation (SSF) with Penicillium roqueforti was used as a natural corrosion inhibitor of carbon steel in an acidic solution with 0.5 mol.L−1 HCl. The evaluation of the corrosive process was carried out using gravimetric, electrochemical, and surface analysis techniques. The gravimetric test data were used to calculate the corrosion rate, current density, and efficiency. Electrochemical measurements provided the polarization curves and the electrochemical impedance spectroscopy (EIS). Finally, the surface analysis was performed using an optical microscope. From Tafel's extrapolation, the largest deviation was noticed at 69.9 mV, confirming that FBCS acted as a partially cathodic inhibitor. Inhibitor molecules were physically adsorbed on the carbon steel surface and the adsorption mechanism followed the Langmuir isotherm model. The results of the EIS confirmed the gravimetric results. FBCS inhibited the acid corrosion of carbon steel AISI 1008 at a concentration range from 0.44 g.L−1 to 1.77 g.L−1, and the higher the concentration, the higher the inhibition rate. The maximum corrosion inhibition efficiency was 93%. The EIS by time results showed that the FBCS should not be applied for very long periods of immersion in the electrolyte. The maximum inhibition efficiency was verified within 12 hours of immersion (95.96%). Therefore, this study encourages the use of FBCS as inhibitor due to good inhibit efficiency and to be environmental friendly, as well as the use of others news materials, such as biomass resulting from the fermentation of other residues, proposed in an unprecedented way in this work. [ABSTRACT FROM AUTHOR]

The periodic immersion corrosion behavior and corrosion mechanism of Q420qNH steel weld, heat‐affected zone and plate sample in simulated industrial atmospheric medium were studied. The corrosion type of the three samples is the non‐uniform total corrosion, and the corrosion products at different stages are different. Ferric oxide and lepidocrocite (γ‐FeOOH) are generated in the immersion stage and the initial stage of infrared drying, respectively. However, lepidocrocite (γ‐FeOOH), ferrosoferric oxide (Fe3O4) and goethite (α‐FeOOH) generated in the later stage of infrared drying. The infrared drying process is conducive to the formation of goethite (α‐FeOOH). The corrosion rate of weld is always lower than that of plate, and the Iα‐FeOOH/Iγ‐FeOOH ratio of the weld is always higher than that of plate and heat‐affected zone sample. In the later stage of corrosion, the self‐corrosion current density of the three samples from small to large is weld, heat‐affected zone and plate, and self‐corrosion potential from large to small is weld, heat‐affected zone and plate. The resistance of the rust layer of the weld and heat‐affected zone sample is 1.81 times, 1.29 times of that of the plate, respectively. This is because the weld is composed of a large number of small angular grain boundary structures dominated by tiny acicular ferrite in the original austenite grain, which is conducive to the improvement of corrosion resistance. In addition, the higher chromium/carbon (Cr/C), copper and nickel elements of the weld can promote the conversion from lepidocrocite (γ‐FeOOH) to goethite (α‐FeOOH), and improve the density and stability of weld rust layer. [ABSTRACT FROM AUTHOR]

Purpose: The poor corrosion resistance of the ferrite-pearlite steel limits its application in marine engineering because of the enhanced galvanic effect caused by continuously accumulated cementite. Cr as one principal alloying element is commonly used to improve the corrosion resistance of steels. This paper aims to study the effect of Cr on corrosion behaviors of ferrite-pearlite steels in an acidic environment. Design/methodology/approach: The tested steels were immersed in a simulated solution of 10 Wt.% NaCl with pH 0.85 for 72 h to evaluate the corrosion rate. After the immersion test, the corrosion morphologies and products were tested by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. Meanwhile, an electrochemical workstation was used to study the electrochemical behaviors of samples. Findings: At the initial corrosion stage, the corrosion rate increased in the sequence of Cr0, Cr0.5 and Cr1 steels, which was because of the competitive effect between the area ratio and the driving force caused by alloyed Cr. However, Cr1 steel exhibited the best corrosion resistance after a 72-h immersion test. This was because the alloyed Cr promoted the formation of protective Fe2O3 and FeCr2O4, which suppressed the preferential dissolution of ferrite and, thus, reduced the accumulation rate of carbides, resulting in the weakened galvanic corrosion. Originality/value: This paper reports the role that Cr plays in the galvanic corrosion of ferrite-pearlite steels, which is important for the engineering application of ferrite-pearlite steels in marine environment. [ABSTRACT FROM AUTHOR]

Alkali‐activated materials (AAMs) are binders that can complement and partially substitute the current use of conventional cement. However, the present knowledge about how AAMs protect steel reinforcement in concrete elements is incomplete, and uncertainties exist regarding the application of electrochemical methods to investigate this issue. The present review by EFC WP11‐Task Force 'Corrosion of steel in alkali‐activated materials' demonstrates that important differences exist between AAMs and Portland cement, and between different classes of AAMs, which are mainly caused by differing pore solution compositions, and which affect the outcomes of electrochemical measurements. The high sulfide concentrations in blast furnace slag‐based AAMs lead to distinct anodic polarisation curves, unusually low open circuit potentials, and low polarisation resistances, which might be incorrectly interpreted as indicating active corrosion of steel reinforcement. No systematic study of the influence of the steel–concrete interface on the susceptibility of steel to corrosion in AAMs is available. Less common electrochemical methods present an opportunity for future progress in the field. [ABSTRACT FROM AUTHOR]

Alkali‐activated materials (AAMs) are considered a promising alternative to materials made from ordinary Portland cement (OPC). Other than considering the durability of the material itself, the use of AAMs for reinforced concrete elements also raises the question of steel corrosion processes in these materials, which are still relatively unknown. Three different alkali‐activated mortars were prepared for this study, based on either fly ash, slag, or metakaolin. Pore solutions were then extracted from each mortar and chemically analyzed. Electrochemical techniques were used to study the corrosion of steel in synthetic pore solutions containing varying concentrations of chlorides. In parallel, the same corrosion tests were performed in a generic pore solution representing OPC mortar. It was shown that the chemical composition differed in each pore solution tested, thus affecting the corrosion properties of the steel. The addition of chloride also had a varying effect on the corrosion properties of the steel in each type of pore solution tested. This study provided a basic overview of the corrosion behavior and mechanisms of the various AAM environments in comparison to that of OPC. [ABSTRACT FROM AUTHOR]

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Oxygen-reducing air flooding is a low-permeability reservoir recovery technology with safety and low-cost advantages. However, in the process of air injection and drive, carbon in the air is oxidized through the crude oil reservoir to generate CO2, and this can cause serious corrosion in the recovery well. In this study, experiments on the corrosion of J55 tubular steel in a fluid environment with coexisting O2 and CO2 in an autoclave are presented. In particular, a weight loss method and a 3D morphometer were used to determine the average and the local corrosion rate. The corrosion surface morphology and composition were also measured by means of scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The corrosion pattern and morphological characteristics of J55 steel were analyzed in the O2/CO2 environment for different degrees of oxygen-reduction. As made evident by the experimental results, the corrosion products were mainly ferrous carbonate and iron oxide. In general, air injection increases the degree of oxygen reduction, from oxygen corrosion characteristics to CO2 corrosion-based characteristics. As a result, the corrosion product film becomes denser, and the corrosion rate is lower. [ABSTRACT FROM AUTHOR]

The corrosion inhibition of metals in seawater can be achieved by the addition of inhibitors to the system that prevent corrosion from taking place on the metal surface. The effect of ascorbic acid on carbone steel corrosion in seawater were investigated by means of different techniques: gravimetric method, electrochemical polarization and electrochemical impedance spectroscopy and the scanning electron microscopy (SEM). The results obtained show that the acid ascorbic effectively inhibits the corrosion of steel X60. The optimal inhibitory efficiency is obtained at a concentration of 0.05 g/L of the inhibitor, with a maximum value of 77%. This inhibitor presents a mixed inhibition character. SEM studies confirm the absence of the deterioration products on the surface of the specimens. [ABSTRACT FROM AUTHOR]