Assessing the corrosion protection property of coatings loaded with corrosion inhibitors using the real-time atmospheric corrosion monitoring technique

The atmospheric corrosion monitoring(ACM)technique has been widely employed to track the real-time corrosion behavior of metal materials.However,limited studies have applied ACM to the corrosion protection properties of organic coatings.This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors,both applied on ACM sensors,to observe their corrosion protection properties over time.Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments,which allowed for monitoring galvanic corrosion currents in real-time.Throughout the corrosion tests,the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating.The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis.This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings.Compared with the blank epoxy coating,the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.

Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

Advancements in enhancing corrosion protection of Mg alloys:A comprehensive review on the synergistic effects of combining inhibitors with PEO coating

Magnesium(Mg)alloys are lightweight materials with excellent mechanical properties,making them attractive for various applications,including aerospace,automotive,and biomedical industries.However,the practical application of Mg alloys is limited due to their high susceptibility to corrosion.Plasma electrolytic oxidation(PEO),or micro-arc oxidation(MAO),is a coating method that boosts Mg alloys'corrosion resistance.However,despite the benefits of PEO coatings,they can still exhibit certain limitations,such as failing to maintain long-term protection as a result of their inherent porosity.To address these challenges,researchers have suggested the use of inhibitors in combination with PEO coatings on Mg alloys.Inhibitors are chemical compounds that can be incorporated into the coating or applied as a post-treatment to further boost the corrosion resistance of the PEO-coated Mg alloys.Corrosion inhibitors,whether organic or inorganic,can act by forming a protective barrier,hindering the corrosion process,or modifying the surface properties to reduce susceptibility to corrosion.Containers can be made of various materials,including polyelectrolyte shells,layered double hydroxides,polymer shells,and mesoporous inorganic materials.Encapsulating corrosion inhibitors in containers fully compatible with the coating matrix and substrate is a promising approach for their incorporation.Laboratory studies of the combination of inhibitors with PEO coatings on Mg alloys have shown promising results,demonstrating significant corrosion mitigation,extending the service life of Mg alloy components in aggressive environments,and providing self-healing properties.In general,this review presents available information on the incorporation of inhibitors with PEO coatings,which can lead to improved performance of Mg alloy components in demanding environments.

Evaluation of the Inhibitory Gel Aloe vera against Corrosion of Reinforcement Concrete in NaCl Medium

Most reinforced concrete structures in seaside locations suffer from corrosion damage to the reinforcement, limiting their durability and necessitating costly repairs. To improve their performance and durability, we have investigated in this paper Aloe vera extracts as a green corrosion inhibitor for reinforcing steel in NaCl environments. Using electrochemical methods (zero-intensity chronopotentiometry, Tafel lines and electrochemical impedance spectroscopy), this experimental work investigated the effect of these Aloe vera (AV) extracts on corrosion inhibition of concrete reinforcing bar (HA, diameter 12mm) immersed in a 0.5M NaCl solution. The results show that Aloe vera extracts have an average corrosion-inhibiting efficacy of around 86% at an optimum concentration of 20%.

In-situ construction of grass-like hybrid architecture responsible for extraordinary corrosion performance: Experimental and theoretical approach

Despite the engineering potential by the co-existence of inorganic and organic substances to protect vulnerable metallic materials from corrosive environments,both their interaction and in-situ formation mechanism to induce the nature-inspired composite remained less understood.The present work used three distinctive mercaptobenzazole(MB)compounds working as corrosion inhibitors,such as 2-mercaptobenzoxazole(MBO),2-mercaptobenzothiazole(MBT),and 2-mercaptobenzimidazole(MBI)in a bid to understand how the geometrical structure arising from O,S,and N atoms affected the interaction toward inorganic layer.MB compounds that were used here to control the corrosion kinetics would be interacted readily with the pre-existing MgO layer fabricated by plasma electrolysis.This phenomenon triggered the nucleation of the root network since MB compounds were seen to be adsorbed actively on the defective surface through the active sites in MB compound.Then,the molecule with twin donor atoms adjacent to the mercapto-sites affected the facile growth of the grass-like structures with‘uniform’distribution via molecular self-assembly,which showed better corrosion performance than those with having dissimilar donor atoms with the inhibition efficiency(η)of 97%approximately.The formation mechanism underlying nucleation and growth behavior of MB molecule was discussed concerning the theoretical calculation of density functional theory.

Synthesis of organic-inorganic 3D-nanocontainers for smart corrosion protection of friction stir welded AZ31B magnesium alloy-titanium dissimilar joints

The joining of different light metals through friction stir welding(FSW)is gaining interest as a method to decrease weight and improve fuel efficiency.However,to ensure durability,these welded metals may require surface treatments to protect against corrosion or wear.This study presents a novel approach for the simultaneous delivery of two distinct corrosion inhibitors to Ti-Mg dissimilar PEO treated joints on demand.The research focuses on the synthesis,characterization,and application of cerium@polystyrene(Ce@PS)nanocontainers,which are loaded with 8-hydroxyquinoline(8-HQ)to enhance corrosion protection.The synthesis involves several key steps,including the formation of a cerium-based outer layer around polystyrene nanospheres,the selective removal of the polystyrene core to create a porous structure,and the subsequent loading of the 8-HQ inhibitor.Structural and compositional analyses,conducted using scanning transmission electron microscopy(STEM)and energy-dispersive X-ray spectroscopy(EDS),confirmed the successful incorporation of 8-HQ within the nanocontainers.Additionally,Fourier-transform infrared spectroscopy(FTIR)provided detailed information about the chemical composition of the organic materials throughout the synthesis process.Thermal decomposition analysis verified the successful fabrication and stability of the dual-shell nanocontainers.Corrosion tests on Ti-Mg joints treated with plasma electrolytic oxidation(PEO)coatings and loaded nanocontainers demonstrated sig-nificantly improved corrosion resistance compared to untreated joints.This research highlights the potential of dual-shell nanocontainers,containing both organic and inorganic inhibitors,to offer prolonged corrosion protection,particularly against galvanic corrosion in dissimilar joints.The findings suggest that these synthesized nanocontainers hold promise for various industrial applications,particularly in the context of friction stir welded(FSW)Ti-Mg dissimilar joints,providing valuable insights for the development of advanced materials designed to mitigate corrosion.

Experimental Study of the Anti-Corrosion Performance of Montmorillonite K-10 on Rebar in HCl Environment: Application in Mortar for the Rehabilitation of Reinforced Concrete Degraded by Corrosion

This work first investigates the corrosion-inhibiting behavior of montmorillonite K-10 on reinforcing steel. The corrosion-inhibiting power of the clay (Montmorillonite) is determined in a medium HCl (C = 1N) using free corrosion potential monitoring, Tafel potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results of this study showed a satisfactory corrosion-inhibiting efficiency of around 72.665% for the optimum content of 1%. This is due to the presence of a stable oxide layer that protects the metal against corrosion. To validate the concept of montmorillonite as a corrosion inhibitor in repair mortar, we now turn to the influence of montmorillonite on the mechanical properties of mortars in the hardened state. In this part, montmorillonite K-10 is added to the mortar by partial substitution of the cement by 5% and 10% of the cement mass. The aim of this study is to ensure that the addition of this clay to the mortar composition will not have a negative effect on its compressive and flexural strengths. The results of the compression and flexural tests showed that the presence of montmorillonite in the mortar improved flexural and compressive strengths for the different compositions studied.

Experiment and numerical simulation of distribution law of waterbased corrosion inhibitor in natural gas gathering and transportation pipeline

The transmission medium of natural gas gathering and transportation pipelines usually contains cor-rosive gases,which will cause serious corrosion on the inner wall of the pipelines when they coexist with water.Therefore,it is necessary to add corrosion inhibitor to form a protective film to protect the pipeline.The distribution of corrosion inhibitors in a gathering and transportation pipeline in Moxi gas field was studied by combining experiment and simulation.The Pearson function was used to calculate the experimental and simulation results,and the correlation was more than 80%,indicating a high degree of agreement.The simulation results show that:①The larger the pipe angle,filling speed and gas flow rate,the smaller the particle size,the better the distribution of corrosion inhibitor particles in the pipe.The filling amount will affect the concentration,but the distribution trend is unchanged;②A method to determine the filling mode based on the loss was proposed,and for this pipeline,the loss of corrosion inhibitor was determined to be 5.31×10^(-3) kg/s,and the flling amount was recommended to be adjusted to 2o L/h,which has certain guiding significance for the actual flling strategy of pipeline corrosion inhibitor.

Prevention of Q235 Steel Corrosion using Waterborne Rust Inhibitor

Sorbitol,triethanolamine,sodium benzoate,boric acid,and sodium carbonate were mixed to prepare a waterborne rust inhibitor.A temperature and humidity accelerated corrosion test was applied to investigate the corrosion behaviour of waterborne rust inhibitor coated Q235 steel and original Q235 steel,which was carried out in a temperature and humidity test chamber(WSHW-1000)at a temperature of 80℃and humidity of 95%.Compared with the original Q235,waterborne rust inhibitor coated Q235 has better resistance to corrosion in hot and humid ambient conditions.Electrochemical impedance spectroscopy and potentiodynamic polarization were measured with a three-electrode cell in 3.5%NaCl aqueous solution on a CHI760E potentiostat/galvanostat.Molecular dynamics was simulated to verify the synergistic corrosion inhibitory mechanism of sodium carbonate and triethanolamine.The test shows that the prepared waterborne rust inhibitor can reduce the tendency of Q235 to corrosion and can also effectively reduce the corrosion rate.

Corrosion Inhibition of a Green Scale Inhibitor Polyepoxysuccinic Acid

The corrosion inhibition of a green scale inhibitor, polyepoxysuccinic acid (PESA) was studied based on dynamic tests. It is found that when PESA is used alone, it had good corrosion inhibition. So, PESA should be included in the category of corrosion inhibitors. It is not only a kind of green scale inhibitor, but also a green corrosion inhibitor. The synergistic effect between PESA and Zn2+ or sodium gluconate is poor. However, the synergistic effect among PESA, Zn2+ and sodium gluconate is excellent, and the corrosion inhibition efficiency for carbon steel is higher than 99%. Further study of corrosion inhibition mechanism reveals that corrosion inhibition of PESA is not affected by carboxyl group, but by the oxygen atom inserted. The existence of oxygen atom in PESA molecular structure makes it easy to form stable chelate with pentacyclic structure.

Electrochemical and analytical characterization of three corrosion inhibitors of steel in simulated concrete pore solutions

Corrosion inhibitors for steel, such as sodium phosphate （Na3PO4）, sodium nitrite （NaNO2）, and benzotriazole （BTA）, in simulated concrete pore solutions （saturated Ca（OH）2） were investigated. Corrosion behaviors of steel in different solutions were studied by means of corrosion potential （Ecorr）, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, and potentiodynamic polarization （PDP）. A field emission scanning electron microscope （FESEM） equipped with energy dispersive X-ray analysis （EDXA） was used for observing the microstructures and morphology of corrosion products of steel. The results indicate that, compared with the commonly used nitrite-based inhibitors, Na3PO4 is not a good inhibitor, while BTA may be a potentially effective inhibitor to prevent steel from corrosion in simulated concrete pore solutions.

Effectiveness of inhibitors in increasing chloride threshold value for steel corrosion

This investigation was aimed at evaluating the effectiveness of corrosion inhibitors in increasing the chloride threshold value for steel corrosion. Three types of corrosion inhibitors, calcium nitrite （Ca（NO2）2）, zinc oxide （ZnO）, and N,N＇-dimethylaminoethanol （DMEA）, which respectively represented the anodic inhibitor, cathodic inhibitor, and mixed inhibitor, were chosen. The experiment was carried out in a saturated calcium hydroxide （Ca（OH）2） solution to simulate the electrolytic environment of concrete. The inhibitors were initially mixed at different levels, and then chloride ions were gradually added into the solution in several steps. The open-circuit potential （Ecorr） and corrosion current density （lcorr） determined by electrochemical impedance spectra （EIS） were used to identify the initiation of active corrosion, thereby determining the chloride threshold value. It was found that although all the inhibitors were effective in decreasing the corrosion rate of steel reinforcement, they had a marginal effect on increasing the chloride threshold value.

The Preparation and Performance Study of a Phosphate-Free Corrosion/Scale Inhibitor

By using acrylic acid copolymer, sodium citrate, hydrolyzed polymaleic anhydride (HPMA), corrosion inhibitor D and Zn2+ synergist as raw materials, a multi-component phosphate-free corrosion and scale inhibitor was developed. The performance of the composite phosphate-free corrosion and scale inhibitor was evaluated using the rotary hanging sheet corrosion test, the static scale inhibition test and the corrosion electrochemical test. And the surface morphology of the carbon steel was observed by scanning electronic microscope (SEM). Orthogonal experiment results indicated that the optimal mass ratios of amino acid: Zn2+ synergist: HPMA: corrosion inhibitor D: acrylic acid copolymer was 0.5:10:12:1:8. It was also observed that phosphate-free corrosion and scale inhibitor based on an anodic reaction through the electrochemical corrosion experiment, its annual corrosion rate and scale inhibition rate reached 0.0176 mm·a–1 and 98.3%, respectively, showing excellent corrosion and scale inhibition performance.

Experimental Study on a New Corrosion and Scale Inhibitor

The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibition efficiency was evaluated by static anti-scaling teat together with rotary coupon test. Compared with the phosphorus corrosion and scale inhibitor, the corrosion inhibition rate and scale inhibition rate of it increased respectively by 2.51% and 1.16%. As the corrosion and scale inhibitor is phosphate-free, it won’t cause eutrophication, considering the product performance and environmental influence, the phosphate-free corrosion and scale inhibitor is superior to the traditional one.

Study on Surface Adsorption and Inhibition Behavior of Corrosion Inhibitors Contained in Copper Foil Rolling Oil

Adsorption and inhibition behavior of 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole(DMTDA) and N-((6-methyl-1H-benzo[d][1,2,3]triazol-1-yl)methyl)-N-octyloctan-1-amine(EAMBA) as corrosion inhibitors contained in copper foil rolling oil have been investigated using gravimetric and electrochemical techniques. Meanwhile, scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS) have been employed to observe the surface topography and analyze the components on copper foil. The results show that the rolling oil containing DMTDA and EAMBA can significantly decrease the dissolution rate and increase the inhibition efficiency of samples, especially in the case of best compounded rolling oil system. The SEM and EDS investigations also confirmed that the protection of the copper foil surface is achieved by strong adsorption of the molecules which can prevent copper from being corroded easily. Reactivity descriptors of the corrosion inhibitors have been calculated by the density functional theory(DFT) and the reactivity has been analyzed through the molecular orbital and Fukui indices. Active sites of inhibitor are mainly concentrated on the ring and the polar functional groups, and in the meanwhile, the distribution is helpful to form coordination and backbonding among molecules and then to form stable adsorption on the metal surface. And this work provides theoretical evidence for the selection of corrosion inhibitors contained in copper foil rolling oil.

Adsorption isotherm mechanism of amino organic compounds as mild steel corrosion inhibitors by electrochemical measurement method

The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.

Effects of Corrosion Inhibitors on Lubrication Performance of Rolling Oil for Copper Foil

The 2,5-bis（ethyldisulfanyl）-l,3,4-thiadiazole （T561）, benzotriazole （BTA）,1-N, N-bis （2-ethylhexyl） aminomethyl-4-methyl-lh-benzotriazole （IRGAMET39） and I-IN, N-bis （2-ethylhexyl） aminomethyl] methyl benzotriazole （TT- LX） have been evaluated as corrosion inhibitors used in rolling oil for cold rolling of copper foil. The MRS-10A four-ball friction and wear tests have been carried out to compare their tribological properties, and the lubricating performance of rolling oils has been studied through rolling experiments. The oil sample containing IRGAMET 39 has the same PB value as that one containing T561, with the coefficient of friction increased by 35.6% and wear scar diameter decreased by 4%. The minimum rolling gauge has been studied after rolling lubrication, but the results show that inhibitors have no effect on it. Scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS） analyses have indicated that the inhibitor is adsorbed on the copper surface to prevent copper from being corroded easily. In addition, the LEXT OLS4000 laser confocal microscopy has been used to observe the foil surface which shows that the streaks of foil surface are clear, the scratches are shallow and the surface failure is improved effectively.

Study on a Novel Composite Eco-Friendly Corrosion and Scale Inhibitor for Steel Surface in Simulated Cooling Water

The use of organophosphorus inhibitor is diminishing because of its toxic effects on aquatic and other life. In this study, a composite eco-friendly phosphate-free corrosion and scale inhibitor HS has been developed using hydrolyzed polymaleic anhydride (HPMA), sodium gluconate, Zn2+ synergist and sulfamic acid. And the formula ratio of each component is 9:5:4:2. The performance of the corrosion and scale inhibitor was evaluated by weight loss experiment and the static scale inhibition test, respectively. The results indicated that HS had positive corrosion and scale inhibition effect at a dosage of 40 mg.L–1 or higher. Potentiodynamic polarization curves indicated that HS inhibits the corrosion of steel based on controlling the anodic reaction. And the surface morphology of the carbon steel was studied by scan-ning electronic microscope (SEM). The inhibition effects were due to the formation of protective films.

A time-saving method to assess the efficiency of corrosion inhibitors by electro osmosis

The corrosion inhibitor is one of the most important technologies to enhance the durability of steel-reinforced concrete. A kind of time-saving method was developed to assess the inhibitor efficiency by using a 32 V electric field to accelerate chloride ion migration in concrete. Potentiodynamic polarization scanning test was used to evaluate the corrosion states. The comprehensive efficiency of an inhibitor should be assessed in two aspects： resistance to chloride ion permeability and inhibiting efficiency. The specimens with different mixing amount of sodium nitrite and migration corrosion inhibitors were used to verify the accuracy and reliability of this method. The results show the differences in inhibiting efficiency of the inhibitors clearly, indicating the reliability of this time-saving method.

Experimental and computational chemical studies on the cationic furanylnicotinamidines as novel corrosion inhibitors in aqueous solutions

The corrosion inhibition action of three newly synthesized furanylnicotinamidine derivatives namely: 6-[5-{4(dimethylamino)phenyl}furan-2-yl]nicotinamidine(MA-1256), 6-[5-(4-chlorophenyl)furan-2-yl]nicotinamidine(MA-1266), and 6-[5-{4-(dimethylamino)phenyl}furan-2-yl]nicotinonitrile(MA-1250) on carbon steel(C-steel) was investigated in 1.0 mol·L-1 HCl solution by weight loss(WL), potentiodynamic polarization(PP), electrochemical impedance spectroscopy(EIS), and electrochemical frequency modulation(EFM)techniques. Morphological analysis was performed on the uninhibited and inhibited C-steel using atomic force microscope(AFM) and Infrared Spectroscopy(ATR-IR) methods. The effect of temperature was studied and discussed. Inspection of experimental results revealed that the inhibition efficiency(IE) increases with the incremental addition of inhibitors and with elevating the temperature of the acid media. The adsorption of furanylnicotinamidine derivatives on C-steel follows Temkin’s isotherm. PP studies indicated that the investigated compounds act as mixed-type inhibitors and showed that p-dimethylaminophenyl furanylnicotinamidine derivative(MA-1256) was the most efficient inhibitor among the other studied derivatives with IE reached(95%)at 21 × 10-6 mol·L-1. MA-1266 is highly soluble in aqueous solution and has non-toxicity profile with LC50 N 37 mg·L-1. Thus, MA-1266 can be a promising green corrosion inhibitor candidate with IE N 91% at 21× 10-6 mol·L-1. The experiments were coupled with computational chemical theories such as quantum chemical and molecular dynamic methods. The experimental results were in good agreement with the computational outputs.