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.

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.

Calcium titanate corrosion inhibitor enabling carbon as inert anode for oxygen evolution in molten chlorides

The corrosion inhibition efficacy of titanate(CaTiO_(3))for carbon anodes in molten salts was investigated through various analytical techniques,including linear sweep voltammetry,X-ray diffraction,scanning electron microscopy,and energy dispersion spectroscopy.The results demonstrate that the addition of CaTiO_(3)corrosion inhibitor efficiently passivates the carbon anode and leads to the formation of a dense CaTiO_(3)layer during the electrolysis process in molten CaCl_(2)-CaO.Subsequently,the passivated carbon anode effectively undergoes the oxygen evolution reaction,with an optimal current density for passivation identified at 400 m A/cm~2.Comprehensive investigations,including CaTiO_(3)solubility tests in molten CaCl_(2)-CaO and numerical modeling of the stability of complex ionic structures,provide compelling evidence supporting“complexation-precipitation”passivation mechanism.This mechanism involves the initial formation of a complex containing TiO_(2)·nCaO by CaTiO_(3)and CaO,which subsequently decomposes to yield CaTiO_(3),firmly coating the surface of the carbon anode.In practical applications,the integration of CaTiO_(3)corrosion inhibitor with the carbon anode leads to the successful preparation of the FeCoNiCrMn high-entropy alloy without carbon contamination in the molten CaCl_(2)-Ca O.

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.

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.

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 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.

Orange Peel Extract Mediated Silver Nanofluid as Corrosion Inhibitor for X80 Steel in Simulated Oilfield Scale Dissolver

Silver nanofluid was prepared by bio-reduction reaction between orange peels extracts(OPE)and silver nitrate and characterized by spectroscopic and microscopic techniques.Colloidal nanoparticles of sizes between 40-50 nm and spherical shape were obtained.The nanofluid was applied as anticorrosion additive to inhibit corrosion of X80 steel in simulated oilfield scale dissolver solution(1.0 M HCl)at various temperatures.The nanofluid(OPE-AgNPs)was 98.9% and 84.3% efficient at 30℃ and 60 ℃ respectively as determined by weight loss measurement.In comparison with OPE,OPE-AgNPs shows better corrosion inhibition and higher resistance to thermal degradation.Some kinetic and thermodynamic models were used to characterize the inhibition process.OPE-AgNPs could be optimized and used as alternative anticorrosion additive for scale dissolution liquor in the industry.

5-methyl-1H-benzotriazole as potential corrosion inhibitor for electrochemical-mechanical planarization of copper

According to the electrochemical analysis, the corrosion inhibition efficiency of 5-methyl-lH-benzotriazole （m-BTA） is higher than that of benzotrizaole （BTA）. The inhibition capability of the m-BTA passive film formed in hydroxyethylidenediphosphonic acid （HEDP） electrolyte containing both m-BTA and chloride ions is superior to that formed in m-BTA-alone electrolyte, even at a high anodic potential. The results of electrical impedance spectroscopy, nano-scratch experiments and energy dispersive analysis of X-ray （EDAX） indicate that the enhancement of m-BTA inhibition capability may be due to the increasing thickness of passive film. Furthermore, X-ray photoelectron spectrometry （XPS） analysis indicates that the increase in passive film thickness can be attributed to the incorporation of C1 into the m-BTA passive film and the formation of [Cu（I）CI（rn-BTA）], polymer film on Cu surface. Therefore, the introduction of C1- into m-BTA-containing HEDP electrolyte is effective to enhance the passivation capability of m-BTA passive film, thus extending the operating potential window.

Effects of chitosan inhibitor on the electrochemical corrosion behavior of 2205 duplex stainless steel

The effects of chitosan inhibitor on the corrosion behavior of 2205 duplex stainless steel were studied by electrochemical measurements, immersion tests, and stereology microscopy. The influences of immersion time, temperature, and chitosan concentration on the corrosion inhibition performance of chitosan were investigated. The optimum parameters of water-soluble chitosan on the corrosion inhibition performance of 2205 duplex stainless steel were also determined. The water-soluble chitosan showed excellent corrosion inhibition performance on the 2205 duplex stainless steel. Polarization curves demonstrated that chitosan acted as a mixed-type inhibitor. When the stainless steel specimen was immersed in the 0.2 g/L chitosan solution for 4 h, a dense and uniform adsorption film covered the sample surface and the inhibition efficiency(IE) reached its maximum value. Moreover, temperature was found to strongly influence the corrosion inhibition of chitosan; the inhibition efficiency gradually decreased with increasing temperature. The 2205 duplex stainless steel specimen immersed in 0.4 g/L water-soluble chitosan at 30°C displayed the best corrosion inhibition among the investigated specimens. Moreover, chitosan decreased the corrosion rate of the 2205 duplex stainless steel in an FeCl_3 solution.

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.

Wear Resistance of CO_2 Corrosion Product Scale Formed at High Temperature

To investigate the correlation between structure characteristics and wear resistance of CO2 corrosion product scales at high temperature and high pressure, an autoclave was used to prepare CO2 corrosion product scales on N80 steel in carbon dioxide corrosion environment. The correlation between wear resistance of the scales and many other factors, such as temperature, pressure, morphology, structure, velocity of fluid medium, sand grain size, and so on, was comparatively analyzed by a self assembled wear device, and the scale morphologies before or after being worn were observed by scanning electron microscope （SEM）. And then the surface grain size and thickness of scale were measured. The results showed that the cross-section of the corrosion scale was of a double-layer structure, the outer layer of which was composed of regular crystals, whereas the inner layer was a thin scale of fine grains. The outer grain size and thickness of scale varied with temperature, and the initial wear loss was consistent with the surface grain size; at the same time, the total wear loss corresponded to the thickness of scale. Compared to wear resist- ance in different depths of the scale, it was found that the structure of scale was a double-layer structure in cross-section, and the wear resistance of inner layer was better than that of the outer layer; the closer the scale to the matrix, the greater was the wear resistance of scale; and the larger the size or the higher the rotary speed of solid grain in multiphase flowing medium, the more was the wear loss of scale.

Active corrosion protection of super-hydrophobic corrosion inhibitor intercalated Mg-Al layered double hydroxide coating on AZ31 magnesium alloy

Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.

Preparation and characterization of a chitosan-based low-pH-sensitive intelligent corrosion inhibitor

A chitosan （CS）-based low-pH-sensitive intelligent corrosion inhibitor was prepared by loading a pH-sensitive hydrogel with benzotriazole （BTA）; the pH-sensitive hydrogel was synthetized by crosslinking CS with glutaraldehyde （GTA）. Analysis by Fou- tier-transform inflared （FT-IR） spectroscopy showed that Schiff reactions occurred between amino and aldehyde groups. The swelling abil- ity of the hydrogel was investigated using a mass method, and it was observed to swell more in an acidic environment than in an alkaline en- vironment. The hydrogel＇s loading capacity of BTA was approximately 0.377 g·g ^-1, and its release speed was faster in an acidic environment than in an alkaline environment because of its swelling behavior. The corrosion inhibition ability of the intelligent inhibitor was tested by immersion and electrochemical methods. The results showed that after 4 h of immersion, the polarization resistance （Rp） value of copper with the intelligent inhibitor was approximately twice of that of copper with BTA, indicating that the intelligent inhibitor could effectively prevent copper from corroding.

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.