Enhanced corrosion inhibition behavior of carbon steel in aqueous solution by Phosphoserine-Zn2+ system

The corrosion inhibition effect of carbon steel in aqueous solution was using a synergistic mixture of an environmentally friendly inhibitor system phosphoserine (PS) and Zn²⁺ using gravimetric studies, potentiodynamic polarization, and electrochemical impedance studies. Potentiodynamic polarization studies showed that the inhibitor system is a mixed type inhibitor. Electrochemical impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous solution. X-ray photoelectron spectroscopic analysis of the protective film exhibited the presence of the elements viz., iron, phosphorus, nitrogen, oxygen, carbon, and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron, Zn(OH)₂, and [Fe(II)/(III)-Zn(II)-PS] complex. Further, the surface examination techniques viz., FTIR, SEM, and AFM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on the results obtained, a suitable mechanism of corrosion inhibition is presented.     

Modification of 1018 carbon steel corrosion process in alkaline sour medium with a formulation of chemical corrosion inhibitors

This work is focused on researching corrosion mechanism modifications of 1018 carbon steel in alkaline sour medium (0.1 M (NH₄)₂S and 10 ppm CN⁻) using inhibitor formulation (IHF) composed of hydroxyoleic imidazoline (C₁₂H₄₂ON₂), HI, and aminoether (C₂₀H₂₈O₃N₂), AE. The accelerated formation of corrosion products was thereby carried out in the presence of the formulation alone and of each of its components separately; these films were subsequently characterized by electrochemical impedance spectroscopy and scanning electron microscopy. The study in the presence of the IHF components revealed that the films formed have different nature, because their physical and chemical properties such as thickness, porosity and (electronic and ionic) conductivity are determined by the media where they are grown. The film formed in the presence of HI has a homogeneous, non-porous topography that impairs the diffusion process of H⁰, in addition, its electronic conductivity is above that observed in the film formed with AE. Then, it was determined that the film formed with IHF presents some distinctive component characteristics which interact in a complementary way improving film passivity.     

4-氨基苯甲酸席夫碱自组装缓蚀膜对20#钢在饱和CO2油田水中的缓蚀性能

利用邻氧乙酸苯甲醛缩4-氨基苯甲酸钾盐席夫碱(K₂L1)缓蚀剂在20#碳钢表面制备了自组装单分子膜(SAMs),通过电化学方法研究了缓蚀剂的合成条件、自组装时间等因素对成膜的影响,结果表明,合成中KOH与邻氧乙酸苯甲醛按2:1摩尔比进行反应得到的K₂L1缓蚀剂在碳钢表面自组装3 h后,可以形成稳定、致密的缓蚀膜。缓蚀性能的研究表明,碳钢表面K₂L1-SAMS抑制了碳钢的阴极还原过程,改变了电极表面双电层结构,具有良好的缓蚀效果(最高缓蚀效率可达95%以上),交流阻抗和极化曲线得到的结论是一致的。同时研究表明K₂L1的吸附行为符合Langmuir吸附等温式,吸附机理是典型的化学吸附。量子化学计算结果表明,K₂L1分子具有多个吸附活性中心,这些活性原子的前线轨道能与碳钢表面铁原子的前线轨道相互作用,因而使得K₂L1分子在碳钢表面形成吸附膜,阻止了碳钢在饱和CO₂油田水介质中的溶解。X射线光电子能谱(XPS)分析表明,K₂L1通过配位键在碳钢表面形成了稳定的缓蚀膜。     

Passivity and passivity breakdown of 304 stainless steel in alkaline sodium sulphate solutions

The passivity and passivity breakdown of 304 stainless steel were investigated in 0.25 M Na₂SO₄solutions of pH 10. The effect of applied potential and the presence of Cl^– ions in the electrolyte were also studied. Different electrochemical methods such as open circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. The results showed that the steel electrode passivates under open circuit conditions and also under potentiostatic control. The rate of passive film thickening under open circuit conditions follows a simple logarithmic law. Addition of Cl^– ion shifts the polarization curves in the active direction and above a critical chloride concentration, [Cl^– ] 0.15 M, pitting corrosion occurs and the pitting potential, E _pit, decreases linearly with the logarithm of [Cl^–]. The addition of sulphate ions to the chloride-containing solutions was found to inhibit the pitting process, and at [SO^2- ₄] 0.25 M, a complete immunity to pitting corrosion was recorded. The impedance measurements provided support for film thickening and film breakdown reactions. An equivalent circuit model which consists of a pure resistor, R , in series with a parallel combination of a pure resistor, R _p, and a constant phase element, Q, was proposed to describe the electrode/electrolyte interface. The passive film thickness was found to increase with applied potential up to a critical value of 0.3 V. At higher voltages, breakdown of the passive film occured.     

Influence of fluid flow on the performance of polyethylene glycol as a green corrosion inhibitor

Abstract

The corrosion behavior of steel in 0.5?M H₂SO₄ solution in the presence of polyethylene glycol (PEG 6000) as a green corrosion inhibitor was investigated under well-defined hydrodynamic conditions simulated by a steel rotating disk electrode with the rotation speeds of 250–5000?rpm. The results obtained from electrochemical impedance spectroscopy and potentiodynamic polarization measurements demonstrated the better protection of steel at higher concentrations of the polymer. Additionally, the corrosion inhibition experienced a dramatic reduction in going from hydrostatic to hydrodynamic conditions. This was indicated by corrosion resistance (R_corr), which reduced from 162 Ω cm² at the stagnant condition to 65.7 Ω cm² at the dynamic state with a flow rate of just 250?rpm in the presence of 5?g L^?1 PEG. This observation was a consequence of the transportation of corrosion products from the metal surface toward the bulk in fluid flow conditions, leading to a restriction in the formation of an adhesive protection layer on the steel surface.     

Comparative study of corrosion inhibition by three anionic surfactants in an acidic environment

Corrosion in carbon steel units of chemical, petrochemical and oil and gas plants poses safety and economic concerns. The goal of our study is to investigate the corrosion inhibition effectiveness of an environmentally benign surfactant, namely sodium lauroyl lactylate (SLL), in comparison to sodium cocoyl glutamate (SCG) and sodium dodecyl sulfate (SDS). The corrosion of carbon steel in 1 M HCl was markedly inhibited by 0.05 and 0.1 M of the anionic surfactant SLL, as determined from weight loss over 96 h, at ambient conditions. X-ray photoelectron spectroscopy (XPS) showed that SLL adsorbed at the carbon steel surface, forming a protective film that decreased corrosion. Scanning electron microscopy (SEM) showed that carbon steel surfaces immersed in 1 M HCl for 96 h had an etched appearance without SLL, whereas they retained their smoothness with 0.1 M SLL. Electrochemical impedance spectroscopy (EIS) measurements confirmed that SLL passivated carbon steel surfaces, markedly increasing the polarization resistance R_p from ≈95 to ≈20,694 Ω cm² over a 12 h period. In contrast, without SLL, R_p decreased from ≈92 to ≈12 Ω cm². These results demonstrate for the first time that the environmentally friendly surfactant SLL is an efficient corrosion inhibitor in extreme environments such as 1 M HCl solutions. Dissimilar to SLL, SCG and SDS were not effective in inhibiting corrosion.     

Underscale corrosion behavior of carbon steel in a NaCl solution using a new occluded cavity cell for simulation

A new occluded corrosion cavity (OCC) simulation cell was designed to study the underscale corrosion behavior of carbon steel (N80) in 0.2 mol L⁻¹ NaCl solution. The chemical components of the solution in the OCC were measured and the electrochemical behavior of the occluded anode and the bulk cathode were studied by electrochemical impedance spectroscopy (EIS). The newly designed OCC cell can easily simulate the auto-catalyzing acidification process and may be used to study the mechanism of underscale corrosion. The corrosion scale exacerbates the underscale corrosion and the area ratio of the bulk cathode to the occluded anode (R = S_c/S_a) determines the development of simulated localized corrosion in the OCC cell. When R was within a certain range, the corrosion rate in the OCC could be kept at a persistently high level. The pH of the solution in the OCC decreased and the chloride ions (Cl⁻) concentrated as the local corrosion developed. The anodic process on the occluded anode was controlled by irreversible charge transfer and the cathodic process on the bulk cathode was controlled mainly by oxygen diffusion.     

The Oil from Mentha rotundifolia as Green Inhibitor of Carbon Steel Corrosion in Hydrochloric Acid

The corrosion inhibition potentials of Mentha rotundifolia oil on carbon steel in 1 M HCl was studied at different concentrations via gravimetric, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Polarization curves reveal that Mentha rotundifolia oil is a mixed-type inhibitor. Changes in impedance parameters (charge transfer resistance R_t, and double-layer capacitance C_dl) were indicative of adsorption of Mentha rotundifolia on the metal surface, leading to the formation of a protective film. The effect of the temperature on the corrosion behavior with addition of the optimal concentration of Mentha rotundifolia oil was studied in the temperature range 308 and 338 K. Adsorption of oil on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Attempts to explain the inhibitory action were carried out using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Quantum chemical parameters most relevant to its potential action as corrosion inhibitor such as E_HOMO (highest occupied molecular orbital energy), E_LUMO (lowest unoccupied molecular orbital energy), energy gap (ΔE), and Mulliken charges have been calculated and discussed. The theoretical results were found to be consistent with the experimental data.     

Electrochemical study on the effect of bipyridine dicarboxylic acid and its cobalt complex on the corrosion behaviour of carbon steel in acidic medium

The 2,2′-bipyridine-3,3′-dicarboxylic acid (bida) and its cobalt complex (Co-bida) were tested as corrosion inhibitors for N80 carbon steel in sulphuric acid solution by electrochemical polarization and electrochemical impedance spectroscopy method. The results indicate that the complex and ligand inhibit the corrosion of mild steel in H₂SO₄ solutions and the extent of inhibition increases with inhibitor concentration and decreases with temperature. The inhibition efficiency of the inhibitors follows the trend Co-bida > bida. A mixed-inhibition mechanism is proposed for the inhibitive effects of the compounds. The adsorption characteristics of the inhibitors were approximated by Temkin isotherm. Morphological study of the carbon steel electrode surface was undertaken by scanning electron microscope and the interfacial species formed on the surface in the presence of inhibitors analyzed by infrared spectroscopy.     

Electrochemically grown passive films on carbon steel (SAE 1018) in alkaline sour medium

Corrosion films were prepared by applying cyclic potential pulses to the 1018 carbon steel-sour medium interface (1 M (NH₄)₂S, 500 ppm CN⁻) for 1 min. Electrochemical behavior and surface morphology of these films were determined using electrochemical impedance spectroscopy (EIS), scanning electron microscopy, and scanning photoelectrochemical microscopy (SPECM). EIS diagrams and SPECM images show the passive properties and homogeneity of the films. Furthermore, X-ray photoelectron spectroscopy (XPS) was used to characterize their chemical nature and structure. XPS results show that different oxide and sulfur structures were developed during the electrochemical oxidation of carbon steel in concentrated sour media. The analysis of O 1s data indicated that, during film growth, H₂O and/or hydroxyl groups are incorporated into the film structure. The XPS spectra of Fe 2p show iron bonds with S as iron sulfide (FeS₂ and FeS) and the corresponding peak of O 1s shows those bonds with oxygen as Fe₂O₃ and/or FeO. XPS depth profile analyses for the film showed that the ratio of FeS and FeO increases from film surface to film-carbon steel interface. This corroborates the diffusion of iron ions through the film during its electrochemical growth. The chemical shift through the film for the peak associated with Fe 2p signal proves that transport mechanism of iron ions through the film is carried out by chemical diffusion.     

Eco friendly corrosion inhibitors: Inhibitive action of quinine for corrosion of low carbon steel in 1 m HCl

Quinine, a natural product, was investigated as a corrosion inhibitor for low carbon steel in 1.0 m HCl solution. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to study the inhibition action in the temperature range 20–50 °C. The corrosion of steel was controlled by a charge transfer process at the prevailing conditions. The electrochemical results showed that quinine is an efficient inhibitor for low carbon steel and an efficiency up to 96% was obtained at 20 °C. The inhibition efficiency increases with inhibitor concentration and reaches a near constant value in the concentration range 0.48 mM and above. Application of the Langmuir adsorption isotherm enabled a study of the extent and the mode of adsorption.     

Electrochemical study of carbon steel corrosion in buffered acetic acid solutions with chlorides and H2S

In this work, the corrosion behavior of SAE 1018 carbon steel in buffered acetic acid (HAc) solutions containing chlorides, with and without H₂S, was studied. Polarization curves obtained by different electrochemical techniques, indicate negligible modification of anodic slopes when adding H₂S; however, the cathodic branch is more sensitive showing an accelerated reduction reaction in the presence of H₂S. Interface characterization was performed by electrochemical impedance technique (EIS) in the absence and presence of H₂S and near to the corrosion potential (E_corr). Analysis of results shows no film of corrosion products, since the impedance spectra characteristics indicate a great activity of steel in the solutions studied, with differences only at low frequencies. The adsorbed complexes formed in the solution containing HAc, acetate and chlorides control the corrosion process and prevent passive film formation, even in the presence of H₂S.     

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

An investigation was made into the corrosion behavior of commercial galvannealed steel in 10⁻² mol dm⁻³ NaCl aqueous solutions and in a tropical marine environment, using scanning electron microscopy (SEM), galvanostatic electrochemical stripping (GES), potentiodynamic linear polarization (PLP), and electrochemical impedance spectroscopy (EIS) techniques and open circuit measurements (E _oc). For purposes of comparison, a commercial galvanized steel was also subjected to similar corrosion tests. GES and SEM techniques allowed for the identification of ζ, δ and Γ intermetallic phases and revealed cracks in the galvannealed steel. The PLP, EIS and E _oc results indicated that the galvannealed coating was more corrosion resistant than galvanized coating in an aqueous medium, but that their corrosion behaviors were similar in the marine environment. The corrosion behavior of the galvannealed steel was affected by the evolution of the cracking process in the Zn–Fe layer due to the dissolution of zinc-rich phases, while the galvanized steel displayed generalized corrosion in the aqueous medium and localized corrosion in the marine environment.     

Amphiphilic amido-amine as an effective corrosion inhibitor for mild steel exposed to CO2 saturated solution: Polarization, EIS and PM-IRRAS studies

The corrosion behavior of mild steel in CO₂-saturated 5% NaCl solution with N-[2-[(2-aminoethyl) amino] ethyl]-9-octadecenamide corrosion inhibitor at 25 °C has been studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) measurements. Both potentiodynamic polarization and EIS measurements reveal that this amido-amine precursor inhibits the carbon steel corrosion and the inhibition efficiency increases with increasing the inhibitor concentration. The corrosion inhibitor exhibits high corrosion efficiencies as a mixed-type inhibitor, with a predominant influence on the anode process. The organic inhibitor acts blocking surface sites at low concentrations and by modifying the adsorption mechanism forming a protective barrier against corrosive ions at high concentrations. EIS results show that the mechanism of its corrosion inhibition at concentrations higher than 0.82 × 10⁻⁵ M is by forming a protective bilayer with small pore sizes that hinders the passage of the reactive species. PM-IRRAS measurements demonstrate that the inhibitor is chemisorbed to surface steel. Therefore, its spectrum reveals that the inhibitor monolayer has an amorphous structure.     

Effects of some ions on ion-selectivity of ferrous sulfide film

The ion-selectivity of ferrous sulfide film formed on a cellulose sheet was determined by measuring the film potentials in neutral chloride solution. The results show that ferrous sulfide film is a bipolar film consisting of an inner cation-selective layer and an outer anion-selective layer. This kind of film structure can accelerate the localized corrosion of steel. The influence of some anions, cations and imidazoline corrosion inhibitor on ion-selectivity of the film was also investigated. The ion-selectivity of the film is altered from bipolar to anion-selective with the adsorption of Ca²⁺, Mg²⁺ and Ba²⁺ ions, or to cation-selective with the adsorption of MoO₄^2-, PO ₄^3-and imidazoline inhibitor. Potentiodynamic polarization, AC impedance technology, and the weight-loss method were used to understand the relationship between the ion-selectivity and corrosion behaviors of steel in sulfide-containing solution.     

Corrosion behavior of SM 80SS tube steel in stimulant solution containing H2S and CO2

Scanning electron microscopy, X-ray diffraction and electrochemical measurement technique were applied to investigate the corrosion of SM 80SS tube steel in stimulant solution with carbon dioxide (CO₂) and hydrogen sulfide (H₂S) at variable conditions of PCO₂/PH₂S and temperature. The results suggest that there exists a synergism of sweet corrosion and sour corrosion on the steel surface, corrosion attack increases in the initial stage and then decrease with the increase of PCO₂ or PH₂S; serious corrosion occurs in the PCO₂/PH₂S ranged from 31 to 520. In addition, the fitted parabola function equation Y = 0.47873 + 0.04014X - (3.23788E−5)X² is established, and the most serious corrosion is 600 for PCO₂/PH₂S. Under the moderate contents of PCO₂ and PH₂S, the corrosion scale consists of FeS_0.9 and FeCO₃; for relatively high PH₂S, additive product FeS comes into being at high temperature such as T = 150 °C, product FeO(OH) is found in the corrosion scale. The H₂S corrosion has a significant effect on the whole reaction process and iron sulfide is superior to precipitating on the steel surface compared with iron carbonate. In addition, the surface scales of iron sulfide almost act as a diffusion barrier and inhibit the corrosion by a coverage effect strongly depending on H₂S concentration by EIS measurement.     

DEIS assessment of AISI 304 stainless steel dissolution process in conditions of intergranular corrosion

Results presented in this paper are first that demonstrate instantaneous impedance changes versus reactivation potential detected by means of dynamic electrochemical impedance spectroscopy (DEIS) technique for AISI 304 stainless steel dissolution process proceeding during intergranular corrosion (IG) in 0.5 M SO₄²⁻ + 0.01 M KSCN solution of different pHs. Application of DEIS method made it possible to evaluate dynamic changes of the examined system's impedance in conditions of IG. As a result, controlling stage of the overall rate of AISI 304 SS dissolution process was determined. Moreover, the paper proposes an alternative way of assessment of AISI 304 SS dissolution rate during intergranular corrosion based on approximation to theory of iron dissolution in sulfuric acid medium. Simultaneously, on the basis of the DEIS measurements it was possible to obtain information about the degree of sensitization (DOS) of the examined material. Accordingly, performed researches revealed the advantage of the DEIS technique over the electrochemical potentiokinetic reactivation (EPR) tests when investigating intergranular corrosion process.     

Corrosion inhibition performance of threonine-modified polyaspartic acid for carbon steel in simulated cooling water

Green polymers as corrosion inhibitors are gradually used to protect metal in solution environment. A polyaspartic acid threonine derivative (PASP-Thr) was synthesized and its structure was characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance. The corrosion inhibition effect of polyaspartic acid (PASP) and PASP-Thr on carbon steel in simulated cooling water was investigated by weight loss tests and electrochemical measurements. Experimental results show PASP-Thr as a mixed-type inhibitor exhibits higher corrosion inhibition efficiency than PASP, and the inhibition efficiency of PASP-Thr reached 93.06% at the dosage was 200 mg L⁻¹. The carbon steel surface in different situations was analyzed using atomic force microscope, scanning electronic microscope/energy dispersive X-ray, and FTIR, demonstrates the formation of a protective film on carbon steel surface. The inhibition effect of PASP-Thr was primarily attributed to the protective film formed on steel surface by physical and chemical adsorption. Moreover, quantum chemical calculation elaborated the relationship between the inhibition efficiency and the PASP-Thr molecular structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47242.     

Electrochemical studies of heat-treated NiCrMoFeCoAl and NiCrMoFeCoAl-30%Cr3C2 HVOF coatings on T22 boiler steel

Herein, we present the corrosion behavior of NiCrMoFeCoAl and NiCrMoFeCoAl-30%Cr₃C₂ high-velocity oxy fuel (HVOF) coatings on the ASTM-SAE213-T22 boiler tube steel alloy. The samples exposed to molten salt (Na₂SO₄–60%V₂O₅) environment at 700℃ under thermocyclic conditions were investigated in conjunction with electrochemical techniques. The surface structures and morphologies of heat-treated samples suggest the extent of corrosion is least for the NiCrMoFeCoAl-30%Cr₃C₂-coated steel. Room-temperature electrochemical analysis of heat-treated samples demonstrate the good stability with NiCrMoFeCoAl-30%Cr₃C₂ layers on T22 steel at solid/liquid interface under neutral pH conditions. The potentiodynamic and impedance analyses reveal that the higher charge transfer resistance was observed for NiCrMoFeCoAl-30%Cr3C2-coated steel, followed by NiCrMoFeCoAl-coated steel and bare T22 steel. The chromium carbide containing the HVOF coating exhibit a highly dense layer and the metal chromites/chromates on the post-heat-treated coatings provide poor access for the electrolyte to base alloy and subsequently improve corrosion stability.     

Effect of PgTPhPBr on the electrochemical and corrosion behaviour of 304 stainless steel in H2SO4 solution

Weight-loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were used to study the inhibition of 304 stainless steel corrosion in 1 M H₂SO₄ at 50 °C by propargyltriphenylphosphonium bromide (PgTPhPBr). The inhibiting effects of propyltriphenylphosphonium bromide (PrTPhPBr) and propargyl alcohol (PA) were also studied for the sake of comparison. For the investigated compounds, Tafel extrapolation in the cathodic region gave a corrosion inhibition efficiency of 98% at 1 × 10^–3 M. Adsorption of both PgTPhPBr and PA was found to follow Frumkin's isotherm while adsorption of PrTPhPBr obeys that of Temkin. In the anodic domain, PgTPhPBr acted as a good passivator. The impedance spectra recorded at the corrosion potential (E _cor) revealed that the charge transfer process in the inhibited and uninhibited states controls corrosion of 304 stainless steel.