Surface characterization and electrochemical corrosion behaviour of 304 stainless steel in aqueous media

A formulation consisting 100 ppm of 3-phosphonopropionic acid, 50 ppm of Zn²⁺ and 150 ppm of Tween 80 (polyoxyethylene sorbitan monooleate) offered 97.4% inhibition to the corrosion of 304 austenitic stainless steel immersed in a groundwater environment. This formulation functioned as a mixed inhibitor. The protective film was analysed by luminescence, XRD and FTIR spectra and pit morphology and was also observed by scanning electron microscopy. Electronic Publication     

Inhibitive action of ethanol extracts from Nauclea latifolia on the corrosion of mild steel in H2SO4 solutions and their adsorption characteristics

The inhibitive action of ethanol extracts from leaves (LV), bark (BK) and roots (RT) of Nauclea latifolia on mild steel corrosion in H₂SO₄ solutions at 30–60 °C was studied using weight loss and gasometric techniques. The extracts were found to inhibit the corrosion of mild steel in H₂SO₄ solutions and the inhibition efficiencies of the extracts follow the trend: RT > LV > BK. The inhibition efficiency increased with the extracts concentration but decreased with temperature rise. Physical adsorption of the phytochemical components of the plant on the metal surface is proposed as the mechanism of inhibition. The adsorption characteristics of the inhibitor were approximated by the thermodynamic-kinetic model of El-Awady et al.     

Protective properties of redox polymer film deposited on stainless steel

We propose a novel composite organic-inorganic coating in the form of a redox polymer film for protection of stainless steel against general corrosion in strong acid medium (2 M H₂SO₄). We utilize an anion exchange polymer, protonated poly(4-vinylpyridine), into which hexacyanoferrate anions have been introduced. Owing to the presence of Fe(CN)₆^3–/4– at the interface formed by the film and the steel, a sparingly soluble metal hexacyanoferrate (mostly Prussian blue, PB) is formed as an overcoating on the steels surface, presumably on the passive (metal oxide) layer. The redox polymer film on the steel seems to act as a composite three-dimensional bilayer-type coating in which hexacyanoferrate(III,II) anions (that are capable of effective charge storage) exist in the outer portions of the film, whereas the inner PB layer improves the systems overall adherence and stability. By analogy to a conducting polymer (e.g. polyaniline, polypyrrole), introduction of the redox polymer composite film leads to stabilization of the steel substrates potential within the passive range.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)     

New anti-corrosion inhibitor (3ar,6ar)-3a,6a-di-p-tolyltetrahydroimidazo[4,5-d]imidazole-2,5(1 h,3h)-dithione for carbon steel in 1 M HCl medium: gravimetric,electrochemical, surface and quantum chemical analyses

The inhibition of (3ar,6ar)-3a,6a-di-p-tolyltetrahydroimidazo[4,5-d]imidazole-2,5(1 h,3h)-dithione (TTHIIDT) for carbon steel was full characterized in a 1 M hydrochloride acid environment at various inhibitor concentrations and temperatures by the gravimetric, electrochemical, surface and quantum chemical analyses. The obtained results confirmed that the inhibition efficiency of TTHIIDT was over 95–97% and nearly stable in the rise of temperature and concentration; TTHIIDT was mixed type inhibitor and effectively influenced both anodic and cathodic corrosion reactions; a protective hydrophobic thin layer of this inhibitor on the carbon steel surface is more stable and non soluble in 1 M HCl medium; this inhibitor adsorbed endothermically on the carbon steel surface by the chemical and physical adsorption processes. The quantum chemical calculations supported the experimental results and showed that the inhibition efficiency is depends on the structure of inhibitor.     

Corrosion inhibition of mild steel in hydrochloric acid by betanin as a green inhibitor

The effect of betanin (2,6-pyridinedicarboxylic acid, 4-(2-(2-carboxy-5-(beta-D-glucopyr-anosyloxy)-2,3-dihydro-6-hydroxy-1H-indol-1-yl)ethenyl)-2,3-dihydro-(S-(R*,R*))) on the corrosion inhibition of mild steel has been investigated in 1 M HCl solution. Weight loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques were applied to study the mild steel corrosion behavior in the absence and presence of different concentrations of betanin under the influence of various experimental conditions. The results obtained showed that betanin is a good “green” inhibitor for mild steel in 1 M HCl solution. Scanning electron microscopy observations of the steel surface confirmed the protective role of the inhibitor. The polarization curves showed that betanin behaves mainly as a mixed-type inhibitor. Maximum inhibition efficiency (98%) is obtained at betanin concentrations of 0.01 M. The results obtained from weight loss, polarization, and impedance measurements are in good agreement.     

Electrochemical Characterization of Stainless Steel as a New Electrode Material in a Medical Device for the Diagnosis of Sudomotor Dysfunction

An electrochemical sensor detects the risk of diabetes and prediabetes; low potentials are applied to nickel electrodes and electrical responses are measured. Although the contact of nickel with skin is short, the risk of allergical reactions cannot be discarded. SS 304L, with lower Ni content, was tested in carbonate buffer solutions containing chloride, lactate and urea to investigate its sensitivity to different parameters in sweat and compare it to nickel. The results show that SS 304L is a suitable material for the assessment of sudomotor dysfunction due to its high capacity to detect the deviation in Cl^? concentration. Sensitivity of SS 304L to Cl^? is much higher than for nickel.     

Synergistic inhibition effects between leaves and stem extracts of Sida acuta and iodide ion for mild steel corrosion in 1 M H2SO4 solutions

The synergistic action caused by iodide ions on the corrosion inhibition of mild steel in 1 M H₂SO₄ by leaves and stem extracts of Sida acuta was studied using weight loss and hydrogen evolution methods at 30–60 °C. It was found that the leaves and stem extracts of S. acuta inhibited the acid induced corrosion of mild steel. Addition of iodide ions enhances the inhibition efficiency to a considerable extent. The inhibition efficiency increases with increase in the iodide ion concentration but decreases with rise in temperature. Adsorption of the extracts alone and in combination of iodide ion was found to obey Freundlich adsorption isotherm at all temperatures studied. Inhibition mechanism is deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. The synergism parameter (S₁) is defined and evaluated from the inhibition efficiency values. This parameter for the different concentrations of iodide ions from the two techniques employed is found to be greater than unity indicating that the enhanced inhibition efficiency of the extracts caused by the addition of iodide ions is due to synergism.     

Interactions and corrosion mitigation prospective of pyrazole derivative on mild steel in HCl environment

The effectiveness of 1H?pyrazole?3,5?dicarboxylic acid 5?benzyl ester 3?phenyl ester (PCBPE) as a preventer for deterioration of IS 513 Gr. D steel in 1 M HCl medium is evaluated via weight loss, electrochemical impedance, and polarization techniques. Kinetic and thermodynamic parameters assessed the feasibility of the adsorption process at diverse temperatures. The inhibition action on mild steel has been enhanced with increasing PCBPE concentration. It is found from the polarization studies that PCBPE behaves as mixed type inhibitor in HCl medium. The adsorption process of PCBPE on mild steel surface from acid environment is favoured Langmuir adsorption isotherm. The shielding efficiency of PCBPE has been enhanced at elevated concentrations, and it has been diminished at amplified temperatures. The Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrum (EDS) were used to establish a surface characterization of metal specimens. A quantum chemical analysis of electron density distributions in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) demonstrated how the inhibitor undergoes adsorption on mild steel in 1 M HCl. All experimental findings substantiate the corrosion mitigation performance of PCBPE on mild steel in acidic environments.     

A combined computational & electrochemical exploration of the Ammi visnaga L. extract as a green corrosion inhibitor for carbon steel in HCl solution

Natural-based corrosion inhibitors have gained great research interest thanks to their low cost and higher performance. In this work, the chemical composition of the methanolic extract of Ammi visnaga umbels (AVU) was evaluated by gas chromatography (GC) coupled with mass spectrometry (MS) and applied for corrosion inhibition of carbon steel (CS) in 1.0 mol/L HCl using chemical and electrochemical techniques along with scanning electron microscope (SEM) and theoretical calculations. A total of 46 compounds were identified, representing 89.89% of the overall chemical composition of AVU extract, including Edulisin III (72.88%), Binapacryl (4.32%), Khellin (1.97%), and Visnagin (1.65%). Chemical (Weight loss) and electrochemical (potentiodynamic polarization curves (PPC), and electrochemical impedance spectroscopy (EIS)) techniques revealed that investigated extract can be used as an effective corrosion inhibitor for carbon steel in 1.0 mol/L HCl solution. At a low dose of 700 ppm, the inhibitory action of AVU extract reached an inhibition efficiency of 84 percent. According to polarization tests, the investigated extract worked as a mixed inhibitor, protecting cathodic and anodic corrosion reactions. The EIS test showed that upon the addition of AVU extract to HCl solution, the polarization resistance increased while the double layer decreased. SEM images showed a protected CS surface in the inhibited solution. Quantum chemical calculations by Density Functional Theory (DFT) for the main components confirmed the major role of heteroatoms and aromatic rings as adsorption sites. Molecular dynamics (MD) simulation was used to study the adsorption configuration of the main components on the Fe(1 1 0) surface. Outcomes from this study further confirmed the significant advantage of using plant-based corrosion inhibitors for protecting metals and alloys.     

Study on the variation of morphology and separation behavior of the stainless steel supported membranes at high temperature

Palladium composite membranes were prepared on stainless steel (SUS) supports modified by nickel submicron powder and colloidal silica sols. Permeation tests of the palladium composite membranes were carried out at high temperature in order to observe the thermal stability of the membrane. The palladium composite membrane failed with formation of plenty of pinholes in the presence of hydrogen at high temperature. The failure of the composite membrane was verified by comparing the nitrogen permeance before hydrogen permeation test with that after hydrogen permeation test and comparing the H₂/N₂ selectivity for single gas permeation test with that for mixture gas permeation test. The variation of the membrane surface due to the failure of the membrane was characterized in scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) analyses. As a result, it can be concluded that reducible metal oxides can be attributed to the failure of the composite membranes resulting from reduction of the metal oxides by hydrogen whichever position in the membrane the metal oxides are layered.     

Inhibition effect of hexadecyl pyridinium bromide on the corrosion behavior of some austenitic stainless steels in H2SO4 solutions

The inhibition effect of hexadecyl pyridinium bromide (HDPB) as a cationic surfactant on the corrosion behavior of some Egyptian austenitic stainless steel SS 304L, SS 316H and SS 304H in 0.5 M H₂SO₄ solutions was investigated by using potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results indicate that HDPB is a good inhibitor for the samples under investigation in 0.5 M H₂SO₄ solutions. In addition, the inhibition efficiency η% increases with the inhibitor concentration while decreases with the increasing temperature referring to physical adsorption. The adsorption of the inhibitor obeys a Temkin adsorption isotherm. Polarization curves show that HDPB is a mixed inhibitor in H₂SO₄ solutions. The results obtained from polarization and impedance measurements are in good agreement. Activation-free energies, enthalpies, and entropies for the inhibition process of HDPB were determined.     

Molecularly imprinted polymer coated on stainless steel fiber for solid-phase microextraction of chloroacetanilide herbicides in soybean and corn

A molecularly imprinted polymer (MIP) with metolachlor as template was firstly coated on stainless steel fiber through chemical bonding strategy to solve the fragility problem of silica fiber substrate for solid-phase microextraction. The surface pretreatment of stainless steel fiber and the polymerization conditions were investigated systematically to enhance the preparation feasibility and MIP coating performance, and then a porous and highly cross-linked MIP coating with 14.8-μm thickness was obtained with over 200 times re-usability which was supported by non-fragile stainless steel fiber adoption. The MIP coating possessed specific selectivities to metolachlor, its metabolites and other chloroacetanilide herbicides with the factors of 1.1–4.6. Good extraction capacities of metolachlor, propisochlor and butachlor were found with MIP coating under quick adsorption and desorption kinetics, and the detection limits of 3.0, 9.6 and 38 μg L⁻¹ were achieved, respectively. Moreover, the MIP-coated stainless steel fiber was evaluated for trace metolachlor, propisochlor and butachlor extraction in the spiked soybean and corn samples, and the enrichment factors of 54–60, 27–31 and 15–20 were obtained, respectively.     

Molecularly-imprinted polypyrrole-modified stainless steel frits for selective solid phase preconcentration of ochratoxin A

A molecularly-imprinted polymer (MIP) was prepared by electropolymerization of pyrrole (Py) onto a stainless steel frit, using ochratoxin A (OTA) as the template, in order to make a micro solid phase preconcentration (SPP) device. The OTA template was removed with 1% triethylamine (TEA) in methanol. Compared to non-imprinted polypyrrole (PPy), the molecularly-imprinted polypyrrole (MIPPy) enhanced the selective binding of OTA. The percentage recovery improved from 0 to 40% when the OTA sample solution was acidified with 1 M HCl (1% by volume). At a flow rate of 0.2 mL/min, maximum OTA binding was reached in 6 min after a total loading of 3.2 ng OTA. Final elution of the OTA was analyzed by high performance liquid chromatography (HPLC) with fluorescence detection, using 20:80 v/v acetonitrile–ammonia buffer (NH₄Cl/NH₃, 20 mM, pH 9.2) as the mobile phase. The MIPPy-SPP-HPLC results clearly demonstrated that the MIPPy-SPP device afforded selective preconcentration of OTA from red wine samples, at OTA concentration levels as low as 0.05 ppb, prior to HPLC analysis.     

Experimental,Monte Carlo and molecular dynamics simulations to investigate corrosion inhibition of mild steel in hydrochloric acid solutions

The efficiency of three furan derivatives, namely 2-(p-toluidinylmethyl)-5-methyl furan (Inh. A), 2-(p-toluidinylmethyl)-5-nitro furan (Inh. B) and 2-(p-toluidinylmethyl)-5-bromo furan (Inh. C), as possible corrosion inhibitors for mild steel in 1.0 M HCl, has been determined by weight loss and electrochemical measurements. These compounds inhibit corrosion even at very low concentrations, and 2-(p-toluidinylmethyl)-5-methyl furan (Inh. A) is the best inhibitor. Polarization curves indicate that all compounds are mixed-type inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of furan derivatives on the mild steel surface follows the Langmuir adsorption isotherm, and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. Monte Carlo simulations technique incorporating molecular mechanics and molecular dynamics can be used to simulate the adsorption of furan derivatives on mild steel surface in 1.0 M HCl.     

Cyclic voltammograms of iron and C-steels in oxalic acid solutions and investigation of the effect of phenyl phthalimide as corrosion inhibitors

Summary The electrochemical behaviour of Fe and C-steel samples in oxalic acid solutions was studied by the use of cyclic voltammetry. Two peaks were observed; the first one was the anodic peak and the second one an unexpected reductive dissolution peak which could be observed in the cathodic branch of cyclic voltammograms of all electrodes studied. The carbon content was found to increase the active dissolution of steels and to decrease their tendency towards passivation. The inhibitive efficiency of phenyl phthalimide derivatives on the active dissolution of Fe and steel samples in 0.1M oxalic acid were investigated.

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Cyclische Voltammogramme von Eisen und C-Stählen in Oxalsäurelösungen und der Einfluß von Phenylphthalimiden als Korrosionsinhibitoren

Zusammenfassung Das elektrochemische Verhalten von Eisen und C-Stählen in Oxalsäurelösungen wurde mit Hilfe cyclischer Voltammetrie studiert. Dabei treten zwei Signale auf: das anodische Signal sowie ein unerwartetes reduktives Lösungssignal. Letzteres wurde im kathodischen Zweig der cyclischen Voltammogramme aller untersuchten Elektroden gefunden. Der Kohlenstoffgehalt erhöht die aktive Auflösung von Stählen und erniedrigt ihre Tendenz zur Passivierung. Die Inhibitionseffizienz von Phenylphthalimiden für die aktive Auflösung von Eisen und Stahlproben in 0.1M Oxalsäure wurde untersucht.

     

Evaluation of Allium sativum as corrosion inhibitor for carbon steel in sulphuric acid under hydrodynamic conditions

ABSTRACT

A study on the use of Allium sativum (garlic) as corrosion inhibitor for carbon steel in 0.5?M H₂SO₄ has been carried out in static and dynamic conditions by using potentiodynamic polarization curves and electrochemical impedance spectroscopy at 0, 200, 500, 1000 and 2000?rpm. Inhibitor concentrations included 0, 100, 200, 400, 600, 800 and 1000?ppm. Under static conditions, inhibitor efficiency increases with increasing its concentration up to 400?ppm, but it decreases with a further increase in its concentration. Under dynamic conditions and short testing times, inhibitor efficiency increases with increasing the rotating speed, due to a better inhibitor transfer towards the steel surface. However, for longer testing times, inhibitor efficiency increases only during the first 2?h, and then it decreases with a further increase in time, indicating a desorption of the inhibitor molecules from the steel surface.     

Polypyrrole modified stainless steel frits for on-line micro solid phase extraction of ochratoxin A

Polypyrrole (PPy) was electrochemically synthesized on stainless steel frits as a sorbent for the micro solid phase extraction (SPE) of ochratoxin A (OTA). Using 20 l of standard solution under a fast flow rate of 0.5 ml/min, 80% recovery of OTA was achieved in the concentration range from 0.1–10 pg/l. This good recovery was achieved within a short residence time of 1.2 s. A binding capacity of 1 ng OTA was estimated for each PPy-modified frit, or 2 ng OTA for two frits in series. The bound OTA could be pulsed eluted (PE) with 20 l of 1% triethylamine in acetonitrile. On-line coupling of this PPy-on-a-frit and PE technique to high performance liquid chromatography (HPLC) was straightforward. On-line SPE-PE-HPLC results clearly demonstrated the capability of PPy-on-a-frit to bind OTA in the presence of red wine, beer, and orange juice components.     

Synthesis and evaluation of novel O-functionalized aminated chitosan derivatives as antibacterial,antioxidant and anticorrosion for 316L stainless steel in simulated body fluid

Chitosan’s Schiff base derivatives are taking the attention of scientists as a promising biomaterial for various applications. In this study, O-functionalized aminated chitosan (O-F-Am-Ch) was coupled with 4,4-dimethyl amino-benzaldehyde and N-methyl-2-pyrrolidone to produce Schiff bases (I) and (II), respectively. The chemical and physical properties of the new derivatives were investigated by Fourier transform infrared (FT-IR) that show a significant band for C=C between 1400 and 1600 cm⁻¹, thermal gravimetric analysis (TGA), which demonstrate an increase in the thermal stability of new derivatives than O-F-Am-Ch and scanning electron microscope (SEM) that indicates a slight increase in the rough structure of the surface. In addition, 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assays that examined the antioxidant properties of the new Schiff bases. The biocidal activity against four different bacterial strains [two gram-negative (Pseudomonas aeruginosa and Escherichia coli) and two gram-positive (Bacillus cereus and Staphylococcus aureus)] demonstrates significant improvement of the inhibition activity compare to O-F-Am-Ch with more activity against Gram-negative bacteria than that against gram-positive bacteria.As an implanted alloy, 316L stainless steel is used as a temporary biomaterial in different countries without any pretreatment. Our study focused on further improving the alloy features by investigating the protection efficiency of O-F-Am-Ch and the synthesized Schiff bases for the 316L stainless steel surface against corrosion in simulated body fluid (SBF). The corrosion inhibition of these compounds was investigated using two electrochemical methods (potentiodynamic polarization technique and electrochemical impedance spectroscopy). The results suggested the formation of self-assembled monolayers (SAMs) of the compounds under investigation. Furthermore, they demonstrated a considerable dose-dependent inhibiting corrosion of 316L stainless steel in SBF, whereas the inhibition efficiency exceeds 77% at 1000 ppm for the Schiff bases II. In conclusion, the tested derivatives show promising properties to refine stainless steel for implant applications.     

Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment—an XPS study

In austenitic stainless steel nitrogen stabilizes the austenitic phase, improves the mechanical properties and increases the corrosion resistance. Nitrogen alloying enables to produce austenitic steels without the element nickel which is high priced and classified as allergy inducing. A novel production route is nitrogen alloying of CrMn‐prealloyed steel powder via the gas phase. This is beneficial as the nitrogen content can be adjusted above the amount that is reached during conventional casting. A problem which has to be overcome is the oxide layer present on the powder surface which impedes both the sintering process and the uptake of nitrogen. This study focuses on whether heat treatment under pure nitrogen is an appropriate procedure to enable sintering and nitrogen uptake by reduction of surface oxides. X‐ray photoelectron spectroscopy (XPS) in combination with scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS) are used to investigate the surface of powdered FeMn19Cr17C0.4N heat treated under nitrogen atmosphere. The analyses showed reduction of iron oxides already at 500 °C leading to oxide‐free metallic surface zones. Mn and Cr oxides are reduced at higher temperatures. Distinct nitrogen uptake was registered, and successful subsequent sintering was reached. Copyright © 2014 John Wiley & Sons, Ltd.