EIS and XPS studies on passive film of AISI 304 stainless steel in dilute sulfuric acid solution

Electrochemical impedance spectroscopy and XPS studies on AISI 304 stainless steel in naturally aerated 0.5 M H₂SO₄ solution were carried out at room temperature. The valuable model of the metal/solution interphase was established, and the reliable equivalent electrical circuits in the solution were presented. The analysis of the chemical composition of passive film on AISI 304 stainless steel was carried out by XPS. The passive film of AISI 304 stainless steel is composed of oxyhydroxides, Fe₂O_3, FeO, Cr₂O₃, NiO, sulfate, sulfite, and sulfide (FeS, NiS). It is reported that the ferrous sulfide film formed on AISI 304 stainless steel in the dilute sulfuric acid solution. The possible process in which sulfuric acid is reduced to sulfite and sulfide is proposed. The galvanic interaction of sulfide inclusions with the base alloy is introduced. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrochemical and XPS studies on corrosion behaviours of AISI 304 and AISI 316 stainless steels under plastic deformation in sulphuric acid solution

The corrosion behaviours of austenitic stainless steels were investigated by electrochemical methods under plastic deformation with constant strain in the naturally aerated 0.5 M H₂SO₄ + 0.2 M KCl solution at room temperature. The work addresses the influence of plastic deformation and molybdenum element on the corrosion resistance of austenitic stainless steels in the test solution. Electrochemical impedance spectroscopy presents the decreasing charge transfer resistance (R_t) and polarization resistance (R_p) values with the immersion time for AISI 304 stainless steel under constant strain deformation, and the increasing R_t and R_p values with the immersion time for AISI 316 stainless steel. The analysis of the chemical composition of the corrosion products was carried out by XPS. Molybdenum addition in AISI 316 stainless steel affects significantly the corrosion resistance because of its high ability to form Mo (VI) and MoCl₅ insoluble compounds in acid medium. Copyright © 2011 John Wiley & Sons, Ltd.     

XPS depth profile study of porous zirconia films deposited on stainless steel by spray pyrolysis: the problem of substrate corrosion

Zirconia (ZrO₂) films of tissue‐like structure and narrow pore size distribution have been deposited by spray pyrolysis using aqueous zirconyl chloride octahydrate (ZrOCl₂·8H₂O) precursor solutions. Stainless‐steel sheets, protected or unprotected by a ZnO barrier layer, have been used as the substrate material held at 473 K. The ZnO barrier layers have been deposited on the stainless steel held at 523 K by spray pyrolysis using a zinc acetate precursor. Their property of corrosion protection to stainless steel has been proved by electrochemical polarization measurements in 0.5 M NaCl solution. A complementary study of XPS (depth profiling, mapping) and x‐ray diffraction has shown that the unprotected steel substrates were corroded during ZrO₂ film post‐annealing in air at T ≥ 773 K, whereas steel substrates protected with a compact barrier layer of crystalline ZnO before ZrO₂ film deposition did not show surface corrosion even after annealing up to 997 K. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrochemical, quantum chemical and SEM investigation of the inhibiting effect and mechanism of ciprofloxacin, norfloxacin and ofloxacin on the corrosion for mild steel in hydrochloric acid

The inhibiting effect and mechanism of 1-cyclopropyl-6-fluoro-1,4-dihydro -4-oxo-7-(1-piperazinyl) -3- quinoline carboxylicacid(ciprofloxacin), 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid (norfloxacin) and (?)-(S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7- oxo-7 H-pyrido(1,2,3-de)-1,4- benzoxazine-6 carboxylic acid (ofloxacin) on the corrosion of mild steel in 1 mol/L HCl have been studied using electrochemical method, quantum chemical method and SEM at 303 K. The potentiodynamic results showed that these compounds suppressed both cathodic and an-odic processes of mild steel corrosion in 1 mol/L HCl. The impedance spectroscopy showed that Rp values increased, and Cdl values decreased with the rising of the working concentration. Quantum chemical calculation showed that there was a positive correlation between some inhibitors structure properties and the inhibitory efficiency. The inhibitors function through adsorption followed Langmuir isotherm, and chemisorption made more contribution to the adsorption of the inhibitors on the steel surface compared with physical adsorption. SEM analysis suggested that the metal had been protected from aggressive corrosion because of the addition of the inhibitors.     

Characterization of bovine serum albumin adsorption on chromium and AISI 304 stainless steel, consequences for the Pseudomonas fragi K1 adhesion

Adsorption of BSA on the surface of chromium and 304 stainless steel, has been characterized by Contact Angle Measurements, X-ray Photoelectron Spectroscopy (XPS) and Infrared Reflection Absorption Spectroscopy (IRRAS). Bacterial adhesion has been tested and compared on these two materials before and after pre-conditioning the surface with BSA. Chromium and stainless steel surfaces, when covered by a natural oxide layer, exhibit different energetic characteristics as shown by their γ_s^- and γ_s^LW respective values. These data vary upon immersion in BSA solutions, tending towards common values for duration of immersions. After immersion in BSA solutions, the evolution of the N 1s XPS signal, specific for the BSA, suggests that the surface is nearly saturated in a few minutes. Longer times of immersion only lead to a re-ordering of the adsorbed layer. Immersion tests in dilute BSA solutions (0.01 g/l) enabled us to make clear a higher reactivity of chromium towards the protein compared to stainless steel. These differences are cancelled at higher BSA concentrations (1 g/l). IRRAS spectra of BSA adsorbed on the two substrates demonstrated the appearance of amide I and amide II bands with small shifts and intensity variations supporting orientation changes of the protein when the concentration or immersion time varies. A model for the building up of the BSA layer is proposed, which accounts for these data. Chromium and stainless steel surfaces, also have different behaviours towards adhesion of Pseudomonas fragi K1, whereas surfaces that are pre-conditioned by BSA behave in a similar way. The overall number of adherent bacteria is decreased on stainless steel, whereas it is hardly affected on chromium. On both surfaces, the fraction of viable cells is increased.     

The influence of Cu on the electrochemical behaviour of 304 stainless steel in 0.1M H3PO4 solution

The effect of different Cu addition on the electrochemical and passivation behaviour of the 304 series stainless steel in 0.1 M phosphoric acid solution was evaluated by the potentiodynamic measurements and electrochemical impedance spectrum (EIS). The effect of Cu on chemical composition of the passive film formed in the solution was also studied by X‐ray photoelectron spectroscopy (XPS). The results indicated that Cu did not appreciably improve the corrosion resistance of the passive film, but enhanced the passivation, lowered the critical and passive current density. The passive and critical current density decreased with Cu content increased. The presence of Cu in the passive film affects passive film stability. Cu can modify the proportion of Cr element in the passive film, and also change the components of Fe in the passive film. Copyright © 2012 John Wiley & Sons, Ltd.     

Benzalkonium chloride/titanium dioxide as an effective corrosion inhibitor for carbon steel in a sulfuric acid solution

In this study, the corrosion performance of carbon steel samples in 0.5 M sulfuric acid by the addition of novel inhibitors, 200 ppm of (25% and 50%) titanium dioxide nanoparticles in benzalkonium chloride, was thoroughly investigated. Gravimetric measurements, cyclic and linear potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and hydrogen collection by water displacement evaluated inhibition performance. Analogously, TiO₂/ILB (50%), TiO₂/ILB (75%), and ILB inhibitors enhanced corrosion protection with over 80% inhibition efficiency in electrochemical tests. In addition, weight loss and hydrogen collection measurements reached comparable results. According to potentiodynamic polarization curves, inhibitors exhibited dual behavior, but cathodic protection was more predominant. Scanning electron microscopy (SEM) was employed to examine the surface morphology before and after immersion using corrosion tests. The correlation between electronic properties and inhibition efficiencies of tilted inhibitors was determined by simple linear regression. Electronic properties were calculated for neutral and protonated forms using a polarizable continuum model by the DFT method at the B3LYP/6-311+G (d, p) level of theory. The active adsorbed sites of HM1-HM3 on the metal surface were determined by analyzing their corresponding electrostatic surface potentials (ESP). Furthermore, molecular dynamics simulations were performed to illustrate the most conceivable adsorption configuration between the inhibitors and metal surfaces.     

Comparative XPS analysis of passive layers composition formed on AISI 304 L SS after standard and high‐current density electropolishing

In the paper, there are described chemical compositions of passive surface layers formed on AISI 304 L (EN 1.4307) stainless steel after standard (EP50; i = 50 A/dm²) and high‐current density (EP1000; i = 1000 A/dm²) electropolishing. For the studies, a mixture of orthophosphoric and sulfuric acid electrolyte in proportion 1:4 was used. The survey and high‐resolution spectra of Cr 2p, Fe 2p, S 2p, P 2p, Ni 2p and C 1s are presented. On the basis of the obtained results it was noted that the chromium‐to‐iron ratio (Cr/Fe) after EP50 was about 3.5 times higher than that after EP1000 treatment. The phosphorus‐to‐sulfur ratios after EP50 and EP1000 electropolishing were 0.13 and 0.3, respectively, and nickel to the sum of chromium and iron coefficient (Ni/Cr + Fe) for both electrochemical polishing was equal to 0.04. Copyright © 2014 John Wiley & Sons, Ltd.     

Characterization of the passive films on electrodeposited Fe-Ni-Cr alloys in borate solution at pH 8.4

The corrosion properties of the passive layers formed on iron-nickel-chromium electrodeposits of Fe₂₉Ni₅₁Cr₂₀ were investigated in 0.3 M borate solution at a‘ pH of 8.4. On the basis of measurements by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy, a low passive dissolution/corrosion rate was identified for the electrodeposited Fe-Ni-Cr alloys due to the nature of the established corrosion layer. The stability of this passive layer was further enhanced after corrosion under oxidizing conditions. Mössbauer spectroscopic measurements confirmed the existence of a thin passive layer on the amorphous electrodeposits.      

Pitting behavior on super 13Cr stainless steel in 3.5% NaCl solution in the presence of acetic acid

The pitting behavior was investigated on super 13Cr stainless steels in 3.5% NaCl solution in the presence of HAc. The electrochemical measurements including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and chronoamperometric experiments were carried out, as well as the SEM surface analysis. The parameters such as E _corr and I _corr were obtained by fitting technique. Moreover, the equivalent circuit model was applied in the analysis of Nyquist plots, and ZsimWin software was used to analyze the EIS data. The results indicate that the pitting corrosion is accelerated with increasing the amounts of HAc. In addition, pitting nucleation and growth mechanisms were described in this work.     

Kinetics of carbon steel dissolution in ammonium chloride solution containing sodium thiosulfate

The dissolution behavior of carbon steel in ammonium chloride (NH₄Cl) solution containing sodium thiosulfate (Na₂S₂O₃) of various concentrations (0.01 and 0.1 M) was investigated using electrochemical impedance spectroscopy (EIS) and other nonelectrochemical techniques. The weight loss and polarization measurements indicate a significant increase in the NH₄Cl corrosion rate of carbon steel on addition of Na₂S₂O_3. The EIS measurements exhibited two capacitive loops at multiple direct current (dc) potentials for both the concentrations. Electrical equivalent circuit (EEC) and reaction mechanism analysis (RMA) were employed to analyze the impedance data. A four-step mechanism with two intermediate adsorbate species of same charge was proposed to explain the dissolution behavior of carbon steel in the given system. The surface coverage values enumerated that the surface was entirely covered with adsorbed species unlike in the pure NH₄Cl system. Charge transfer resistance and polarization resistance values estimated from RMA parameters indicate the increase in a dissolution rate with dc potential. The surface morphology was inspected via field emission scanning electron microscopy, and the corrosion products including surface state of carbon steel electrode were analyzed using energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.     

海洋微生物对316不锈钢的电化学腐蚀行为

采用自腐蚀电位、电化学极化曲线、电化学阻抗谱技术研究了316不锈钢在无菌培养基介质和海水微生物接种培养有菌培养基介质中不同周期的腐蚀行为．结果表明,316不锈钢电极在有菌介质中比在无菌介质中的腐蚀电流密度大,腐蚀电位负移,微生物加速了不锈钢的腐蚀速度．随着浸泡时间的增加,有菌介质中的不锈钢电极极化电阻值逐渐减小,表明了海洋微生物的附着和繁殖加速了316不锈钢的腐蚀速率,降低了其在海洋环境中的耐蚀性．     

Photoelectron spectroscopic studies of the formation of hydroxyapatite films on 316L stainless steel pretreated with etidronic acid

The valence band and core‐level X‐ray photoelectron spectroscopy was used to probe hydroxyapatite films formed on the surface of stainless steel. These films formed on steel may find application in medical implants. The key to the successful adhesion of the hydroxyapatite films is shown to be the initial formation of a thin, oxide‐free etidronate film on the metal. It was not found possible to prepare the hydroxyapatite films directly on the metal surfaces. Since hydroxyapatite is a key component of bone and teeth, it is likely that the coated metals will have desirable biocompatible properties. The hydroxyapatite film was exposed to air, water, and 1M sodium chloride solution as representative components of the environment of the film in the human body, and these exposures led to no detectable decomposition of the film. The thin hydroxyapatite and etidronate film on the metal show differential charging effects that caused a doubling of the peaks in some core level spectra. The valence band spectra proved especially valuable in the identification of the surface chemistry of the films, and these spectra were interpreted by comparing the experimental spectra with spectra calculated using band structure calculations which showed good agreement with experiment. The calculated spectrum of etidronic acid was found to be significantly different to that of etidronate. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental and theoretical studies of carbon steel corrosion protection in phosphoric acid solution by expired lansoprazole and rabeprazole drugs

The effects of expired lansoprazole and rabeprazole on the corrosion protection of carbon steel in phosphoric acid (3.0 ?M) solution were examined by Tafel polarization and electrochemical impedance spectroscopy (EIS). Lansoprazole and rabeprazole concentrations (0.5, 1.0, 5.0 and 10 ?mM) in acid solution were raised, which improved corrosion prevention. Both lansoprazole and rabeprazole as the mixed inhibitors retarded the anodic and cathodic processes, as indicated by polarization data. With the increasing temperature in the range of 25–55 ?°C, the inhibition efficiency drops from 92.9% to 69.3% for lansoprazole and from 94.8% to 74.2% for rabeprazole. The major decrease in the inhibition efficiency with ascending temperature proved the physisorption of the drugs. The activation energies for carbon steel corrosion in H₃PO₄solution were enhanced from 41.6 ?kJ ?mol^?1 to 81.9 ?kJ.mol^?1and 85.9 ?kJ ?mol^?1 for lansoprazole and rabeprazole, respectively. The influence of temperature on the corrosion process of carbon steel in the acid medium was used to derive the thermodynamic quantities of corrosion. The adsorption of both lansoprazole and rabeprazole on carbon steel followed the Langmuir adsorption isotherm. The polarization data yielded outcomes that were consistent with the results arising from impedance measurements. The theoretical study of both lansoprazole and rabeprazole was done by a density functional theory (DFT) approach to realize the effects of molecular structure on their inhibitive action. Both lansoprazole and rabeprazole contain a higher E_HOMO, a lower E_LUMO and a lower energy gap than some inhibitors earlier reported as good corrosion inhibitors in the literature.     

Corrosion resistances of passive films on low‐Cr steel and carbon steel in simulated concrete pore solution

The passive ranges of carbon steel rebar and 3Cr steel rebar in saturated Ca(OH)₂‐simulated concrete pore solution with pH 12.6 were determined by means of cyclic voltammetry and potentiodynamic polarization curves. Chronopotentiometry was used to obtain steady‐state conditions for the formation of passive films on rebar samples at different anodic potentials. Electrochemical impedance spectroscopy, Mott–Schottky and X‐ray photoelectron spectrometer curves were employed to compare the formed passive films at different potentials. Additionally, cyclic polarization curves were used to compare the corrosion resistances of formed passive films on the two rebars in saturated Ca(OH)₂‐simulated concrete pore solution with different concentration of Cl^?. The results show that the passive ranges of the two rebars are all between ?0.15 and +0.6 V, and more stable passive films can be formed on both rebars at the anodic potential of +0.3 V. In the absence of Cl^?, the stability and corrosion resistance of the passive film formed on the 3Cr rebar are better than those of CS rebar. The passive film of 3Cr steel has the relatively better pitting corrosion resistance than carbon steel in saturated Ca(OH)₂‐simulated concrete pore solution that contains different concentration of Cl^?. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of hydrostatic extrusion on passivity breakdown on 303 austenitic stainless steel in chloride solution

The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic deformation by hydrostatic extrusion (HE) leading to nanostructurization was investigated in an aggressive environment containing Cl⁻ ions by anodic polarization. Transmission electron microscopy (TEM) and stereological image analysis were used to examine structural changes introduced by HE. Surface analytical techniques such as light microscopy, scanning electron microscopy, Auger electron spectroscopy (AES), and scanning Auger microscopy (SAM) were used to characterize the morphology, grain size, and chemistry of the surface, including local characterization of nonmetallic inclusions and their surface before and after HE. SAM analysis revealed discontinuities of the passive oxide film on MnS inclusions. TEM and scanning transmission electron microscopy examinations confirm a drastic reduction of grain size accompanied by a distinct refinement of the size of sulfide inclusions in the HE matrix. These changes in the HE 303 stainless steel are apparently responsible for its reduced pitting resistance compared to the as-received material. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical–Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007.     

The influence of Ce3+ ions on the corrosion rate of stainless steel in acidic solutions of different pH-values

The corrosion resistance of AISI 420 stainless steel in 0.1 mol L^?1 H₂SO₄ + 0.1 mol L^?1 Na₂SO₄ solutions at different pH-values and the inhibiting effect of Ce³⁺ ions was studied using electrochemical polarization methods. The results reveal decreasing of the corrosion rate with an increasing the pH of the solution, which demonstrates the progressive protective character of the inhibitor used. At pH lower than 3.33, the corrosion inhibition was most probably a result of the competitive adsorption of Ce³⁺ with H⁺ ions on the cathodic sites of the electrode surface, and it was found to be dependent on the relative concentration of H⁺/Ce³⁺. The peroxide generated from the oxygen reduction reaction at pH 3.33 was found to be capable oxidize trivalent cerium (Ce) to the tetravalent state. As obtained hydroxide precipitates act as diffusion barrier hindering the corrosion processes, whereafter a spontaneous passivity occurs on the steel surface at this pH.     

Corrosion and tribocorrosion behaviour of super‐thick diamond‐like carbon films deposited on stainless steel in NaCl solution

Super‐thick diamond‐like carbon (DLC) film is a potential protective coating in corrosive environments. In the present work, three kinds of DLC films whose thickness and modulation periods are 4 µm and 3, 21 µm and 17 and 21 µm and 7, respectively, were fabricated on stainless steel. The effect of different thickness and modulation periods on corrosion and tribocorrosion behaviour of the DLC‐coating stainless steel was investigated in 3.5 wt% NaCl aqueous solution by a ball‐on‐flat tribometer equipped with a three‐electrode electrochemical cell. The DLC‐coating stainless steel served as a working electrode, and its OCP and potentiodynamic polarization were monitored before and during rubbing. The wear–corrosion mechanism of the DLC films was investigated by SEM. The results showed that the increasing thickness can prolong significantly lifetime of DLC films in NaCl aqueous solution. In particular, the modulation period has a significant impact on the tribocorrosion resistance of the DLC super‐thick films. The study suggested that the increasing thickness of compressive stress layer could suppress film damage by reducing crack propagation rate. Thus, the super‐thick DLC film with thickness of 21 µm and 7 periods presented the best tribocorrosion resistance among all studied films. Copyright © 2016 John Wiley & Sons, Ltd.     

Adsorption and inhibition properties of Tephrosia Purpurea as corrosion inhibitor for mild steel in sulphuric acid solution

Abstract

The present study investigated the adsorption and inhibition behavior of leaf extract of Tephrosia Purpurea (T. purpurea) on mild steel corrosion in 1?N H₂SO₄ solution using electrochemical and surface morphological methods. Techniques adopted for electrochemical studies were Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) technique; and surface morphological studies were carried out using Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The leaf extract of T. purpurea was characterized using UV-Visible spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance Spectroscopy (NMR) and Gas Chromatography – Mass Spectrometry (GCMS). The results obtained from electrochemical studies exhibited the potential of T. purpurea as good corrosion inhibitor. And, it was found that, the inhibition efficiency (I.E in %) increases with increase in concentration of the inhibitor molecules, the optimum inhibitor concentration observed was 300?ppm and the inhibition efficiency of 93% was observed at this inhibitor concentration. Above 300?ppm, there was not much changes in inhibition efficiency. Polarization studies provided the information that the inhibition is of mixed type and EIS confirmed that the corrosion process is controlled by single charge transfer mechanism. And, it was obtained that, the adsorption of inhibitor molecules obeys Langmuir adsorption isotherm. The inhibition is mainly by the adsorption of inhibitor molecules on the mild steel electrode surface, which was confirmed by FT-IR, SEM and AFM studies. Through all the experimental results, it can be arrived that, the leaf extract of T. purpurea performed as a good corrosion inhibitor for mild steel in 1?N sulfuric acid medium.     

Inhibition effect of butan-1-ol on the corrosion behavior of austenitic stainless steel (Type 304) in dilute sulfuric acid

The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance.