In situ Raman spectroscopy and electrochemical techniques for studying corrosion and corrosion inhibition of iron in sodium chloride solutions

The corrosion of single crystal pure iron in 3.5% NaCl solutions and its inhibition by 3-amino-5-mercapto-1,2,4-triazole (AMTA) have been studied using in situ and ex situ Raman spectroscopy, cyclic voltammetry (CV), open-circuit potential (OCP), potentiodynamic polarization (PDP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. CV experiments indicated that the iron electrode in the chloride solution alone showed an anodic peak at ∼−650 mV after the 5th cycle shifted to ∼−610 mV after the 20th cycle; another cathodic peak appeared at ∼−990 mV. In the presence of 1.0 mM AMTA, these two peaks shifted to ∼550 and −1050 mV, respectively. OCP, PDP, CA and EIS revealed that the presence of AMTA and the increase of its concentration move the corrosion potential to more positive values and decrease both the corrosion current and corrosion rate. This effect also increases with increasing the immersion time of iron electrode to 24 h in the test electrolyte. In situ and ex situ Raman investigations confirmed that the addition of AMTA molecules to the chloride solution strongly inhibits the iron corrosion through their adsorption onto the surface blocking its active sites and preventing its corrosion.     

Inhibition of copper corrosion in acidic pickling solutions by N-phenyl-1,4-phenylenediamine

Inhibition of copper corrosion by N-phenyl-1,4-phenylenediamine (NPPD) has been investigated in de-aerated, aerated, and oxygenated aqueous 0.50 M HCl solutions by using potentiodynamic polarization, potentiostatic current-time, electrochemical impedance spectroscopy, and weight-loss measurements, along with scanning electron microscopic (SEM) and energy dispersive X-ray (EDX) experiments. Potentiodynamic polarization measurements showed that the NPPD molecules significantly decrease cathodic, anodic, and corrosion currents in all these solutions. Potentiostatic current-time measurements as well as SEM and EDX investigations of the copper surface revealed that NPPD suppresses the copper dissolution current due to its adsorption on the copper surface as a Cu(I)-NPPD complex. Impedance measurements also supported the results obtained from both the potentiodynamic and potentiostatic experiments. The inhibition efficiencies measured from polarization, electrochemical impedance spectroscopy (EIS), and weight-loss experiments are all internally consistent with each other. These results together showed that NPPD is a good mixed-type inhibitor for copper corrosion in all solutions studied.     

正十二烷基硫醇对铜在酸性介质中的缓蚀行为

以往人们对铜在各类溶液、水和低电导率的介质中的腐蚀行为进行了许多研究．     

Inhibition of corrosion processes on copper in aerated sodium chloride solutions by 5-(3-aminophenyl)-tetrazole

Inhibition of corrosion processes of copper in aerated 3.5% NaCl solutions by 5-(3-aminophenyl)-tetrazole (APT) has been investigated using open-circuit potential, potentiodynamic polarization, potentiostatic current–time, electrochemical impedance spectroscopy, and weight loss measurements together with pH and Raman spectroscopy. Increasing concentrations of APT greatly decreased the corrosion rate and increased the surface and polarization resistance. It was concluded that the adsorption of APT blocks the active sites on the copper surface leading to the formation of cuprous chloride and oxychloride complexes. This was supported by the Raman spectrum obtained from the copper surface after 24 days of immersion in a 3.5% NaCl solution containing 5.0 mM APT. The results collectively are in good agreement and show clearly that APT is a good corrosion inhibitor for copper under the conditions studied. El-Sayed M. Sherif is on leave from Physical Chemistry Department, National Research Centre, Dokki, Cairo, Egypt.     

Experimental and theoretical studies of anti-ulcer drugs with benzimidazole rings as corrosion inhibitor for copper in 1 M nitric acid medium

The adsorption effect of esomeprazole (ESP) and lansoprazole (LP) on corrosion behavior of copper in 1 M HNO₃ solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The experimental results indicate that both ESP and LP inhibited the corrosion of copper in nitric acid solution and the inhibition efficiency increased as the concentration of the compounds increased. EIS measurements confirmed that the charge transfer resistance increases on increasing the inhibitor concentration. Polarization measurements showed that the inhibitors are of mixed type. From the weight loss measurements, the inhibition efficiency of the inhibitors was found to vary with concentration, immersion time, and temperature. The adsorption of inhibitors on the copper surface follows Langmuir isotherm. The surface morphology was examined by scanning electron microscope and atomic force microscope. Further, the computational calculations are performed to find a relation between their electronic and structural properties.     

Study on the effect of vanillin on the corrosion inhibition of aluminum alloy

The effect of vanillin on the corrosion inhibition of aluminum (Al) alloy in seawater was studied by potentiodynamic polarization (PP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) techniques. The surface morphology after its exposure to seawater with and without vanillin was examined by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). All the studied parameters showed good inhibitive characteristics against the corrosion of Al alloy in the tested solution, and their performance was observed to increase with the inhibitor concentration. Polarization data indicated that the studied inhibitor is a mixed-type inhibitor. Linear polarization and EIS studies showed that there were significant increases in the overall resistance after the addition of vanillin. The adsorption of inhibitor on Al alloy was found to obey the Langmuir adsorption isotherm. The analysis of SEM and EDS confirmed the formation of precipitates of vanillin on the metal surface, which reduced the overall corrosion reaction.     

Studying the in vitro corrosion response of nanostructured TaN coatings in Hank's physiological solution

The goal of this research is to determine the effect of N₂ pressure to argon pressure on the microstructural analysis and corrosion behavior of nanostructured TaN deposited coatings using a reactive DC-magnetron sputtering (RDCMS) technique. The samples coated microstructure was studied by the X-ray diffraction (XRD) and scanning electron microscope (SEM), and elemental distribution was studied using energy-dispersive X-ray spectroscopy (EDS). To investigate the corrosion behavior of nanostructured TaN coatings, the potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests were performed in Hank's physiological solution. The results of different tests revealed that the coating with a content of 17.6% P_N2/P_Ar consisted of hexagonal and orthorhombic TaN phases and had denser microstructure and free pores. This coating showed superior corrosion behavior in comparison to the other ones. Also, the corrosion resistance of this coating raised by increasing the time of immersion from 48 to 168 h.     

Self-assembled 1-octadecyl-1H-1,2,4-triazole films on copper for corrosion protection

A film of 1-octadecyl-1H-1,2,4-triazole (OTA) was formed on a fresh copper surface by self-assembly technique. The optimum concentration of OTA and immersion time for the formation of a protective OTA film have been established using electrochemical impedance spectroscopy (EIS). These are (i) 15 mM concentration of OTA in methanol and (ii) immersion period of 48 h. X-ray photoelectron spectroscopy (XPS), reflection absorption FTIR spectroscopy, atomic force microscopy (AFM), and contact angle measurements have been used to characterize the OTA film on copper surface. The efficiency of OTA film to protect copper from corrosion in aqueous NaCl environment has been investigated using EIS, potentiodynamic polarization studies, cyclic voltammetry and weight-loss studies. All these studies showed that the OTA film affords excellent protection against corrosion of copper.     

Effects of 2-amino-5-ethylthio-1,3,4-thiadiazole on copper corrosion as a corrosion inhibitor in aerated acidic pickling solutions

Effects of 2-amino-5-ethylthio-1,3,4-thiadiazole (AETD) on copper corrosion as a corrosion inhibitor in an aerated acidic pickling solution of 0.50 M HCl have been investigated using gravimetric and electrochemical techniques. Weight losses of copper coupons in 0.50 M HCl measured after varied exposure periods of 2–12 h indicate that the addition of AETD significantly decreases the dissolution rate and the effect increases upon increasing its concentration. Results of potentiodynamic polarization experiments show a large decrease in cathodic, anodic, and corrosion currents due to the presence of the organic molecules. Potentiostatic current–time measurements at 200 mV versus Ag/AgCl for 120 min, scanning electron microscope (SEM), and energy dispersive X-ray (EDX) investigations also indicate that AETD greatly lowers the dissolution currents as a result of its strong adsorption onto the copper surface preventing it from being corroded easily. EIS measurements confirmed that the charge transfer resistance increases and mass transport decreases in the presence of AETD upon increasing its concentration.     

Protection of copper surface in acidic chloride solution by non-toxic thiadiazole derivative

This paper deals with electrochemical properties of copper in the presence of the non-toxic compound 2-amino- 5-ethyl- 1,3,4-thiadiazole (AETDA) in acidic chloride solution. Electrochemical techniques: open circuit potential measurements, linear potentiodynamic measurements, cyclic voltammetry measurements and chronoamperometric measurements in addition to SEM–EDS analysis were used during the work. Results show that inhibition efficiency of 2-amino-5-ethyl-1,3,4-thiadiazole depends on inhibitor concentration and immersion time of copper electrode in inhibitor solution. Cyclic voltammetry and linear potentiodynamic measurements beside chronoamperometric measurements indicate formation of protective layer on copper surface. Moreover, results obtained by electrochemical measurements point out that the stability of formed layer depends primarily on the concentration of inhibitor and of potential values at which protective film is formed. Also, potentiodynamic measurements show that AETDA in acidic chloride solutions acts as mixed-type inhibitor. Inhibition mechanism of 2-amino-5-ethyl-1,3,4-thiadiazole includes adsorption of inhibitor on active sites on electrode surface which was confirmed by SEM–EDS analysis of the electrode surface. Adsorption of the AETDA in HCl solution obeys Langmuir adsorption isotherm.     

Amikacin disulfate: an aminoglycoside antibiotic drug as a corrosion inhibitor for copper in 1 M nitric acid medium

The effect of commercially available pharmaceutically active compound amikacin disulfate (AMK) against the corrosion of copper in 1 M HNO₃ solution was investigated using Tafel polarization, electrochemical impedance spectroscopy (EIS), and weight loss techniques. The results show that inhibition efficiency (IE %) increases with increasing inhibitor concentration from 0.1 to 1.0 mM. Increasing the temperature increased the corrosion rate, and results decreased the inhibition efficiency. The adsorption of inhibitor obeyed Langmuir adsorption isotherm model via physisorption mechanism. EIS technique exhibits one capacitive loop, indicating that the corrosion reaction is controlled by charge transfer process. Polarization measurements showed that the AMK is mixed-type inhibitor. The surface morphologies were studied by scanning electron microscopy and atomic force microscopic techniques. The corrosion mechanism were explained by Fourier transform infrared spectroscopy.     

Aminothiazolyl coumarin derivatives as effectual inhibitors to alleviate corrosion on mild steel in 0.5 M H2SO4

To diminish corrosion which leads to structural damages and to implement a green mitigator has induced the usage of aminothiazolyl coumarin derivatives to study mild steel (MS) corrosion using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), weight loss, atomic force microscopy (AFM), and electron microscopy with energy dispersive spectroscopy (SEM–EDS) spectrometry in acid medium. The results showed that the inhibition efficiency was 90.8% for the least effective inhibitor and 97.1% for the most effective inhibitor at optimal concentration (10 mM). Enhancement of inhibition efficiency in weight loss method and increase in R_p values in impedance and mixed nature of the inhibition in polarization measurement reveals the best inhibition capacity of coumarins over the MS. The coumarins were characterized using FT-IR, NMR and Mass spectroscopy. The adsorption was well fitted with the Langmuir adsorption isotherm model. SEM–EDS and AFM images confirmed the shielding effect of coumarin derivatives through a layer formation on MS against acid medium. The adsorption mechanism of aminothiazolyl coumarin derivatives was further explored by quantum chemical calculations (DFT) and molecular dynamics (MD).

Graphic abstract

     

Weight loss, polarization, electrochemical impedance spectroscopy, SEM and EDX studies of the corrosion inhibition of copper in aerated NaCl solutions

This work reports results of weight loss, potentiodynamic polarization and impedance measurements on the corrosion inhibition of copper in aerated non-stirred 3% NaCl solutions in the temperature range 15–65 °C using sodium oleate (SO) as an anionic surfactant inhibitor. These studies have shown that SO is a very good ”green”, mixed-type inhibitor. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) observations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increasing surfactant concentration and time of immersion, while it decreases with solution temperature. Maximum inhibition efficiency of the surfactant is observed at concentrations around its critical micellar concentration (CMC). The potential of zero charge (pzc) of copper was studied by ac impedance, and the mechanism of adsorption is discussed. The sigmoidal shape of the adsorption isotherm confirms the applicability of Frumkin’s equation to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.     

An ecofriendly approach for corrosion control of 6061 Al-15％(v) SiC(p) composite and its base alloy

Corrosion inhibition characteristics of bio polymer dextran was studied for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite and its base alloy in 1 mol·L~(-1) HCl. Standard electrochemical techniques such as potentiodynamic polarization(PDP) measurements and electrochemical impedance spectroscopy(EIS) method were adopted for corrosion rate measurement. Surface morphology was studied by scanning electron microscopy(SEM) and elemental mapping was done by energy dispersive X-ray(EDX) analysis. Suitable mechanism was proposed for corrosion and inhibition process. Results indicated that dextran acts as an excellent anticorrosive agent for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite, with maximum inhibition efficiency of 91% for the concentration of 0.4 g·L~(-1) at 303 K. Dextran acted as a mixed type of inhibitor, and got physically adsorbed both on composite and base alloy by obeying Langmuir adsorption isotherm. Dextran is proved to be a green inhibitor with environmental and economic benefits.     

The inhibition of low carbon steel corrosion in hydrochloric acid solutions by succinic acid: Part I. Weight loss, polarization, EIS, PZC, EDX and SEM studies

The effect of succinic acid (SA) on the corrosion inhibition of a low carbon steel (LCS) electrode has been investigated in aerated non-stirred 1.0 M HCl solutions in the pH range (2-8) at 25 °C. Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of SA under the influence of various experimental conditions. Measurements of open circuit potential (OCP) as a function of time till steady-state potentials (E_st) were also established. Surface analysis using energy dispersive X-ray (EDX) and scanning electron microscope (SEM) allowed us to clarify the mechanistic aspects and evaluate the relative inhibition efficiency. Results obtained showed that SA is a good “green” inhibitor for LCS in HCl solutions. The polarization curves showed that SA behaves mainly as an anodic-type inhibitor. EDX and SEM observations of the electrode surface confirmed existence of a protective adsorbed film of the inhibitor on the electrode surface. The inhibition efficiency increases with increase in SA concentration, pH of solution and time of immersion. Maximum inhibition efficiency (≈97.5%) is obtained at SA concentrations >0.01 M at pH 8. The effect of SA concentration and pH on the potential of zero charge (PZC) of the LCS electrode in 1.0 M HCl solutions has been studied and the mechanism of adsorption is discussed. Results obtained from weight loss, polarization and impedance measurements are in good agreements.     

Effects of 1,4-naphthoquinone on aluminum corrosion in 0.50 M sodium chloride solutions

Effects of 1,4-naphthoquinone (NQ) have been investigated as a corrosion inhibitor for aluminum in aerated and de-aerated solutions of 0.50 M NaCl using potentiodynamic polarization, chronoamperometry (CA), open-circuit potential (OCP), electrochemical impedance spectroscopic (EIS), scanning electron microscopic (SEM), cyclic voltammetric, and quartz crystal analyzer (QCA) techniques. These measurements revealed that the presence of NQ shifted the corrosion and pitting potentials to more noble values and decreased the anodic currents in the passive region in both aerated and de-aerated chloride solutions, and the surface and polarization resistances are increased as the concentration of NQ is increased. The most effective concentration of NQ for corrosion inhibition was found to be 1.0 × 10⁻³ M in both aerated and de-aerated chloride solutions. The QCA data indicate that adsorption of NQ molecules plays an important role in protecting the pits on the aluminum surface. The SEM images show that the presence of NQ decreased the severity of the pitting corrosion of aluminum to a great extent at −675 mV versus Ag/AgCl.     

Anticorrosive coating based on poly(vinyl acetate) formed by electropolymerization on the copper surface

The poly(vinyl acetate) (PVAC) film was obtained by electropolymerization on the copper electrode using cyclic voltammetry performed in mixed electrolyte based on water/ethyl alcohol/acetic acid containing vinyl acetate (VAc) and benzoyl peroxide as polymerization initiator. The coatings were characterized by optical microscopy, scanning electron microscopy (SEM) and infrared (IR) spectroscopy. The corrosion was induced in hydrochloric acid solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The microscopic and SEM images revealed the PVAC coating formation and IR spectroscopy confirmed that it exhibits the same characteristic bands as a standard PVAC sample. From the potentiodynamic polarization, the PVAC protective performance of 78% was computed. The EIS measurements showed the occurrence of the surface adsorbed layer with a higher impedance response to the frequency and a phase angle maximum shifted to lower values than those of uncoated samples. In addition, the VAc electropolymerization mechanism was discussed and the PVAC adsorption mechanism on the copper surface was proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47320.     

Mitigation of corrosion of zinc with amylopectin: Electrochemical,adsorption, and surface studies

Carbohydrate polymers are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco-friendliness. Work undertaken reflects the effectiveness of biopolymer amylopectin (AMP) as an eco-friendly green inhibitor to mitigate the deterioration of zinc in 0.1 M sulphamic acid (NH₂SO₃H). Electrochemical studies like potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were applied for corrosion rate measurement in the absence and presence of AMP. Thermodynamic and kinetic parameters were calculated and described in detail. The results were fitted into a suitable adsorption isotherm model, and an appropriate mechanism was proposed for the corrosion inhibition process. A detailed surface morphology study was done using scanning electron microscopy (SEM), electron-dispersive X-ray (EDX), and atomic force microscopy (AFM) techniques. The inhibition efficacy of AMP increased with an increase in its concentration and temperature. Upon the addition of the inhibitor, corrosion potential shifted more towards the positive side, indicating more control of the anodic process. The adsorption of AMP over zinc conformed to the Freundlich adsorption isotherm. For the concentration of 0.1 gL⁻¹, maximum corrosion inhibition efficiency of 74% could be accomplished. Surface studies reaffirmed the adsorption of AMP on the surface of the metal. Thus, AMP turned out to be an effective green inhibitor with economic benefits.     

Protection of self-assembled monolayers formed from triethyl phosphate and mixed self-assembled monolayers from triethyl phosphate and cetyltrimethyl ammonium bromide for copper against corrosion

Self-assembled monolayers (SAMs) of triethyl phosphate (TEP) and the mixed SAMs of TEP with cetyltrimethyl ammonium bromide (CTAB) were prepared on copper surfaces. The protection abilities of these films against copper corrosion in 0.2 M NaCl aqueous solution were investigated using electrochemical impedance spectroscopy (EIS) and polarization techniques. Results showed that the inhibition efficiency (IE) increased with an increase in the immersion time of copper in the TEP-containing solutions. When the TEP films were modified with CTAB, the ability of the corrosion inhibition of the mixed films improved markedly. Furthermore, the influence of an external magnetic field on the formation of SAMs was studied. Ab initio calculations were performed to provide some theoretical studies for our experiment.     

Newly synthesized pyrimidine compound as CO2 corrosion inhibitor for steel in highly aggressive simulated oilfield brine

A newly synthesized pyrimidine–based compound, 5-(4-hydroxy-3-methoxyphenyl)-2,7-dithioxo-2,3,5,6,7,8-hexahydropyrimido[4,5-d]pyrimidin-4(1H)-one (PP), was evaluated as a promising inhibitor for the CO₂ corrosion of API X60 steel in NACE 1D196 brine solution. Under rotation speed of 1000?rpm, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) were complemented with scanning electron microscopy (SEM), X-ray diffraction (XRD) and Attenuated total reflectance infrared (ATR-IR) techniques to assess the corrosion inhibition performance. PP provided inhibition efficiency up to 90% at 20?ppm. It adsorbs on the Fe (110) phase on the steel using its heteroatoms and aromatic rings. Its adsorption greatly reduces the steel surface pitting corrosion.