Corrosion Inhibition Mechanism Research Articles

Corrosion inhibition property of azomethine functionalized triazole derivatives in 1 mol L−1 HCl medium for mild steel: Experimental and theoretical exploration

With the aim to explore the effect of heteroatoms on corrosion inhibiting efficacy of structurally similar azomethine based organic molecules, namely, 5-((furan-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (FMT) and 5-((thiophen-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (TMT) were synthesized and its corrosion inhibiting property were investigated by potentiodynamic polarization and non-destructive electrochemical impedance spectroscopy. These electrochemical techniques revealed the excellent corrosion inhibiting efficacy of synthesized inhibitor molecules for mild steel exposed to 1 molL−1 HCl at ambient condition. Surface analyses using FESEM, AFM and contact angle measurement of mild steel retrieved from corrosive medium containing inhibitor molecules confirmed the formation of protective layer of inhibitor molecules on its surface. The consequences of efficient corrosion inhibiting property has been explained based on Hard-Soft-Acid-Base principle as well as electronegativity and polarizability difference of heteroatoms present in the skeleton of inhibitor molecules. Moreover, in order to validate the corrosion inhibiting property obtained from electrochemical experimentations, the insight of corrosion inhibition mechanism has been further explored by employing theoretical calculations viz density functional theory, Fukui indices analyses, molecular dynamics simulation and radial distribution function. Mulliken atomic charges, frontier molecular orbital and Fukui indices analysis of the free as well as adsorbed inhibitor molecules confirms the interaction of the susceptible reactive sites.

Virtual corrosion testing on stainless steel AISI 304 welded pipe with Hydroxyethyl Cellulose in 3.5% NaCl solution and turbulent flow

A virtual corrosion testing machine is used to investigate the corrosion inhibition efficiency and mechanism of an inhibitor in stainless-steel 304 pipes under turbulent flow conditions. The pipes are welded by the gas tungsten arc welding method and evaluated in 3.5 percent sodium chloride solution with absence (0 ppm) and presence 100, 300, and 600 ppm hydroxyethyl cellulose concentrations. The solutions are absence and presence the inhibitor, are fed in the welded pipe at a flow rate of 7,500 and 15,000 cm3 per minute as behaves to be turbulent flows. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques are used to investigate the corrosion inhibition process. The inhibitor can adsorp on the surface of stainless steel welded pipe and inhibit the corrosion rate of the stainless steel. The concentration volumes of the inhibitor are correlating the corrosion rate in the same direction. The turbulent flow is to reduce the adsorption mechanism of the inhibitor, affect to corrosion reaction for the stainless-steel welded pipe and relate to the corrosion rate. If the flow rate increases, the corrosion rate would also increase. The corrosion inhibition efficiency is reached up to 66% by addition HEC 600ppm concentration in the condition. Pitting corrosion is observed on the heat-affected zone of the welded pipe by scanning electron microscope.

Experimental, Monte Carlo and Molecular Dynamic Study on Corrosion Inhibition of Mild Steel by Pyridine Derivatives in Aqueous Perchloric Acid

The corrosion of mild steel in aqueous perchloric acid solution was studied in the presence and absence of four different pyridine derivatives. Electrochemical measurements point out that these molecules inhibit the corrosion of mild steel by acting as mixed inhibitors. The adsorbed molecules act as a barrier that prevents the oxidation of the metal and the hydrogen evolution reaction at the mild steel surface. Molecular insights vis-à-vis the corrosion process were acquired by the use of Density Functional Theory (DFT), Molecular Dynamics, and Monte Carlo calculations. Monte Carlo and Molecular Dynamic simulation were used to understand at the molecular level the adsorption ability of the studied molecules onto Fe(110) surface. The experimental results and theoretical calculations provided important support for the understanding of the corrosion inhibition mechanism expressed by the pyridine molecules.

Surface analysis and adsorption behavior of caffeine as an environmentally friendly corrosion inhibitor at the copper/aqueous chloride solution interface

Corrosion inhibitors based on environmentally friendly and harmless products are currently being studied and developed. The corrosion inhibition properties of caffeine (1,3,7-trimethylxanthine) on copper corrosion in aqueous chloride solution (3.5 wt.% NaCl) are analysed here using stationary and transient electrochemical methods, and a theoretical study based on density functional theory is carried out. Caffeine is a very competitive compared to the chemical inhibitors that are often used for copper protection. Electrochemical and impedance experiments reveal that the protective efficiency of caffeine reaches a value of 96% at a concentration of 10−2 mol L−1. Based on these results, the Langmuir model appears to be the best representation of the adsorption of caffeine onto the copper surface. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used to determine the surface morphology and the chemical composition of the copper surface in chloride media, in the absence and presence of caffeine. The results show the development of a mechanism of corrosion inhibition. In order to confirm the correlation between the inhibitory effect and the molecular structure of caffeine, quantum chemical parameters are used to calculate its electronic properties.

Effect of Modified Hexagonal Boron Nitride Nanoparticles on the Emulsion Stability, Viscosity and Electrochemical Behavior of Nanostructured Acrylic Coatings for the Corrosion Protection of AISI 304 Stainless Steel

In this study, the effect of pure and modified hexagonal boron nitride (h-BN) nanosheet incorporation on the stability, viscosity, and electrochemical behavior of a waterborne emulsion acrylic coating was studied. The functionalization of h-BN nanoplatelets with polyacrylic acid (PAA) plasma polymerization was performed, and the successful surface modification was determined through water dispersion testing, Fourier transform infrared spectroscopy and thermogravimetric analysis, X-ray photoelectron spectroscopy, and also by transmission electronic microscopy. Later, the stability and viscosity properties of emulsion nanostructured acrylic coatings, which were previously prepared by an ultrasound-assisted mixing system, were analyzed using zeta potential and rheometry testing, respectively. The electrochemical behavior was analyzed by electrochemical impedance spectroscopy. The results prove an effective deposition of PAA films on the h-BN surfaces, which enhanced the stability and viscosity acrylic of nanostructured coatings due to the interactions between the h-BN nanoplatelets surface and emulsion acrylic paint and also with the thickener additives. On the other hand, the electrochemical analysis demonstrated a significant increase (two orders of magnitude) in corrosion resistance in the acrylic nanostructured coatings with 1 wt.% of unmodified and modified h-BN nanoplatelets concerning pure acrylic paint due to a barrier protection mechanism of corrosion inhibition. Therefore, the results demonstrate that the surface modification of h-BN by plasma polymerization (green technology) helped to solve the low dispersibility issue of BN nanosheet surfaces in a waterborne polymer matrix to obtained green nanostructured acrylic coatings with the right balance in in-can properties and corrosion inhibition of AISI 304 stainless steel.

Surface and corrosion properties of AA6063-T5 aluminum alloy in molybdate-containing sodium chloride solutions

Corrosion properties of aluminum alloy AA6063-T5 were investigated in molybdate-containing NaCl solutions. Electrochemical, microscopic, and spectroscopic experiments were utilized to examine the mechanism of corrosion inhibition by molybdates. SEM-EDX, magnetic force, and intermodulation electrostatic force microscopy data suggested that the inhibition initiation preferentially occurred over Fe-rich cathodic IMPs. Spectroscopic measurements demonstrated that the formed surface layer consists of mixed Mo(VI, V, IV) species. This layer provided inhibition with an efficiency of ∼90% after 4 h of exposure. High efficacy of ∼70% was achieved even after one week of exposure. A two-step oxidation-reduction mechanism of corrosion inhibition by aqueous molybdates was proposed.

Inhibition behavior of synthesized ZIF-8 derivative for copper in sodium chloride solution

A zeolitic imidazole framework-8 (ZIF-8) derivative was synthesized and developed as the corrosion inhibitor of copper in 0.5 mol/L NaCl solution, and its inhibition performance was investigated by electrochemical measurement and surface analysis. Results show that the ZIF-8 derivative could effectively inhibit copper from corrosion, and the inhibition efficiency was 87.2% at an optimal ZIF-8 derivative concentration of 45 mg/L. The corrosion inhibition mechanism of the ZIF-8 derivative could be explained as follows: the amino functional groups and the π-system formed by aromatic rings of the ZIF-8 derivative were tightly adsorbed on the copper substrates, which systematically formed a hydrophobic film, thereby effectively inhibiting the corrosion caused by aggressive ions.

Imidazole derivatives as corrosion inhibitors for copper: A DFT and reactive force field study

We have investigated the corrosion inhibition mechanisms of imidazole, adenine, purine and 6-benzylaminopurine for copper using density functional theory (DFT) and reactive force fields (ReaxFF). The computed quantum chemical descriptors and interaction energy magnitudes correlate well with the experimental corrosion inhibition efficiencies: BAP > Adenine > Purine > Imidazole. The optimized geometries indicate formation of strong chemical bonds between surface Cu-atoms and N-atoms of the adsorbed molecules. This work shows the tremendous potential of ReaxFF calculations in successfully modeling adsorption of inhibitor molecules on metal surfaces at much lower computational costs compared to DFT.

Electrochemical and thermodynamic properties of 1-phenyl-3-(phenylamino)propan-1-one with Na2WO4 on N80 steel.

The corrosion inhibition effect and adsorption behaviour of 1-phenyl-3-(phenylamino)propan-1-one (PPAPO) on N80 steel in hydrochloric acid solution have been investigated by Fourier transform infrared (FTIR), electrochemical method and scanning electron microscopy. The corrosion inhibition mechanism of PPAPO mixed with Na2WO4 was interpreted from the thermodynamic point of view. The results indicated that PPAPO mixed with Na2WO4 acted as a mixed-type inhibitor. The inhibition film formed on N80 steel surface can increase the charge transfer resistance and prevent the occurrence of corrosion reaction, thereby reducing the corrosion rate of metal surface. The inhibition efficiency was up to 96.65%; the inhibitor PPAPO with Na2WO4 showed good synergistic effect on N80 corrosion behaviour in HCl solution. The adsorption behaviour of inhibitors on N80 steel surface was in accordance with the Langmuir adsorption model and mainly belonged to chemisorption. The adsorption process of PPAPO on N80 surface was spontaneous and irreversible endothermic reaction.

Corrosion Inhibition of Pipeline Steel in 0.5 M HCL Using Cotyledon of Chrysophyllum cainito

The corrosion inhibition characteristics of Chrysophyllum cainto cotyledon aqueous extract was studied for the corrosion of pipeline steel in 0.5 M HCl using gravimetric technique. The corrosion surface morphology and corrosion surface film were studied using Scanning electron microscope and Fourier transform infrared spectroscopy respectively. The results obtained showed Chrysophyllum cainto aqueous extract as a good corrosion inhibitors of pipeline steel corrosion in acidic environment, recording an average corrosion inhibition efficiency above 90% at 303 K. The Scanning electron micrograph showed a smoother corrosion surface morphology in the presence of the extract while the Fourier transform infrared spectroscopic data showed the corrosion inhibition mechanism to be through adsorption.

Inhibitory effect of a new isoniazid derivative as an effective inhibitor for mild steel corrosion in 1.0 M HCl: combined experimental and computational study

Controlling corrosion of metals such as mild steel (MS), which is extensively employed in various industrial fields, is a topic of great interest for researchers and scientists. At the same time, designing highly effective and environmentally friendly corrosion inhibitors is most desired yet still challenging. In this context, this study focuses on the use of a new corrosion inhibitor namely (E)-N′-(4-(2-(methyl(pyridin-2-yl)amino)ethoxy)benzylidene) isonicotinohydrazide (INH) as efficient, sustainable inhibitors for MS corrosion in acidic medium (1.0 M HCl). Different chemical, electrochemical and theoretical approaches were used to study and give new insights into the mechanism of corrosion protection of MS by the synthesized isonicotinohydrazide derivative. Experimental results disclosed that this compound could effectively control and reduce the corrosion of MS through physicochemical adsorption, which follows the Langmuir isotherm model. Potentiodynamic polarization technique (PDP) showed that the studied inhibitor affects both anodic and cathodic reactions; thus, it demonstrated that it is a mixed-type inhibitor. Moreover, surface characterization of metal by scanning electron microscope confirms that our inhibitor is subject to strong adsorption over the iron surface. Besides experimental techniques, theoretical approaches like DFT calculations, molecular dynamics simulation and radial distribution function were used to give precise information about the mechanism of corrosion inhibition and unveiled factors controlling the performance of the investigated inhibitor.

Electrochemical performance of PVA/Al2O3 composite in 3.5% NaCl

A new corrosion inhibitor namely poly(vinyl alcohol-Al2O3) composite (PVAl) has been synthesized and characterized by FTIR, XRD and SEM. Its influence on corrosion inhibition of mild steel in 3.5% NaCl solution has been studied by potentiodynamic and polarization techniques. The composite (PVAl) showed more than 95% inhibition efficiency (IE) at an optimum concentration of 0.6% by weight. The inhibition efficiency of inhibitor has been found to vary with inhibitor concentration. Potentiodynamic polarization studies showed PVAl as mixed type inhibitor. It inhibits mild steel corrosion by blocking the active sites of the metal. Electrochemical impedance spectroscopic (EIS) techniques were also used to investigate the mechanism of corrosion inhibition. The adsorption of the inhibitors on metal surface was further confirmed by surface analysis using SEM.

Calculation of Quantum Chemical Values of Corrosion Inhibitors Molecules by Heterocyclic Compounds

Theoretical concepts of inhibition mechanism in metal corrosion and forecasting of protective properties of substances are connected with experimental (electrochemical, adsorption, mechano-chemical) research. Inhibition mechanism may be fully demonstrated by comparing experimental research data with results of calculating quantum-chemical values of the proposed corrosion inhibitors molecules. The latter therewith enable to detect those physico-chemical characteristics that directly demonstrate protective properties of the inhibitor. Molecular moment, number of atoms in molecule and number of electrons in outer molecular orbitals are found to have maximum affect on the protection level. Application of petrochemical products including semi-finished products and petrochemical wastes for making new highly efficient and relatively inexpensive corrosion inhibitors is shown to be promising. Calculation results of quantum chemical values of corrosion inhibitors molecules by heterocyclic compounds may be used in learning corrosion inhibition mechanism by the compounds studied.

Study on Crack Initiation and Propagation of New Corrosion Inhibitor during Stress Corrosion of Aluminum Alloy

In this paper, a novel method combining electrochemical impedance spectroscopy (EIS) and phase shift was used to systematically study the effect of corrosion inhibitor (sodium succinate, sodium dodecyl benzene sulfonate, and new corrosion inhibitor, namely, bis [2-amino-3-(dodecyl dimethyl quaternary ammonium) propyl]-propylamine dichloro) on crack initiation and propagation of aluminum alloy during the slow strain rate tensile process. Using a variety of characterization methods to verify the feasibility of using the new method for in-situ prediction, Kramers–Kronig transformations have been used to validate the experimental data obtained with the EIS measurements. The corrosion inhibition mechanism of these three kinds of inhibitors in the SSRT process was analyzed.

Theoretical evaluation of corrosion inhibition performance of six thiadiazole derivatives

Corrosion inhibition mechanism of six 2-amino-5-alkyl-1,3,4-thiadiazole compounds, for metal surface corrosion was studied by combining quantum chemistry, molecular mechanics and molecular dynamics simulation methods. Molecular reactivity parameters such as [Formula: see text], [Formula: see text], Fukui index were obtained and revealed that the change in alkyl chain length has little influence on the reactivity of thiadiazole inhibitor molecules. Molecular mechanics calculation results show that the molecule with elongated alkyl chain could form self-assembled membrane with higher stability and coverage rate to prevent the diffusion of corrosive substances to metal surface. Molecular dynamics simulation revealed the -equilibrium adsorption behavior of these thiadiazole molecules on metal surface and the calculated results were in agreement with the experimentally determined inhibition efficiencies.

Amino acids as copper corrosion inhibitors: A density functional theory approach

Density functional theory was employed to investigate the corrosion inhibition mechanisms of four amino acids, viz. glutamic acid, cysteine, glycine, and their derivative glutathione. Quantum chemical descriptors such as highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, and energy gap (ΔEgap) were calculated to establish the relationship between the descriptors and corrosion inhibition efficiency. Further, in order to understand the adsorption mechanisms of amino acids with the copper surface, detailed adsorption studies were performed on Cu (1 1 1), Cu (1 0 0) and Cu (1 1 0) surfaces. The computed quantum chemical descriptors and the adsorption energies successfully predict the experimental inhibition efficiency trends. The optimized structures show formation of chemical bonds between the O, S, and N-atoms of the molecules and Cu (1 1 1) surface, confirmed by electron density difference and projected density of states plots Besides, the trends in computed adsorption energy were found to be unaffected by surface coverage studied by adsorbing multiple molecules (1–3) on Cu (1 1 1) surface.

Effects of Ultrafine Bismuth Powder on the Properties of Zinc Electrodes in Zinc-Air Batteries

Ultrafine spherical zinc powder prepared by direct-current arc plasma evaporation increased the capacity and life of zinc-air batteries. To decelerate the corrosion of the ultrafine zinc powder and improve the charge–discharge performance of the zinc-air batteries, we added different amounts of ultrafine bismuth powder to a zinc electrode. The hydrogen evolution rate of the Zn-Bi electrode and the properties of zinc-air batteries were investigated by hydrogen evolution experiments and electrochemical performance tests. The corrosion inhibition mechanism of the newly added bismuth powder on the zinc electrode was studied via x-ray diffraction, scanning electron microscopy and x-ray photoelectron spectroscopy. The results show that when the amount of the ultrafine bismuth powder was 1.5 wt.% of the zinc powder, the anticorrosion efficiency of the Zn-Bi electrode was the highest, reaching 53.8%. After the battery assembly, the Zn-Bi electrode reached a capacity retention rate of 84.6% and had a 21.7% higher specific capacity than that of a blank zinc electrode (419 mA h g−1 versus 344.3 mA h g−1) after 60 cycles. The ultrafine bismuth powder improved the nucleation efficiency, reduced the corrosion current, increased the polarization resistance threefold, and inhibited the formation of dendrites and corrosion, thereby increasing the battery specific capacity and cycle efficiency.

A novel slippery surface with enhanced stability and corrosion resistance

Herein, slippery liquid infused porous surface (SLIPS) was prepared by a facile spraying method with co-introduction of silica sol and carbon nanotubes (CNTs) and subsequent oil infusion. Abundant micropores and nanopores were formed during the solvent evaporation and silica sol shrinkage in molten PVDF process, both of which functioned as reservoirs to hold oil. Then the effects of CNTs on oil-holding capability and corrosion inhibition mechanism were investigated in detail. The interaction between SiO2 nanoparticles and CNTs endowed original hierarchical structures with more abundant morphologies and micropores quantities increasing. These two factors synergistically enhanced oil-locking ability, indicating more stable properties of SLIPS. With only 0.58 wt. % CNTs incorporation in SLIPS, it could lock 12 % more oil than unincorporated one under increasing high shear rates up to 5000 rpm/min. The Electrochemical Impedance Spectroscopy (EIS) results indicated that the |Z|0.01Hz of optimum SLIPS remained 1.41 × 109 after 10 days immersion in 3.5 wt. % NaCl solution, nearly 2 orders of magnitude higher than that of untreated SLIPS. The optimum SLIPS could maintain slippery properties even when subjected to some harsh manipulating environments including 12 h immersion in strong acid/alkali immersion, high temperature and abrasion.

The effect of the alkyl chain length on corrosion inhibition performances of 1,2,4-triazole-based compounds for mild steel in 1.0 M HCl: Insights from experimental and theoretical studies

The performance of two 1,2,4-triazole derivatives bearing an alkyl chain of variable length named 5-octylsulfanyl-1,2,4-triazole (TR8) and 5-decylsulfanyl-1,2,4-triazole (TR10) against mild steel (MS) corrosion in 1.0 M HCl was first evaluated utilizing experimental methods such as weight loss (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. Then, theoretical methods like Density Functional Theory (DFT) and molecular dynamics (MD) simulations were used to explore corrosion inhibition mechanisms. Effect of molecules on the MS surface was analyzed by scanning electron microscope (SEM) and atomic force microscopy (AFM). A correlation between corrosion inhibition properties and physicochemical and electronic properties as determined by DFT and MD was demonstrated. 1,2,4-triazole derivatives behave as effective inhibitors for MS corrosion in HCl at all concentrations tested with better efficacy at an optimal concentration of 10−3 M. The maximum inhibition efficiencies (based on EIS results) were obtained 92% and 88% for TR10 and TR8, respectively. The adsorption is following the Langmuir isotherm model. Theoretical studies clearly showed that differences in carbon chain length alter inhibition performances of inhibitors and were found to be compatible with experimental results.

Inhibition effect of the synergistic properties of 4-methyl-norvalin and 2-methoxy-4-formylphenol on the electrochemical deterioration of P4 low carbon mold steel

AbstractStudy of the synergistic inhibition properties of the combined admixture of 4-methyl-norvalin and 2-methoxy-4-formylphenol (non-toxic organic compounds) on the corrosion of P4 low carbon mold steel in 1.5 M H2SO4and HCl solution was performed with weight loss measurement, potentiodynamic polarization and optical microscopy analysis. Results obtained showed the inhibition efficiency of the admixed compound performed above the value for effective corrosion inhibition at very low concentrations in H2SO4solution. However, from mid concentration to the highest concentration studied, the inhibition efficiency of the compound was above 85% from electrochemical tests. In HCl solution the inhibition efficiency of the compound was well above 80% and 90% for weight loss and polarization tests at all concentration studied. Anodic corrosion inhibition mechanism was determined for the compound in H2SO4according to Freundlich and Frumkin adsorption isotherms due to weak Van der Waals attraction between the inhibitor molecules and the steel’s surface. The mechanism of corrosion inhibition in HCl was calculated to be cathodic type according to Langmuir isotherm model.Morphological images of inhibited and non-inhibited steel surfaces significantly contrast each other though the extent of deterioration was much severe for the steel from H2SO4solution.