Electrochemical Behavior Of Mild Steel Research Articles

Electrochemical behavior of mild steel coated with long alkyl-chain benzothiazole derivatives in acid solution: Effect of aliphatic chain length

Mild steel surfaces were coated with four different benzothiazole derivatives with long alkyl chain, namely 2-(heptyl)-benzothiazole (HEBT), 2-(tridecyl)-benzothiazole (TDBT), 2- (pentadecyl)-benzothiazole (PDBT), and 2-(heptadec-8-en-1-yl)benzothiazole (HDBT) from their respective chloroform solutions. Electrochemical experiments were conducted with coated and uncoated mild steel samples exposed to 1 M aqueous HCl at temperatures between 20°C to 50°C and at different immersion times from 6 h to 48 h. TDBT behaves as the best corrosion inhibitor among the four (more than 99 % efficiency at 40°C) and the order of inhibition efficiency follows the trend: TDBT>HDBT>PDBT>HEBT. This reflects the inhibition efficiency to increase with chain length initially, but decreases after a threshold. HDBT, in-spite of having longest aliphatic chain, exhibits better inhibitory performance over PDBT. This is attributed to the presence of unsaturation in HDBT. TDBT coating maintains high corrosion inhibition efficiency even after the 24 h of exposure (above 98 %). Occurrence of spatial hindrance during adsorption of BT derivatives with long aliphatic chain has been manifested by MD simulation.

Two novel phosphoramide derivatives moiety as corrosion inhibitor for mild steel: Experimental and theoretical study

Two novel phosphoramide containing thiazole derivatives with the name of bis(5‐amino‐1,3,4‐thiadiazol‐2‐yl) phenylphosphonotrithioate (C1) and O, O‐diethyl (5‐((diethoxyphosphorothioyl) thio)‐1,3,4‐thiadiazol‐2yl) phosphoramidothioate (C2) as corrosion inhibition were synthesized and identified by 1H NMR, 13C NMR, 31P NMR, IR, and mass spectroscopies. The electrochemical behavior of mild steel (MS) in hydrochloric acid 1‐M (HCl) solution was perused in the absence and presence of C1 and C2. To determine corrosion inhibition of phosphoramide compounds, scanning electron microscopy (SEM), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were used. The EIS results show that the charge transfer resistance increases with the addition of inhibitors to the hydrochloric acid solution. The most inhibitor efficiency was 89%, which demonstrated the appropriate anti‐corrosion property of C1. EIS results show better charge transfer resistance on the surface of MS at increased inhibitor concentrations. The PDP analysis showed that C1 and C2 are mixed‐type inhibitors. The PDP examination appeared that C1 and C2 are mixed‐type inhibitors. To way better get the comes about of corrosion inhibition and structure of target compounds, the highest occupied molecular orbital (HOMO) and least unoccupied molecular orbital (LUMO) energies, hardness, dipole moment, and electrophilicity index of synthesized compounds were explored computationally using the density functional theory (DFT) strategy. The hypothetical comes about in great understanding with the exploratory information.

The Inhibition Effect of (E)-2-Hydroxy-5-(2-benzylidene) Aminobenzoic Acid on Corrosion behaviour of Mild Steel in 1.0 M HCl Solution

It has recently been synthesized a Schiff base (E)-2-hydroxy-5-(2-benzylidene) aminobenzoic acid and characterized by FTIR, UV–vis and 1H NMR analysis. The electrochemical behaviour of mild steel in 1.0 M HCl solutions in the absence and presence of Hha has been investigated by electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy. The inhibition efficiency was found to increase with rise in concentration of synthesized molecule. Scanning electron microscopy observations of mild steel surface confirmed the existence of such an adsorbed film. Contact angle on the metal surface was also measured. Computational analyses of (E)2-hydroxy-5-((2-hydroxybenzylidene) amino benzoic acid were done at B3LYP/6-31G(d) level in gas phase. Sensitivity of this compound towards Fe2+ and Fe3+ ions were determined. Interaction mechanism was proposed.

Experimental and Theoretical Studies of Mild Steel Corrosion Inhibition in Phosphoric Acid Using Tetrazoles Derivatives

The electrochemical behavior of mild steel in phosphoric acidic solutions was investigated in the absence and presence of three heterocyclic tetrazoles derivatives using polarization and electrochemical impedance techniques. The corrosion rate is affected by both acid and inhibitors concentration. Inhibitors reduce the corrosion rate values by suppression of anodic dissolution of steel rather than the cathodic process of hydrogen evolution. Corrosion potential values were shifted to positive direction. Addition of inhibitors did not change the mechanism of corrosion process, which indicates that these compounds act by forming a film on metal surface. Impedance measurements showed that the charge transfer resistance increases and the double layer capacity decreases with addition of inhibitors. Charge transfer resistance increased with time. Maximum inhibitor efficiency was 71.5%, which leads to conclude that the studied inhibitors represent moderate anticorrosion materials. Quantum chemical investigations were also used to optimize the chemical structure of inhibitors.

Influence of Grain Size on Corrosion Resistance and Electrochemical behaviour of Mild Steel

Influence of Grain Size on Corrosion Resistance and Electrochemical behaviour of Mild Steel

A study of the electrochemical behaviour of mild steel in potassium gluconate-0.5 M hydrochloric acid solution: grey relational model

The inhibition effect of potassium gluconate on the corrosion behaviour of mild steel in 0.5 M HCl at ambient temperature has been examined by open circuit potential and potentiodynamic polarization measurements. Morphology of the mild steel specimens was studied using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS) before and after corrosion tests. The corrosion rate decreased with an increase in inhibitor concentration. The inhibition efficiency increased with increasing concentration of inhibitors. Results show that potassium gluconate is a mixed type inhibitor; the adsorption of the inhibitor on the mild steel surface is in agreement with Frumkin, Langmuir, and Freundlich adsorption isotherm. The grey relational model used corresponds with the experimental results.

Effect of Dissolved Oxygen and Immersion Time on the Corrosion Behaviour of Mild Steel in Bicarbonate/Chloride Solution.

The electrochemical behavior of mild steel in bicarbonate solution at different dissolved oxygen (DO) concentrations and immersion times has been studied under dynamic conditions using electrochemical techniques. The results show that both DO and immersion times influence the morphology of the corrosion products. In comparative tests, the corrosion rate was systematically found to be lower in solutions with lower DO, lower HCO3− concentrations and longer immersion time. The SEM analyses reveal that the iron dissolution rate was more severe in solutions containing higher DO. The decrease in corrosion rate can be attributed to the formation of a passive layer containing mainly -FeO (OH) and (-Fe2O3/Fe3O4) as confirmed by the X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Passivation of mild steel is evident in electrochemical test at ≈ −600 mVSCE at pH 8 in dearated (0.8 ppm DO) chloride bicarbonate solution under dynamic conditions.

Electrochemical behaviour of Mild Steel in Acidic Medium Based on Eco-Friendly Stabilized Monodisperse Silver Nanocomposite

Electrochemical behaviour of Mild Steel in Acidic Medium Based on Eco-Friendly Stabilized Monodisperse Silver Nanocomposite

Effect of Ferrous Gluconate Inhibition on the Electrochemical Behaviour of Mild Steel in 3.5% NaCl

Effect of Ferrous Gluconate Inhibition on the Electrochemical Behaviour of Mild Steel in 3.5% NaCl

Electrochemical investigation of Substituted Pyranopyrazoles Adsorption on Mild Steel in Acid Solution

Four substituted pyranopyrazole derivatives (PPZs) were synthesized and their effects on the electrochemical behavior of mild steel in 1 M HCl were investigated using gravimetric measurements, Tafel extrapolation method, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS). Tafel polarization measurements revealed that these compounds effectively suppressed both the anodic and cathodic processes of mild steel corrosion in acid solution and acted as mixed-type inhibitors. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) examinations of electrode surface confirmed the existence of adherent layer of inhibitor on electrode surface. The UV–visible absorption spectrum of inhibitor solution containing mild steel indicated the formation of Fe–PPZ complex. Quantum chemical calculations have been used to evaluate the structural, electronic, and reactivity parameters of the selected pyranopyrazole derivatives in relation to their inhibition action.

Novel molecular approach using triazine inhibitor to control corrosion and limit chloride ion penetration in steel reinforced concrete

The presence of chloride ions exceeding its critical concentration in its surrounding is one of the major causes for reinforcing steel corrosion, and subsequently, reduction in the strength of the structure occurs. A common method of preventing such deterioration is to prevent chlorides from penetrating the structure to the level of the reinforcing steel bar by organic corrosion inhibitors. The electrochemical behaviour of mild steel in seawater with or without 4[{(4,6-diamino-1,3,5-triazine-2-yl)imino}methyl]-2,5-cyclohexadiene-1-one, a new triazine inhibitor, is identified and synthesised by Insilco techniques in parts I and II of our previous study. Part III presents the evaluation of the new inhibitor in reinforced steel concrete specimens by current induced accelerated corrosion method and also its performance to prevent chloride penetration in concrete structures. Tests were conducted to Indian standards, ASTM standards and Council of Scientific and Industrial Research guidelines to control rebar corrosion. Results showed that the inhibitor efficiency is up to 85%, and also the rate of chloride penetration into the concrete specimens was decreased when the new inhibitor is used as admixture. In addition, the relationship between the molecular structure of these compounds and their inhibition efficiency has been investigated by ab initio quantum chemical calculations using Cerius software program.

Effect of New Synthesised Pyridazine Derivatives on the Electrochemical Behaviour of Mild Steel in 1M HCl Solution: Part-1

Effect of New Synthesised Pyridazine Derivatives on the Electrochemical Behaviour of Mild Steel in 1M HCl Solution: Part-1

A comparative study on the electrochemical behavior of mild steel in sulfamic acid solution in the presence of monomeric and gemini surfactants

The electrochemical behavior of mild steel in sulfamic acid solution in the presence of a gemini cationic surfcatant, butanediyl-1,4-bis(dodecyldimethylammonium bromide (12-4-12), and its monomeric counterpart, dodecyltrimethylammonium bromide (DTAB), was investigated as a function of the surfactant concentration by means of electrochemical impedance spectroscopy (EIS). The critical micelle concentration (cmc) values of DTAB and 12-4-12 in 1 M sulfamic acid solution, measured by surface tension measurement, were found to be 1.2 and 0.02 mM, respectively. The EIS results revealed a higher charge transfer resistance in 12-4-12 solution compared to that in DTAB solution at the same concentration normalized by the cmc (c/cmc). The morphology of the steel samples after being exposed to the acidic test solutions was examined by atomic force microscopy (AFM). The AFM micrographs showed a reduction of surface roughness in the presence of the surfactant which is more evident at higher surfactant concentrations. The adsorption of both surfactants in the sulfamic acid solution was studied by Langmuir and Flory-Huggins adsorption isotherms at submicellar concentrations.

Electrochemical Behavior of Mild Steel in Dimethyl Sulfoxide Containing Hydrochloric Acid

The corrosion behavior of mild steel in dimethyl sulfoxide containing various concentrations, i.e., 0.001, 0.005, 0.010, 0.015 and 0.020 M of hydrochloric acid has been studied in presence of 0.1 M tetra ethyl ammonium chloride as supporting electrolyte by applying electrochemical techniques. The results of these experiments have been supplemented by surface analysis of the samples exposed to corrosive solution under different experimental conditions. The electrochemical investigation was done potentiostatically by varying the concentration of HCl in DMSO and the experimental temperature as well.

Acetyl thiourea chitosan as an eco-friendly inhibitor for mild steel in sulphuric acid medium

Acetyl thiourea chitosan polymer (ATUCS) has been synthesized and evaluated as corrosion inhibitor. The electrochemical behavior of mild steel in naturally aerated 0.5 M H 2SO 4 acid containing different concentrations of ATUCS has been studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The results of EIS showed that the resistance ( R t) increases slightly with increasing immersion time indicating a slight decrease in corrosion rate of the steel with time. Also, the corrosion rate increases with either increasing temperature or decreasing the polymer concentration as observed by polarization technique. Electrochemical impedance spectroscopy measurements under open-circuit conditions confirmed well polarization results. ATUCS has shown very good inhibition efficiency (IE) in 0.5 M sulphuric acid solution reaches to 94.5% for 0.76 mM concentration. IE of this compound has been found to vary with the concentration of the polymer solution, immersion time and temperature.

The effect of benzimidazole and zinc acetylacetonate mixture on cathodic disbonding of epoxy coated mild steel

Electrochemical behavior of mild steel in the presence of zinc acetylacetonate (Zn(acac) 2) and benzimidazole (BIMIDA) was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution and compared to zinc phosphate (ZP) pigment and zinc potassium chromate (ZPC) pigment extracts. Results showed superior performance of Zn(acac) 2 and BIMIDA mixture (ZBM) compared to ZP pigment, while it introduced inferior inhibitive action compared to ZPC pigment. The epoxy coatings were formulated with ZBM as anticorrosive additive, ZP and ZPC pigments. The disbonding rate of coated steel follows the order: Blank > ZP > ZBM > ZPC. EIS results showed a complex film could be formed at the hole area for the coatings formulated with ZP, ZBM and ZPC. It is concluded that the stronger the complex film on the surface, the lesser the cathodic disbonding rate would be.

The influence of different variables on the electrochemical behavior of mild steel in circulating cooling water containing aggressive anionic species

Cyclic voltammetric, potentiodynamic anodic polarization and current–time transient studies were carried out on mild steel in circulating cooling water containing Cl− and SO 4 −2 ions under the effect of different variables such as coolant flow, the availability of oxygen, cooling system temperature, and cooling system pH. The anodic excursion span of mild steel in cooling corrosive solution was characterized by the occurrence of a well-defined anodic peak (A1), while the reverse sweep was characterized by the appearance of two cathodic peaks (C1 and C2). The presence of Cl− and SO 4 −2 ions in cooling water enhance the active dissolution of mild steel and tend to breakdown the passive film and induce pitting attack. The data reveal that increasing flow rate and temperature of cooling solution enhances the anodic peak current density (j A1) and shifts the pitting potential (E pit) towards more active values. It is seen that the peak current density of the anodic peak A1 increases and the pitting potential (E pit) displaced in the noble direction in the aerated solution compared that in de-aerated solution. The pitting corrosion of mild steel by Cl− and SO 4 −2 ions initiates more readily in acidic medium (pH 2.0). It was found that the incubation time (t i) increase and in turn the pitting corrosion decrease in the order: pH 10 > pH 6.8 > pH 2.0.

The Electrochemical Behavior of Mild Steel in Sulfide Polluted NaCl at Different Velocities

The Electrochemical Behavior of Mild Steel in Sulfide Polluted NaCl at Different Velocities

Synergistic effect of benzoate and benzotriazole on passivation of mild steel

The electrochemical behaviour of mild steel was investigated in near neutral air saturated solutions containing benzoate (Bzo) and benzotriazole (BTA), separately or mixed. In the benzoate/BTA mixtures the open circuit passivation was found to be much better than in pure benzoate electrolytes. Electrochemical impedance spectroscopy (EIS) measurements resulted in characteristic Bode plots due to the synergistic effect of both inhibitors in the presence of oxygen. Open circuit potential (OCP) measurements vs. time supported the observed behaviour. The inhibition effect can be attributed to the blocking of surface sites for anodic dissolution by benzoate and a subsequent strong adsorption of benzotriazole on the natural oxide layer.

Effect of the molecular weight and structure of some novel water-soluble triblock copolymers on the electrochemical behaviour of mild steel

The inhibitive performance of novel synthesised water-soluble triblock copolymers – 2-(diethylamino)ethyl methacrylate- block-2-(dimethylamino)ethyl methacrylate- block-2-( N-morpholino)ethyl methacrylate [PDEA-PDMA-PMEMA] and 2-(diisopropylamino)ethyl methacrylate- block-2-(dimethylamino)ethyl methacrylate- block-2-( N-morpholino)ethyl methacrylate [PDPA-PDMA-PMEMA] of two different molecular weight – on the corrosion behaviour of mild steel in 0.5 M HCl were investigated using potentiodynamic polarisation, electrochemical impedance spectroscopy and linear polarisation methods. Polarisation curves indicate that all studied copolymers were acting as mixed type inhibitors. All measurements show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on steel surface. Adsorption of these inhibitors follows Langmuir adsorption isotherm. Thermodynamic parameters of adsorption ( K ads, Δ G ads) of studied triblock copolymers were calculated using Langmuir adsorption isotherm. The variation in inhibitive efficiency mainly depends on the type and the nature of the substituents present in the inhibitor molecule and also depends on the molecular weight of the inhibitors. The correlation between the inhibition efficiencies of studied triblock copolymers and their molecular structures has been investigated using quantum chemical parameters obtained by PM3 semi-empirical SCF-MO methods. These results indicate that adsorption of studied triblock copolymers depends on the charge density of adsorption centres and dipole moments.