جستجوی مقالات مرتبط با کلیدواژه « Potentiodynamic polarization » در نشریات گروه « شیمی »

Materials made with copper, find widespread use in various industries and several fields due to its important chemical and physical properties. However, these materials are susceptible to corrosion in harsh environments. This study explores the anti-corrosive properties of copper when exposed to solanum elaeagnifolium extract in 0.5 M H2SO4 solutions, employing electrochemical techniques such as electrochemical impedance spectroscopy and potentiodynamic polarization. The extract effectively protects by acting as a mixed-type inhibitor, as demonstrated by potentiodynamic polarization testing, with cathodic predominance. slowing down the cathodic and anodic reactions. An appropriate electrical analog circuit model was utilized to determine the electrochemical impedance characteristics. The analysis revealed that the inhibitor effectiveness is influenced by the inhibitor concentration, the temperature, and the exposure duration. This effectiveness achieved a maximum of 94% at a concentration of 2.5 g/L. The results obtained from electrochemical measurements are strongly supported by the examination of surface morphology. The addition of SE leads to a visibly smoother appearance of the copper, effectively suppressing corrosion of the copper sample. This observation implies the development of an SE–adsorption layer on the copper substrate.

The inhibition effect of Bhumyamalakhi (Phyllanthus Niruri) on 6061 aluminium alloy erosion-corrosion in simulated seawater was explored using potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS) techniques. Experiments were performed to examine the hydrodynamic effects on the behavior of the inhibitor. Conditions were optimized to achieve maximum inhibition efficiency by varying the concentration of inhibitor (500 and 1000ppm), temperature (30 , 40 , 50 ), and flowrate (4, 8, 12 L/min) of slurry. Surface morphology was studied with Scanning Electron Microscopy (SEM) and Energy Dispersion X ray (EDX) studies. The experimental findings indicated that an increase in flowrate and temperature decreased the efficiency of inhibitor and an increase in inhibitor concentration caused an increase in inhibitor efficiency. The inhibition efficiency of 80% and 53% was obtained at 30 °C and 50 °C at 4 L/min for 1000 ppm of inhibitor. Surface morphology demonstrated the complete damage of the material due to erosion corrosion and the surface became relatively smooth after the addition of the inhibitor.

Herein, an electroplating method has been developed in order to improve the anti-corrosion properties of steel. Ni-based compounds to which solid Al2O3 particles have been electrochemically inserted. Nickel-alumina mixtures were deposited on steel substrates from the electroplating bath using different concentrations of Al2O3. The electrochemical corrosion tests of the samples were carried out in two different solutions 0.5 M K2SO4 and 0.5 M NaCl. Structural and morphological analyzes were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled to microanalysis (EDAX) analyses respectively. The electrochemical behavior of co-electrodeposited coatings (Ni-Al2O3) in corrosive solutions was followed using potentiodynamic methods and electrochemical impedance spectroscopy (EIS). The various tests carried out under working conditions revealed that the Al2O3 particles added to the bath have a beneficial effect on the electrochemical behavior of the steel by reducing its tendency to corrosion. In this work, we were also able to determine the optimal concentration leading to significant inhibition of the steel tested. This synthesized and studied concentration related to Al2O3 was evaluated at around 20 g.L-1.

Herein, an electroplating method has been developed in order to improve the anti-corrosion properties of steel. Ni-based compounds to which solid Al2O3 particles have been electrochemically inserted. Nickel-alumina mixtures were deposited on steel substrates from the electroplating bath using different concentrations of Al2O3. The electrochemical corrosion tests of the samples were carried out in two different solutions 0.5 M K2SO4 and 0.5 M NaCl. Structural and morphological analyzes were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled to microanalysis (EDAX) analyses respectively. The electrochemical behavior of co-electrodeposited coatings (Ni-Al2O3) in corrosive solutions was followed using potentiodynamic methods and electrochemical impedance spectroscopy (EIS). The various tests carried out under working conditions revealed that the Al2O3 particles added to the bath have a beneficial effect on the electrochemical behavior of the steel by reducing its tendency to corrosion. In this work, we were also able to determine the optimal concentration leading to significant inhibition of the steel tested. This synthesized and studied concentration related to Al2O3 was evaluated at around 20 g.L-1.

The present work deals with the corrosion inhibition mechanism of mild steel in 1 M H2SO4 employing the new carbonitrile derivative viz. 2-amino-4-(4-hydroxyphenyl)-6-(p-tolyl)-4H-pyran-3-carbonitrile (HCN). A such mechanism was elicited by means of the potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques and weight loss (WL). The experimental results revealed maximal inhibition efficiency (IE) rates up to 92.4% in weight loss. WL measurement revealed a decrease in corrosion rate with increasing concentration of corrosion inhibitor and decreasing with increasing temperature up to 333 K. The Nyquist curves indicated that the corrosion inhibition was controlled by a charge transfer process whereas the PDP curves showed that the HCN behaved as a mixed-type corrosion inhibitor. The Langmuir isotherm was used to determine the adsorption thermodynamic parameters. Thermodynamic characteristics for activation and adsorption were determined and discussed. Adsorption free energy at 303 K ( = -22.26 kJ mol-1 for HCN) indicated a combination of chemisorption and physisorption. The inhibitor (HCN) formed a protective layer that acted as a barrier between the surface of the metal and the acid medium which was investigated through surface studies like Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS).  The surface studies were in coincidence with weight loss and electrochemical studies. Density functional theory (DFT) was performed to support the experimental data in an aqueous medium using the basis set 6-311G(d,p). From the Mulliken population analysis, the adsorption sites have been studied and the results of DFT were steady with the experimental studies.

[3-(4-Methoxyphenyl)isoxazole-5-yl]-methanol was synthesized and used as an efficient inhibitor to protect copper in 1 M sulfuric acid solution. Corrosion studies were performed by electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), and quantum chemical calculations (Gaussian). The effect of temperature on the copper corrosion and inhibitor performance was also investigated. The data obtained from the analysis of the polarization curves disclosed that the corrosion current density (Icorr) of the metal dissolution decreased in the presence of inhibitor. This may indicate a reduction in the corrosion rate, resulting from the adsorption of inhibitor molecules on the active sites of the copper surface. Such a result was confirmed by the measured Nyquist diagrams, where total resistance increased with the addition of inhibitor to the medium. Langmuir’s adsorption isotherm was confined as best fitted isotherm describes the physical-chemical adsorption capability of the inhibitor on the copper surface. The results revealed that [3-(4-Methoxyphenyl)isoxazole-5-yl]-methanol could effectively improve the corrosion resistance of copper. The theoretical calculation of quantum chemical demonstrated the experimental findings.

Plant extracts are extensively researched as a source of green corrosion inhibitors. Herein, we report on a highly efficient and thermally stable corrosion inhibitor from the stem extract of high-altitude shrub Berberis aristata. The corrosion inhibition efficiency (IE) of the extract was tested in 1.0 M H2SO4 for the corrosion protection of mild steel (MS) by using gravimetric and electrochemical measurements. It displayed a remarkable IE of 90% at 200 ppm and reached to 98.18% at high concentration (1000 ppm) at room temperature. The thermal stability of the adsorbed extract was uncommon among the recently reported plant extracts, giving an IE of 80% at 338K. Besides, the adsorption of the extract was extremely efficient, producing an IE of 90% in 15 min. The thermodynamic parameters (ΔG and Ea) showed a chemisorption dominated behavior of the extract. Electrochemical measurements indicated a mixed type of inhibitor, and the extract suppressed the corrosion rate by blocking the active surface of the MS.

The inhibition effect of three acetanilide compounds namely acetanilide (Ac1), o-methyl acetanilide (Ac2) and p-nitroacetanilide (Ac3) on the corrosion of 304L in 1 M HCl solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy methods. The results show that compound Ac3 is the best inhibitor and the inhibition efficiency follows the order: Ac3>Ac2>Ac1. Potentiodynamic polarization curves indicated that the inhibitors acted as mixed-type inhibitors. The adsorption of inhibitors on the stainless steel surface obeys to the Langmuir adsorption isotherm and has physisorption mechanism. All techniques employed in this study show the same order of inhibition efficiency.

In this research, plasma electrolytic oxidation (PEO) coating on AZ31B magnesium alloy having various concentrations has been studied in order to amend the surface corrosion resistance. To do this, phosphate electrolyte with different concentrations of 4, 8 and 10 g/l is investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization tests on an uncoated base alloy and a coated one are studied in a body simulant physiological solution (Ringer's solution). Surface morphology and microstructural surveys were done by X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM). The obtained results of this study displayed that rising the sodium phosphate concentration led to an increase in coating thickness and decreases its porosity. The highest corrosion resistance arose from the lowest corrosion current density (0.45×10-6 A/cm2) of the formed coating in electrolyte containing 10 g/l sodium phosphate.

The present work describes the application of expired drug Lumerax as corrosion inhibitor for mild steel (MS) in 1 M HCl after its expiry date using gravimetric measurements, electrochemical studies and surface analysis. The adsorption of Lumerax on MS surface obeys the Langmuir isotherm. And protection film confirmed by SEM and AFM. Impedance analysis showed that the presence of inhibitor considerably affects the charge transfer resistance and the double layer capacitance of MS surface. Potentiodynamic polarization shows that Lumerax behaves as a mixed type corrosion inhibitor.DFT calculations were used to evaluate the structural, electronic and reactivity parameters of the drug components (Artemether and Lumefantrine) and the theoretical investigation verifies the validity of the use of expired Lumerax drug as a novel and efficient corrosion inhibitor for mild steel.

The present study aims at investigating the corrosion inhibition performance of a new triazole inhibitor namely (Z)-4-((2,4-dihydroxybenzylidene) amino)-5-methy-2,4dihydro-3H-1,2,4-triazole-3-thione on mild steel corrosion in 1.0 M HCl solution using weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization measurements and density functional (DFT) methods. The results show that inhibition efficiency increases with increase in the inhibitor concentration and maximum inhibition efficiency of 80.74% was obtained at a concentration of 10-3 M. The corrosion behavior was also studied in the absence and presence of inhibitor at various concentrations in the temperature range of 318-348 K. Potentiodynamic polarization results showed that the inhibitor is mixed-type. The Nyquist plots showed that on increasing the inhibitor concentration charge-transfer resistance increased and double-layer capacitance values decreased thereby suggesting that corrosion inhibition is charge transfer controlled process and inhibition occurs due to the adsorption of inhibitor molecules on the metal surface. The adsorption of inhibitors followed Langmuir a isotherm Quantum chemical calculations very well supported the experimental results.

In this study, corrosion behavior of copper that was deformed by Simple Shear Extrusion (SSE) method was investigated in 3%wt NaCl solution. Modified Williamson-Hall method, applied on the X-ray diffraction patterns of the samples, showed that increase in the number of SSE passes led to increasing in the dislocation density in the copper samples. Moreover, such deformed samples exhibited fewer corrosion currents, in the potentiodynamic polarization test results, than that of annealed one. In addition, Electrochemical Impedance Spectroscopy (EIS) test was employed to assess the SSEed copper corrosion performance, and the results revealed that the SSE technique has a beneficial effect on the corrosion behavior of copper in 3 wt% NaCl aquatic solution.