Experimental and molecular dynamics studies on corrosion inhibition of mild steel by 2-amino-5-phenyl-1,3,4-thiadiazole

The corrosion inhibition of mild steel in 0.5 M H₂SO₄ and 1.0 M HCl by 2-amino-5-phenyl-1,3,4-thiadiazole (APT) has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the inhibition efficiency increases with the increase of APT concentration in both acids, and the higher inhibition efficiency is obtained in 0.5 M H₂SO₄. The adsorption of APT molecules on the steel surface obeys Langmuir adsorption isotherm in both acids, and occurs spontaneously. The molecular dynamics method has also been used to simulate the adsorption of ATP molecule and solvent ions on the iron surface. The results show that with the adsorption of sulfate ions the Fe + anion + APT system has the higher negative interaction energy comparing to the case of the adsorption of chloride ions.     

纯镁在1.0%NaCl中性溶液中的腐蚀与电化学行为(英文)

研究纯镁在1.0%NaCl中性溶液中的腐蚀行为及其相应的电化学阻抗谱(EIS)和极化曲线,探讨不同时间段EIS的分形维数。结果表明,腐蚀过程及相应的EIS发展可分为3个阶段。初始阶段,EIS由2个重叠的容抗弧组成,相应的极化电阻及电荷转移电阻随着时间的延长而快速增加,而腐蚀速率则降低。而后,EIS图谱上出现2个容易辨认的容抗弧,电荷转移电阻及腐蚀速率基本保持稳定。长时间浸泡后,EIS图谱中低频部分出现感抗成分,电荷转移电阻降低,而腐蚀速率增加。EIS分形维数与材料表面形貌直接相关,将是分析腐蚀形貌极有用的工具。     

Synthesis and evaluation of Tris-hydroxymethyl-(2-hydroxybenzylidenamino)-methane as a corrosion inhibitor for cold rolled steel in hydrochloric acid

Tris-hydroxymethyl-(2-hydroxybenzylidenamino)-methane (THHM) was synthesized. The effect of THHM on the corrosion of cold rolled steel (CRS) in 0.1 M hydrochloric acid was then investigated by Tafel polarization curve and electrochemical impedance spectroscopy (EIS). Polarization curve results clearly reveal the fact that THHM is a good cathodic type inhibitor. EIS results confirm its corrosion inhibition ability. The inhibition efficiency increases with increasing THHM concentration but decreases with immersion time. Atomic force microscopy (AFM) reveals that a protective film forms on the surface of the inhibited sample. The adsorption of this inhibitor is found to follow the Langmuir adsorption isotherm. THHM adsorbs on the sample probably by chemisorption.     

2-Amino-5-ethyl-1,3,4-thiadiazole as a corrosion inhibitor for copper in 3.0% NaCl solutions

2-Amino-5-ethyl-1,3,4-thiadiazole (AETDA) has been evaluated as a corrosion inhibitor for copper in 3.0% NaCl solutions using weight loss, pH, potentiodynamic polarization, potentiostatic current–time, and electrochemical impedance spectroscopic (EIS) measurements. The study was also complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. Weight loss measurements gave an inhibition efficiency of about 60% with 1.0 × 10⁻³ M AETDA present, increasing to about 97% at the AETDA concentration of 5.0 × 10⁻³ M. Potentiodynamic polarization measurements showed that the presence of AETDA in de-aerated, aerated and oxygenated 3.0% NaCl solutions decreases cathodic, anodic, and corrosion currents to a great extent and shifts the corrosion potential slightly towards more negative values. Potentiostatic current–time measurements, SEM and EDX investigations also confirmed that the protection of the copper surface is achieved by strong adsorption of AETDA molecules. EIS measurements revealed that the surface and the charge transfer resistances increase upon increasing the AETDA concentration. Results together showed clearly that AETDA is a good mixed-type inhibitor for copper corrosion and its inhibition efficiency increases in the order of oxygenated > aerated > de-aerated 3.0% NaCl solutions.     

Inhibition of 304 stainless steel corrosion in acidic solution by Ferula gumosa (galbanum) extract

The inhibition effect of the extract of galbanum (Ferula gummosa Boiss.) on the corrosion of 304 stainless steel in 2 M HCl solution was studied by weight loss measurements, Tafel polarization, and electrochemical impedance spectroscopy (EIS) methods. It was found that the inhibition efficiency (IE) increases as the extract concentration is increased. Tafel polarization method revealed the mixed mode inhibition of galbanum extract (GE) with predominant control of anodic reaction. The effect of temperature on the corrosion behavior of steel indicates that inhibition efficiency of the natural substance increases with the rise in temperature. At all temperatures, the adsorption of the extract components onto the steel surface was found to follow the Temkin adsorption isotherm.     

Synergistic effect of potassium iodide with phthalazone on the corrosion inhibition of mild steel in 1.0 M HCl

The effects of phthalazone (PTO) and its synergistic effect with KI on the corrosion of mild steel in 1.0 M HCl solution were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The inhibition efficiency increases with the concentration of the inhibitor and increased further with the presence of 6.02 mM KI. The synergistic effect of 6.02 mM KI at different concentrations of PTO was determined by calculating the synergism parameters, which showed that a cooperative mechanism exists between the iodide anion and PTO cations.     

The corrosion inhibition of copper in hydrochloric acid solutions by a tripeptide compound

The efficiency of glutathione as a non-toxic corrosion inhibitor for copper in 0.5 M HCl has been studied by using the weight-loss technique, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Maximum protection efficiency reaches about 92.7% for glutathione at 10 mM concentration level. Results obtained from potentiodynamic polarization and impedance measurements are in good agreement. The adsorption of glutathione on copper surface follows Langmuir isotherm. The adsorption free energy of glutathione on copper (−32 kJ mol⁻¹) reveals a strong physical adsorption of the inhibition on the metal surface.     

Control of zinc corrosion in acidic media: Green fenugreek inhibitor

Fenugreek seeds extract was examined as a green corrosion inhibitor for Zn in 2.0 mol/L H₂SO₄ and 2.0 mol/L HCl solutions by mass loss and electrochemical measurements. Scanning electron microscope (SEM) images show that the surface damage is decreased in the presence of the inhibitor. X-rays photoelectron spectroscopy (XPS) analysis was performed to identify the corrosion product, ZnO, and to prove the inhibitor adsorption mechanism. The maximum inhibition efficiency values are 90.7% after 1 h and 66.6% after 0.5 h by 200 mL/L of fenugreek extract in H₂SO₄ and HCl solutions, respectively. Addition of I⁻ ion greatly improves the inhibition efficiency of fenugreek seeds extract for Zn corrosion in HCl due to the synergistic effect. Potentiodynamic polarization and EIS measurements prove the inhibition ability of fenugreek for Zn corrosion in HCl as indicated by the decreased corrosion current density and increased charge transfer resistance values in the presence of fenugreek.     

Experimental and theoretical evaluation of semicarbazones and thiosemicarbazones as organic corrosion inhibitors

The inhibition ability of four thiosemicarbazones (1A–D) and two semicarbazones (2A–B) towards carbon steel corrosion in 1.0 M HCl was evaluated by molecular modeling, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) at different inhibitor concentrations. Polarization curves showed that all of the evaluated compounds acted as mixed inhibitors. EIS plots indicated that the presence of the inhibitors increases the charge transfer resistance of the corrosion process, increasing the inhibition efficiency. The adsorption of the evaluated inhibitors obeys the Langmuir adsorption isotherm. The theoretical results were corroborated by experimental data, with both the experimental and theoretical data showing that the thiosemicarbazones are better corrosion inhibitors than the semicarbazones.     

Acid violet 6B as a novel corrosion inhibitor for cold rolled steel in hydrochloric acid solution

The inhibition effect of acid violet 6B (AV6B) on the corrosion of cold rolled steel (CRS) in 1.0–5.0 M HCl solution was studied for the first time by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that AV6B is a very good inhibitor in 1.0 M HCl, and the adsorption of AV6B on CRS surface obeys Langmuir adsorption isotherm. Polarization curves reveal that AV6B behaves as a mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. Effects of immersion time and acid concentration on inhibition performance were also discussed.     

Potent inhibition of copper corrosion in neutral chloride media by novel non-toxic thiadiazole derivatives

Inhibiting effect of two novel non-toxic thiadiazole derivatives on copper were investigated in 3.5% NaCl solution using weight loss and electrochemical measurements. Presence of inhibitors and increase of concentration greatly decrease corrosion rate, parameters determined from polarization curves and EIS plots show that inhibitors decrease both cathodic and anodic current densities, suppressing charge transfer process by adsorption on copper surface. Thermodynamic calculation indicates chemisorption obeys Langmuir isotherm. Surface layers were characterized by SEM coupled with EDX. Raman micro-spectroscopy reveals that inhibitor molecules suppress copper corrosion via formation of thiadiazole–Cu complex. Relationships between inhibition efficiency and molecular orbital were also evaluated.     

Effect of Schiff base as corrosion inhibitor on AZ31 magnesium alloy in hydrochloric acid solution

Schiff base derived from the condensation reaction of analar grade 1-amino-2-naphthol 4-sulphonic acid with cinnamaldehyde was prepared under microwave condition. The Schiff base was analysed by infrared spectroscopy. This Schiff base as a corrosion inhibitor of AZ31 magnesium alloy in 0.05 mol/L HCl solution was studied. The inhibition effect of the Schiff base compound (4Z)-4-(3-phenyl allylidene amino)-3-hydroxy naphthalene-1-sulfonic acid (AC) on AZ31 magnesium alloy corrosion was studied using mass loss, potentiodynamic polarization technique, electrochemical impedance spectroscopy methods. The potentiodynamic polarization curve shows that Schiff base AC inhibits both anodic and cathodic reactions at all concentration, which indicates it is a mixed type inhibitor. EIS results indicate that as the additive concentration is increased, the polarization resistance increases whereas double-layer capacitance decreases. The adsorption of AC on the AZ31 magnesium alloy surface in 0.05 mol/L HCl obeys the Langmuir adsorption isotherm.     

Corrosion Mitigation of Copper in Acidic Chloride Pickling Solutions by 2-Amino-5-ethyl-1,3,4-thiadiazole

Corrosion of copper in acidic chloride pickling solutions of 0.5 M HCl and its mitigation by 2-amino-5-ethyl-1,3,4-thiadiazole (AETDA) have been investigated using potentiodynamic polarization, chronoamperometry, electrochemical impedance spectroscopy (EIS), and weight-loss measurements. The study was also complemented by scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and UV-Visible absorption spectroscopy investigations. The presence of AETDA and the increase of its concentration in the chloride solutions greatly decreased the corrosion rate and increased the surface and polarization resistances of copper as indicated by the electrochemical measurements. Weight-loss data also indicated that AETDA decreases the dissolution of copper coupons in the studied chloride solution. SEM/EDX investigations showed that AETDA molecules are strongly adsorbed onto copper surface. The UV-Visible absorption spectra confirmed that AETDA molecules suppress the corrosion of copper via their interactions with the copper surface via their adsorption then formation of AETDA-Cu complex.     

Cefotaxime sodium: A new and efficient corrosion inhibitor for mild steel in hydrochloric acid solution

The corrosion inhibition of mild steel in 1 M HCl solution by cefotaxime sodium has been studied by Tafel polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The inhibitor showed 95.8% inhibition efficiency at optimum concentration 300 ppm. Results obtained revealed that inhibition occurs through adsorption of the cefotaxime on metal surface without modifying the mechanism of corrosion process. Potentiodynamic polarization studies suggest that it is a mixed type of inhibitor. Electrochemical impedance spectroscopy techniques were also used to investigate the mechanism of corrosion inhibition.     

Corrosion behaviour of copper under chloride-containing thin electrolyte layer

The corrosion behaviour of copper under chloride-containing thin electrolyte layers (TEL) was investigated using electrochemical impedance spectroscopy (EIS), cathodic polarization, linear polarization, SEM/EDS and XRD. The results indicate that the copper corrosion rate increases as TEL thickness decreases during the initial stages. After 192 h of immersion, the corrosion rate of copper under TEL in this order: 300 > 402 > 199 > bulk solution > 101 μm. The corrosion behaviour is uniform under TEL, and pitting is the primary corrosion type in the bulk solution. A corrosion model of the behaviour of copper under chloride-containing TEL is proposed.     

Adsorption and corrosion inhibition of phytic acid calcium on the copper surface in 3 wt% NaCl solution

The adsorption and corrosion protection effect of phytic acid calcium (PAC) film on the copper surface in 3 wt% NaCl solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Raman spectroscopy. Polarization curves indicate that PAC is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. The inhibition efficiency of PAC film reached 92.53% at an optimized condition. Adsorption of PAC molecules on the surface followed Langmuir adsorption isotherm and the standard Gibbs energy of −37.32 kJ mol⁻¹ indicated a chemisorptive way. Raman studies suggested that PAC molecule chemically anchored at the surface via PO groups.     

应用电化学方法原位研究薄液膜下青铜的大气腐蚀行为(英文)

采用阴极极化曲线、开路电位和电化学阻抗谱,监测青铜在不同薄液膜厚度下的大气腐蚀行为。阴极极化曲线结果表明,阴极极限电流密度随着液膜的减薄而增大。电化学阻抗谱结果表明,在腐蚀初期,腐蚀速率随着液膜的减薄而增加,这主要是由于腐蚀速率是由阴极过程控制的;随着时间的延长,腐蚀程度随着液膜厚度的变化从强到弱的趋势为:150μm,310μm,100μm,本体溶液,57μm。开路电位和电化学阻抗谱实验较好地再现了原位电化学腐蚀信息,且电化学结果与物理表征具有良好的一致性。     

Performance of Quebracho extract as eco-friendly corrosion inhibitor for SAE 1010 steel in the oil field environment

The inhibitive behavior of Quebracho tannin extract on SAE 1010 steel corrosion in the acidic media is investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are first used to determine the inhibition efficiency of Quebracho in 0.1 M HCl solution to identify the best extract concentration to subsequently evaluate the inhibitor activity in CO₂-rich aqueous solution at high pressure (15 MPa) and high temperature (70°C). Polarization curves revealed that Quebracho extract acted as cathodic inhibitor and that the inhibition efficiency is dependent on the extract concentration. The EIS measurements and SEM analysis showed that the inhibitor had been adsorbed on the steel surface. The inhibition efficiency of Quebracho in CO₂ medium was similar to the 0.1 M HCl, reducing expressively the corrosion rate. The SEM images and X-ray diffraction analysis showed that iron carbonate was the main corrosion product formed on the metal surface in CO₂-rich environment in the presence of Quebracho. Besides, the corrosion scale was thinner and more compact in the presence of inhibitor.     

Corrosion inhibition of C38 steel in 1 M hydrochloric acid medium by alkaloids extract from Oxandra asbeckii plant

The inhibition effect of alkaloids extract from Oxandra asbeckii plant (OAPE) on the corrosion of C38 steel in 1 M hydrochloric acid solution has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The corrosion inhibition efficiency increases on increasing plant extracts concentration. Cathodic and anodic polarization curves show that OAPE is a mixed-type inhibitor. The effect of temperature on the corrosion behavior of C38 steel in 1 M HCl with and without addition of plant extract was studied in the temperature range 25–55 °C. The thermodynamic functions of dissolution and adsorption processes were calculated from experimental polarization data and the interpretation of the results are given. The adsorption of this plant extract on the C38 steel surface obeys the Langmuir adsorption isotherm. Surface analysis (Raman) was also carried out to establish the corrosion inhibitive property of this plant extract in HCl solution.     

Electrochemical assessment of inhibitive behavior of some antibacterial drugs on 316 stainless steel in acidic medium

In this work, the inhibitive effect of some antibacterial drugs against the corrosion of 316 stainless steel in 1M HCl has been studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The inhibiting effect explained by adsorption of the additives on steel surface. The inhibition efficiency increases with increasing the inhibitors concentrations and decreases with increasing the temperature. The data obtained fit well to Langmuir adsorption isotherm and the kinetic-thermodynamic model. The results of polarization studies indicate that the investigated antibacterial drugs are mixed type inhibitors. Increasing the inhibition efficiency of the investigated inhibitors with the addition of iodide ions indicates that iodide ions play important role in the adsorption process. The efficiencies obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in the measurements of the tested inhibitors.