scholarly journals Adsorption Studies of the Effect of Thiosemicarbazides on the Corrosion of Steel in Phosphoric Acid

2000 ◽  
Vol 18 (3) ◽  
pp. 177-194 ◽  
Author(s):  
M.A. Ameer ◽  
E. Khamis ◽  
G. Al-Senani
Keyword(s):  
Phosphoric Acid ◽  
Active Sites ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Molecular Structures ◽  
Active Centre ◽  
Inhibitor Molecule ◽  
Thiosemicarbazide Derivatives ◽  
Experimental Findings ◽  
Corrosion Of Steel

The corrosion inhibition of steel in phosphoric acid by thiosemicarbazide derivatives has been studied using different chemical and electrochemical techniques. The observed order of increasing inhibition efficiency was correlated with changes in the molecular structures of the inhibitors. Potentiodynamic polarization curves indicate that the compounds are mixed-type inhibitors. Electrochemical impedance spectroscopy has been used successfully to evaluate the performance of the inhibitors. AC measurements showed that the dissolution process was activation-controlled. The kinetic–thermodynamic model and the Flory–Huggins adsorption isotherm described the experimental findings well. The number of active sites, binding constant and change in free energy were computed for all the inhibitors studied. It was found that the inhibitor molecule was adsorbed through more than one active centre and occupied more than one active site on the steel surface.

scholarly journals Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2491
Author(s):  
Elena Garcia ◽  
Julio Torres ◽  
Nuria Rebolledo ◽  
Raul Arrabal ◽  
Javier Sanchez
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Chloride Content ◽  
Offshore Platforms ◽  
Anoxic Conditions ◽  
Current Limit ◽  
Anoxic Environments ◽  
Corrosion Of Steel ◽  
Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

scholarly journals Experimental and computational chemical studies on the corrosion inhibitive properties of carbonitrile compounds for carbon steel in aqueous solutions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abd El-Aziz S. Fouda ◽  
Abdelmonem H. El-Askalany ◽  
Ahmed F. S. Molouk ◽  
Niveen S. Elsheikh ◽  
Ashraf S. Abousalem
Keyword(s):  
Carbon Steel ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Adsorption Model ◽  
Hydrochloric Acid Medium ◽  
Chemical Measurements ◽  
Carbon Steel Surface ◽  
Chemical Studies ◽  
Experimental Findings

AbstractThe present work aims to study 6-amino-4-aryl-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives namely: 6-Amino-2-oxo-1,4-diphenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-H), 6-Amino-2-oxo-1-phenyl-4-(p-tolyl)-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-Me) and 6-Amino-4-(4-hydroxyphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-OH) as corrosion inhibitors to provide protection for carbon steel in a molar hydrochloric acid medium. Chemical measurements such as (weight loss) and electrochemical techniques such as (Potentiodynamic polarization, electrochemical impedance spectroscopy, and Electron frequency modulation) were applied to characterize the inhibitory properties of the synthesized derivatives. The adsorption of these derivatives on the carbon steel surface was confirmed by Attenuated Total Refraction Infrared (ATR-IR), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectroscopy (XPS). Our findings revealed that the tested derivatives have corrosion inhibition power, which increased significantly from 75.7 to 91.67% on the addition of KI (PdC-OH:KI = 1:1) to inhibited test solution with PdC-OH derivative at 25 °C. The adsorption process on the metal surface follows the Langmuir adsorption model. XPS analysis showed that the inhibitor layer consists of an iron oxide/hydroxide mixture in which the inhibitor molecules are incorporated. Computational chemical theories such as DFT calculations and Mont Carlo simulation have been performed to correlate the molecular properties of the investigated inhibitors with experimental efficiency. The theoretical speculation by Dmol3 corroborates with the results from the experimental findings.

scholarly journals The Inhibitive Effect of 2-Phenyl-3-nitroso-imidazo [1, 2-a]pyridine on the Corrosion of Steel in 0.5 M HCl Acid Solution

2010 ◽  
Vol 7 (s1) ◽  
pp. S35-S42 ◽  
Author(s):  
K. Bouhrira ◽  
F. Ouahiba ◽  
D. Zerouali ◽  
B. Hammouti ◽  
M. Zertoubi ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Steel Surface ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Carbon Steel Surface ◽  
Langmuir Isotherm Model ◽  
Corrosion Of Steel ◽  
Good Agreement

The effect of 2-phenyl-3-nitroso-imidazo[1,2-a]pyridine (PNIP) on the corrosion inhibition of carbon-steel in 0.5 M HCl was studied by weight loss and different electrochemical techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization. The obtained results showed that PNIP effectively reduces the corrosion rate of carbon steel. Inhibition efficiency (E%) increases with inhibitor concentration to attain 88% at 10-3M. Adsorption of that PNIP on the carbon steel surface in 0.5 M HCl follows the Langmuir isotherm model. E% values obtained from various methods used are in good agreement. SEM characterization of the steel surface is made.

scholarly journals Experimental and Theoretical Study of Corrosion Behaviour of Maraging Steel in 1 M HCl in Presence of 5-Methyl-4-[(E)-(thiophen-2-ylmethylidene)amino]-4H-1,2,4-triazole-3-thiol

2020 ◽  
Vol 32 (4) ◽  
pp. 845-852 ◽  
Author(s):  
R.N. Mary ◽  
R. Nazareth ◽  
P. Krishna Murthy ◽  
P.A. Suchetan
Keyword(s):  
Maraging Steel ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Theoretical Calculations ◽  
Electrochemical Techniques ◽  
Activation Parameters ◽  
Dft Method ◽  
Basis Set ◽  
Inhibitor Molecule ◽  
Tafel Polarization

The inhibitory action of a synthesized Schiff base (5-methyl-4-[(E)-(thiophen-2-ylmethylidene)amino]-4H-1,2,4-triazole-3-thiol) [MTATT] on the corrosion behaviour of maraging steel in 1 M HCl was investigated by electrochemical techniques like Tafel polarization studies and electrochemical impedance spectroscopy. According to experimental data, inhibition efficiency increased with increase in temperature and concentration of the inhibitor where MTATT acts as a mixed type inhibitor. The mode of inhibitor adsorption on maraging steel follows Langmuir adsorption isotherm. The calculated thermodynamic and activation parameters suggested chemisorption mode of inhibitor adsorption. Scanning electron microscope technology with energy dispersive X-ray spectroscopy (SEM-EDX) studies confirmed the adsorption of inhibitor molecule on the surface of maraging steel. Several global reactivity parameters were calculated using DFT method at B3LYP/6-311++(d,p) basis set. Theoretical calculations are in good concurrence with the experimental results.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Dual Function ◽  
Core Shell ◽  
Protection Efficiency ◽  
Content Type ◽  
Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

scholarly journals Spilanthes acmella Leaves Extract for Corrosion Inhibition in Acid Medium

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 106
Author(s):  
Akbar Ali Samsath Begum ◽  
Raja Mohamed Abdul Vahith ◽  
Vijay Kotra ◽  
Mohammed Rafi Shaik ◽  
Abdelatty Abdelgawad ◽  
...  
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Active Sites ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Film Formation ◽  
Protective Film ◽  
Surface Protection ◽  
Tafel Polarization ◽  
Spilanthes Acmella

In the present study, the corrosion inhibition effect of Spilanthes acmella aqueous leaves extract (SA-LE) on mild steel was investigated in 1.0 M HCl solution at different temperature using weight loss, Tafel polarization, linear polarization resistance (LPR), and electrochemical impedance (EIS) measurements. Adsorption of inhibitor on the surface of the mild steel obeyed both Langmuir and Temkin adsorption isotherms. The thermodynamic and kinetic parameters were also calculated to determine the mechanism of corrosion inhibition. The inhibition efficiency was found to increase with an increase in the inhibitor concentration i.e., Spilanthes acmella aqueous leaves extract, however, the inhibition efficiency decreased with an increase in the temperature. The phytochemical constituents with functional groups including electronegative hetero atoms such as N, O, and S in the extract adsorbed on the metal surface are found responsible for the effective performance of the inhibitor, which was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet–visible spectroscopic (UV-Vis) studies. Protective film formation against corrosion was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle studies. The result shows that the leaves extract acts as corrosion inhibitor and is able to promote surface protection by blocking active sites on the metal.

Application of Electrochemical Techniques to Characterization of the Corrosion Behaviors of GW63 Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 571-574
Author(s):  
Xing Wu Guo ◽  
Jian Wei Chang ◽  
Shang Ming He ◽  
Peng Huai Fu ◽  
Wen Jiang Ding
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Time Curve ◽  
Completely Monotonic ◽  
Treatment Conditions ◽  
Impedance Variation ◽  
Corrosion Behaviors

The corrosion behavior of GW63 (Mg-6wt.%Gd-3wt.%Y-0.4wt.%Zr) alloys in 5% NaCl aqueous solution has been investigated by PARSTAT 2273 instrument. The Open Circuit Potential (ECORR) vs. time curve, cyclic polarization (Pitting Scans) curve and Electrochemical Impedance Spectroscopy (EIS) was measured for the GW63 alloys in as-cast and T6 heat treatment conditions. The EIS results indicated that the tendency of impedance variation for as-cast condition was monotonic decreasing, however, the tendency of variation for T6 condition was not completely monotonic but the total tendency was decreasing. The values of impedance of GW63 alloy at 0.1 Hz are about 103 ohm-cm2 for as-cast and T6 condition.

Effect of Nano-Silica Volume Reinforcement on the Microstructure, Mechanical, Phase Distribution and Electrochemical Behavior of Pre-Alloyed Titanium-Nickel (Ti-Ni) Powder

2021 ◽  
Vol 875 ◽  
pp. 60-69
Author(s):  
Syed Abbas Raza ◽  
Muhammad Imran Khan ◽  
Mairaj Ahmad ◽  
Danish Tahir ◽  
Asim Iltaf ◽  
...  
Keyword(s):  
Phase Distribution ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Microstructural Analysis ◽  
Furnace Cool ◽  
Neutral Salt ◽  
Nano Silica ◽  
Corrosion Properties ◽  
Volume Percentage ◽  
Titanium Nickel

Titanium-Nickel pre-alloyed powder was reinforced with Nano-Silica in 2%, 4% , 6% and 8 wt. % due to effectiveness of Nanoscale ceramic Reinforcement in improving the properties of Metals and Alloys. The compositions of the Pre-Alloyed powders and Nano Silica Approximately 50 nm in diameter and spherical in shape were weighed and mixed in Planetary Ball Mill followed by compaction at 50 MPa using a Uniaxial Compaction machine The green pellets obtained were sintered in Argon Environment for 5 hrs and allowed to furnace cool. The pellets were then sectioned through their cross-section for slices 3 mm thick followed by Cold-mounting and Soldering followed by cold mounting additionally. The Samples were analyzed via X-Ray Diffraction (XRD) for phase distribution as a function of variation in nano-Silica reinforcements and Microstructural analysis was performed via Optical Microscope. The effect of Volume percentage on the densification was determined via Archimedes principle and Micro-Vickers hardness was used for mechanical Evaluation. The Electrochemical Properties were evaluated using Potentio-Dynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in neutral salt solution (3.5% NaCl). The results indicated increasing dissolution of the TiNi phase into intermetallic Titanium-rich and Ni-rich phases in the matrix and hardening due to the Nano-Silica effect of Grain Boundary impingement and phase dissolution of Equiatomic phase and mixed behavior in Corrosion properties as determined by the electrochemical techniques whereas densification decreased due to poor plasticity of Nano-Silica and hinderance in diffusion during the sintering process.

scholarly journals Protection of Petroleum Pipeline Carbon Steel Alloys with New Modified Core-Shell Magnetite Nanogel against Corrosion in Acidic Medium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Gamal A. El Mahdy ◽  
Ayman M. Atta ◽  
Amro K. F. Dyab ◽  
Hamad A. Al-Lohedan
Keyword(s):  
Carbon Steel ◽  
Sulfonic Acid ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Core Shell ◽  
Magnetite Nanoparticle ◽  
Potassium Peroxydisulfate ◽  
Redox Initiator ◽  
Initiator System ◽  
First Time

New method was used to prepare magnetite nanoparticle based on reduction of Fe(III) ions with potassium iodide to produce Fe3O4nanoparticle. The prepared magnetite was stabilized with cross-linked polymer based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS to prepare novel core-shell nanogel. In this respect, Fe3O4/poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) magnetic nanogels with controllable particle size produced via free aqueous polymerization at 65°C have been developed for the first time. The polymer was crosslinked in the presence of N,N-methylenebisacrylamide (MBA) as a crosslinker and potassium peroxydisulfate (KPS) as redox initiator system. The structure and morphology of the magnetic nanogel were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission and scanning electron microscopy (TEM and SEM). The effectiveness of the synthesized compounds as corrosion inhibitors for carbon steel in 1 M HCl was investigated by various electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed enhancement in inhibition efficiencies with increasing the inhibitor concentrations. The results showed that the nanogel particles act as mixed inhibitors. EIS data revealed thatRctincreases with increasing inhibitor concentration.

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