C-steel Surface Research Articles

Corrosion inhibition performance and adsorption mechanism of new synthesized symmetrical diarylidenacetone-based inhibitor on C38 steel in 15 % HCl medium: Theoretical insight and experimental validation

Despite the engineering potential of using organic substances to protect vulnerable metallic materials from corrosive environments, the interaction mechanisms and adsorption processes that lead to the formation of hybrid materials remain poorly understood. Further research is necessary to elucidate how these organic compounds interact with metallic surfaces and the specific pathways through which they adsorb to form protective layers. Understanding these mechanisms is crucial for developing more effective corrosion-resistant hybrid materials, which could significantly enhance the properties of metallic components and provide excellent electrochemical stability in various industrial applications. This work aims to explore the corrosion performance and interfacial mechanism of two symmetrical diarylidenacetone-based compounds, namely, (1E,4E)-1,5-bis(4-methoxyphenyl) penta-1,4-dien-3-one (MPD) and 2,6-di((E)-benzylidene) cyclohexan-1-one (BZC), in a bid to control the corrosion kinetics of C38 steel in aggressive environment. This assessment integrated experimental, surface, and theoretical explorations. The results of our study revealed the remarkable ability of MPD and BZC molecules to generate a dense, resistant protective film on the C38 steel surface. This protective film acted as a barrier, effectively blocking the penetration of corrosive ions and their interaction with the C38 substrate. The inhibition efficiencies of the investigated products exhibited a consistent rise with increased amounts of additives. The inhibition efficiency reached 95 % for MPD and 90 % for BZC at 10−3 M, as calculated from the fitting Nyquist diagrams. The interaction between the inhibitor and Fe(110) was studied utilizing density functional tight binding (DFTB) and Molecular dynamics simulations (MDS). The results demonstrate the formation of covalent bonds, with the molecules aligning in a parallel orientation of MPD and BZC. This alignment with experimental findings provides strong validation for the efficacy of the inhibitors in corrosion inhibition.

Synthesis and Performance of a New and Simple Schiff Base Structure for Corrosion Inhibition of C38 steel in 1 M HCl Solution: Experimental Studies and DFT Investigation

In order to investigate the corrosion of carbon steel (C38) in acidic media, experimental studies (weight loss measurements, electrochemical methods, thermodynamic adsorption isotherms and field emission scanning electron microscopy coupled with energy dispersive X-ray) and computational approach were adopted to study the newly synthesized and simple Schiff base structure, namely 4-((phenylimino)methyl) phenol (PIMP) as a corrosion inhibitor for C38 steel in 1M HCl. Characterization techniques (Fourier Transform Infrared spectroscopy, mass spectrometry, proton nuclear magnetic resonance) showed that PIMP was successfully synthesized with a yield of 63%. Experimental methods (weight loss, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP)) showed that PIMP is a mixed-type inhibitor with an inhibition percentage of 91.1% under optimal conditions (7.5 mM PIMP at 30°C). These experimental results were supported by surface analysis (Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-Ray (EDX)), where PIMP molecules are adsorbed on the steel surface and form a protective barrier against aggressive ions, thereby limiting steel oxidation. The adsorption of PIMP on the carbon steel surface followed the Langmuir adsorption isotherm along with a mixture of physical and chemical adsorption, forming a complete and dense protective film on the C38 steel surface. Theoretical results using density functional theory (DFT) calculations showed that PIMP contains highly reactive centers and confirmed the experimental results obtained.

An Exploratory Experimental Analysis Backed by Quantum Mechanical Modeling, Spectroscopic, and Surface Study for C-Steel Surface in the Presence of Hydrazone-Based Schiff Bases to Fix Corrosion Defects in Acidic Media.

This work focuses on developing corrosion control and protecting the environment by creating affordable, sustainable, environmentally friendly, and efficient corrosion resistance chemicals. That is, through synthesized three hydrazone Schiff bases E-2-(1-hydrazonoethyl)thiazole (HTZ), 2-((E)-(((Z)-1-(thiazol-2-yl)ethylidene)hydrazono)methyl)phenol (HTZS), and 2-((E)-(((Z)-1-(pyridin-2-yl)ethylidene)hydrazono)methyl)phenol (HPYS) and corrosion inhibitors for C-steel in 8 M H3PO4 solution that were studied. The chemicals were analyzed by using 1H NMR and 13C NMR spectroscopy to learn more about them. Predominantly, the hydrazone-based Schiff bases have been considered powerful inhibitors due to their ability to be adsorbed with very low concentrations through their reactive sites (N, O, and S). Maximum surface (θmax) coverage and inhibition efficiency of 83.33% were sufficiently found at 99.00 × 10-3 mol/L concentration of HTZS at 293 K. Galvanostatic experiments demonstrated that raising the concentration of hydrazones improved mass transfer resistance. To study microstructure, scanning, reflectance, and energy-dispersive X-rays were used. Roughness and qualitative adhesion of the adsorbed layer were estimated by an atomic force microscope. After adding 99.00 × 10-3 mol/L of HTZS, the degree of surface brightness and reflectance increases to 137.20, relative to the corroded electrolyte-free solution 27.70. The roughness (Ra) decreased from 0.468 to 0.088 μm by adding HTZS. A surface morphology study confirmed that adding hydrazones to the C-steel dissolution bath greatly improves the surface's look and texture quality. The atomic absorption spectroscopy technique was used to compare the concentration of the iron ions that remained in the solution after galvanostatic analysis in the absence and presence of the hydrazones under different conditions; it was found that the inhibited solution contained lower concentrations of iron ions as compared to the uninhibited solution. The DFT theoretical analysis verified the observation of hydrazone physical adsorption through bonding electrons that obey kinetic adsorption isotherms. It is based on examining the highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO), the Fukui functions, and the Mulliken atomic charge. Overall, the results suggest that HTZS is a good corrosion inhibitor with a large surface area due to the presence of S, N, and O atoms, allowing for creating a larger surface due to the large molecular volume of atoms protecting against the corrosion process.

The study of expired pharmaceutical drugs as corrosion inhibitor for carbon steel in acidic media using the design of experiment

The performance of Bromhexine syrup has been investigated as a corrosion inhibitor for carbon steel (C-steel) in acid medium using the weight loss method and response surface methodology (RSM) of the design experiment. The effect of the concentration of the inhibitor, temperature and exposure time on inhibition efficiency and corrosion rate was studied. The experimental results revealed that expired drug is an effective inhibitor and its inhibition efficiency increases with the increasing concentration to attain a maximum of 97.23 % at 1.0 (v/v %) at 293 K. The thermodynamic parameters show that adsorption reaction on the C-steel surface is spontaneous and exothermic. Moreover, the energy barrier for the corrosion reaction increases in presence of the inhibitor. The individual and interactive effects of these three parameters were optimized for maximum response of inhibition efficiency using response surface methodology (RSM) within the experimental design. Second-order polynomial model was suggested to predict the inhibition efficiency as a function of three variables. The results from RSM gave a best second order polynomial model for the inhibition efficiencies (IE) with high R2= 0.998 and R2Adj= 0.997. Moreover, the value of Q2 greater than 0.9 indicating that the model used is excellent. This confirms a good agreement between experimental observed data and the predicted ones. The optimal inhibition efficiency (IE) obtained by RSM is 101.65 % for a concentration of 0.282 %, temperature of 20.87 °C and immersion time of 4h.

Molecules from Sargassum algae as Green Inhibitor for C38 in HCl Medium: Extraction, Characterization and Electrochemical Study

The aim of this work is to develop new organic bio-sourced inhibitors that are ecofriendly and biodegradable. These natural inhibitors are organic, non-toxic molecules derived from plant extracts, containing numerous secondary metabolites, and are capable of being highly effective in protecting metals against corrosion. This study concerns the extraction, characterization and electrochemical study of natural organic compounds extracted from a species of Sargassum abundant on the coasts of Martinique, Sargassum fluitans III. The objective is to inhibit the corrosion of carbon steel. Electrochemical impedance spectroscopy (EIS) and linear polarization (LP) techniques have led to new experimental results showing inhibitor efficacy. The results obtained show that this plant extract could serve as an effective inhibitor for the C38 steel in acidic media. Studies on the phytochemicals of the crude extract were also carried out. Electrochemical studies, on each chemical families present, were also established to find the main constituents responsible for corrosion inhibition properties of the algae extract. The adsorption of Sargassum fluitans III extract on the C38 steel surface, obeys the Langmuir adsorption isotherm.

Corrosion inhibition and synergistic effect of ionic liquids and iodide ions on the corrosion of C-steel in formation water associated with crude oil

AbstractThe inhibition effect of some of three different ionic liquids namely, IL-4, IL-8, and IL-10 on the corrosion behavior of C-steel immersed in 10% formation water (FW) solutions was examined at various concentrations and temperatures. Gravimetric measurements were complemented by surface investigation for some corroded C-steel samples using a scanning electron microscope (SCE). The inhibition efficiency, IE %, was found to increase with increasing the inhibitor concentration depending on its type while the rise in the solution temperature reduces the IE %. At optimum concentration of 500 the IE % reaches 52.21%, 45.83%, and 43.98%, successively, with IL10, IL8, and IL4. The presence of 0.02 M KI mixed with 500 ppm enhances the IE % to reach a maximum value of 90.5%, 85.6%, and 77.9%, successively, with IL10, IL8, and IL4. The existence of KI is considered an effective co-inhibitor that introduces a synergistic effect and stimulates the synergism. The inhibition mechanism was discussed through an adsorption process that follows the Langmuir model. The thermodynamic data suggests the existence of physisorption besides chemisorption processes on the surface of the C-steel surface.

Electrochemical, surface and theoretical investigations of a new tri-tolyl imidazole designed for corrosion inhibition of carbon steel in normal hydrochloric acid medium

Throughout this work, it is intended to evaluate the effect of a new ((4RS,5SR)-2,4,5-tri-p-tolyl-4,5-dihydro-1H-imidazole (4T-C) on Carbon Steel (C-steel) corrosion inhibition in 1 M HCl medium. For this purpose, potentiodynamic polarization measurements and Electrochemical Impedance Spectroscopy (EIS) were realized. It could be perceived that the inhibitor concentration increase led to substantial corrosion level drop of C-steel in the harsh medium, with inhibitive efficiency value reaching 96 % at 10−3 M inhibitor concentration. The polarization curves showed that the inhibitor 4T-C operated as a mixed cathodic and anodic type inhibitor. The Nyquist diagrams illustrated that increasing 4T-C’s amount in solution occasioned an increase in polarization resistance values, implying an increase of the inhibitory efficiency and a decrease of the double layer capacity. SEM and UV–Vis. spectroscopy have been utilised to specify the impact of the inhibitor’s existence on the superficial condition of the C-steel in the harsh solution. Temperature impact of the 4T-C molecule on the corrosion conducts of C-steel in 1 M HCl at the inhibitor’s optimal amount of 10−3 M has been explored in the T range of 303–333 K. It could be stated that inhibitive efficiency was not significantly affected by the temperature rise. The Langmuir isotherm model was found to govern 4T-C adsorption on C-steel surface. Energy, enthalpy and entropy of activation were calculated and discussed. The Arrhenius law was used to calculate the adsorption free energy. The chemisorption of 4T-C on the C-steel surface was confirmed by a free adsorption energy of −44.04 kJ/mol. To support the experimental results, the investigated inhibitor molecule was optimized using B3LYP/6–31+ G(d,p) level of theory and Molecular Dynamic Simulation (MDS). The calculation was apprehended in aqueous medium. The global and local chemical reactivity describing parameters were determined and analysed.

Electrochemical Investigation of C-Steel Corrosion Inhibition, In Silico, and Sulfate-Reducing Bacteria Investigations Using Pyrazole Derivatives.

The inhibitory impact of the two synthesized pyrazole derivatives (3 and 4) toward metallic and microbial corrosion was investigated. Using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, it was possible to determine their ability to prevent the corrosion of C-steel in 1 M HCl, which was significantly enhanced with increasing concentration (ex. 93%). They act as mixed-type inhibitors, according to polarization curves. The compounds under investigation were adsorbed on a C-steel surface in 1 M HCl following the Langmuir isotherm model. The double-layer capacitance was decreased, and the charge transfer resistance (Rct) was raised due to the examined inhibitors' adsorption. Investigating changes in the surface morphology and confirming the corrosion inhibition mechanism are done using scanning electron microscopy. Density functional theory calculations and Monte Carlo simulations were also conducted to show the adsorption affinity of the understudied compounds over the steel substrate in neutral and protonated forms. Furthermore, the antimicrobial performance of the two synthesized pyrazoles against sulfate-reducing bacteria was evaluated, and the recorded inhibition efficiency was 100%. The current research shows important developments in producing highly effective anticorrosion and antimicrobial pyrazole derivatives.

Investigations of non-ionic surfactants derived from triazoles and pyrroles as potent corrosion inhibitors for carbon steel in hydrochloric acid

The effectiveness of two synthetic non-ionic surfactants (NIS), including triazole and pyrrole derivatives, to inhibit corrosion of C-steel in 1.0 M HCl solution was tested. Their chemical compositions were verified using some of the analytical data. All of the synthesized compounds displayed good surface activity when different surface coefficients were tested. The corrosion parameters were determined employing chemical and electrochemical methods. The surface features of these compounds were identified. The anticorrosion efficacy (AE%) rises with rising the concentration of NIS compounds and with reducing temperature, surface and interfacial tension, and critical micelle concentration. The EIS diagram showed that as the concentration of NIS compounds increased, charge transfer resistance raised and double-layer capacitance reduced due to its adsorption of on the C-Steel surface. The values of AEPDP %. reached 89.98% and 91.45% at 500 ppm of compounds A and B, respectively by applying the polarization method. The anti-corrosion process was explained by the formation of adsorbed film that separated the C-steel surface from the corrosive HCl solution. The adsorption is subjected to Freundlich isotherm. The two NIS compounds functioned as mixed-type inhibitors, as revealed by potentiodynamic polarization. Some surface characteristics. were identified and emphasized the anticorrosive effect of two NIS compounds

Surface interaction and corrosion inhibition of carbon steel in sulfuric acid using Petroselinum crispum extract

With the aid of the mass loss (ML) method, and a few electrochemical techniques [potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)], the inhibitory impact of Petroselinum crispum (PC) extract on C-steel corrosion in solutions of 1 M sulfuric acid was assessed. By employing Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques, the C-steel surface morphology was investigated. The data showed that the solution of plant extract can be effectively utilized to inhibit C-steel corrosion in solutions of 1 M sulfuric acid. The effectiveness of the extract was enhanced by the higher extract dose and rising temperature. The apparent activation energy and the enthalpy of the dissolution process were determined and discussed. The presence of PC decreases the double-layer capacity from 493.1 to 107.3 μF cm−2 and raises the charge transfer resistance in a solution of 1 M sulfuric acid from 43.39 to 287.7 Ω cm2. PC is a mixed-type inhibitor, as demonstrated by PDP tests. The PC extract demonstrated the highest productivity for the C-steel protection up to 90.2% at 300 ppm from the extract, according with the PDP technique. The attained data indicated that PC extract was adsorbed chemically (ΔGoads > 40 kJ mol−1) onto the surface of the C-steel following the Temkin isotherm. The results of numerous tests appear to agree.

Anti-corrosion and anti-microbial evaluation of novel water-soluble bis azo pyrazole derivative for carbon steel pipelines in petroleum industries by experimental and theoretical studies

In this research, we investigated the synthesis of a novel water-soluble bis azo pyrazolin-5-one (ABP) which was synthesized efficiently via the regioselective reaction of hydrazine with coumarin hydrazone (CMH). Also, we evaluate their anti-corrosion and anti-bacterial behavior. The inhibition efficiency of ABP in an acidic medium (1.0 M HCl) was evaluated using various electrochemical and surface morphology measurements. The novel bis pyrazole-based azo dye ABP (16 × 10−6 M) demonstrated a higher protection capacity (93.3 %). Tafel curves revealed that ABP was a mixed-type inhibitor. The adsorption of ABP on the C-steel (CS) surface is proven by the alteration in (Rct and Cdl) impedance characteristics and obeyed the Langmuir isotherm model. SEM/EDX, AFM, and XPS surface examinations confirmed the enhancement of an adsorbed film protects the CS surface from acid corrosion at the appropriate dose. Furthermore, theoretical calculations using DFT and MC simulations were performed to identify the active sites on ABP molecules in charge of the adsorption and surface protection of the CS. The adsorption of bis pyrazole-based azo dye on the metal surface explained the protection mechanism. Moreover, the ABP screened for its antimicrobial activity against sulfate-reducing bacteria (SRB), and the calculated inhibition efficiency was 100 %. The current work presents significant results in manufacturing and producing novel water-soluble bis pyrazole-based azo dye derivative with high anti-corrosion and anti-microbial efficiency.

Corrosion Inhibition Efficiency, Experimental and Quantum Chemical Studies of Neutral Red Dye for Carbon Steel in Perchloric Acidic Media

The Neutral Red (NR) has been investigated as a corrosion inhibitor for carbon steel (C-steel) in 1M perchloric acid using a weight loss method and theoretical calculations based on density functional theory (DFT). The obtained results revealed that NR is an effective inhibitor and its inhibition efficiency increases with the increasing concentration to attain 89.50 % at 5•10-3 M at 293 K. The thermodynamic parameters as enthalpy, entropy and Gibbs free energy for both dissolution and adsorption processes are calculated and discussed. Moreover, the free energy of adsorption showed that the corrosion inhibition takes place by a spontaneous physicochemical adsorption of inhibitor molecules on the C-steel surface. The results show that the calculated values of the quantum chemical parameters indicate a possible existing link between the effectiveness of the inhibitor and its electronic properties.

An Eco-Friendly Quaternary Ammonium Salt as a Corrosion Inhibitor for Carbon Steel in 5 M HCl Solution: Theoretical and Experimental Investigation.

The corrosion of industrial material is a costly problem associated with global economic losses reaching trillions of US dollars in the repair of failures. Injecting corrosion inhibitors is the most practically promising method for decelerating corrosion reactions and protecting surfaces. Recent investigations have focused on surfactants as corrosion inhibitors due to their amphiphilic nature, low cost, and simple chemical preparation procedures. This study aims to investigate the performance of an environment-friendly Quaternium-22 (Q-22) surfactant which is widely used in cosmetics for C-steel corrosion inhibition in a 5 M HCl medium. Weight loss experiments were performed at different concentrations and immersion times, presenting a maximum efficiency at 2.22 mmol·L−1. The influence of Q-22 on the corrosion behavior of C-steel was elucidated using non-destructive electrochemical measurements. The overall results revealed that adding varied concentrations of Q-22 significantly decreases the corrosion rate of C-steel. The results revealed the physisorption nature of Q-22 onto the C-steel surface, with adsorption following the Freundlich isotherm (∆= −16.40 kJ·mol−1). The relative inhibition performance of Q-22 was also evaluated by SEM and AFM analyses. Lastly, quantum chemical calculations based on density functional theory (DFT) demonstrated that Q-22 has promising molecular features concerning the anticorrosive mechanism.

Novel naphthybithiophene derivatives as corrosion inhibitors for carbon steel in 1 M HCl: Electrochemical, surface characterization and computational approaches

Corrosion suppression performance and adsorption attitude of 5′-(naphthalen-2-yl)-[2,2′-bithiophene]-5-carboxamidine hydrochloride salt (MA-1341), 5′-(isoquinolin-4-yl)-[2,2′-bithiophene]-5-carboxamidine hydrochloride salt (MA-1348) and 5′-(4-chlorophenyl)-2,2′-bithiophene-5-carboxamidine hydrochloride salt (MA-1340) for the inhibition of the carbon steel (C-steel) surface dissolution in 1.0 M hydrochloric acid solution were investigated using different techniques. A chemical technique (weight loss method), electrochemical techniques (including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) analysis) and theoretical studies (Density Functions Theory (DFT)) were performed. Moreover, the adsorption of these inhibitors on the surface of C-steel was affirmed using Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). The surface morphology of the C-steel was examined using Scanning Electron Microscopy (SEM). The obtained results revealed high inhibition performance resulting from the adsorption of these compounds on the C-steel surface, developing a shielding layer that prevents the dissolution of the metal in the acidic solution. The inhibition efficiency (%η) found to be increased with growing the inhibitor dose and solution temperature giving the higher efficiency 95.14 %, 93.55 % and 91.05 % for MA-1348, MA-1341 and MA-1340, respectively at the optimum concentration 30 × 10−6 mol/L and temperature 328 K. The studied inhibitors were chemically adsorbed on the steel surface and obeyed the Langmuir adsorption isotherm. The quantum computations and Monte Carlo simulation methods were used to prove the inhibition mechanism of naphthybithiophene derivatives at the molecular level.

Performance assessment by experimental and Theoretical approaches of newly synthetized benzyl amide derivatives as corrosion inhibitors for carbon steel in 1.0 M hydrochloric acid environment

• The anticorrosion effect of two inhibitors on C-steel in 1 M HCl was studied. • The polarization results show that (HBEDA) and (HBDETA) are mixed-type inhibitors. • The impedance data suggest the adsorption of the inhibitors on C-steel surface. • The Langmuir adsorption isotherm governs the adsorption mechanism. • QC and MC show that hetero atoms serve as active sites to facilitate adsorption. As part of the efforts made by many researchers to evaluate a lot of chemical compounds as inhibitors for carbon steel corrosion, this research focuses on novel two compounds of benzamide derivatives. The investigated compounds namely N, N -bis (p-hydroxybenzoyl) ethylenediamine (HBEDA) and N, N -bis (p-hydroxybenzoyl) Diethylenetriamine (HBDETA), were formulated then characterized using FTIR, 1 HNMR, and elemental analysis to elucidate the structures chemically. Theoretical and experimental (electrochemical and morphology) studies made clear that (HBEDA) and (HBDETA) improve carbon steel (C-steel) inhibition efficiency in 1 M hydrochloric acid as concentrations increase (25, 50, 100, 150, 200, 250 ppm). The benzamide derivatives acted as interface corrosion inhibitors in an electrochemical impedance spectroscope (EIS) experiment, and they acted as mixed type corrosion inhibitors in a polarization test. They yielded best efficiency gains of 95.8 percent for HBEDA and 99.6 percent for HBDETA. Information collected from the EIS technique was studied in order to represent the corrosion inhibition procedure using an equivalent circuit (EC). The elevated K ads values and negative ΔG ads (-28.71, −28.79 kJ/mol) values of the two compounds (understudy) revealed that they were strongly and spontaneously adsorbed at C-steel/electrolyte connections respectively, and the adsorption isotherm of Langmuir fitted widely with the empirical data. The Surface examination (morphology) of metal employing energy dispersive X-ray (EDX) and scanning electron microscope (SEM) evaluations confirmed the adsorption of (HBEDA) and (HBDETA) on the substrate (C-steel).

Robust corrosion guard, mechanical and UV aging properties of metal complex/epoxy hybrid composite coating for C-steel applications

Incorporation of novel-prepared metal–organic complexes as crosslinking accelerators for multifunctional epoxy was on top of interest by coating formulators. The present work investigated the loading of mixed ligand metal complexes (Zr(IV) and Cu(II)) of metformin (MF) and 2.2′bipyridine (Bipy) against the free ligands as crosslinking modifiers via some epoxy coating formulations to assess their superb performances on the C-steel surface. Zr(IV) and Cu(II) demonstrated the minor energy gap (∆E) values at 0.190 au compared to free MF and Bipy according to the calculated energy values, and this behavior reflected their enhanced properties via epoxy coating applications. EIS measurements using high saline formation water as a corrosive medium were performed and offered that PA-DGEBA/MC-Cu coated film showed the superior resistance values (Rct = 940 and Rc = 930 kΩ cm2). The accelerated corrosion salt spray experiment clarified that PA-DGEBA/MC-Cu coating achieved the least corrosion rate at 0.00049 mm/y and exhibited the highest protection efficiency of 99.84%. SEM/EDX combination survey affirmed the protective performance of the checked coatings. AFM microanalysis confirmed that surface-treated Cu(II) coating displayed the smoothest film surface with complete curing. Mechanical durability properties were evaluated and the obtained results illustrated that pull-off adhesion for PA-DGEBA/MC-Cu coated film fulfilled the highest adhesion strength at 6.3 MPa, the best bend character at 77, and the maximum impact resistance at 59.7 J. UV immovability trial was performed at 10 irradiance and 80 h duration. PA-DGEBA/MC-Cu coated film displayed the highest resistance to UV irradiance with blistering (#8 size and few frequencies) in addition to offering a minor gloss variation and matt properties.

Synthesis and characterization of N-(2-aminophenyl)- 2-(5-methyl-1H-pyrazol-3-yl) acetamide (AMPA) and its use as a corrosion inhibitor for C38 steel in 1 M HCl. Experimental and theoretical study

A new synthesized organic compound namely N-(2-aminophenyl)-2-(5-methyl-1H-pyrazol-3-yl) acetamide (AMPA), its structure was identified based on spectral data 1H NMR and 13C NMR, its inhibiting effect against the corrosion of C38 steel in a 1 M HCl solution has been studied by experimental and theoretical studies. The experimental studies are performed using electrochemical tests, while the theoretical studies are performed using density functional theory (DFT) calculations and Monte Carlo simulations. The results obtained show that AMPA is an effective inhibitor against the corrosion of C38 steel in an acid medium, and that its performance efficiency reaches 93% for a concentration of 5 mM. The polarization curves show that AMPA functions as a mixed inhibitor; its adsorption on the C38 steel surface undergoes the Langmuir isotherm. The electrochemical impedance spectra indicate that the value of the charge transfer resistance increases with increasing inhibitor concentrations and with increasing immersion time. The surface morphology of C38 steel in the absence and in the presence the inhibitor was analyzed by scanning electron microscopy (SEM) combined with EDX analysis. Computer calculations of synthetic corrosion inhibitor are employed to study the role of their molecular skeleton of AMPA in the corrosion inhibition process. The calculated results support the empirical results.

Experimental and computational investigation of 3,5-di-tert-butyl-2-(((3-((2-morpholinoethyl)(pyridin-2-ylmethyl) amino)propyl)imino) methyl)phenol and related reduced form as an inhibitor for C-steel

The effect of new compounds containing morpholine moiety including: 3,5-di-tert-butyl-2-(((3-((2-morpholinoethyl)(pyridine-2-ylmethyl)amino)propyl)imino)methyl)phenol (L1) and its reduced form, 3,5-di-tert-butyl-2-(((3-((2-morpholinoethyl)(pyridine-2-ylmethyl)amino)propyl)amino) methyl)phenol (L2) on the corrosion inhibiting of C-steel in 1.0 M HCl and 3.5 wt% NaCl was tested by experimental and computational techniques. The concentration of inhibitor varied in the range of 0.2–2.0 mM. The corrosion behavior of C-steel was investigated using electrochemical techniques, including open circuit potential (OCP), potentiodynamic polarization (Tafel), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) inhibitor-free and inhibitor-containing solutions. From the Tafel diagram, the icorr of the C-steel electrode in the 1.0 M hydrochloric acid solution represents the highest value among the other inhibitor-containing solutions. The icorr for C-steel in L1 containing solution decreases gradually from 1.43 × 10−4 to 0.91 × 10−4 A/cm2, with the concentration of L1 increasing from 0.2 to 2.0 mM. Along with the increase of the L2 concentration from 0.2 to 2.0 mM, the icorr is reduced by about 41%. EIS studies demonstrated that the capacitance of the double layer increased by the addition of inhibitors and increasing the resistance of charge transfer, suggesting an improvement of the corrosion protection in inhibitor-containing acidic solution. SEM images confirmed the corrosion results in which inhibitor-containing solution protects the C-steel surface against the attack of species. The results showed that in all solutions containing equivalent concentrations of inhibitors, the reduced form of L1 had a better inhibition efficiency than the L1 inhibitor. Inhibitors, L1 and its reduced form exhibit Langmuir adsorption isotherm, in which monolayer adsorption of inhibitors is carried out on the C-steel electrode. The properties of the studied molecules to be corrosion inhibitors were examined with the Gaussian software program. The calculations of the molecules were made in different methods and basis sets.

Combined Electrochemical, Raman Analysis and Machine Learning Assessments of the Inhibitive Properties of an 1,3,4-Oxadiazole-2-Thiol Derivative against Carbon Steel Corrosion in HCl Solution.

The inhibiting properties of 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol (PyODT) on the corrosion of carbon steel in 1.0 M HCl solution were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, Raman spectroscopy, and SEM-EDX analysis. An approach based on machine learning algorithms and Raman data was also applied to follow the carbon steel degradation in different experimental conditions. The electrochemical measurements revealed that PyODT behaves as a mixed-type corrosion inhibitor, reaching an efficiency of about 93.1% at a concentration of 5 mM, after 1 h exposure to 1.0 M HCl solution. Due to the molecular adsorption and structural organization of PyODT molecules on the C-steel surface, higher inhibitive effectiveness of about 97% was obtained at 24 h immersion. The surface analysis showed a significantly reduced degradation state of the carbon steel surface in the presence of PyODT due to the inhibitor adsorption revealed by Raman spectroscopy and the presence of N and S atoms in the EDX spectra. The combination of Raman spectroscopy and machine learning algorithms was proved to be a facile and reliable tool for an incipient identification of the corrosion sites on a metallic surface exposed to corrosive environments.

Evaluation of inhibitive corrosion potential of symmetrical hydrazine derivatives containing nitrophenyl moiety in 1M HCl for C38 steel: experimental and theoretical studies

The exploitation of cost-effective, sustainable, green and efficient compounds is a renewed science and a demanding mission for today's chemists and technologists. In this view, the inhibitive corrosion properties of some hydrazine derivatives named (1E,2E)-bis(1-(2-nitrophenyl)ethylidene)hydrazine (SSBO), (1E,2E)-bis(1-(3-nitrophenyl)ethylidene)hydrazine (SSBM) and (1E,2E)-bis(1-(4-nitrophenyl)ethylidene)hydrazine (SSBP) on the C38 steel corrosion in 1M HCl media has been evaluated by different techniques like electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The EIS results showed that SSBM is the greatest inhibitor (η>93%) among the three tested compounds. The SSBM gives considerable inhibition efficiency against corrosion of steel compared to the previous studies. The PDP curves indicated that the studied inhibitors were a mixed-type inhibitor with a predominantly cathodic control. Quantum calculations of some descriptors derived from the density functional theory (DFT), the transition state theory (TST), the quantum theory of atoms in molecules (QTAIM) and molecular dynamics simulation have delivered helpful information regarding electron transfer and mechanism during adsorption of inhibitors on C38 steel surface.