Effect of stereochemical conformation into the corrosion inhibitive behaviour of double azomethine based Schiff bases on mild steel surface in 1 mol L−1 HCl medium: An experimental, density functional theory and molecular dynamics simulation study

Two hitherto unexplored double condensed Schiff bases, namely, 4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PMB) and 4-(4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PPMB) were synthesized and their corrosion inhibitive performances on mild steel have been investigated in 1 mol L−1 HCl medium by gravimetric and electrochemical measurements. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy affirmed the formation of protective films on mild steel surfaces. Contact angle measurement revealed the hydrophobic nature of surface modified by the inhibitor molecules applied in the corrosive solution. The influence of molecular configuration in corrosion inhibition behaviour of inhibitors has been explored by DFT, DFTB calculation and MD simulation

Amine cured double Schiff base epoxy as efficient anticorrosive coating materials for protection of mild steel in 3.5% NaCl medium

A double Schiff base epoxy (DSBE) molecule comprising of 1-phenoxybenzene unit, double azomethine functionalities, two benzene moieties and two terminal epoxy groups (i.e., glycidylether) has been successfully synthesized with an aim of serving as an alternative for the commercially available bisphenol based epoxies. The structure of the synthesized molecule has been affirmed by sophisticated analytical instrumentations such as FT-IR, matrix-assisted laser desorption ionization (MALDI) mass spectrometry and 1H-NMR spectroscopy. Diethylenetriamine (DETA), triethylenetetramine (TETA) i.e., aliphatic and p-phenylenediamine (PPD) i.e., aromatic curing agents have been used to cure DSBE. The amine cured DSBE viz., DSBE + DETA, DSBE + TETA and DSBE + PPD have been further analysed by FT-IR spectroscopy and differential scanning calorimetry. The curing mechanism of epoxy with aliphatic and aromatic amine has also been discussed. The thermal stability of DSBE and amine cured DSBE has been confirmed by thermogravimetry analysis (TGA). The solution of stoichiometric quantity of amines and DSBE in tetrahydrofuran has been applied as coating materials on the surfaces of mild steels. In order to establish the corrosion resistance properties of amine cured DSBE coated substrates, the potentiodynamic polarization technique and electrochemical impedance spectroscopy have been performed in 3.5% NaCl medium which transparently exhibited the superior corrosion inhibition efficacy of DSBE + PPD coated surface showing highest polarization resistance and the lowest rate of corrosion than that of DSBE + DETA and DSBE + TETA. Additionally, the morphological and topographical analysis of the coated substrates have been performed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) to reveal the uniformity as well as soaring smoothness in the surfaces of coating. The hydrophobicity of the developed coating has also been analysed by contact angle measurements

Evaluating electronic structure of quinazolinone and pyrimidinone molecules for its corrosion inhibition effectiveness on target specific mild steel in the acidic medium: A combined DFT and MD simulation study

The quantum chemical calculations, based on density functional theory, have been implemented to explore the corrosion inhibition mechanism and the corresponding inhibition effectiveness of quinazolinone and pyrimidinone compounds, viz., 6-chloroquinazolin-4(3H)-one (Q1A); 2,3-dihydro-3-phenethyl-2-thioxopyrido[2,3-d]pyrimidin-4(1H)-one (Q1B) and 6-chloro-2,3-dihydro-3-phenethyl-2-thioxoquinazolin-4(1H)-one (Q1C) for mild steel in acidic solution. Global reactivity of the molecules related to the quantum chemical parameters such as EHOMO, ELUMO, energy gap (ΔE), softness (S), hardness (η) and fraction of electron transferred (ΔN) between the inhibitor molecule and the metal surface atom have been calculated and explored. In order to describe the reactive sites of the inhibitor molecules Fukui indices analysis has been performed. To mimic the real environment of corrosion inhibition, molecular dynamic (MD) simulations have also been modelled consisting of all concerned species (inhibitor molecule, H2O, H3O+ ion, SO42 − ion and Fe surface) and thereby simulated by the consistent-valence force field (CVFF)

A prolonged exposure of Ti-Si-B-C nanocomposite coating in 3.5 wt% NaCl solution: Electrochemical and morphological analysis

The electrochemical behaviour of magnetron sputtered Ti-Si-B-C nanocomposite coating on SS 304 substrate has been examined using potentiodynamic polarization and electrochemical impedance spectroscopy after long time immersion (1, 20, 40, 70 days) in 3.5 wt% NaCl solution. The surface morphology, elemental composition and surface topography of coated and uncoated surfaces have been analyzed using FESEM, EDX spectroscopy and AFM, respectively. The XRD study revealed the presence of TiB2 and TiSi2 phases in the film which were exposed to 70 days immersion test. It implies that the grains of TiB2 and TiSi2 have grown on the Ti-Si-B-C coating. The results obtained from the electrochemical measurements of sputtered coatings showed the increase of corrosion inhibition capability for Ti-Si-B-C coating compared to SS 304 as the immersion time increases in simulated marine environment

Magnetron sputtered films prepared from sintered Ti-based target and evaluation of tribological properties under the ball on disc condition with varying thickness and load

The hard nanocomposite coatings comprised of titanium, silicon, boron, and carbon (Ti-Si-B-C) and titanium, silicon, boron, carbon, and nitrogen (Ti-Si-B-C-N) were deposited on SS 304 substrate using magnetron sputtering technique. The tribological properties of these Ti-Si-B-C and Ti-Si-B-C-N coatings were explored with the variation of load (200-600 g) and thickness (3-25 mu m) against high strength steel ball using a ball on a disc tribometer. The nanoindentation technique was used to investigate the wear tracks and its consequent effect on the mechanical behaviour of uncoated and coated films. The analyses of the phases, microstructure, states of valence, shift of electron, and elemental compositions of the coatings were carried out by HRTEM, FESEM, AFM, XPS, EDX, and Raman spectroscopy techniques, respectively. The 2D cross-sectional profiles and 3D topographies of the wear tracks were explored using a 3D profilometer. All these studies established that the 10 mu m thick titanium-based sputtered nanocomposite coatings on SS 304 are efficient wear-resistant materials that showed excellent protection of the substrates from wear up till application of 500 g load. A good correlation between the composition, structure, properties, and processing of materials has been discussed based on the obtained wear behaviour

Magnetron sputtered films prepared from sintered Ti-based target and evaluation of tribological properties under the ball on disc condition with varying thickness and load

The hard nanocomposite coatings comprised of titanium, silicon, boron, and carbon (Ti-Si-B-C) and titanium, silicon, boron, carbon, and nitrogen (Ti-Si-B-C-N) were deposited on SS 304 substrate using magnetron sputtering technique. The tribological properties of these Ti-Si-B-C and Ti-Si-B-C-N coatings were explored with the variation of load (200-600 g) and thickness (3-25 mu m) against high strength steel ball using a ball on a disc tribometer. The nanoindentation technique was used to investigate the wear tracks and its consequent effect on the mechanical behaviour of uncoated and coated films. The analyses of the phases, microstructure, states of valence, shift of electron, and elemental compositions of the coatings were carried out by HRTEM, FESEM, AFM, XPS, EDX, and Raman spectroscopy techniques, respectively. The 2D cross-sectional profiles and 3D topographies of the wear tracks were explored using a 3D profilometer. All these studies established that the 10 mu m thick titanium-based sputtered nanocomposite coatings on SS 304 are efficient wear-resistant materials that showed excellent protection of the substrates from wear up till application of 500 g load. A good correlation between the composition, structure, properties, and processing of materials has been discussed based on the obtained wear behaviour

Palmitic acid based environmentally benign corrosion inhibiting formulation useful during acid cleansing process in MSF desalination plants

Palmitic acid imidazole (PI) was synthesized in microwave reactor. The obtained product was explored to reveal the mild steel's corrosion inhibiting property in 1 mol L−1 H2SO4. It gave maximum inhibition efficiency of 90% at ambient condition. Addition of little amount of KI (6 × 10−3 mol L−1) into 1× 10−3 mol L−1 of PI further increased its efficiency up to 98%. High corrosion inhibiting property of PI was observed owing to its adsorption on mild steel surface. The synthesized inhibitor molecule adsorbs via physisorption and chemisorption phenomenon; and followed Langmuir adsorption isotherm. Synergistic effect of KI addition with inhibitors was investigated and the obtained synergism parameters revealed a co-operative mechanism. The surface topography analysis and water angle measurements exhibited surface protective and water repelling property of PI. Furthermore, DFT, FIs analysis, MD simulations and RDF analysis were performed for exploring intrinsic molecular property and insightful elucidation of corrosion inhibiting mechanism. It unveiled spontaneous and strong adsorption of both neutral and protonated PI on metals' surfaces in presence of iodide ions. The obtained outcomes suggested that the combination of KI and PI may be the preferable corrosion inhibitor during acid cleansing process in MSF desalination plants

Corrosion inhibition property of azomethine functionalized triazole derivatives in 1 mol L−1 HCl medium for mild steel: Experimental and theoretical exploration

With the aim to explore the effect of heteroatoms on corrosion inhibiting efficacy of structurally similar azomethine based organic molecules, namely, 5-((furan-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (FMT) and 5-((thiophen-2-yl)methyleneamino)-2H-1,2,4-triazole-3-thiol (TMT) were synthesized and its corrosion inhibiting property were investigated by potentiodynamic polarization and non-destructive electrochemical impedance spectroscopy. These electrochemical techniques revealed the excellent corrosion inhibiting efficacy of synthesized inhibitor molecules for mild steel exposed to 1 molL−1 HCl at ambient condition. Surface analyses using FESEM, AFM and contact angle measurement of mild steel retrieved from corrosive medium containing inhibitor molecules confirmed the formation of protective layer of inhibitor molecules on its surface. The consequences of efficient corrosion inhibiting property has been explained based on Hard-Soft-Acid-Base principle as well as electronegativity and polarizability difference of heteroatoms present in the skeleton of inhibitor molecules. Moreover, in order to validate the corrosion inhibiting property obtained from electrochemical experimentations, the insight of corrosion inhibition mechanism has been further explored by employing theoretical calculations viz density functional theory, Fukui indices analyses, molecular dynamics simulation and radial distribution function. Mulliken atomic charges, frontier molecular orbital and Fukui indices analysis of the free as well as adsorbed inhibitor molecules confirms the interaction of the susceptible reactive sites