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Poly(styrenesulphonic acid)‐doped polyaniline has been synthesised and the influence of this polymeric compound on the inhibition of corrosion of mild steel in 1M HCl has been investigated using weight loss measurements, galvanostatic polarisation studies, electropermeation studies and a.c. impedance measurements. The polymer acts predominantly as an anodic inhibitor. Hydrogen permeation studies and a.c. impedance measurements clearly indicate a very effective performance of the compound as a corrosion inhibitor. The adsorption of the compound on the mild steel surface obeys Temkin's adsorption isotherm.

The purpose of this paper is to investigate the inhibitive properties of black pepper extract (BPE) for aluminium in 1M hydrochloric acid (HCl) medium.

Gravimetric, electrochemical impedance spectroscopy, galvanostatic polarization, scanning electron microscopy with energy dispersive X-ray examinations (SEM-EDX) techniques were used to study the corrosion inhibitive study.

The gravimetric measurement indicates that inhibition efficiency shows direct proportional relation with concentration of inhibitor. The impedance results illustrates that there was a presence of protective layer of inhibitor adsorbed on the metal/solution interface. Polarization outcome showed that BPE is mixed type inhibitor. The existence of adherent layer of inhibitor on the Al surface was confirmed by SEM-EDX. Quantum chemical calculations were performed using the density functional theory at B3LYP/6-31G(d) level of theory to evaluate the activity of inhibitor molecules present in extract towards the corrosion inhibition of Al.

Due to the presence of large number of compounds in the extract, it becomes difficult to understand the most active compound responsible for inhibition. However, from gas chromatography mass spectrometry and quantum data, the approximation has been made that the major compound piperine present in the extract can be most probable component responsible for the inhibition activity. Further calculation of binding energy between Al and inhibitor molecules can be performed using Material Studio software.

The extract can be used in cleaning and etching solutions. It can be used to limit the loss of Al metal during etching process.

BPE can be used as a potential source of eco-friendly corrosion inhibitor for Al in HCl medium.

To investigate the capability of a series of nitrogen‐based heterocyclic organic compounds in inhibiting corrosion of iron in HCl and elucidate the dominant active form of the applied compounds during the adsorption process to explore the mechanism of their action.

The tested compounds were pyrimidine containing compounds, which were selected, based on molecular structure considerations. Gravimetric method has been applied with various electrochemical techniques (polarisation resistance, polarisation curves and electrochemical impedance spectroscopy) to investigate inhibition efficiency and mechanism.

The inhibiting action of the investigated pyrimidine containing compounds depends primarily on their concentration and molecular structure. These compounds act as mixed type inhibitors and function via adsorption on the surface, which follows Frumkin adsorption isotherm. The inhibition by the tested pyrimidine derivatives could be attributed to their chemisorption on the metal surface forming donor/acceptor type of bond between the inhibitor molecules and the vacant d orbitals of the surface iron atoms. Contribution from electrostatic adsorption, via interaction between the protonated form of the inhibitor and the charged metal surface, is also possible.

The applied inhibitors were tested in the presence of chloride ions as a corrosive medium. Whether these inhibitors will function well in the presence of other ions that are typically present in natural corrosive environment is unknown.

This paper provides useful information regarding inhibition effect of pyrimidine and series of its derivatives. The outcome of this work contributes to better understanding of the mechanism of inhibition by this class of N‐based heterocyclic organic compounds.

Corrosion inhibitors are widely used in industry, although in many cases their surface chemistry is not well understood. Several nitrogen‐containing organic compounds have been used as corrosion inhibitors. Corrosion inhibition is a surface process which involves the specific adsorption of inhibitors on the metal surface. The extent of inhibition of metallic corrosion may depend on the nature of the metal surface and extent of adsorption of the inhibitor. The type of interaction of the inhibitor on the metal surface during corrosion has been deduced from its adsorption characteristics.

Introduction Although investigation of a corrosion problem using only one or two techniques can give useful information, the most complete picture of the processes involved, and thus the best approach for a satisfactory solution of the problem, often only results from the use and interpretation of a combination of techniques. In this respect, the Corrosion Centre is fortunate in having a wide range of long‐established and modern facilities at its disposal, enabling reasonable investigations to be carried out on many different types of corrosion problems. These techniques are used primarily for research and teaching purposes, but many of them can be made available to industrial users. Table 1 gives an indication of some of the techniques to which the Centre has access and briefly mentions some of their possible applications in corrosion studies.

Zn‐Al alloys are widely used as coatings for corrosion protection of steel. These alloys provide long‐term protection to steel in several aqueous media; however, little attention has been paid to their behaviour in acidic media. The aim of this investigation is to study the corrosion and inhibition of 90 per cent Zn‐10 per cent Al alloy in hydrochloric acid.

Pyridine and a number of its methyl‐containing derivatives were applied in controlling the corrosion of 90 per cent Zn‐10 per cent Al alloy. The inhibitive action and mechanism of these compounds were investigated by weight loss tests, linear polarisation resistance measurements, galvanostatic polarisation tests and electrochemical impedance spectroscopy.

It was found that the corrosion rate of this alloy was much higher than that of either Zn or Al alone. Pyridine and its derivatives exhibited good inhibition for the corrosion of 90 per cent Zn‐10 per cent Al alloy, their inhibition efficiency increased in the order: I < II < III < IV. Potentiodynamic polarisation studies revealed that the investigated pyridine derivatives were mixed‐type inhibitors and functioned by adsorption on reactive sites on the alloy surface through the influence of the nucleophilic nitrogen atom forming a good physical barrier to prevent access of aggressive ions to the alloy surface. This was supported by the impedance measurements which showed a change in the charge transfer resistance and double layer capacitance indicating adsorption on the alloy surface. It was shown that the introduction of the methyl group(s) into the pyridine ring enhanced the effectiveness of pyridine inhibition. The improvement was attributable to the electron‐donating tendency of this group that gives rise to the increase in the electron density at the adsorption site. All the investigated substituents showed negative values of the Hammett constant (σ), indicating their electron‐donating property. The negative value of this constant increased according to the order: I < II < III < IV, the greater the negative value of σ being consistent with the greater degree of corrosion inhibition. It also was revealed that the presence of these inhibitors increased the value of activation energy for corrosion with a ranking order that was consistent with that of their inhibition effectiveness.

The evaluated inhibitors assured significant corrosion inhibition of the Zn‐Al alloy in HCl, however, their behaviour in different acid media was ambiguous.

This paper makes significant contibution to understanding the corrosion and inhibition of one of the widely apply coatings for steel protection in one of the most widely used aqueous mineral acids in industry.

The purpose of this paper is to show how to develop inhibition 57S aluminium in 2M NaOH solution.

The approach is used to measure gravimetric and polarization measurements.

The results of the paper clearly reveal that the 0.2 M ZnO with 700 ppm polyaniline in N‐methyl‐2‐pyrrolidone solution is found to offer inhibition up to 71.2 per cent.

The paper deals with the development of newer inhibitor based on polyaniline. Gravimetric and galvanostatic methods were employed to evaluate inhibition efficiency.

The corrosion behaviour of a ferritic (alloy 1) and two austenitic stainless steel alloys (alloys 2 and 3) was studied in a molten Li₂CO₃‐Na₂CO₃‐K₂CO₃ ternary mixture in the presence of Na₂O₂ additions at temperatures of 475, 500, 525 and 550°C. The techniques of measurements were open circuit potential, galvanostatic anodic polarisation and cyclic voltametry. The addition of Na₂O₂ increased the concentration of oxide ions in the carbonate melt. There is a tendency for oxidation and passivation of the alloys to commence immediately on their immersion in the melt, and end at the passivity breakdown, where the decomposition of carbonate ions occurs with the formation of CO₂ and O₂ gases. The oxide scales of a ferritic alloy are less protective than those formed on the austenitic alloys. The oxide scales, in most cases, are multilayered, and the presence of Na₂O₂ in the carbonate melt gives rise to the formation of a more protective inner layer of oxide scales on the surface of the austenitic alloys.

The purpose of this study was to compare the electrodeposition behavior and corrosion resistance of ternary and binary alloys.

Potentiodynamic polarization resistance measurement and anodic linear sweep voltammetry techniques were used for the corrosion study. The surface morphology and chemical composition of the deposits were examined using scanning electron microscopy and atomic absorption spectroscopy, respectively. The phase structure was characterized by X-ray diffraction analysis. Electrodeposition behavior was carried out using cyclic voltammetry and galvanostatic techniques.

It was found that the obtained ternary alloy exhibited better corrosion resistance and a more-preferred surface appearance compared to the binary alloys that were electrodeposited under similar conditions.

The ternary alloy showed better anticorrosion properties compared to binary deposits that were electroplated successfully from the plating baths. The Zn-Co-Fe alloy could be used advantageously in industry because the ternary alloy exhibits the collective properties of the binary alloys in one alloy via the electrodeposition of Zn-Ni-Co alloy.

Increasing the corrosion resistance implies to social economic increases.

To date, the electrodeposition of Zn-Co-Fe alloy was studied in only a small number of articles. It was found that the presence of Co or Fe could provide a useful coating on the steel that would reduce its susceptibility to corrosion attack.

The purpose of this paper is to present a novel five‐electrode electrochemical corrosion sensor. Health degradation by the corrosion of steel in civil engineering is a persistent problem. Structural health monitoring (SHM) techniques, including embedded sensors, can greatly improve the quantification of the steel corrosion information, which can lead to promote assessments of structural safety and serviceability. To integrate the corrosion monitoring system in future, the corrosion sensor and the monitoring methods have been explored here in advance. Also, the corrosion monitoring system has been applied preliminarily in the investigation of reinforcing concrete (RC) beams.

First, a novel five‐electrode electrochemical corrosion sensor has been developed as the hardware to provide the platform for corrosion monitoring methods. Second, half‐cell potential of the RC beams has been measured before and after corrosion. Third, galvanostatic step method has been used to excite the steel‐concrete system, and the transient response of the system has been obtained and analyzed. Finally, wavelet transform algorithm has been established to analyze the electrochemical noise (EN) data of the steel bars in RC beams.

The results show that the corrosion sensor can be used effectively as the hardware to support the electrochemical measuring techniques. Much valuable information which is extracted by analyzing the potential response to the galvanostatic pulse excitation can be applied to determine the general corrosion state of the reinforcing steel. For pitting corrosion, the energy distribution plot of EN can be adopted as a benchmark method to identify the presence of the corrosion pit.

The paper provides the key techniques for a SHM system to realize corrosion monitoring of large‐scale RC structures in the future.