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The aim of this work is to evaluate the electrochemical noise (EN) method as a way of evaluating quickly the aggressiveness of natural atmospheres.

Wire‐on‐bolt tests were used, which implies an exposure of at least three months of bimetallic specimens such as aluminium wire/steel bolt and aluminium wire/copper bolt (CLIMAT units). Electrochemical noise measurements (ENM) also were used.

EN is a powerful tool in the assessing of aggressiveness of atmospheres in short time exposure. Statistical analyses of EN were carried out and provided clear differences between atmospheres depending on pollutants. Results of noise resistance (R_n), root mean square of current (I_rms) and localization index are discussed.

The possible application of ENM to atmospheric corrosion is interesting from a practical point of view. However, more experiments are necessary in order to test a wide range of atmospheres.

EN has proved to be a useful tool when localised corrosion is detected and the presence of chlorides in atmospheres, due to sea fog, results in pitting on the metallic samples.

Illustrates that electrochemical noise can be a powerful tool for assessing the aggressiveness of natural atmospheres.

The purpose of this paper was to characterize the surface of steel reinforcement of concrete under cathodic protection (CP), submerged in seawater, to understand the surface changes due to the application of CP and their consequences on cathodic current requirements.

Reinforced concrete specimens with applied CP were immersed in natural seawater. The experimental methodology included monitoring of corrosion potential (E_corr); measurement of galvanic current (Igalv), protection potential (E_protection) and the depolarization potential of steel during the time of exposure; and electrochemical impedance spectroscopy (EIS). The chemical composition of the steel surface was assessed using X-ray diffraction (XRD).

The application of CP leads to the formation of a deposit on the steel surface that according to XRD results, Pourbaix diagram and physical characteristics, is a protective oxide: magnetite (Fe₃O₄). This oxide causes a decrease in the corrosion rate and requires application of the protection current. It was found that the surface remained protected even after eight days when the CP system was interrupted.

It is necessary to carry out analysis of the chemical composition of deposits formed on the steel surface, perhaps using X-ray photoelectron spectroscopy, Mössbauer, to verify the presence of the magnetite.

Determination of the main cause of the decrease in current required for protection and deposit formation conditions will enable the design of a CP system to be optimized and economized. At present, the CP design considers only a constant current value for the duration of the protection time.

CP is a technique that has proven effective for the protection of metal structures. However, little attention has been devoted to the surface changes that occur under applied CP and their impact on the electrochemical behavior of the system. This paper describes the phenomena produced at the metal surface and determines kinetic parameters and their consequences on the CP behavior.

The purpose of this paper is to characterize the surface of steel under cathodic protection while submerged in seawater, to understand the mechanism that controls the operation of the protection system.

Steel rods were immersed in seawater and NaCl solution with applied cathodic protection. The experimental methodology included monitoring of corrosion potential (E_corr), galvanic current (I_galv) protection potential (E_protection) and the depolarization potential of steel during the time of exposure. In addition, the chemical composition of the steel surface was assessed using a Scanning Electron Microscope (SEM).

In this research it was determined that the effectiveness of the CP system was mainly attributable to the formation of an iron oxide film on the steel surface.

It is necessary to carry out analysis of the chemical composition of deposits formed on the steel surface, perhaps using X‐ray diffraction (XRD), to verify the presence of a protective oxide.

Deposits on the steel surface have the beneficial effect of reducing the current required for efficient protection. Deposit formation therefore is of economic interest, as it decreases the cost of protection.

A unique feature of cathodic protection in seawater is the formation of calcareous deposits on metal surfaces. Advantageous aspects of these deposits, such as decrease in cathodic current requirement, have been investigated by various authors from various viewpoints. However, very little attention has been paid to the impact of any iron corrosion product films; the present paper contributes useful understanding and explains the importance of the mechanism that controls the operation of the protection system.

The purpose of this study was to examine the copper protection against corrosion using 3-thiophenemalonic acid (3TMA).

The heterocyclic organic molecule was tested experimentally as a corrosion inhibitor of copper in two different concentrations (0.01 M and 0.001 M) in 0.5 M solutions of sodium chloride and sulfuric acid by AC electrochemical and DC techniques.

Results showed that the organic compound was adsorbed chemically on the copper surface, and the inhibitions mechanism was both anodic and cathodic. The corrosion mechanism was under mixed control: charge transfer from metal to the environment through the double electrochemical layer, and diffusion processes.

This inhibitor could have application in water cooling systems.

The results of this paper showed that 3TMA could be used for reducing corrosion rates of copper in solutions of sodium chloride and sulfuric acid.

This study attempts to investigate corrosion inhibition properties of 1H-benzimidazole (B) and 1H-benzotriazole (BTA) on aluminum in 0.25 M HCl solution at different concentrations.

To this end, electrochemical techniques including electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used.

Results showed a greater corrosion inhibition efficiency of BTA than B on aluminum in HCl solution. BTA showed greater tendency to adsorption on the metal surface than B because of the inclusion of three nitrogen atoms.

The novelty of this work is comparing EN data with EIS and potentiodynamic polarization parameters.

To evaluate the effect of synthesised calixarenes as new inhibitors on the corrosion of steel in HCl media at various temperatures.

Calixarenes have been synthesised and tested as corrosion inhibitors. Gravimetric technique and potentiodynamic polarisation and impedance spectroscopy methods were used.

Calixarenes exhibited a good inhibition. Their efficiency decreases slightly with temperature.

It was found that the inhibition efficiency increases with the concentration of inhibitors to reach 92 per cent at 10⁻⁴M.

The efficiency of calixarene derivatives increases with the concentration and falls slowly with temperature to attain 84 per cent at 353 K range. Calixarenes can be used in chemical cleaning and pickling processes.

The originality of this work is to find an inhibitor to give protection close to 100 per cent.

Among the many influencing effects that the medium has on the CO₂ corrosion of carbon steel, flow is one of the most important because it can determine the formation of corrosion product scales and its stabilisation, thus influencing the attack morphology and corrosion rate. This paper aims to summarise some factors affecting aqueous CO₂ corrosion and the laboratory methodologies to evaluate one of the most important, the flow, with an emphasis on less costly rotating cage (RC) laboratory methodology.

Regarding the key factors affecting CO₂ corrosion, both well-established factors and some not well addressed in current corrosion prediction models are presented. The wall shear stress (WSS) values that can be obtained by laboratory flow simulation methodologies in pipelines and its effects over iron carbonate (FeCO₃) scales or inhibition films are discussed. In addition, promising applications of electrochemical techniques coupled to RC methodology under mild or harsh conditions are presented.

More studies could be addressed that also consider both the salting-out effects and the presence of oxygen in CO₂ corrosion. The RC methodology may be appropriate to simulate a WSS close to that obtained by laboratory flow loops, especially when using only water as the corrosive medium.

The WSS generated by the RC methodology might not be able to cause destruction of protective FeCO₃ scales or inhibition films. However, this may be an issue even when using methodologies that allow high-magnitude hydrodynamic stresses.

It is a challenge in the design to determine the feasible anode position and the supply current when the hull is protected by the impressed current cathodic protection method. It is difficult to obtain these parameters through traditional experimental methods due to the huge hull surface area and geometric complexity. This study aims to solve the problem by finite element method.

First, a great number of experiments need to be conducted; second, experiments are empirical; finally, there exist measurement errors, etc. All these factors make the experimental results less reliable. The application of the finite element method, combined with other technologies, is expected to overcome these deficiencies. In this paper, the combined Matlab and Comsol method was used to calculate various anode positions and corresponding protection areas with a series of input current conditions. The calculation is implemented via the script in Matlab.

As a result, the best design can be obtained. The results show that the method provided in this paper can replace the experiment to a certain extent, save human and material resources and reduce the design time. The method also can be applied to other similar fields, having a good universality.

This optimization method can be extended to other areas of relevant production and research, having a good universality.

The paper aims to investigate the effectiveness of hydroxypropyl methylcellulose (HPMC) as corrosion inhibitor for aluminium in 0.5 M H₂SO₄ solution.

This study was carried out using weight loss and electrochemical techniques. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of inhibitor system. Quantum chemical computations were performed using density functional theory to assess the parameters responsible for the inhibition process and also to analyse the local reactivity of the molecule.

HPMC inhibited aluminium corrosion in the acidic environment. The inhibition efficiency was found to depend on concentration of the inhibitor. Impedance results reveal that HPMC is adsorbed on the corroding metal surface. Polarization results show that the dissolution reaction is due to destabilization of the passive oxide film on the Al surface. Adsorption of the inhibitor is approximated by Freundlich adsorption isotherm and the calculated standard free energy of adsorption indicates weak physical interaction between the inhibitor molecules and aluminium surface. This can be attributed to preferential interaction of the active sites with the passive oxide layer. The calculated quantum chemical parameters show good correlation with the inhibition efficiency.

HPMC could find possible application as a polymeric thickener and additive to improve corrosion resistance and barrier properties of anticorrosion paints.

This paper provides novel information on the inhibitive characteristics of HPMC under the stated conditions. The inhibitor systems provide an effective means for suppressing aluminium corrosion even in highly aggressive acidic environments.

Although stainless steel (SS) has good corrosion resistance in most aqueous solutions, it suffers corrosion in some solutions which contain aggressive ions such as sulfide ions. This study aims to use some cephalosporins (cefotaxime, cephapirin and cefazolin) as corrosion inhibitors of commercial SS in 0.5 M H₂SO₄ solution containing sulfide ions at 30°C.

The study was carried out using weight loss method, potential-time, linear polarization, potentiodynamic polarization, electrochemical impedance measurements, scanning electron microscopy, Fourier transform infrared and energy dispersive X-ray analysis.

The presence of the cephalosporin compound in the corrosive medium shifted the corrosion potential of SS to much positive side, which enhances self-passivation of SS, and the shifting increased with increasing inhibitor concentration. The cephalosporin compounds worked as effective inhibitors with mainly anodic and the efficiency increase as cefotaxime < cephapirin < cefazolin. The inhibitors form a protective adsorbed layer, which enriches the surface content of Ni and Cr and thus assists the SS to be passive.

The antibiotics cephalosporins could be used as effective corrosion inhibitors for SS in acidic solutions containing sulfide ions. The inhibitors enhances the the passive oxide film of SS even in presence of aggressive ions such as sulfide ions.