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Application of rare earth (RE) salts as a corrosion inhibitor was first proposed by Goldie and McCarrol in 1984. They showed that, with the addition of 0.001 M of Ce(NO₃) or La(NO₃) to 3.5% NaCl solution, the inhibition efficiencies were 91 and 82% for carbon steel, respectively. The aim of this paper is to study the inhibition of a mixture of Ce and La cations on the corrosion prevention of St37 carbon steel in aerated NaCl solutions using weight loss, potentiodynamic polarization, open circuit potential and constant potential measurements.

In this study, St37 steel was used as an experimental sample. The applied inhibitor was a powder mixture of Ce and La oxides with the ratio of Ce/La = 2/1. Each gram of this powder was dissolved in 4 cc acetic acid because of their insolubility in water. Steel samples were polished with 120 to 800 grit SiC polishing papers, deoxidized in 15 per cent HCl, and then ultrasonically cleaned in ethanol. They were degreased in acetone and were dried in a flow of hot air.

It has been shown that a mixture of RE cations (Ce and La) can be used as a corrosion inhibitor for carbon steel in NaCl containing solutions. The optimum inhibitor concentration was found to be 500 ppm with a maximum inhibition efficiency of 76%. An increase in Cl⁻ ion concentration and a rise in temperature from room temperature to 70°C can have an adverse effect on corrosion inhibition efficiency.

The results obtained from various experiments indicated that the mixture of Ce and La cations could be considered as a suitable inhibitor for carbon steel in low to medium chloride‐containing solutions. Owing to their non‐toxic nature, they may be suitable to use in potable water pipelines.

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.

This paper aims to evaluate the inhibitive action of different concentrations of Sesbania grandiflora leaf extract on the mild steel corrosion in an aggressive HCl medium under different experimental conditions.

Weight loss investigation, open-circuit voltage analysis, Tafel polarisation, AC impedance analysis, etc. were used for the evaluation of inhibition efficiency. The influence of immersion period on inhibition efficiency was evaluated. The mechanism of action of the inhibitor is also discussed. Infrared (IR) spectroscopy and energy-dispersive X-ray spectroscopy analysis were used to characterise the passive film.

The results suggested that 10,000 ppm solution has maximum inhibition efficiency of 98.01 per cent at room temperature, while 1,000 ppm solution also exhibited a better efficiency of about 96.16 per cent. Efficiency of inhibitor solution was found to increase with an increase in its concentration. Polarisation study proposed the solution as an anodic inhibitor. Impedance study confirmed the formation of a protective layer over the surface of the specimen, and the constituents of the film were identified using IR spectroscopy. Stability of the film adsorbed on the steel was cleared from the steady open-circuit potential value. Study on action of the inhibitor under accelerated conditions revealed the fact that the efficiency of extract in preventing corrosion is good under stimulated conditions also.

The action of inhibitor sustains for a sufficient time period and could sustain under stimulated conditions. Hence, its application is practically possible in industries. The proposed inhibitor is widely available and is environmentally safe.

HCl is an industrially important chemical used for acid cleaning, acid pickling, etc. HCl was used as an aggressive corrosion environment. As the chances for mild steel to be in contact with HCl were very high, it was important to develop an efficient, economical and eco-friendly inhibitor for corrosion.

This paper aims to identify an inhibitor to protect rebar corrosion in concrete.

The authors use the simple method of polarization and calculate the change in open-circuit potential and corrosion current density.

Sodium molybdate is an efficient inhibitor compared with sodium tungstate for rebar corrosion in concrete.

This paper has limitation of 0.0001 M concentration of inhibitors for 400 days of exposure in 3.5 per cent sodium chloride solution.

The research focused on the concentration of both inhibitors in the range from 0.1 to 0.0001 M, which resulted in greater structural protection from corrosion in adverse conditions, such as coastal areas.

The influence of such variables as temperature, agitation, oxygenation, etc., on the corrosion of aluminium bronze specimens with and without heat‐treatment in 3 and 24% NaCI solution has been studied by electrochemical methods and weight loss measurements. It has been observed that the corrosion process is under cathodic control under most of the experimental conditions. Properly heat‐treated specimens with beta‐phase present in preference to gamma2‐phase exhibit better corrosion‐resistance. Thus, with the improved corrosion‐resistance shown by suitably heat‐treated alloys the aluminium bronzes merit consideration as a substitute for other ferrous alloys for use in salt water.

Considers the advantages of highly alloyed stainless steel such as duplex stainless steels or nickel‐based alloys in highly corrosive environments. Looks at corrosion rates for alloys in acetic acid and presents results of tests on the influence of contaminants in the acid. Gives practical applications. Concludes that duplex stainless steels demonstrate higher corrosion resistance than austenitic stainless steels and are often comparable to nickel base alloys.

The purpose of this paper is to investigate the effect of iron content (2% and up to 6% Fe) on the corrosion behavior of 90Cu‐10Ni alloys in 3.5% NaCl at different temperatures (23, 50 and 80°C) under stagnant conditions and fluid flow (with an agitation speed of 350 and 900 RPM). The laboratory study was conducted following a failure of high iron content (up to 6%) 90Cu‐10Ni heat exchanger tubes in a desalination plant.

Potentiodynamic polarization measurement (DC) was used to estimate the corrosion rate of the 90Cu‐10Ni alloys in NaCl solutions under stagnant and fluid flow conditions.

It was found that the higher iron content cupronickel material suffered higher corrosion rates in all tests. The intensity of the corrosion attack of both materials was increased significantly with increasing experimental temperature or flow velocity. The results support a previous prediction that the presence of excess iron (well above 2%) has played a major role in corrosion failure of 90Cu‐10Ni heat exchanger tubing material in seawater.

This paper explains the role of iron content on the corrosion behavior of 90Cu‐10Ni alloys in 3.5% NaCl under stagnant and fluid flow conditions.

To study the corrosion behavior of pipeline steel in coastal areas, a tidal seawater macro-cell corrosion device was built using a cycle soaking tank and a macro-cell corrosion facility to simulate the corrosion behavior of pipeline steel in a simulated coastal environment (dry and wet alternations during seawater-soil corrosion macro-cell processes).

The corrosion behaviors were studied via the weight loss method, electrochemical methods and morphological observations on corrosion.

The results show that during the initial stage of tidal seawater/soil macro-cell corrosion process of the X65 steel, the working electrode on the seawater side is the anode of the macro-battery. As corrosion progresses, the anode and the cathode of the macro-battery become inverted. As the area ratio and the dry – wet ratio increase, the time of anode and cathode inversion shortens. Galvanic current density decreases as the dry – wet ratio increases and increases as the area ratio increases. The corrosion process of macro-cell is affected by the reversal of anode and cathode. After the reversal of anode and cathode, the corrosion rate is mainly controlled by dry – wet alternating corrosion.

The corrosion behavior of a pipeline steel in a coastal environment was studied using a tidal seawater macro-cell corrosion device. The synergism effect between the tidal seawater and seawater-soil macro-cell on corrosion behavior was clarified.

Aluminum alloy is susceptible to chloride ion attack in sea water, resulting in pitting damage and hence serious security risks for the related applications. To improve the corrosion resistance of Al alloy, micro-arc oxidation (MAO) technology has been developed to produce a protective dense oxide layer on top of Al alloy. However, the mechanism of MAO-induced corrosion resistance is still not fully understood, particularly on local corrosion issue. This paper aims to focus on comprehensively studying the corrosion-resistance mechanism by a series of technologies.

The corrosion behavior of samples was studied by open circuit potential (OCP), potentiodynamic polarization (PDP), electrode impedance spectroscopy (EIS) and localized electrode impedance spectroscopy (LEIS) tests in NaCl solution.

The MAO-coated Al alloy shows a more positive corrosion potential and a higher corrosion current density compared to the untreated counterpart, indicating a significantly enhanced corrosion-resistance. The study of surface morphology and structure also suggest significantly enhanced corrosion-resistance due to the MAO treatment.

Based on the results, a new corrosion model was proposed to describe the influence of MAO treatment on the corrosion process and corrosion mechanism of Al alloy, providing insights on the design of the corrosion-resistance coating for metallic alloys in marine applications.

The purpose of this study was to investigate the polyacrylic polymer/Al₂O₃ as a new nanocomposite coating to protect brass and Al-bronze in 3.5% NaCl and the role of alumina formulation on their protection efficiency

The corrosion efficiency of the nanocomposite coating (NCC) was evaluated by open circuit potential and electrochemical impedance spectroscopy (EIS).

The protection efficiency was more in the case of Al-bronze even for the same formulation of alumina NCC indicated the Cu substrate contribution. The Cu oxides in alloys and Al₂O₃ from the NCC and Al-bronze were responsible for this protection.

All the techniques supported each other, the presence of alumina was responsible for the corrosion protection efficiency.