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The aim of this research was to develop corrosion protection systems for reinforced concrete structures under chloride attack. Benzotriazole (BTA) and BTA derivatives were used as corrosion protection materials for the steel.

The effect of BTA and four other BTA derivatives on the corrosion resistance of steel in simulated concrete pore (SCP) solutions was studied. BTA derivatives were used as two separate protection systems: inhibition and pickling protection systems. The experiments were performed in SCP solutions which simulated concrete with and without severe chloride attacks. Electrochemical techniques, i.e. potentiodynamic polarization and electrochemical impedance, and Fourier transform infrared spectroscopy (FTIR) were used to assess the steel corrosion protection systems.

The potentiodynamic polarization studies showed an increase in the pitting potential for all protection systems tested. In addition, a large increase in the steel solution interfacial resistance was observed by electrochemical impedance studies (EIS) due to the formation of steel‐BTA derivatives complex on the surface. This film was formed on the steel surface with either mono‐or bi‐dentate bonds between the triazolic nitrogen ring and the steel surface as shown by the FTIR.

BTA derivatives provided good protection for steel in SCP solutions, indicating their applicability in reinforced concrete structures. However, tests using reinforced concrete samples are required to study possible interactions between steel, BTA derivatives and concrete constitutes, e.g. sand, gravel, cement and chemical admixtures. These BTA‐based systems also should be studied under carbonation attack.

BTA derivatives provided a good protection for steel in the SCP solutions, and this indicates the applicability to use them in reinforced concrete structures.

The purpose of this work is to provide theoretical guidance and experimental analysis for optimized cathodic protection (CP) design of low alloy steel in deep water environments.

In the present study, the CP criteria of 10Ni5CrMoV low alloy steel were investigated in a simulated deep water environment (350 m) regarding the theoretical protection potential and measured protection potential. The influences of hydrostatic pressure (HP) and temperature were also discussed in detail. The theoretical protection potential was analyzed with the Nernst equation, and the measured minimum protection potential was derived by extrapolating the Tafel portion of anodic polarization curves.

The results indicate that the minimum protection potential of low alloy steel shifts to a positive value in a deep-ocean environment. This can be attributed to the combined effects of HP and the temperature. Moreover, the temperature has a stronger influence compared with HP. The results suggest that the CP potential criteria used in shallow water are still applicable in the deep ocean, which is further confirmed through the SEM and x-ray diffraction analysis of the corrosion products resulted from the potentiostatic cathodic polarization experiments at −0.85 V_CSE.

In recent decades, successful applications of CP for long-term corrosion protection of the steel components applied at a subsea level have enabled the offshore industry to develop reliable and optimized CP systems for shallow water. However, differences in the seawater environment at greater depths have raised concerns regarding the applicability of the existing CP design for deeper water environments. Hence, this research focuses on the CP criteria of low alloy steel in simulated deep water environment concerning the theoretical protection potential and measured protection potential. The influences of HP and temperature were also discussed.

To evaluate the performance of two cathodic protection (CP) systems applied to steel reinforced concrete structures manufactured with calcareous aggregates and exposed to the tropical‐humid marine environment at the Yucatán peninsula in Mexico.

Rectangular concrete beams were manufactured using a water/cement ratio = 0.65, with and without the addition of NaCl in the mixing water. Specimens subjected to CP, eight to impressed current cathodic protection (ICCP) and eight to sacrificial anode cathodic protection (SACP) were partially immersed in natural seawater during 360 days. The half cell potential (HCP) and the current consumption were recorded during the total exposure time.

The measured HCP values of the steel rebar in the beams subjected to SACP did not attain protection potential levels. However, the galvanic couple Zn‐steel provided enough current for the protection of the steel. Visual inspection of concrete cores extracted from the beams indicated that corrosion products were not present at the steel‐concrete boundary. On the other hand, the ICCP applied to eight concrete beams provided excellent corrosion protection to the steel rebar.

This work revealed that the SACP system (thermally sprayed zinc) works well in high relative humidity environments and can be successfully used to protect steel reinforced concrete structures manufactured with calcareous aggregates which are endemic of the region and commonly used for infrastructure construction in the Yucatán peninsula.

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.

Irrespective of the type of cathodic protection system applied to an offshore platform or pipeline the longevity and effectiveness of that system, and therefore the safety and continued revenue earning capacity of the platform or pipeline, can be assured only if adequate monitoring and surveying of the performance is undertaken.

This paper aims to investigate the protection efficiency of a thin film of electrochemically synthesized conducting polymers, such as poly m‐toluidine, poly N‐methyl aniline, and its copolymer, poly (aniline‐co‐N‐methyl aniline) (PANINMA), on plain carbon steel in 0.1 M HCl. It also attempts to compare the protection efficiency of these compounds with polyaniline (PANI)‐coated carbon steel.

The green coloured and adherent coatings were obtained by cyclic voltammetry during sequential scanning of the potential region between −0.6 and 1.6 V at a scan rate of 10 mVs⁻¹. Potentiodynamic polarization measurement (DC) was used to obtain an estimate of the corrosion rate and protection efficiency for these electrodeposited polymers on the carbon steel. Scanning electron micrographs (SEM) also were obtained to characterize the deposited coatings.

It was observed that these polymer coatings showed better protection efficiency than the PANI coating. Of the compounds studied, the copolymer PANINMA coating showed higher protection efficiency than other coatings. The SEM observations revealed that the compact continuous dense morphology of PANINMA provided better protection than other coatings.

This paper explains the protection efficiency of the substituted and copolymer coatings of PANI on carbon steel.

This paper aims to prepare a residual rust epoxy coating by adding different quantities of phytic acid (PA) on the surface of the rusty steel and investigate the corrosion protection of PA and its action mechanisms.

A residual rust epoxy coating by adding different quantities of PA was prepared on the surface of the rusty steel. The influence of PA on the corrosion resistance of epoxy-coated rusty steel was investigated by means of electrochemical impedance spectroscopy and adhesion testing.

Results indicated that PA can substantially improve the corrosion resistance of epoxy-coated rusty steel. This improvement is due to the reaction of PA with residual rust and generation of new compounds with protection properties and increased adhesive strength effects on the coating/metal interface. The coating showed better protection performance when 2 per cent PA was added.

Considering the structure of the active groups, PA has strong chelating capability with many metal ions and can form stable complex compounds on the surface of a metal substrate, thereby improving corrosion resistance. In recent years, PA has been reported to be useful in the conversion of coatings or as green corrosion inhibitor. To the best of the authors’ knowledge, few studies have reported the use of PA as a rust converter or residual rust coating. The present work aims to improve the corrosion resistance of residual rust epoxy coating by adding PA.

The Corrosion Group of the Society of Chemical Industry had a gratifying high attendance at their symposium on ‘The Protection of Structural Steel,’ held in London on March 31 and April 1 under the chairmanship of Dr. J. C. Hudson, of the British Iron and Steel Research Association. Well over 200 engineers, steel makers, steel users and paint and metal finish manufacturers and academic workers attended, together with an impressive foreign contingent from a number of countries. A wide variety of papers were delivered, followed by considerable discussion. Widespread interest was shown in the relative merits of paint and metal‐spraying protective techniques and particularly in the question of comparative costs. Reports of the papers delivered during the first day of the symposium are given below. These will be continued next month.

Thin coatings are of great importance to minimize corrosion attack of steel in different environments. A review of recent work on electrodeposition and corrosion performance of Zn-Ni-based alloys for sacrificial corrosion protection of ferrous substrates is presented. The purpose of this study is to provide a systematic comparison of the corrosion resistances of Zn-Ni alloy coatings. The review contains key and outstanding comparisons of references for the period from 2007 to 2017. Binary and ternary Zn-Ni-based alloys were compared and contrasted to provide a good knowledge basis for selection of best coating system to steel substrates.

This article is a review article.

Zn-Ni-(X) alloys show great potential for replacing Cd metal in corrosion protection of steel substrates.

The research on plating of binary Zn-Ni alloys from aqueous electrolytes is now well advanced and these alloys show improved corrosion resistance compared to pure Zn. Pulse plated and compositionally modulated multilayer Zn-Ni alloy coatings showed enhanced corrosion properties compared to direct plated Zn-Ni coatings of similar composition.

The work on electrodeposition of Zn-Ni based alloys from ionic liquids is still scarce, yet these liquids show great promise in improving corrosion resistance and reducing coating thickness when compared to aqueous electrolytes. Advanced plating techniques in ionic liquids such as electromagnetic, compositionally modulated multilayer, pulse plating, ternary alloys and composites should be considered as these electrolytes avoid water chemistry and associated defects.

Introduction Virtually all our knowledge of the principles of steel protection by organic coatings has been gained during the past forty years and this probably explains why so many bad practices persist. It is well known that it requires more than a full generation entirely to remove deeply impressed traditions, and since paint manufacture and painting practice have only during this period slowly emerged from traditional crafts it seems likely that another ten or twenty years will pass before the scientific principles now understood will be fully incorporated into everyday practice. The disruptive effect of a world war which, while accelerating the acquisition of knowledge, often submerged truth by expediency, and the subsequent sterility produced by accountancy methods based only on historical misconceptions, led to a delay of 20 years. Much thought and effort is now being given to repairing the damage as can be seen by the frequency of corrosion colloquia, metal protection seminars and the like. Also during the last few years the steel industry itself has taken note of the painstaking work over some decades of its own Research Organization, while the paint industry has, through the stimulus of the plastics industry and its own raw materials suppliers, started to meet the challenge of the greater demands of the steel using industries. However, the paint industry generally is still far too prone to offer materials at a so‐called competitive price per litre, i.e. a cut price, rather than to sell the idea of the cost per square yard per year of adequate protection. Only when there is a true understanding of protection methods by both client and supplier, working with the painter, will full advantage be taken of the information and skills already to hand.