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The objective of this work was to examine the anticorrosive behaviour of four different epoxy coatings, which were formulated with zinc pigments and were applied on pretreated steel panels exposed to deionised/deaerated water taken from the installations of the Greek Public Electricity Company, as well as to compare the results of this study with those of a relevant, previous work. The coating's performance was assessed by the measurement of the potentiodynamic polarisation resistance, by electrochemical impedance spectroscopy and the measurement of dielectric permittivity, during the deionised/deaerated water immersion tests. Additionally, accelerated salt spray tests were performed. All types of coatings tested exhibited a high protective performance. It was concluded that the epoxy system containing zinc dust was the most effective anticorrosion coating under the conditions relevant to this study.

The aim of the present work was to compare the performance of two coating systems applied on steel specimens. The first of them demands sandblasting pretreatment of the metal surface while the second one, which does not need it, leads to rust transformation. These systems were examined in three corrosive environments i.e. a geothermal fluid of low enthalpy, a 3.5 wt per cent NaCl solution and a 5wt per cent NaCl in a salt spray cabinet. The anticorrosive capability of the two coating systems was evaluated at predetermined exposure times by mass loss measurements of the steel substrate, by potentiodynamic polarization curves and by the half‐cell potential time evolution. Visual examination of the degree of rusting and blistering was also carried out. The results indicate that both coating systems exhibit almost similar protective behavior under the same conditions of pretreatment. In all cases, the corrosion rate increases with the increase of the surface roughness.

Galvanized steel specimens were coated with four different organic systems, containing either special acrylic resins or epoxy resins with or without wash primer. The anticorrosive performance of these duplex systems when exposed to an environment of 3.5 percent w/w NaCl solution, was investigated by electrochemical impedance spectroscopy, corrosion potential monitoring, potentiodynamic polarization and dielectric measurements. Interrelation of the obtained results, confirmed by visual observations after salt spray and weathering tests, shows that all four coating systems are more protective than simple galvanizing. The system, comprising a wash primer, a two‐component epoxy resin primer and an epoxy resin finish paint, demonstrates the best anticorrosive behavior among the four systems examined.

The use of coatings (organic and inorganic) for the protection of reinforced concrete is widespread. The advantages of inorganic coatings are that they are stable in UV‐radiation, non‐combustible, do not foul and have a microcrystalline texture, while organic coatings have the advantage of low permeability of carbon dioxide, sulphur dioxide and water. The aim of the present work was to compare, in the presence of chloride ions, the performance of an acrylic dispersion and a silicate coating, when the latter was or was not combined with a corrosion inhibitor (N‐N’‐dimethylaminoethanol). The behaviour of the silicate coating was examined as its use is increasing due to environmental reasons and as it can be applied for the rehabilitation of old structures. Half‐cell potential measurements, mass loss and carbonation depth measurements, as well as chloride diffusion rate revealed that the acrylic dispersion provides better protection of reinforcing steel in concrete than the silicate coating, but the combination of the silicate coating with the corrosion inhibitor provides the best level of concrete protection.

To study the effect of feldspars as inorganic filler on the mechanical and dielectric properties of epoxy coatings.

Coating systems used were of either filler‐free epoxy resin (as reference), or epoxy resin filled with feldspars powder at four different levels by weight. Mechanical properties of the coatings were evaluated via damping hardness and abrasion and impact resistance measurements. Electrochemical impedance spectroscopy measurements were used for the evaluation of the dielectric properties while visual observations of the test panels after salt‐spray test were also made.

The addition of 15 per cent w/w feldspars resulted in a formulation giving the most positive results, e.g. improvement of the coating's mechanical characteristics and dielectric behaviour similar to that of filler‐free epoxy coatings. Practically comparable to this behaviour was that possessed by coatings with 30 per cent w/w feldspars, while further increase of the feldspars content resulted either in a reduction in the extent of the enhancement of the mechanical behaviour or even in a worsening of both mechanical and dielectric characteristics.

Feldspars are the most abundant group of minerals in the earth's crust; it is an inorganic, environmentally friendly material, which exhibits high Mohs hardness. The effects of feldspars in improving the mechanical characteristics of organic coatings, while not causing any reduction in the anticorrosive performance of the polymeric matrix was found through the study.

Four different organic systems, containing either vinyl acetate resins or epoxy resins were applied on steel pretreated specimens exposed to deionized and deaerated water taken from the installations of the Public Greek Electricity Company. Electrochemical Impedance Spectroscopy, potentiodynamic polarization measurements, dielectric measurements and visual observations after salt spray test were performed for monitoring the changes of the organic systems characteristics at predetermined exposure time in the deionized – deaerated water. All four coating systems found providing protection on steel surfaces. The classification of their performance depends mainly on the composition of the primer, as well as, on the intrinsic characteristics of the other layers. Thus the system consisting of epoxy primer with zinc dust, epoxy high build layer and a two component epoxy paint with iron oxide is the one exhibiting the highest protection efficiency.

The aim of this fieldwork was the study of the effect of 50Hz AC, induced by high‐voltage power lines, on the cathodic protection system of a natural gas pipeline. The effectiveness of cathodic protection was checked through in situ long‐term monitoring and analysis of pipeline electrical parameters. The results gave an insight into the problems of the cathodic protection system operation, caused by AC interference. An AC and DC potential interdependence was observed, that previously has hardly been reported, and was scrutinized in relation to cathodically protected pipelines. The effects of the AC‐interference and low frequency DC potential fluctuations, as well as the potential deviations from the protection potential, are examined. These phenomena are associated with corrosion susceptibility and difficulties in obtaining reliable cathodic protection measurements.

The purpose of this paper is to develop and optimize anti‐corrosive multi‐layered coatings of zinc‐nickel alloy on carbon steel.

A variety of composition‐modulated multi‐layer alloy (CMMA) coatings of zinc‐nickel were developed on a carbon steel substrate by cyclic changes in cathode current during electrodeposition, coupled with variation of the thicknesses of the individual layers. The corrosion behavior of the coatings was studied in 5 percent NaCl solution by electrochemical methods. Cyclic cathode current densities (CCCDs) and the number of alloy layers were optimized for highest performance of the coatings against corrosion. The factors responsible for improved corrosion resistance were analyzed in terms of change in the intrinsic electrical properties of the capacitance value at the electrical double layer that was associated with micro/nanometric layering. The formation of the semi‐conductive surface film, which was responsible for the improved corrosion resistance, was supported by a Mott‐Schottky plot and the cyclic polarization study. The formation of multi‐layered deposit and the mechanism of corrosion degradation of the coating were analyzed using scanning electron microscopy.

CMMA coatings with an optimal configuration of (Zn‐Ni)_2.0/4.0/300 showed ∼35 times better corrosion resistance compared to a monolithic (Zn‐Ni)_3.0 alloy coating of the same thickness. The peak performance was attributed to the change in intrinsic electrical properties of the coating and this conclusion was supported by dielectric spectroscopy.

The paper describes the optimization of CCCD and the number of deposited layers by development of electrolytic deposition of anti‐corrosive multi‐layered zinc‐nickel coatings from a single plating technique.

A number of applications selected with variations of factors affecting the corrosion of mortar steel reinforcements are discussed in this paper. Corrosion estimation by means of a strain gauge (SG) technique was used in several cases to confirm the validity of the method. The efficiency of corrosion inhibitors, the protection offered by the addition of minerals, the curing time influence, and the corrosion resistance of various steel types can be estimated by means of the short term SG test technique. Good correlations were found in all cases of application between the corrosion rates computed from SG technique and the mass loss data. Additionally, the method was applied for swelling measurements of mortar specimens caused by the degradation of FRP reinforcements in the corrosive environments.