Hydrogen embrittlement risk of high strength galvanized steel in contact with alkaline media

Recio, Francisco J.; Alonso, C.; Gaillet, Laurent; Sánchez, M. E.

doi:10.1016/j.corsci.2011.05.023

Cited by 45 publications

(34 citation statements)

References 22 publications

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“…The conjugation of these factors may cause rupture of the film passivation and initiate rusting of steel originating failure in reinforced concrete structures. However, premature failure in RCS by reinforcement corrosion in aggressive environments, especially structures exposed to marine environments, might be mitigated if the reinforcing steel is hot dip galvanized [4][5][6][7]. The zinc coating on rebars embedded in concrete acts as a physical barrier avoiding direct contact between the coated reinforcing steel and the aggressive environment.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

Figueira¹,

Pereira²,

Silva³

et al. 2013

Port. Electrochim. Acta

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Corrosion of steel in concrete is one of the major causes of structure degradation, requiring expensive maintenance. The using of hot dip galvanized steel (HDGS) has been recognized as one effective measure to increase the service life of reinforced concrete structures in marine environmental. However, HDGS corrodes in contact with high alkaline environment of fresh concrete. Although this initial corrosion process allows the formation of a protecting layer barrier, the corrosion that occurs initially is harmful and chromate conversion layers are usually used to prevent it. Due to toxicity of Cr(VI), these kinds of pre-treatments have been forbidden and hybrid coatings have been proposed as alternatives [1][2][3]. To evaluate the performance of these coatings, beyond the laboratory characterization, in situ tests in real conditions should be performed. An electrochemical system to measure the macrocell current density (i gal ) was designed to evaluate the degradation of HDGS coated samples with different organic-inorganic hybrid films, embedded in mortar during 70 days, using an automatic data acquisition system. This system revealed to be feasible and highly sensitive to coatings degradation. Also, allow distinguishing different hybrid coatings with different thicknesses.

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Section: Introductionmentioning

confidence: 99%

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

Figueira¹,

Pereira²,

Silva³

et al. 2013

Port. Electrochim. Acta

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“…SCPS were prepared according to the literature 10,53 by the addition of analytical reagent grades 0.2 M KOH to a Ca(OH) 2 saturated solution previously prepared with distilled water. A final solution with a pH = 13.2 was obtained and 1 wt% of chlorides was added as sodium chloride.…”

Section: Methodsmentioning

confidence: 99%

“…8,12 However, when the HDGS is in contact with concrete pore solution, (which is essentially a Ca(OH) 2 saturated solution containing significant amounts of KOH and NaOH) the zinc corrodes. [8][9][10]13,14 The pH of this medium is typically above 12.5. This initial corrosion process, which may vary from hours to days, may lead to zinc consumption until either the formation of a passivation layer or until all the zinc layer is consumed.…”

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confidence: 99%

“…1,[5][6][7] In the last few years, the use of hot-dip galvanized steel (HDGS) has been recognized as an effective measure to increase the service life of RCS. [8][9][10][11] The galvanized coating (zinc layer) acts as a physical barrier, hindering the contact of aggressive agents with the steel substrate and the zinc acts as a sacrificial anode protecting the steel against corrosion. In addition, the formed zinc corrosion products have a smaller volume than those produced from iron, thus reducing the corrosion-induced delamination, cracking or spalling of the concrete.…”

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confidence: 99%

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Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Chloride-Contaminated Simulated Concrete Pore Solution

Figueira

Silva

Pereira

2015

J. Electrochem. Soc.

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Organic-inorganic hybrid (OIH) sol-gel coatings based on ureasilicates (U(X)) have promising properties for use as eco-friendly coatings on hot dip galvanized steel (HDGS) and may be considered potential substitutes for pre-treatment systems containing Cr(VI). These OIH coatings reduce corrosion activity during the initial stages of contact of the HDGS samples with highly alkaline environments (cementitious media) and allow the mitigation of harmful effects of an initial excessive reaction between cement pastes and the zinc layer. However, the behavior of HDGS coated with U(X) in the presence of chloride ions has never been reported. In this paper, the performance of HDGS coated with five different U(X) coatings was assessed by electrochemical measurements in chloride-contaminated simulated concrete pore solution (SCPS). U(X) sol-gel coatings were produced and deposited on HDGS by a dip coating method. The coatings performance was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization curves measurements, macrocell current density and polarization resistance in contact with chloride-contaminated SCPS. The SEM/EDS analyses of the coatings before and after the tests were also performed. The results showed that the HDGS samples coated with the OIH coatings exhibited enhanced corrosion resistance to chloride ions when compared to uncoated galvanized steel. Corrosion of the reinforcing steel is one of the most important causes of degradation in reinforced concrete structures (RCS).1 The presence of chloride, carbonation of the concrete or the low quality of the concrete cover causes serious damage to RCS. The entrance of chloride ions through the concrete from marine environments or deicing salts can cause rupture of the passive layer, allowing the steel surface to act as a coupled anodic and cathodic reaction cell in which corrosion processes take place.1-3 Therefore, the presence of chlorides in concrete can seriously shorten the service life of RCS. 3,4The expanded volume of corrosion products deposited in the interface between the concrete and the steel imposes expansive stresses, leading to delamination, cracking or spalling and eventually to the collapse of the RCS. 1 Several methods to improve the corrosion resistance of RCS have been proposed. 1,[5][6][7] In the last few years, the use of hot-dip galvanized steel (HDGS) has been recognized as an effective measure to increase the service life of RCS. [8][9][10][11] The galvanized coating (zinc layer) acts as a physical barrier, hindering the contact of aggressive agents with the steel substrate and the zinc acts as a sacrificial anode protecting the steel against corrosion. In addition, the formed zinc corrosion products have a smaller volume than those produced from iron, thus reducing the corrosion-induced delamination, cracking or spalling of the concrete.8 Additionally, the galvanized steel reinforcement can withstand exposure to chloride ion concentrations several times higher than the chloride level that causes corrosion in ste...

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“…In the last few years, the use of galvanized rebars has been recognized as an effective measure to increase the service life of RCS [7][8][9][10], mainly due to its low cost when compared to other protection systems [11].…”

Section: Introductionmentioning

confidence: 99%

Influence of Experimental Parameters Using the Dip-Coating Method on the Barrier Performance of Hybrid Sol-Gel Coatings in Strong Alkaline Environments

2015

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Abstract:Previous studies have shown that the barrier effect and the performance of organic-inorganic hybrid (OIH) sol-gel coatings are highly dependent on the coating deposition method as well as on the processing conditions. However, studies on how the coating deposition method influences the barrier properties in alkaline environments are scarce. The aim of this experimental research was to study the influence of experimental parameters using the dip-coating method on the barrier performance of an OIH sol-gel coating in contact with simulated concrete pore solutions (SCPS). The influence of residence time (Rt), a curing step between each dip step and the number of layers of sol-gel OIH films deposited on hot-dip galvanized steel to prevent corrosion in highly alkaline environments was studied. The barrier performance of these OIH sol-gel coatings, named U(400), was assessed in the first instants of contact with SCPS, using electrochemical impedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings in SCPS was monitored during eight days by macrocell current density. The morphological characterization of the surface was performed by Scanning Electronic Microscopy before and after exposure to SCPS. Glow Discharge Optical Emission Spectroscopy was used to investigate the thickness of the U(400) sol-gel coatings as a function of the number of layers deposited with and without Rt in the coatings thickness. OPEN ACCESSCoatings 2015, 5 125

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Hydrogen embrittlement risk of high strength galvanized steel in contact with alkaline media

Cited by 45 publications

References 22 publications

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Chloride-Contaminated Simulated Concrete Pore Solution

Influence of Experimental Parameters Using the Dip-Coating Method on the Barrier Performance of Hybrid Sol-Gel Coatings in Strong Alkaline Environments

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