Corrosion resistance of zinc–magnesium coated steel

Hosking, Niamh C.; Ström, Mats; Shipway, P.H.; Rudd, C.D.

doi:10.1016/j.corsci.2007.03.032

Cited by 352 publications

(217 citation statements)

References 21 publications

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“…3,[8][9][10][11][12][13][14] The improved corrosion stability of the Zn-Mg alloy has been attributed the formation of a compact simonkolleite (Zn 5 (OH) 8 Cl 2 · H 2 O) layer, on the Zn-Mg coating serving as a barrier to oxygen diffusion. 8,9 Further, it has been suggested that the precipitation of alkali-resistant Mg(OH) 2 is responsible for the reduced oxygen activity at the Zn cathode. Schürz et al 3 measured surface corrosion products on Zn-Al-Mg coated steel after a salt spray test.…”

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Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Han

Ogle

2017

J. Electrochem. Soc.

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The role of dealloying in the corrosion resistance of MgZn 2 has been investigated for the first time. The elemental dissolution kinetics of a synthetic, nominally pure MgZn 2 intermetallic compound was investigated and compared with pure Mg and Zn in 30 mM NaCl with pH = 10.1. Atomic emission spectroelectrochemistry was used to monitor Zn and Mg dissolution as a function of time at open circuit, during linear scan polarization, and at various applied potentials. Zn and Mg displayed a mutual inhibitive effect at open circuit which was explained by the formation of Mg depleted Zn / Zn oxide film. Polarization experiments revealed a Type II dealloying mechanism in which Zn and Mg dissolve simultaneously and congruently above the critical potential, E c , while preferential Mg dissolution dominates below E c . Preferential Mg dissolution leads to the formation of a Mg depleted metallic Zn layer which suppresses further Mg dissolution. In oxygen saturated electrolyte, O 2 reduction was the major cathodic reaction on Zn but was completely inhibited on Mg. The intense cathodic reduction of O 2 on Zn led to a cathodic dissolution of Zn, probably due to the increased interfacial pH.

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Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Han

Ogle

2017

J. Electrochem. Soc.

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“…typically 1 to 4 wt% of magnesium and aluminum), showing better corrosion properties than HDG, have been developed for continuous galvanized steel sheet. [4][5][6][7][8][9][10][11][12][13] From the extensive literature on the atmospheric corrosion of zinc in field exposures and laboratory tests, [14][15][16][17][18][19][20][21][22][23] zinc is indeed well known to be highly affected by chloride and sulfur dioxide in particular. The level of CO 2 in the atmosphere has also been reported to have a noticeable influence on the corrosion of zinc [24][25][26][27] and zinc coatings including HDG, Zn-5Al and Zn-Al-Mg (ZM).…”

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confidence: 99%

Atmospheric Corrosion of Zinc-Aluminum Alloyed Coated Steel in Depleted Carbon Dioxide Environments

LeBozec

Thierry

Persson

et al. 2018

J. Electrochem. Soc.

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NaCl induced corrosion of Zn-0.2Al, Zn-5Al and Zn-55Al coated steel was investigated at low and ambient CO 2 levels. Weight loss measurements revealed an enhancement of the corrosion of Zn-0.2Al and particularly Zn-5Al in low CO 2 . This was connected to an increase of surface pH in a low CO 2 atmosphere promoting the formation of ZnO and layered double hydroxide for Zn-5Al. For Zn-55Al, CO 2 depletion did not affect the surface pH due to the acidification effect of Al 3+ . Preferential dissolution of zinc rich phase was observed on cross-sections, particularly in depleted CO 2 experiments. Different sequences of corrosion product formation were proposed for the different Zn-Al coatings. Among Zn-Al coated steels, which are widely used in the construction industry as a better corrosion resistant alternative to replace hot-dip galvanized steel (HDG), two main compositions may be found i.e. Galfan containing 5% aluminum (Zn-5Al) and Galvalume containing 55% aluminum and about 1.6% Si (Zn-55Al). These Zn-Al coatings indeed present a better corrosion performance than HDG in marine and industrial atmospheres, where the main corrosive elements are chloride from seawater aerosols and sulfur dioxide from fume emissions. 1-3 The corrosion rate upon long term field exposure was generally 1.5 to 2 and 2 to 4 times lower than that of HDG for Zn-5Al and Zn-55Al, respectively. Hydrotalcite compounds identified in the corrosion products are believed to play an important role in the corrosion protection. Their formation in the interdendritic areas of Zn-55Al blocks the cathodic reaction because of their inability to act as cathodes, and thus, the overall corrosion rate should decrease.More recently, new zinc coatings alloyed with aluminum and magnesium (i.e. typically 1 to 4 wt% of magnesium and aluminum), showing better corrosion properties than HDG, have been developed for continuous galvanized steel sheet. [4][5][6][7][8][9][10][11][12][13] From the extensive literature on the atmospheric corrosion of zinc in field exposures and laboratory tests, [14][15][16][17][18][19][20][21][22][23] zinc is indeed well known to be highly affected by chloride and sulfur dioxide in particular. The level of CO 2 in the atmosphere has also been reported to have a noticeable influence on the corrosion of zinc 24-27 and zinc coatings including HDG, Zn-5Al and Zn-Al-Mg (ZM). 28 Thus, an enhancement of the corrosion of zinc and zinc coated steel has been observed in depleted CO 2 conditions, which may be achieved in confined situations or under paints for example. Such results were also observed on aluminum and aluminum alloys, 26 as well as on magnesium and magnesium alloys. [29][30][31] Whilst the corrosion performance of Zn-5Al and ZM coated steel is always superior to HDG in chloride containing environments, the situation is opposite in low CO 2 atmosphere, presumably due to the rather high pH of the surface, which induces a more rapid dissolution of zinc and the aluminum phases. 28 In the present study, the aim was to examine the effect of ...

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“…[14][15][16][17][18][19][20] Tsuru et al reported the hydrogen entry process when the steel surface is covered by passive films and reported the hydrogen permeation through steels during wet and dry corrosion cycles. 15) With Zn and Zn alloys coatings are widely used to increase the corrosion resistance of steels [21][22][23] because the atmospheric corrosion rate of Zn is more than twenty times smaller than that of steels. 24) To elucidate the hydrogen permeability of the coatings, the hydrogen permeation characteristics of steel with Zn and Zn-Cr coatings have been investigated.…”

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Effect of Surface Conditions and Specimen Composition on Hydrogen Permeation Behavior of Coated and Uncoated Steels during Wet and Dry Corrosion at a Constant Dew Point

Igarashi

Sakairi

2016

ISIJ Int.

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A wet and dry corrosion test with a constant dew point was applied to investigate the effects of scratches and specimen composition on the hydrogen permeation behavior of Zn and 55 mass% Al-Zn coated steels as well as of uncoated steel. There was an etched size controlled scratch formed on specimens with a laser machining technique. The hydrogen permeation current was observed to be independent of the specimen composition and the area of the formed scratches, the corrosion products were observed after the tests. The hydrogen permeation current of the steels with the formed scratches decreased with number of cycles of the wet and dry tests. Except in the first cycle there were no significant changes in the current with cycle number on steels without formed scratches. It was suggested that the composition, scratch, and corrosion products play an important role in the hydrogen permeation behavior during wet and dry corrosion.

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Corrosion resistance of zinc–magnesium coated steel

Cited by 352 publications

References 21 publications

Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Atmospheric Corrosion of Zinc-Aluminum Alloyed Coated Steel in Depleted Carbon Dioxide Environments

Effect of Surface Conditions and Specimen Composition on Hydrogen Permeation Behavior of Coated and Uncoated Steels during Wet and Dry Corrosion at a Constant Dew Point

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Corrosion resistance of zinc–magnesium coated steel

Cited by 352 publications

References 21 publications

Editors' Choice—Dealloying of MgZn2Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Editors' Choice—Dealloying of MgZn2Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Atmospheric Corrosion of Zinc-Aluminum Alloyed Coated Steel in Depleted Carbon Dioxide Environments

Effect of Surface Conditions and Specimen Composition on Hydrogen Permeation Behavior of Coated and Uncoated Steels during Wet and Dry Corrosion at a Constant Dew Point

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Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

Editors' Choice—Dealloying of MgZn₂Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance