Simulation of galvanic corrosion of magnesium coupled to a steel fastener in NaCl solution

Jia, Jimmy Xueshan; Atrens, Andrej; Song, Guang‐Ling; Muster, Tim H.

doi:10.1002/maco.200403855

Cited by 108 publications

(60 citation statements)

References 17 publications

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“…In addition, such simulations have the longterm potential to predict critical aspects of the corrosion behavior of galvanically coupled Mg. 13,14,24,25 Jia et al used the Boundary Element Method (BEM) to calculate the corrosion rate of a galvanically coupled Mg alloy with use of a measured polarization curve, and compared the calculated results with their experimental measurements. 13,14 Overall, they observed that the model adequately predicted the corrosion distribution for different anode-to-cathode area ratios and electrolyte thicknesses.14 However, in some instances the model was observed to underpredict the experimental dissolution rate by more than 50%.13 They interpreted the underprediction as the evidence for selfcorrosion, which they estimated to be up to 230 mm/year. …”

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confidence: 99%

Hydrogen Evolution during the Corrosion of Galvanically Coupled Magnesium

Banjade

Porter

McMullan

et al. 2016

J. Electrochem. Soc.

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In this study, the impact of galvanic coupling of magnesium to steel on the corrosion rate, surface morphology, and surface film formation was investigated. In particular, experiments were performed to examine and quantify the role of self-corrosion (also called negative difference effect (NDE) or anodic hydrogen) during the corrosion of galvanically coupled Mg. It was found that galvanic coupling at high cathode-to-anode area ratios resulted in high rates of corrosion that impacted hydrogen evolution on the Mg surface. Self-corrosion accounted for, on average, approximately one-third of the total observed corrosion. The self-corrosion fraction varied with time and was found to reach values in excess of 50%. Surface film formation was observed, and approximately 30% of the Mg lost to corrosion was found in the film at the end of our experiments. The surface morphology observed during galvanic corrosion was dramatically different from the filiform structures associated with free corrosion of our samples, but showed similarities to the morphology observed previously for anodically polarized samples. Film formation appeared to slow the rate of self-corrosion with time. These results complement previous studies of Mg corrosion and add important insight into the role of hydrogen evolution on the Mg surface during galvanic corrosion. New environmental regulations, good mechanical properties, abundant availability and reasonable cost have generated renewed interest in the wider use of magnesium (Mg), especially for automobile and aerospace applications.1-4 There has also been growing interest in the use of Mg for batteries and in hydrogen generation systems. 5-8A key obstacle to the use of Mg is its corrosion susceptibility. Consequently, several previous studies have focused on understanding the corrosion mechanisms that control the dissolution rate and surface morphology of Mg during corrosion. Both disk-shaped and filiform corrosion have been observed for unalloyed Mg, depending on the concentration of impurities in the metal and the concentration of Cl − in the electrolyte. [9][10][11] In both cases, the morphology is strongly influenced by the cathodic reaction, which limits the rate of corrosion. 11,12The situation changes dramatically when Mg is coupled to another metal because of the increased cathodic area that significantly diminishes limitations due to the cathodic reaction on the Mg surface. Although most hydrogen evolution occurs on the coupled metal, hydrogen evolution on the Mg surface does not cease. The purpose of this paper is to investigate the impact of galvanic coupling on Mg corrosion that is associated with hydrogen evolution on the Mg surface, and the extent to which such coupling influences both the morphology and rate of Mg self-corrosion.In this paper, we use the term "self-corrosion" to refer to the dissolution of Mg that is not associated with the galvanic current that passes between the coupled metal and the Mg, similar to the definition used previously by others in galvanically coupled st...

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confidence: 99%

Hydrogen Evolution during the Corrosion of Galvanically Coupled Magnesium

Banjade

Porter

McMullan

et al. 2016

J. Electrochem. Soc.

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“…Importantly, the VPD observed was an effective indicator of how corrosion developed due to microstructural features. Subsequent to these findings, several research groups [31][32][33][34][35][36][37][38][39] have been able to verify that SKPFM is both reliable and effective in characterizing various alloy systems to accurately explain corrosion initiation behavior.…”

Section: Discussionmentioning

confidence: 95%

Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

Kvryan¹,

Livingston²,

Efaw³

et al. 2016

Metals

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Abstract:The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM) was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS) measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 M NaCl, corrosion occurred at the braze-316L interface preceded by preferential dissolution of the Cu-rich phase within the braze alloy. Braze corrosion was driven by galvanic couples between the braze alloys and stainless steel as well as between different phases within the braze microstructure. Microgalvanic corrosion between phases of the braze alloys was investigated via SKPFM to determine how corrosion of the brazed joints developed.

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“…A better compatibility in salt water environment exhibit steel fasteners with zinc or tin-zinc coatings, however they also experience corrosion due to the coating porosity. During performance simulation of mild steel fastener to AZ91 cast alloy in 5% NaCl solution, two corrosion mechanisms active in area from 1 to 2 cm from the interface were identified: galvanic corrosion and self corrosion (Jia et al, 2005). It was confirmed that the microgalvanic cells exist on the surface of AZ91D alloy which have potential differences of the order of 100 mV between alloy phases: matrix of α-Mg and Mg 17 Al 12 intermetallics.…”

Section: Threaded Fastenersmentioning

confidence: 85%

Welding and Joining of Magnesium Alloys

Czerwiński¹

2011

Magnesium Alloys - Design, Processing and Properties

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Simulation of galvanic corrosion of magnesium coupled to a steel fastener in NaCl solution

Cited by 108 publications

References 17 publications

Hydrogen Evolution during the Corrosion of Galvanically Coupled Magnesium

Hydrogen Evolution during the Corrosion of Galvanically Coupled Magnesium

Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

Welding and Joining of Magnesium Alloys

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