Influence of Dichromate Ions on Corrosion of Pure Aluminum and AA2024‐T3 in NaCl Solution Studied by AFM Scratching

Schmutz, Patrik; Frankel, G. S.

doi:10.1149/1.1392659

Cited by 107 publications

(84 citation statements)

References 35 publications

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“…Scanning Kelvin probe force microscopy (SKPFM) was used to produce maps of the Volta potential distribution across surfaces of AA2024-T3 in air. [18][19][20][21] Used in conjunction with topographic measurements, SKPFM, which has a resolution of at least 100 nm, has generated considerable understanding of the role of intermetallic compounds on the corrosion behavior in terms of shape, location, and local practical nobility. Studies of the delamination of ultrathin (20-100 nm) plasma polymers on specially designed gold samples by SKPFM have shown a loss of spatial resolution of only about 10 µm attributable to sample/tip separation and electrical charging of the coating.…”

Section: Fontana Corrosion Center Department Of Materials Science Anmentioning

confidence: 99%

Investigation of Filiform Corrosion of Epoxy-Coated 1045 Carbon Steel by Scanning Kelvin Probe Force Microscopy

Leblanc

Frankel

2004

J. Electrochem. Soc.

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The mechanism for filiform corrosion (FFC) is thought to involve oxygen diffusion through the tail to the active head. The primary cathodic region is near the back of the head (at the head/tail boundary), where oxygen concentration is higher, and the primary anodic region is at the front edge of the head of the filament. Although there is experimental support for this mechanism, a high-resolution description of the FFC process has not been presented. The aim of this study was to provide detailed information about the mechanism of FFC on coated steel using the high spatial resolution of scanning Kelvin probe force microscopy. Segments of active filaments were successfully investigated through 150 and 300 nm thin epoxy coatings in air of 93% relative humidity. Volta potential and topographic maps showed separation of active anodes and cathodes in the head and revealed the presence of voids associated with delamination of the coating along the edge of the tail. The morphology of filaments and Volta potential distributions were strongly dependent on the film thickness. Differences in growth characteristics were explained by mass transport considerations.Filiform corrosion (FFC) affects many metals underneath organic, inorganic, or metallic coatings and results in networks of thread-like corrosion products propagating across the metal surface. Early studies of FFC focused on steel substrates coated with a variety of varnishes or lacquers. The development of new paint systems and the increased use of lightweight alloys in the aeronautical industry have widened the field of study to aluminum and magnesium alloys and to more modern coatings. FFC of steel, aluminum, and magnesium has been observed in various humidity conditions and under many different types of coatings. The growth pattern, behavior, physical dimension, and velocity of the filaments have been reviewed in detail. [1][2][3][4] The literature reveals that there are many common characteristics of FFC, regardless of the nature of the metal or coating. A filament consists of two visually distinguishable parts: an active head, where dissolution of the metal occurs, and a trailing tail, composed of dry corrosion products. The interface between the dry tail and the head on iron is characterized by a V-shaped boundary. The width of filaments ranges from 0.05 to 3 mm, and the filaments can travel considerable distances and weave intricate patterns. The average growth rate ranges between 0.01 to 0.5 mm/day, but growth is not uniform. Degradation of the metal is superficial, as the depth of attack rarely exceeds 10 µm, but FFC can destroy the protectiveness of a coating system. On steel, filaments never cross each other and are simply deflected without actually touching, or split into two heads, which then reflect or stop growing at ''near-collision.'' Most of the characteristics of FFC are consistent with a differential oxygen concentration cell mechanism, 5 which requires that the oxygen concentration be much lower in the head than in

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Section: Fontana Corrosion Center Department Of Materials Science Anmentioning

confidence: 99%

Investigation of Filiform Corrosion of Epoxy-Coated 1045 Carbon Steel by Scanning Kelvin Probe Force Microscopy

Leblanc

Frankel

2004

J. Electrochem. Soc.

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“…A great effort has been made to analyze the corrosion behavior of high strength aluminum alloys. In particular, AA2024-T3 is among the most extensively studied alloys, and the mechanisms of corrosion have been debated in the literature [5,[7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

A study of the mechanisms of corrosion inhibition of AA2024-T3 by vanadates using the split cell technique

Iannuzzi

Kovač

Frankel

2007

Electrochimica Acta

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The mechanisms of corrosion inhibition of AA2024-T3 by vanadates were studied in this work using the split cell technique and polarization curves. The electrochemical behavior of clear solutions containing metavanadates and orange solutions containing decavanadates was clearly distinctive. Injection of metavanadates to the cathode side of the different split cell setups greatly reduced the galvanic current, indicating a potent inhibition of the oxygen reduction kinetics. The galvanic current never exhibited a transient current peak, suggesting that metavanadates inhibit AA2024-T3 corrosion by a mechanism that does not involve electrochemical reduction. Injection of metavanadate to the anode side of the different split cells had no effect on the galvanic current. Injection of orange decavanadate to the cathode side of the AA2024-T3 split cell resulted in a large current peak, associated with the electrochemical reduction of decavanadate. However, decavanadates did not impart significant corrosion protection.

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“…The goal of using SKPFM was to measure Volta potential differences between phases within the microstructure to determine relative nobility of the individual phases. Schmutz and Frankel, along with Leblanc, have established a direct correlation between Volta potentials measured in air and respective solution potentials of metals [26,27,30]. Importantly, the VPD observed was an effective indicator of how corrosion developed due to microstructural features.…”

Section: Discussionmentioning

confidence: 89%

“…SKPFM measurements were obtained prior to SEM/EDS characterization of the same regions on both braze alloy joints to avoid any effect of electron irradiation on surface potential measurements [22,26,27]. Potential maps acquired from SKPFM coupled with composition maps obtained from SEM/EDS clearly showed that the observed variations in potential correlated with changes in composition within the braze regions (Figures 8 and 9).…”

Section: Skpfm Measurementsmentioning

confidence: 97%

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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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Influence of Dichromate Ions on Corrosion of Pure Aluminum and AA2024‐T3 in NaCl Solution Studied by AFM Scratching

Cited by 107 publications

References 35 publications

Investigation of Filiform Corrosion of Epoxy-Coated 1045 Carbon Steel by Scanning Kelvin Probe Force Microscopy

Investigation of Filiform Corrosion of Epoxy-Coated 1045 Carbon Steel by Scanning Kelvin Probe Force Microscopy

A study of the mechanisms of corrosion inhibition of AA2024-T3 by vanadates using the split cell technique

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

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