The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

Natishan, Paul M.; McCafferty, E.

doi:10.1149/1.2096613

Cited by 43 publications

(17 citation statements)

References 28 publications

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“…122,123 Pit caps were observed for Al earlier. 124 Blister formation/pit caps have also been observed on other metals including stainless steel.…”

Section: Oxide Blister Formation and Rupturementioning

confidence: 79%

“…124 Blister formation/pit caps have also been observed on other metals including stainless steel. 125,126 Natishan et al 122 observed blisters using optical and scanning electron microscopy on ion-implanted Al surfaces after polarization above E pit in deaerated 0.1 M NaCl. Although this work is not directly related to Cl − interactions with the oxide film per se, the observation of blisters suggests that the oxide film was not dissolved locally to the underlying metal (film thinning) during pit initiation; rather pits initiated beneath the oxide film.…”

Section: Oxide Blister Formation and Rupturementioning

confidence: 99%

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Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

Natishan

O’Grady

2014

J. Electrochem. Soc.

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238

122

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Metals and alloys such as aluminum (Al), stainless steels, and nickel-based alloys exhibit corrosion resistance in a wide range of environments due to the presence of protective, passive oxides. However, in environments that contain aggressive anions such as chloride, Cl − , the passive film becomes unstable and degrades locally causing film breakdown and pitting corrosion. A number of theories describing the initiation of pitting corrosion have been postulated and discussed but to date there is no consensus on the mechanism of breakdown. Since all current mechanisms require Cl − interactions for oxide film breakdown in Cl − containing environments, the question is what is the nature of the interaction of aggressive anions such as Cl − with the passive film, adsorption and/or absorption, leading to pitting? This communication focuses on the interaction of Cl − with the passive oxide film on pure aluminum by reviewing and summarizing the available experimental data concerning Cl − interactions. It should also be noted that the observations for Cl − interactions with Al reviewed and summarized herein might not be applicable to all metals and alloys. Technologically important metals and alloys such as aluminum (Al), stainless steels, and nickel-based alloys exhibit corrosion resistance in a wide range of environments due to the presence of protective, passive oxides.1-90 The passive oxides behave as kinetic barriers, which inhibit further oxidation of the underlying thermodynamically reactive metals. However, in environments that contain aggressive anions such as chloride, Cl − , the passive film becomes unstable and degrades locally causing film breakdown and localized corrosion, which in turn decreases the service life of the materials. The consequence of discrete oxide failure is localized corrosion, which occurs in the forms of crevice corrosion in occluded sites and metastable or stable pitting corrosion on open surfaces. It is generally agreed that localized corrosion occurs in two distinct steps: initiation and propagation.A number of theories describing the initiation of pitting corrosion have been postulated and discussed.

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“…122,123 Pit caps were observed for Al earlier. 124 Blister formation/pit caps have also been observed on other metals including stainless steel.…”

Section: Oxide Blister Formation and Rupturementioning

confidence: 79%

Section: Oxide Blister Formation and Rupturementioning

confidence: 99%

Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

Natishan

O’Grady

2014

J. Electrochem. Soc.

Self Cite

238

122

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“…Exposure to water can modify the aluminum oxide lattice by replacing O 2 − ions or occupying the oxygen vacancies with more mobile species including protons, hydroxyl ions, or water molecules . Hydroxyl ions are not only responsible for pit stabilization while coupled with chloride ions in the form of Al(OH) 2 Cl or Al(OH)Cl 2 but also can be eliminated with water by electrochemical reactions at the Al/Al 2 O 3 interface to produce hydrogen blisters . Higher hydroxyl concentrations can promote the pit stabilization, propagation, and growth.…”

Section: Resultsmentioning

confidence: 99%

On the Relationship between Nonstoichiometry and Passivity Breakdown in Ultrathin Oxides: Combined Depth-Dependent Spectroscopy, Mott−Schottky Analysis, and Molecular Dynamics Simulation Studies

et al. 2009

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Understanding the relationship between nonstoichiometry and physical properties of ultrathin oxides is of great importance from both scientific and technological aspects. A specific example includes the onset of passivity breakdown in an ultrathin oxide film in aqueous medium leading to the onset of corrosion. In this work, using the model system of ultrathin oxide of alumina on aluminum synthesized by natural oxidation and photon-assisted oxidation processes, we demonstrate a direct correlation between passivity and quality of the oxide film quantitatively. Depth-dependent high-resolution X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nuclear reaction analysis (NRA) have been performed to characterize the physical and chemical properties of the oxide films, while detailed impedance measurements and Mott−Schottky studies have been performed to understand electronic transport. Combined NRA and TEM analysis reveal an 18% increase in oxygen density (for oxide films with near identical thicknesses ∼3.8 nm) in the case of photon-assisted oxidation. The denser oxide film results in a ∼34% more blockage of chloride ions transport as indicated by XPS analysis. Mott−Schottky measurements on these oxide films indicates a 43% reduction of defect levels for UV-synthesized alumina when compared to native one, suggestive of chloride ion transport via oxygen vacancies. Additionally, molecular dynamics simulations have been performed to provide insights into the structure of the oxides at the atomic level to correlate with the experimental measurements. These simulations employ dynamic charge transfer between atoms and are used to investigate nanoscale oxides grown on Al (100) surfaces because of atomic and molecular oxygen. Oxidation using molecular and atomic oxygen resulted in an amorphous oxide scale with self-limiting thickness of ∼16 and 22 Å, respectively, at 300 K. Structural and dynamic correlations indicate significant charge transfer to exist in the oxide film in both the cases. The oxide growth in both the cases occurs due to the inward oxygen and outward cation diffusion. The calculated in-plane and out-of-plane atomic diffusivities are 40−70% higher in case of atomic oxidation. In the presence of atomic oxygen, the O/Al ratio is more uniform and varies from 1.37 at the oxide−gas interface to 1.30 at the metal−oxide interface, whereas that formed by natural oxidation was substoichiometric and oxygen deficient with O/Al values varying from 1.27 (oxide−gas interface) to 1.05 (metal−oxide interface) at room temperature. The simulation results are consistent with the reported experimental investigations.

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“…This soluble anion reacts with water forming aluminum hydroxide, given by [Al III Cl 4 ] − +3 H 2 O→[Al III (OH) 3 ]+3 H + +4 Cl − . The propagation phase yields localized blisters of acidic pH that eventually erupt and expose the corrosion pit . The corrosion rate decreases over time, but perforation may occur, and chromium‐based coatings have been commonly used .…”

Section: Figurementioning

confidence: 99%

“…[Al III (OH) 3 ] + 3H + + 4Cl À .T he propagationp hase yields localized blisters of acidic pH that eventually erupt and exposet he corrosion pit. [14] The corrosion rate decreases over time, but perforation may occur, and chromium-based coatings have been commonly used. [15,16] However, concerns with the environmental impact of hexavalent chromium generated by these coatings imposes teep restrictionst ot heir use.…”

mentioning

confidence: 99%

A Molecular Approach for Mitigation of Aluminum Pitting based on Films of Zinc(II) and Gallium(III) Metallosurfactants

Weeraratne

Hewa-Rahinduwage

Gonawala

et al. 2019

Chemistry A European J

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The use of metallosurfactants to prevent pitting corrosion of aluminum surfacesi sd iscussed based on the behavior of the metallosurfactants [Zn II (L N2O2 )H 2 O] (1)a nd [Ga III (L N2O3 )] (2). These speciesw ere deposited as multilayer Langmuir-Blodgett films and characterized by IR reflection absorption spectroscopy and UV/Vis spectroscopy.S canning electron microscopy images, potentiodynamic polarization experiments,a nd electrochemical impedance spectroscopy were used to assessc orrosion mitigation. Both metallosurfactants demonstrate superior anticorrosiona ctivity due to the presence of redox-inactive3 d 10 metal ions that enhancet he structuralr esistance of the ordered molecular films and limit chloride mobility and electron transfer.Aluminumi salight, malleable, moldable, and nonmagnetic metal that resists atmosphericc orrosion,a nd displays electrical and thermalc onductivity. These attributes enable wideu se in automotive, aerospace, and naval industries. Although the metal is the third most abundant element in the crust (80 700 ppm), isolation from bauxite has ah igh environmental cost and generates an estimated1 3tons of CO 2 per ton of Al, [1] along with at oxic solid waste known as red mud. As such, conservation efforts are necessarya tall levelsa nd include recycling and corrosion mitigation.Unlike iron, in which adventitious oxygen and water leads to the formation of Fe(OH) 3 and Fe 2 O 3 , [2][3][4][5][6] the mechanismso fA l corrosion are more complex and less understood. Nonetheless, the action of pitting corrosionl eads to perniciouss tructural failures in car frames, airplane fuselages, and ship hulls, and demands immediate attention. With an electronic configuration given by [Ne] 3s 2 3p 1 ,t he metal has as tandard potential of À1.7 V SHE associated with the loss of the 3s 2 and3 p 1 electrons during the processg iven by Al (s) ÐAl 3 + + 3e À .P itting is initiated in neutral media by the presence of chloride [7] and other anions [8] that physisorb at the positively charged surface of the Al 2 O 3 passivation layer. [2,9] The Cl À anions penetrate through nanometer-sized cracks or migrate via oxygen vacancies [10][11][12] reaching the Al 2 O 3 j Al 0 interface, quickly converting Al 0 into AlCl 3 ,a nd then the anionic tetrahedral [13] complex [Al III Cl 4 ] À .T his soluble anion reacts with water forming aluminum hydroxide,g iven by [Al III Cl 4 ] À + 3H 2 O![Al III (OH) 3 ] + 3H + + 4Cl À .T he propagationp hase yields localized blisters of acidic pH that eventually erupt and exposet he corrosion pit. [14] The corrosion rate decreases over time, but perforation may occur, and chromium-based coatings have been commonly used. [15,16] However, concerns with the environmental impact of hexavalent chromium generated by these coatings imposes teep restrictionst ot heir use. [16] In searching for potential alternatives, we hypothesize that the presence of an ordered Langmuir-Blodgett (LB) multilayer of molecularm etallosurfactants would act as ah ydrophobic barriert hat decreases access of w...

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The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

Cited by 43 publications

References 28 publications

Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

On the Relationship between Nonstoichiometry and Passivity Breakdown in Ultrathin Oxides: Combined Depth-Dependent Spectroscopy, Mott−Schottky Analysis, and Molecular Dynamics Simulation Studies

A Molecular Approach for Mitigation of Aluminum Pitting based on Films of Zinc(II) and Gallium(III) Metallosurfactants

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