The Growth of Hydrous Oxide Films on Aluminum

Alwitt, Robert S.

doi:10.1149/1.2401679

Cited by 121 publications

(90 citation statements)

References 2 publications

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“…In the polished sample, the surface sample consisted of a layer of chemisorbed water and oxyhydroxide. The presence of these peaks was attributed to the hydration reaction of the surface with moisture, which occurs rapidly under ambient conditions (Ref [13][14][15][16]. However, the oxyhydroxide proportion was much smaller than the oxide proportion.…”

Section: Xps Resultsmentioning

confidence: 99%

“…The surface layers on aluminum and stainless steel formed under ambient conditions are mixtures of oxides and oxyhydroxides (Ref [13][14][15][16][17][18]. Heat treatment causes changes in the relative amounts of these species and consequent release of gases from the surface (Ref [19][20][21][22][23] and can also induce segregation of elements to the surface due to differences in free energy of formation oxides ( Ref 24,25).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Surface Chemistry on Splat Formation During Plasma Spraying

et al. 2008

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Ni-Cr single splats were plasma-sprayed at room temperature onto aluminum and stainless steel substrates, which were modified by thermal and hydrothermal treatments to control the oxide surface chemistry. The proportions of the different splat types were found to vary as a function of substrate pretreatment, especially when the pretreatment involved heating. It was observed that surface roughness did not correlate with changes in splat morphology. Substrate surfaces were characterized by X-ray photoelectron spectroscopy using in situ heating in vacuum to determine the effect of thermal pretreatment on substrate surface chemistry. It was found that the surface layers were composed primarily of oxyhydroxides. When the substrates were heated to 350°C, water vapor was released from the dehydration of oxyhydroxide. Preheating the substrate can remove the water prior to spraying: preheated substrates had improved the physical contact between the splat and substrate, which enhanced the formation of disk splats and increased the number of splats.

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Section: Xps Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Surface Chemistry on Splat Formation During Plasma Spraying

et al. 2008

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“…[55] Further work is needed to establish if the conditions promoting this decrease in crack growth rate are associated with the formation of a hydrous film formed on aluminum surfaces exposed to water, which are known to undergo significant changes at temperatures around 313 K (40°C). [56,57] Although data are available for the initiation of sustained-load cracking in copper-free Al-Zn-Mg alloys in distilled water, [48,49] no published data have been found for copper-containing alloys. Abe et al [48] demonstrated that intergranular cracking for a peak-aged Al-6Zn-1.6Mg alloy (equiaxed grain structure:~100 lm; yield stress: 333 MPa) initiated almost immediately on loading to stresses above the 0.2 pct proof stress, while for lower stress, above a critical minimum, incubation time was required for sharp intergranular cracks to initiate by a thermally activated process.…”

Section: Influence Of Temperature On Crack Initiation and Growthmentioning

confidence: 99%

Crack Propagation During Sustained-Load Cracking of Al-Zn-Mg-Cu Aluminum Alloys Exposed to Moist Air or Distilled Water

Holroyd¹,

Scamans

2011

Metall Mater Trans A

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Intergranular sustained-load cracking of Al-Zn-Mg-Cu (AA7xxx series) aluminum alloys exposed to moist air or distilled water at temperatures in the range 283 K to 353 K (10°C to 80°C) has been reviewed in detail, paying particular attention to local processes occurring in the crack-tip region during crack propagation. Distinct crack-arrest markings formed on intergranular fracture faces generated under fixed-displacement loading conditions are not generated under monotonic rising-load conditions, but can form under cyclic-loading conditions if loading frequencies are sufficiently low. The observed crack-arrest markings are insensitive to applied stress intensity factor, alloy copper content and temper, but are temperature sensitive, increasing from~150 nm at room temperature to~400 nm at 313 K (40°C). A re-evaluation of published data reveals the apparent activation energy, E a for crack propagation in Al-Zn-Mg(-Cu) alloys is consistently~35 kJ/mol for temperatures above~313 K (40°C), independent of copper content or the applied stress intensity factor, unless the alloy contains a significant volume fraction of S-phase, Al 2 CuMg where E a is~80 kJ/mol. For temperatures below~313 K (40°C) E a is independent of copper content for stress intensity factors below~14 MNm À3/2 , with a value~80 kJ/mol but is sensitive to copper content for stress intensity factors abovẽ 14 MNm À3/2 , with E a , ranging from~35 kJ/mol for copper-free alloys to~80 kJ/mol for alloys containing 1.5 pct Cu. The apparent activation energy for intergranular sustained-load crack initiation is consistently~110 kJ/mol for both notched and un-notched samples. Mechanistic implications are discussed and processes controlling crack growth, as a function of temperature, alloy copper content, and loading conditions are proposed that are consistent with the calculated apparent activation energies and known characteristics of intergranular sustained-load cracking. It is suggested, depending on the circumstances, that intergranular crack propagation in humid air and distilled water can be enhanced by the generation of aluminum hydride, AlH 3, ahead of a propagating crack and/or its decomposition after formation within the confines of the nanoscale volumes available after increments of crack growth, defined by the crack arrest markings on intergranular fracture surfaces.

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“…Its thickness is similar to that which might be developed through a short immersion in a solution containing water at 45°C. 20 The growth rate and the ultimate thickness of these types of themally activated coatings, as well as anodic coatings, depend on ion (Al 3C and OH ) transport through the developing oxide. 21 In this instance the process of oxide growth appeared to be terminated when ceria began to deposit on the external surface.…”

Section: Aluminium Oxide Growthmentioning

confidence: 99%

Development of cerium‐based conversion coatings on 2024‐T3 Al alloy after rare‐earth desmutting

Hughés

Gorman

Miller

et al. 2004

Surface & Interface Analysis

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The deposition of Ce-based conversion coatings onto 2024-T3 Al alloy sheet was studied using Rutherford backscattering spectroscopy, scanning electron microscopy, Auger electron spectroscopy, x-ray photoelectron spectroscopy and atomic force microscopy. The Al sheet was pretreated with an alkaline clean followed by treatment in a Ce(IV) and H 2 SO 4 -based desmutter. The Ce(IV)-based conversion coating solution contained 0.1 M CeCl 3 ·7H 2 O and 3% H 2 O 2 and was acidified to pH 1.9 with HCl. Upon immersion, there was an induction period that included activation followed by aluminium oxide growth over the matrix and cerium oxide deposition onto cathodic intermetallic particles and along rolling marks on the surface. After the induction period cerium oxide deposited generally across the whole surface and thickened. The strongest anodic sites initially were adjacent to the intermetallic cathodes and resulted in aluminium dissolution but also oxide thickening.

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The Growth of Hydrous Oxide Films on Aluminum

Cited by 121 publications

References 2 publications

Effects of Surface Chemistry on Splat Formation During Plasma Spraying

Effects of Surface Chemistry on Splat Formation During Plasma Spraying

Crack Propagation During Sustained-Load Cracking of Al-Zn-Mg-Cu Aluminum Alloys Exposed to Moist Air or Distilled Water

Development of cerium‐based conversion coatings on 2024‐T3 Al alloy after rare‐earth desmutting

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