Properties and Characterization of Surface Oxides on Aluminum Alloys

Wefers, K.

doi:10.1007/978-1-4615-8339-4_20

Cited by 43 publications

(54 citation statements)

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“…2. As the surface of aluminium foils readily oxidizes, we assume a 10 nm layer of aluminium oxide formed on either side of the foil 20 , which matches both our data at the lowest fluence and transmission 22 . Thus, the photo-excited electrons rapidly lose their energy and thermalize with the initial cold valence electrons on a timescale considerably shorter than the FLASH pulse.…”

supporting

confidence: 77%

Turning solid aluminium transparent by intense soft X-ray photoionization

Nagler¹,

Zastrau²,

Fäustlin³

et al. 2009

Nature Phys

252

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Saturable absorption is a phenomenon readily seen in the optical and infrared wavelengths. It has never been observed in core-electron transitions owing to the short lifetime of the excited states involved and the high intensities of the soft X-rays needed. We report saturable absorption of an L-shell transition in aluminium using record intensities over 10 16 W cm −2 at a photon energy of 92 eV. From a consideration of the relevant timescales, we infer that immediately after the X-rays have passed, the sample is in an exotic state where all of the aluminium atoms have an L-shell hole, and the valence band has approximately a 9 eV temperature, whereas the atoms are still on their crystallographic positions. Subsequently, Auger decay heats the material to the warm dense matter regime, at around 25 eV temperatures. The method is an ideal candidate to study homogeneous warm dense matter, highly relevant to planetary science, astrophysics and inertial confinement fusion. Saturable absorption, the decrease in the absorption of light with increasing intensity, is a well-known effect in the visible and near-visible region of the electromagnetic spectrum 1 , and is a widely exploited phenomenon in laser technology. Although there are many ways to induce this effect, in the simplest two-level system it will occur when the population of the lower, absorbing level is severely depleted, which requires light intensities sufficiently high to overcome relaxation from the upper level. Here, we report on the production of saturable absorption of a metal in the soft X-ray regime by the creation of highly uniform warm dense conditions, a regime that is of great interest in high-pressure science 2,3 , the geophysics of large planets 4,5 , astrophysics 6 , plasma production and inertial confinement fusion 7 . Furthermore, the process by which the saturation of the absorption occurs will lead, after the X-ray pulse, to the storage of about 100 eV per atom, which in turn evolves to a warm dense state. This manner of creation is unique as it requires intense, subpicosecond, soft X-rays. As such, it has not hitherto been observed in this region of the spectrum, owing both to the lack of high-intensity sources, and the rapid recombination times associated with such high photon energies. However, with the advent of new fourth-generation X-ray light sources, including the free-electron laser in Hamburg 8 (FLASH), soft X-ray intensities that have previously remained the province of high-power optical lasers can now be produced. Experiments at such high intensities using gas jets have already exhibited novel absorption phenomena 9 , and the possibility of irradiating solid samples with intense soft and hard X-rays has aroused interest as a possible means of producing warm dense matter (WDM) at known atomic densities 10,11 .We present the first measurements of the absorption coefficient of solid samples subject to subpicosecond soft X-ray pulses with intensities up to and in excess of 10 16 W cm −2 , two orders of magnitude higher than could ...

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supporting

confidence: 77%

Turning solid aluminium transparent by intense soft X-ray photoionization

Nagler¹,

Zastrau²,

Fäustlin³

et al. 2009

Nature Phys

252

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“…Aluminum hydroxide gel is constructed by chemical behavior of aluminum ion toward pH. The extracted aluminum ions in the gut are released to the seawater of around pH 8, where they are transformed to the gel state of aluminum hydroxide and then mainly stored in the H. gigas telson [44, 45]. The aluminum spread on the surface of exoskeleton without discharging together with excrement.…”

Section: Discussionmentioning

confidence: 99%

Electron microscopic analysis of the exo-skeleton of hadal zone amphipodHirondellea gigas

Kobayashi

Shimoshige

Nakajima

et al. 2018

Preprint

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The amphipod Hirondellea gigas inhabits the deepest regions of the oceans in extra high-pressure. However, the mechanisms by which they adapt to their high-pressure environments remain unknown. In this study, we investigated elements of the exoskeleton of H. gigas captured from the deepest points of the Mariana Trench. The H. gigas exoskeleton contained aluminum, as well as a major amount of calcium carbonate. Unlike other accumulated metals, aluminum was distributed on the surface of exoskeletons. To investigate how H. gigas obtains aluminum, we conducted a metabolome analysis and found that gluconic acid/gluconolactone was capable of extracting metals from the sediment under the habitat conditions of H. gigas. The extracted aluminum ions are transformed into the gel state of aluminum hydroxide in alkaline seawater, and this gel covers the body to protect the amphipod. The aluminum gel would be one of good materials to adapt to such high-pressure environment.

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“…The oxygen concentration of the laser pretreated surfaces grows as a function of the fluence from 8.4 wt. [25][26][27][28] Unfortunately, this also reduces the growth rate of the aluminum oxide layer. % (LP 3).…”

Section: B Edx Measurementsmentioning

confidence: 99%

Optimization of the aluminum oxide properties for adhesive bonding by laser surface pretreatment

Rechner

Jansen

Beyer

2012

Journal of Laser Applications

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The laser pretreatment of AlMg3 has been conducted to investigate the influence of the fluence on the oxide properties. Therefore, the aluminum surface is pretreated by a fiber laser and subsequently analyzed by SEM, EDX, and XPS. Finally, mechanical measurements are performed on adhesively bonded specimens to study the surface properties produced. For the purpose of comparison, the two state-of-the-art pretreatment methods etching and phosphoric acid anodizing are also investigated. The results show that laser pretreatment changes the properties of the aluminum surface and especially those of the oxide layer. The latter grows in comparison to the natural oxide layer of etched surfaces but does not reach the dimensions of an electrochemically formed oxide layer. Mechanical testing showed that the laser treated specimens reach and exceed the strength values of etched and anodized surfaces, respectively. However, strength after aging does not keep up with the good long-term resistance of anodized aluminum, but it exceeds by far the values obtained for etched surfaces. Overall the study showed that optimizing the oxide layer by laser pretreatment leads to improved adhesion and enhances the strength of adhesively bonded aluminum. Therefore, the laser pretreatment of aluminum is an excellent alternative to wet (electro)chemical processes

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Properties and Characterization of Surface Oxides on Aluminum Alloys

Cited by 43 publications

References 0 publications

Turning solid aluminium transparent by intense soft X-ray photoionization

Turning solid aluminium transparent by intense soft X-ray photoionization

Electron microscopic analysis of the exo-skeleton of hadal zone amphipodHirondellea gigas

Optimization of the aluminum oxide properties for adhesive bonding by laser surface pretreatment

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