Interpretation of AES depth profiles of porous Al anodic oxides

Sun, Tairen; McNamara, D.K.; Ahearn, J. S.; Chen, J.M.; Ditchek, B. M.; Venables, J. D.

doi:10.1016/0378-5963(80)90105-1

Cited by 51 publications

(12 citation statements)

References 21 publications

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“…Hence, only one peak at 120 eV is present. This 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 peak is characteristic to phosphate (PO 4 3-) species 23 . The two peaks are, therefore, co-added to create the PAA profile in Fig.…”

Section: Aes Depth Profilesmentioning

confidence: 96%

XPS Analysis of the Surface Chemistry and Interfacial Bonding of Barrier-Type Cr(VI)-Free Anodic Oxides

Abrahami

Hauffman

Kok³

et al. 2015

J. Phys. Chem. C

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In the transition to environmental friendly pretreatment of aerospace aluminum alloys, chromic acid anodizing (CAA) is being replaced by sulfuric acid (SAA), phosphoric acid (PAA) or phosphoric-sulfuric acid (PSA) anodizing. While generally the main concern is controlling the film morphology, such as the pore diameter, oxide-, and barrier layer thickness, little is known on how the anodic oxide chemistry affects the interactions at the interface upon adhesive bonding. To study the link between surface chemistry and interfacial bonding, featureless oxides were prepared by stopping the anodizing during the formation of the barrier layer. A model was developed to quantify the relative amounts of OH -, PO 4 3-and SO 4 2-by curve-fitting the XPS data.Calculations showed that almost 40% of the surface species in PAA oxide are phosphates (PO 4 3-), while about 15% are sulfates (SO 4 2 ) in SAA. When both anions were present in the electrolyte, phosphate incorporation was inhibited. Studies of the interaction between this set of Cr(VI)-free oxides and diethylenetriamine (DETA) -an amine curing-agent for epoxy resin, showed that all oxides interact with the nitrogen of DETA. However, larger ratios of Lewis-like acid-base bonding between the amine electron pair and the acidic hydroxyl on phosphate surface sites were observed.

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Section: Aes Depth Profilesmentioning

confidence: 96%

XPS Analysis of the Surface Chemistry and Interfacial Bonding of Barrier-Type Cr(VI)-Free Anodic Oxides

Abrahami

Hauffman

Kok³

et al. 2015

J. Phys. Chem. C

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“…3a and 3b). 13 The anodic film formed under the pulse potential shared several features in common with that formed under the constant potential. First, the same initial increases in the Mg and O signals due to the removal of contaminants such as hydrocarbons on the surfaces of the anodic films were found.…”

Section: Resultsmentioning

confidence: 97%

“…First, the same initial increases in the Mg and O signals due to the removal of contaminants such as hydrocarbons on the surfaces of the anodic films were found. [13][14][15] Second, the Mg/O molar ratios in the anodic film region were almost constant with depth and maintained a suitable composition with excess Mg 2+ . Third, Gaussian-shaped distributions of the Mg signal were found in the film/substrate transition region.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Corrosion Resistance of AZ31 Magnesium Alloy by Pulse Anodization

Choi

Salman

Kuroda

et al. 2013

J. Electrochem. Soc.

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AZ31 Mg alloy was anodized with a pulse potential between the transpassive (10 V Ag/AgCl ) and active regions (−1.35 V Ag/AgCl ) in 2 M NaOH aqueous solution at 303 K. Optimal conditions for the pulse anodizing were a duty ratio of 91%, a frequency of 0.09 Hz, and an anodizing time of 600 s. Pulse anodizing caused a remarkable 11-fold decrease in the surface porosity and a 1.6-fold increase in the film thickness from those obtained under a constant potential of 10 V Ag/AgCl . Furthermore, an Al-enriched crystalline oxide layer was formed on the outer surface of MgO, which improves the corrosion resistance of the Mg alloy in neutral solutions. In consequence, the pitting potential E pit increased to −1.36 V Ag/AgCl and the corrosion current density i corr decreased to 60 ± 10 μA cm −2 , resulting in an approximately 3-fold decrease in the corroded area after anodic breakdown and salt spray tests.Recently, major automobile makers have been hastening their plans to use wrought magnesium (Mg) alloys in vehicles. 1 Reducing the weight of automobiles is one implementable strategy for effectively coping with global warming, and its main purpose is to improve vehicle performance and fuel efficiency. A 100 kg reduction in the weight of an automobile can decrease its CO 2 emissions by 8-12 g km −1 . Moreover, this strategy is useful for improving the cruising distances of electric vehicles.However, applications of wrought Mg alloys have not been as successful as those of aluminum (Al) alloys because of the high corrosion susceptibility under certain service conditions (such as vehicle and marine environments). A modern die casting Mg alloy has a general corrosion resistance almost equal to that of mild steel in under normal environmental exposure. 1 Nevertheless, the effective protection of the Mg alloys against various types of corrosion is still difficult with only simple alloy development. 2 Thus, it is urgently necessary to develop protective coatings for the widespread use of Mg alloys.Anodization is an electrolytic passivation process that produces a thick, chemically stable protective oxide film on valve metals. Anodization mitigates the general and galvanic corrosion of bare Mg alloys, but the formed anodic films are more water soluble than those formed on Al alloys, which are rival traditional materials for weight reduction. Therefore, anodization is often used to produce an undercoating layer to provide better adhesion for various organic finishes. 3,4 In general, the anodic films formed on Mg alloys can be divided into two sub-layers: a very thin but dense inner layer and thick porous outer layer. 2,3 Of these layers, the porosity of outer layer is strongly influenced by the various anodizing parameters such as the electrolyte, concentration, temperature, electric field applied, and so on. The formation of compact anodic films on Mg alloys is limited, because MgO has a molar volume of 11.3 cm 3 mol −1 , whereas metallic Mg has a molar volume of 14.0 cm 3 mol −1 , and therefore the Pilling-Bedworth ratio is 0.81....

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“…In the case of aluminium, etching with either a chromate–sulphuric acid or phosphoric acid etch process. 42–45 Chromic acid anodising (CAA) produces a surface oxide typically 1.5–3 µm porous and highly structured with cell wall thickness of ∼30 nm. 44,45 The oxide formed is resistant to attack by moisture although the surface may contain OH groups.…”

Section: Mechanisms Of Ageing In Various Environmentsmentioning

confidence: 99%

Design and ageing of adhesives for structural adhesive bonding – A review

Pethrick

2014

Proceedings of the Institution of Mechanical Engineers, Part L:

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This review outlines some of the issues which have to be addressed when selecting an adhesive for a particular structural adhesive bonding application. The designer may find that a number of adhesives provide the required load bearing properties and the selection may require a more detailed consideration of the processes involved in the fabrication of the joint, the temperature over which it is to work and the environment in which it will have to operate. The article attempts to provide the reader with an insight into the effects of factors such as time and temperature used in the cure process, details of the components in the mixture and the effects of various additives on the physical properties of the adhesives which are created. The performance of an adhesive may vary with time as a consequence of stress-induced changes which are triggered by thermal effects or by hygrothermal factors. The review considers joints created using metal substrates and carbon fibre composites. The performance and durability of an adhesive bond is critically dependent on the stability of the interface between the adhesive and adherend and is sensitive to the pre-treatment processes used in the creation of the bond. The review outlines how broadband dielectric measurements can be used to non-destructively monitor the cure of adhesive bonds and the processes involved in ageing of joint. The dielectric method gives an insight into the fundamental processes which are giving rise to the changes in the mechanical properties of the joint as they age.

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Interpretation of AES depth profiles of porous Al anodic oxides

Cited by 51 publications

References 21 publications

XPS Analysis of the Surface Chemistry and Interfacial Bonding of Barrier-Type Cr(VI)-Free Anodic Oxides

XPS Analysis of the Surface Chemistry and Interfacial Bonding of Barrier-Type Cr(VI)-Free Anodic Oxides

Enhanced Corrosion Resistance of AZ31 Magnesium Alloy by Pulse Anodization

Design and ageing of adhesives for structural adhesive bonding – A review

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