Study of anodic oxidation of aluminum in mixed acid using a pulsed current

Shih, Hsing-Hsiang; Tzou, S.F.

doi:10.1016/s0257-8972(99)00646-5

Cited by 63 publications

(29 citation statements)

References 5 publications

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“…One reason for this could be the embrittlement of the coatings due to the incorporation of additional elements from the electrolyte. Shih et al [10] proposed that the enhanced hardness of anodic oxide coatings obtained from a sulphuric acid electrolyte after nitric acid addition results from a higher sulfur content within the oxide. Another explanation could be the influence of nitric acid and oxalic acid on the conversion behavior of the iron-rich intermetallic phases.…”

Section: Discussionmentioning

confidence: 99%

Effect of Nitric and Oxalic Acid Addition on Hard Anodizing of AlCu4Mg1 in Sulphuric Acid

Sieber¹,

Morgenstern

Scharf

et al. 2018

Metals

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Abstract:The anodic oxidation process is an established means for the improvement of the wear and corrosion resistance of high-strength aluminum alloys. For high-strength aluminum-copper alloys of the 2000 series, both the current efficiency of the anodic oxidation process and the hardness of the oxide coatings are significantly reduced in comparison to unalloyed substrates. With regard to this challenge, recent investigations have indicated a beneficial effect of nitric acid addition to the commonly used sulphuric acid electrolytes both in terms of coating properties and process efficiency. The present work investigates the anodic oxidation of the AlCu 4 Mg 1 alloy in a sulphuric acid electrolyte with additions of nitric acid as well as oxalic acid as a reference in a full-factorial design of experiments (DOE). The effect of the electrolyte composition on process efficiency, coating thickness and hardness is established by using response functions. A mechanism for the participation of the nitric acid additive during the oxide formation is proposed. The statistical significance of the results is assessed by an analysis of variance (ANOVA). Eventually, scratch testing is applied in order to evaluate the failure mechanisms and the abrasion resistance of the obtained conversion coatings.

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Section: Discussionmentioning

confidence: 99%

Effect of Nitric and Oxalic Acid Addition on Hard Anodizing of AlCu4Mg1 in Sulphuric Acid

Sieber¹,

Morgenstern

Scharf

et al. 2018

Metals

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show abstract

“…1(g)), the electrode is passive from open circuit potential to 3.0 V SCE . During the polarization of Al at positive potentials, gas is evolved from the Al electrode surface, and no passive region is observed in the various concentrations of HClO 4 solutions, as in the Al/HCl system [22], except in 12 M HClO 4 solution. The gas was collected carefully in a small beaker during the polarization of the Al electrode in 1.0 M perchloric acidic solutions.…”

Section: Methodsmentioning

confidence: 99%

Pitting corrosion induced current oscillations during electrodissolution of Al in HClO4 solutions

Chen

Yang

et al. 2004

Journal of Electroanalytical Chemistry

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“…Instead Cr, Ti, Al and Mg have been observed to passivize copper surfaces [2,3]. Al-containing copper alloys have high corrosion resistance, and they have been widely used in several fields ranging from microelectronics to aerospace [29][30][31]6]. The results of refractory metal nitration of Cu thin films deposited on Si 2 O show that a protective layer can be formed by annealing either a Cu-(27 at.% Ti) or a Cu-(26 at.% Cr) alloys.…”

Section: Introductionmentioning

confidence: 99%