Selective dissolution during acid pickling of aluminum alloys by element-resolved electrochemistry

• Published in: Electrochimica acta Vol. 404; p. 139737
• Main Authors: Sultan, B. Bin Mohamad, Thierry, D., Torrescano-Alvarez, J.M., Ogle, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2022; Elsevier BV
• Subjects: AA7449; Acid pickling; Aerospace alloys; AESEC; Alloy; Alloying elements; Aluminum; Aluminum alloys; Aluminum base alloys; Copper; Cu dissolutions; Dissolution; Electrochemistry; High strength alloys; High-strength; Iron compounds; Magnesium; Oxidation; Pickling; Pickling solutions; Selective dissolution; Solution components; Sulfuric acid; Surface reactivity; Acid pickling; AESEC; AA7449; Aluminum; Alloy
• ISSN: 0013-4686; 1873-3859; 1873-3859
• DOI: 10.1016/j.electacta.2021.139737

•A7xxx pickling mechanisms & Cu removal studied with element resolved electrochemistry.•Galvanic interactions between elements lead to a period of non-congruent dissolution.•Nitrate enhanced Cu dissolution by charge transfer mechanism.•Fe(III) effect on Cu dissolution rate investigated by experimental Evans diagrams.•Effect of Fe(III) may be interpreted as a catalytic effect on nitrate reduction. The surface reactivity and the elemental dissolution of a high-strength aerospace alloy (AA7449-T651) during acid pickling was investigated with element-resolved electrochemistry (AESEC). The results demonstrated a sequential dissolution of Mg, Al, Zn and Cu, following the order of their respective galvanic reactivity in common acid pickling solutions. The enrichment of Cu during pickling with the H2SO4 solution was observed. The effect of oxidizing solution components HNO3 and Fe(III) on Cu dissolution were investigated using an experimental Evans diagram approach. [Display omitted]