Temperature dependence of the passivation and dissolution of Al, Zn, and α-phase Zn-68Al
2019 (English)In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 75, no 1, p. 69-79Article in journal (Refereed) Published
Abstract [en]
The reactivity of the α-phase of Al-Zn (Zn-68 wt% Al, Al 5.2 Zn) in deaerated 0.1 M NaOH solution (simulating industrial pretreatments) was investigated and compared with that of pure Al and Zn. The elementary phenomena of metal oxidation, dissolution, oxide formation, and hydrogen evolution were decoupled using atomic emission spectroelectrochemistry. At the open-circuit potential, the Al 5.2 Zn phase reacted similarly as pure Al, undergoing selective Al dissolution to form a Zn(0) enriched layer. The Zn in the alloy shifted the potential to just below the onset of Zn dissolution. Elementary polarization curves showed that Zn dissolution was similar for the Al 5.2 Zn phase as for pure Zn. Near the open-circuit potential, Zn dissolution was faradaic limited by the formation of surface Zn(OH) 2 . At higher temperature, significant amounts of ZnO formed resulting in passivation. For the Al 5.2 Zn phase, the rates of Al and Zn dissolution were determined by a charge transfer mechanism across the ZnO film. Kinetic parameters (activation energies and Tafel slopes) were measured for some of the elementary processes.
Place, publisher, year, edition, pages
National Assoc. of Corrosion Engineers International , 2019. Vol. 75, no 1, p. 69-79
Keywords [en]
Aluminum, Aluminum alloy, Corrosion rate, Dealloying, Zinc, Activation energy, Aluminum alloys, Aluminum corrosion, Binary alloys, Charge transfer, Dissolution, II-VI semiconductors, Passivation, Sodium hydroxide, Spectroelectrochemistry, Temperature distribution, Zinc oxide, Atomic emission spectroelectrochemistries, Charge transfer mechanisms, Elementary phenomena, Elementary process, Hydrogen evolution, Open circuit potential, Polarization curves, Temperature dependence, Zinc alloys
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-39997DOI: 10.5006/2914Scopus ID: 2-s2.0-85059764565OAI: oai:DiVA.org:ri-39997DiVA, id: diva2:1359518
Note
Funding details: Beijing University of Chemical Technology, BUCT; Funding text 1: Authors would like to appreciate to Dr. Grégory Lefèvre of Chimie ParisTech, France for discussion of equilibrium simulations and Dr. Jan Stoulil of the University of Chemistry and Technology (UCT) in Prague, Czech Republic for supplying the Al5.2Zn phase.
2019-10-092019-10-092023-05-16Bibliographically approved