Zirconium-based conversion film formation on zinc, aluminium and magnesium oxides and their interactions with functionalized molecules

L. I. Fockaert, P. Taheri, S. T. Abrahami, B. Boelen, H. Terryn, J. M.C. Mol*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    32 Citations (Scopus)

    Abstract

    Zirconium-based conversion treatment of zinc, aluminium and magnesium oxides have been studied in-situ using ATR-FTIR in a Kretschmann geometry. This set-up was coupled to an electrochemical cell, which allowed to obtain chemical and electrochemical information simultaneously as a function of conversion time. This elucidated the strong relation between physico-chemical surface properties and zirconium-based conversion kinetics. Whereas the surface hydroxyl density of zinc and aluminium increased during conversion, magnesium (hydr)oxide was shown to dissolve in the acid solution. Due to this dissolution, strong surface alkalization can be expected, explaining the rapid conversion kinetics. AES depth profiling was used to determine the final oxide thickness and elemental composition. This confirmed that magnesium is most active and forms a zirconium oxide layer approximately 10 times thicker than zinc. On the other hand, the presence of zirconium oxide on aluminium is very low and can be considered as not fully covering the metal oxide. Additionally, the converted oxide chemistry was related to the bonding mechanisms of amide functionalized molecules using ATR-FTIR and XPS. It was shown that inclusion of zirconium altered the acid-base properties, increasing the substrate proton donating capabilities in case of magnesium oxide and increasing hydrogen bonding and Bronsted interactions due to increased surface hydroxide fractions on zinc and aluminium substrates.

    Original languageEnglish
    Pages (from-to)817-828
    JournalApplied Surface Science
    Volume423
    DOIs
    Publication statusPublished - 2017

    Keywords

    • Amide
    • Chemisorption
    • Interfacial interactions
    • Surface characterization
    • Zirconium-based conversion coating

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