The Effect of Cerium Ions on the Structure, Porosity and Electrochemical Properties of Si/Zr-Based Hybrid Sol-Gel Coatings Deposited on Aluminum
Peter Rodič,
Jozefina Katić,
Dorota Korte,
Paula M. Desimone,
Mladen Franko,
Silvia M. Ceré,
Mirjana Metikoš-Huković,
Ingrid Milošev
Affiliations
Peter Rodič
Department of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova c. 39, Ljubljana 1000, Slovenia
Jozefina Katić
Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, Zagreb 10000, Croatia
Dorota Korte
Laboratory for Environmental and Life Sciences, University of Nova Gorica, Vipavska cesta 13, Nova Gorica 5000, Slovenia
Paula M. Desimone
Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), Av. J. B. Justo 4302, Mar del Plata 7600, Argentina
Mladen Franko
Laboratory for Environmental and Life Sciences, University of Nova Gorica, Vipavska cesta 13, Nova Gorica 5000, Slovenia
Silvia M. Ceré
Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), Av. J. B. Justo 4302, Mar del Plata 7600, Argentina
Mirjana Metikoš-Huković
Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, Zagreb 10000, Croatia
Ingrid Milošev
Department of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova c. 39, Ljubljana 1000, Slovenia
This study was focused on the synthesis and characterization of Si/Zr-based hybrid sol-gel coatings with and without the addition of cerium(III) ions. The coatings were deposited on aluminum aiming to act as an effective and ecologically harmless alternative to toxic chromate coatings. The chemical composition, structure, thermal properties and porosity of the non-doped and Ce-doped coatings containing various Zr contents were examined by Raman spectroscopy and photothermal beam deflection spectroscopy. The corrosion properties of the coated aluminum substrates were studied using AC and DC electrochemical methods in 0.1 M NaCl electrolyte solution. Barrier and protecting properties of the coatings were monitored upon long-term immersion in chloride solution using electrochemical impedance spectroscopy. The effect of cerium ions was two-fold: on the formation of a more condensed Si−O−Zr network structure and on the formation of Ce-based deposits, which diminish the rate of cathodic reaction at the coating/metal interface. These effects acted synergistically and resulted in the creation of the coatings with effective barrier and active corrosion protection.
