The Effect of Cerium Ions on the Structure, Porosity and Electrochemical Properties of Si/Zr-Based Hybrid Sol-Gel Coatings Deposited on Aluminum

PETER RODIC; JOZEFINA KATIC; DOROTA KORTE; PAULA M. DESIMONE; MLADEN FRANKO; SILVIA M. CERÉ; MIRJANA METIKO-HUKOVIC; INGRID MILOSEV

Metals

MDPI

Lugar: Basel; Año: 2018 vol. 8 p. 1 - 20

2075-4701

This study was focused on the synthesis and characterization of Si/Zr-based hybridsol-gel coatings with and without the addition of cerium(III) ions. The coatings were depositedon aluminum aiming to act as an effective and ecologically harmless alternative to toxic chromatecoatings. The chemical composition, structure, thermal properties and porosity of the non-dopedand Ce-doped coatings containing various Zr contents were examined by Raman spectroscopyand photothermal beam deflection spectroscopy. The corrosion properties of the coated aluminumsubstrates were studied using AC and DC electrochemical methods in 0.1MNaCl electrolyte solution.Barrier and protecting properties of the coatings were monitored upon long-term immersion inchloride solution using electrochemical impedance spectroscopy. The effect of cerium ions wastwo-fold: on the formation of a more condensed Si􀀀O􀀀Zr network structure and on the formationof 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 barrierand active corrosion protection.