Hexafluorozirconic Acid-Based Nanoceramic Conversion Coatings on AA3105 Aluminum Alloy: Influence of the Presence of Copper in the Deposition Bath

Zirconium-based conversion coatings provide an environmentally friendly, chromate-free alternative to traditional phosphating and chromating processes for enhancing the corrosion protection of metal substrates. This study investigates the formation and characterization of zirconium-based conversion coatings (Zr-CC) on AA3105-H16. The coatings were produced by immersion in an hexafuorozirconic acid (H2ZrF6) solution and characterized using SEM-FEG, SEM/EDS, and Raman spectroscopy. Considering that the incorporation of organic and/or inorganic additives can enhance the anticorrosive performance of Zr-CCs, electrochemical techniques were employed to assess the influence of Cu2+ ions on corrosion resistance in a sodium chloride medium. The results indicate that, under the tested conditions, Cu2+ ions act as precursors for film formation, increasing the open-circuit potential and decreasing the coating formation time. However, coatings formed in the presence of Cu2+ ions exhibited lower corrosion resistance, revealing a detrimental effect on anticorrosive performance.