Corrosion Performance of 6061 Aluminium Alloy Protected by Plasma Electrolytic Oxidation Coatings Modified by Acrylic Acid

Long-term corrosion studies (six weeks) of aluminium alloy 6061 treated by plasma electrolytic oxidation (PEO) with or without the addition of a corrosion inhibitor (acrylic acid) in oxygenated 3.5 wt% NaCl are reported. A two-step sequential procedure (PEO + enrichment with acrylic acid) was compared with PEO carried out in the presence of the inhibitor. EIS backed by ICP-OES and SEM data showed that the sequential method offers the best long-term protection. A new approach for testing weight loss due to corrosion underneath the PEO coatings is proposed. The obtained results are consistent with other methods used in the study.