Studies on film forming corrosion inhibitors on aluminium alloy, AA2024-T3

In today's society, corrosion protection of structural aluminium alloys in the aerospace, marine, automotive and construction industry is of paramount importance. This is commonly achieved through the use of corrosion inhibiting compounds. Constraints such as potential health issues associated with exposure to conventional chromate-based corrosion inhibitors, has led to the development of low toxicity corrosion inhibitors for a wide range of industries and since then, much work has been carried out on evaluating inhibitor performance and associated mechanisms, but only a few studies have been done on understanding in detail film forming characteristics of certain inhibitors. Therefore, this study presents key aspects of the film forming behaviour of the selected inhibitors and the test methods used to evaluate the inhibitor induced films in a chloride solution. This study also aims to provide significant insights to the film tenacity, the influence of the molecular structure as well as the film stability in the absence of inhibitors to provide a deeper understanding of the film forming and film breakdown mechanisms. This study was focussed on two inhibitors that are known for their high corrosion inhibition efficiency for the protection of aluminium AA2024-T3 alloy, namely 2-mercaptobenzothiazole and Na-mercaptopropionic acid. During this work, a wide range of electrochemical methods were utilised in conjunction with various surface analysis methods to understand inhibitor induced film formation.