Influence of inhibitor addition on the corrosion protection performance of sol–gel coatings on AA2024

Abstract

Sol–gel films are actively investigated during the last decade as possible candidates for environmentally friendly pre-treatments. However, the important drawback in this case is the lack of active corrosion protection and self-healing ability. In this work a certain number of corrosion inhibitors for AA2024 was used as additives to the hybrid sol–gel formulations in order to confer active corrosion protection without damaging the coating. The 8-hydroxyquinoline, benzotriazole and cerium nitrate were added at different stages of the synthesis process to understand the role of possible interaction of the inhibitor with components of the sol–gel system. The Scanning Vibrating Electrode Technique and Electrochemical Impedance Spectroscopy were employed as two main techniques to characterize the corrosion protection performance of the hybrid sol–gel films doped with inhibitors and to understand the mechanisms of corrosion protection. The results demonstrate that 8-hydroxyquinoline and cerium nitrate do not affect the stability of sol–gel films and confer additional active corrosion protection effect. In contrast to this, benzotriazole leads to deterioration of the corrosion protection properties of hybrid sol–gel films.