Unravelling the corrosion protection mechanism of silyl ester by combined electrochemistry and x-ray computed tomography

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Recently, encapsulated silyl esters have been shown to act as efficient healing agents for self-healing anticorrosive coatings. While the positive protective effects were irrefutable, the actual protection mechanism has not been clarified yet. In this study, x-ray computed ?-tomography and electrochemical impedance spectroscopy have been employed to unravel the protection mechanisms for a coated AA7050 aluminium alloy. The results show that the employed silyl ester protects the damaged coating-metal system by delaying the delamination initiation and growth kinetics while at the same time decreasing the underfilm pit area growth. The study also shows the potential of x-ray computed ?-tomography to follow the delamination front line and underfilm pits in coated metallic samples. The combination with EIS led to a major understanding of both EIS plots and the protection mechanisms offered by the silyl ester used.