SECM study of defect repair in self-healing polymer coatings on metals

In this paper the local healing efficiency of shape-memory polymers as a new alternative for the protection against corrosion of damaged coated metals is studied by scanning electrochemical microscopy (SECM). These measurements allowed us to evaluate the local corrosion activity at a damaged self-healing polymer coating on an aluminum alloy before and after the thermally healing process of the shape-memory polymer film. SECM operating in redox-competition mode is applied to monitor in situ the reduction of oxygen as a cathodic process in the corrosion onset at a coating defect as a function of exposure time in 0.05 M NaCl solution. It is proven that the physical repair of the film in the defect leads to a recovery of the local barrier properties of the coated system and subsequent protection of the aluminum alloy. Keywords: Self-healing, Scanning electrochemical microscopy, Organic coatings, Shape-memory polymer