Plasma Electrolytic Oxidation (PEO) is an environmentally friendly surface modification technique capable of producing highly corrosion and wear resistant coatings on light alloys. This technique is used in high-performance applications where weight reduction is a key factor, such as aerospace and transportation. However, these coatings only provide passive protection, i.e. act only as a physical barrier between the metallic substrate and the aggressive environment.
PEO coatings present a layered and porous morphology, which is usually sealed in order to prevent corrosion damage. Most sealings enhance the barrier properties of the coatings by blocking the porosity and preventing the electrolyte access to the metallic substrate. The aim of this work is to provide PEO coatings with active properties through a sealing treatment. For that, halloysite nanotubes are used as nano-containers to carry corrosion inhibitors, which are incorporated into the coatings by an immersion sealing post-treatment. The active functionalisation is based on the controlled release of the corrosion inhibitors triggered by pH changes arisen from the electrochemical activity.