Effect of inhibitor loading into nanocontainer additives of self-healing corrosion protection coatings on aluminum alloy A356.0

Halloysite nanotubes loaded with and without cationic corrosion inhibitors (Ce3+/Zr4+) were dispersed in a hybrid sol-gel silica matrix sol, which was used to generate coatings on aluminum alloy A356.0. Coatings generated by dip coating technique were cured at 130 °C. Inhibitor loading into the lumen of HNTs was confirmed by BET pore volume and X-ray diffraction studies. Corrosion resistance of coatings containing inhibitor loaded and unloaded HNTs was investigated by electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss experiments, which were compared with that of uncoated substrates. Elemental analysis was carried out on scribed substrates, before and after salt fog test. Scanning vibrating electrode technique experiments were carried out for evaluating the self-healing property. Coatings generated using the corrosion inhibitor loaded nanotubes dispersed in matrix sol were seen to provide the maximum corrosion protection, after prolonged duration of exposure to corrosive medium. Corrosion inhibitors were released into the scribed area to heal the damaged substrate. •HNT loaded with and without cationic inhibitors dispersed in hybrid sol-gel matrix.•Loaded and unloaded HNT dispersed in matrix sol deposited on aluminum alloy A 356.0•Corrosion resistance behavior studied and compared for coated substrates.•Only inhibitor loaded HNT-based coating exhibited prolonged corrosion resistance.•SVET analysis confirmed self-healing action of inhibitor loaded nanotubes.