Self-healing ability of nanoclay-based hybrid sol-gel coatings on magnesium alloy AZ91D

The main objective of the study was to investigate the effect of loading cationic corrosion inhibitors into halloysite nanotubes on the corrosion resistance of self-healing coatings derived from these materials. For this purpose, corrosion inhibitors Ce3 +/Zr4 + were encapsulated into halloysite clay nanotubes. The encapsulated nanotubes were dispersed into a hybrid silica sol-gel matrix and deposited on magnesium alloy AZ91D substrates by dip coating method. The coatings were cured at 130 °C for 1 h in air. The bare, matrix sol coated and self-healing sol coated substrates were evaluated for their self-healing and corrosion protection abilities using weight loss experiments, potentiodynamic polarization and electrochemical impedance spectroscopy measurements after immersion in 3.5% NaCl solution for varying time durations between 1 h to 24 h. These results were further corroborated with those obtained from scanning vibrating electrode technique. The self-healing property and the promising nature of cationic corrosion inhibitor loaded halloysite nanotube based corrosion protection coatings on AZ91D substrates could be confirmed from the present investigations.