Evaluation of self-healing properties of inhibitor loaded nanoclay-based anticorrosive coatings on magnesium alloy AZ91D

This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers. In this case, naturally available clay nanotubes (halloysite) were loaded with cationic corrosion inhibitors Ce3+/Zr4+. These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol. Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130 °C for 1 h in air. Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt% NaCl solution for varying time durations between 24 h to 120 h. Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt% NaCl solution. Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings, after prolonged exposure to corrosive environment.