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

Abstract

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.