Self-cleaning and self-healing protective coating on magnesium alloy

The work aims to realize the intelligent protection for magnesium alloy by preparing the coating with the self-cleaning and self-healing properties on the surface. The inorganic-organic hybrid silicon coating containing pH-sensitive core/shell nanostructure inhibitors was prepared on the AZ61 magnesium alloy surface by dip-coating method. The obtained coating had self-cleaning and self-healing properties. The surface morphology of the coating was observed by scanning electron microscopy (SEM). The wettability and adhesion to water were evaluated by contact angle measuring instrument (CA). The chalk ashes were used to simulate the self-cleaning property of the coating. The corrosion protection performance of the coating was analyzed by the electrochemical workstation, and the spectrophotometer was used to evaluate the self-healing property of the coating by measuring the release concentration of the inhibitors. The as-prepared coating had the rough surface, which contained a large number of pH-sensitive core/shell nanostructure corrosion inhibitors. The coating surface had a high static water contact angle of 156.7° and low roll-off angle of 5°, which indicated that the coating had superhydrophobic and low adhesive characteristics, so that water droplets could take away the pollutants when rolling down to the surface, thus realizing the self-cleaning property. Open-circuit potential tests and spectrophotometer measurements showed that the change of solution pH led to the release of corrosion inhibitors, thus the coating could heal. From the results of polarization curves, the corrosion current density of the coating containing core/shell nanostructure inhibitors was nearly two orders of magnitude smaller than that of the substrate, and the corrosion inhibition efficiency could reach 99.36%. From the electrochemical impedance spectroscopy (EIS), the resistance of the coating containing core/shell nanostructure inhibitors was as high as 85 105 ω·cm2, which had long-term self-healing protection ability. The inorganic-organic hybrid silicon coating containing pH-sensitive core/shell nanostructure inhibitors has been successfully prepared and has self-cleaning, self-healing and excellent protective properties. © 2019, Chongqing Wujiu Periodicals Press. All rights reserved.