Robust Damage‐Sensing and Corrosion‐Warning Polymeric Coatings: a New Approach to Visually Monitor the Degradation Dynamics of Coated Mg‐Alloys

Corrosion and degradation of magnesium (Mg) alloy result in serious damage and limit its application in new-energy automobile industry. Considerable protective coating is proposed, yet it is hindered by the difficulties in avoiding and visually monitoring coating micro-damage and localized metal corrosion. Herein, a novel anticorrosion coating system with autonomously monitoring multiple levels of damages in coated Mg-alloy system, is proposed. In this design, the top layer of coating consists of polymethyl methacrylate (PMMA) microcapsules containing crystal violet lactone (CVL) and polyurethane resin dispersed with SiO