Self-healing coatings of inorganic particles using a pH-sensitive organic agent

► A self-healing coating was developed using TiO 2 particles and casein. ► The polarization resistance of the scratched specimen increased with time. ► A deposited film consisting of casein and TiO 2 particles was observed. ► The self-healing effect is due to the release of the casein and TiO 2 particles. A self-healing corrosion protective coating was developed using TiO 2 particles and casein as pH-sensitive organic agents that is also environmentally friendly materials. A film structured of TiO 2 particles was formed on a substrate (magnesium alloy) by dip-coating followed by immersion in a casein solution. Casein was inserted and fixed in the particle film by changing the pH of the casein solution. The polarization resistance of the scratched specimen prepared by changing the pH of the solution from 12 to 5 increased with testing time, and a deposited film consisting of TiO 2 particles and casein was observed after the test.