Advanced microcapsules for self-healing conversion coating on magnesium alloy in Ce(NO3)3 solution with microcapsules containing La(NO3)3

- Gelatin-chitosan microcapsules containing lanthanum nitrate were prepared by complex coacervation.
- Cerium conversion coating with microcapsules demonstrates self-healing performance.
- Microcapsules rupture and release lanthanum nitrate to repair the conversion coating.

Microcapsules with self-healing coatings for corrosion protection of magnesium substrates have attracted tremendous interest due to their capability of preventing the propagation of cracks in protective coatings by releasing inhibitors from the microcapsules. Gelatin-chitosan microcapsules containing La(NO3)3 were prepared by complex coacervation. The morphology of the cerium-based conversion coating shows a globular structure with microcapsules distributing in the tiny cracks of the coating. In 3.5 wt% sodium chloride solution environment, the coating is damaged and microcapsules migrate into the damaged area, the triggering release of inhibitors supplement to the conversion coating. The cerium conversion coating with microcapsules shows a much higher corrosive resistance than the coating without microcapsules, and demonstrates the achievement of a self-healing performance.