Microencapsulation Report

Researchers at the University of Duisburg-Essen in Germany have developed a self-healing nanocapsule coating for metal that will prevent corrosion. This is the first such coating that can be electroplated onto a metal surface. From the Technology Review article:

The self-healing metal can be electroplated, which opens up applications in construction, car manufacturing, and other industries that use or manufacture steel machines. (Nuts, bolts, and screws made of steel, which is susceptible to corrosion, are already electroplated with rustproof metals such as zinc and chromium.)

The new coating is around 15 micrometers thick and contains polymer capsules a few hundred nanometers in diameter. When the plating is scratched, the capsules should burst and release their contents – which could be a polymer capable of sealing the crack, or corrosion-inhibiting liquids.

So far, the researchers have made nanocapsule-infused coatings from metals or alloys including copper, zinc, and nickel. In principle, it should be possible to make them from any metal that can be electroplated, says Harald Holeczek, a Fraunhofer researcher who was involved in the work.

Although Holeczek and his colleagues haven’t yet demonstrated the material’s self-healing property, being able to incorporate liquid-filled nanocapsules into electroplated layers is significant, says Michael Kessler, a materials science and engineering professor at Iowa State University. “This is the first self-healing coating that can be electroplated,” he says. “The advantage is that electroplating is a widely used industrial process.”