Fixer capsules

German researchers have electroplated metal with nanometre-sized capsules that release fluid and repair the surface of the metal if it becomes damaged.

The researchers, from the Fraunhofer Institute for Manufacturing, Engineering and Automation IPA in Stuttgart, together with colleagues from Duisburg-Essen University, developed the process for producing the electroplated layers with the nano-capsules in a project financed by the Volkswagen Foundation.

The researchers have produced the first copper, nickel and zinc coatings with the new capsules, although surface coverage does not extend beyond a few centimetres. They estimate that it will be another one and a half to two years before whole components can be coated.

The new coating could be put to good use in mechanical bearings. Bearings usually have a electroplated coating in which the capsules might be embedded.

If there was a temporary shortage of lubricant, part of the bearing’s coating would be lost, and the capsules at the top of the layer would burst and release lubricant. The bearing would, therefore, not be damaged if it temporarily ran dry.

The team also worked on more complex systems involving capsules filled with different fluids that reacted with one another like a two component adhesive.

The nano-capsules in the electroplated layer contain a fluid. If the layer is scratched, the capsules burst, the fluid escapes and repairs the scratch