Engineers at ETH Zurich have developed a versatile new material to help fight the ongoing corrosion of buildings and vehicles. Not only does the polymer coating protect against corrosion, it can also highlight cracks, automatically repair damage, and can be recycled at the end of its life.
Corrosion ultimately affects almost everything humans build, from skyscrapers and bridges to planes, trains, and automobiles. There is a constant need to develop new corrosion-resistant materials and coatings, and scientists are now developing ones with many interesting features.
The new material, called poly(phenylene methylene), or PPM for short, can be sprayed onto a surface and cured to form a solid polymer coating. To test how well it functions as a barrier to corrosion, the team conducted accelerated aging experiments exposing aluminum alloy samples with and without PPM coatings to salt solutions. And indeed, metals coated with his PPM layers of thicknesses of 30 and 50 micrometers showed no significant corrosion even after many cycles of accelerated aging.
PPM also showed self-healing ability. When the team deliberately scratched the coating and exposed it to the solution, it found that the coating quickly repaired the damage on its own. This is because the solution reacts with the aluminum underneath, heating the area and causing the polymer to melt and flow into the crevices. Filling breaks the contact between the solution and the metal, allowing it to cool and harden the coating again.
Polymers also give advance warning of this kind of damage in case human intervention is required. PPM fluoresces under UV light, but not when damaged. This allows you to clearly see cracks that would otherwise be difficult to find.
At the end of its life, this excellent material does not stop and can be recycled and applied to new surfaces. In contrast, similar polymers must be dumped in landfills or incinerated. In tests, the researchers removed it and recycled it, with only 5% material loss and no performance degradation after 5 reuses.
The researchers are currently applying for a patent on this material and will conduct further studies to investigate ways to improve the formulation.
A study was published in a journal polymer.
Source: ETH Zurich
