Self-healing coating protects metals from corrosion

Corrosionin metals can lead to the structural fatigue or failure of bridges,pipelines, and plane fuselages. Anti-corrosion coatings help preventthis, but they become ineffective when pierced, cracked, or scratchedaway. Researchers at Northwestern University have now developed aself-healing coating that can patch up its imperfections in a matterof seconds.

"Localcorrosion in metal is quite dangerous because it is hard to predict,and when it happens, oftentimes it is hard to detect, thus leftunattended," Prof. Jiaxing Huang, who led the research efforts, told NewAtlas. "There are [detection] methods based on visual inspection,or techniques such as those based on electrochemistry to monitor therate of corrosion. But because corrosion is local, finding the spotsin a large metal structure is not easy."

We'vealready seen self-healing coatings powered by the Sun and others inspired by a snake's skin, but these can only repair microscopic defects.In order to heal bigger imperfections on the millimeter scale, Huangand his colleagues took a different inspiration.

"Whena boat cuts through water, the water goes right back together,"says Huang. "The 'cut' quickly heals because water flowsreadily. We were inspired to realize that fluids, such as oils, arethe ultimate self-healing system."

Theoil-based coating had to be fluid enough to quickly self-repair in amatter of seconds, but not so liquid that it would simply drip offthe metal's surface. The "Goldilocks zone" was achieved by addingmicroscopic and lightweight graphene capsules which thicken the oiland help it stick to the metal extremely well even in harshenvironments, whether underwater or in acid baths.

Thescientists showed that the material can heal quickly and repeatedly,even after scratching the same spot for 200 times in a row, on anumber of different metals including aluminum, brass, and steel.Huang tells us that the coating should in principle work with anymetal, since it is not based on a specific surface chemistry.

Nextup, the researchers will work on anti-fouling coatings and findingways to mass-produce their graphene capsules.

Thecoating is further described in the video below.

Source:Northwestern University