Graphene, the wonder child of materials science, has yet another claim to fame: New research anoints it as the thinnest coating ever developed for protecting metals from corrosion.
The super-strong single layer of carbon atoms—the subject of Nobel Prize-winning research in 2010— has already found significant potential in several coatings applications: as an invisible component of non-invasive coatings, as an energy-harvesting “smart skin” and as an antifouling.
Alexander AIUS / Wikimedia Commons
|Known for its distinctive “atomic-scale chicken-wire” structure, graphene is so thin that a stack of three million sheets would be only one millimeter thick.|
But the new findings, by Vanderbilt University researchers, are the most significant yet for those involved in the multibillion-dollar fight against corrosion.
The scientists report their findings in “Graphene: Corrosion-Inhibiting Coating,” in ACS Nano, a journal of the American Chemical Society.
20x Slower Corrosion
The scientists studied the use of “atomically thin” layers of graphene as a protective coating that inhibits corrosion of underlying metals. They employed electrochemical methods to study the corrosion inhibition of copper and nickel by either growing graphene on these metals, or by mechanically transferring multilayer graphene onto them.
The finding: Both methods did the job.
|Nickel with a multilayer graphene film grown on it corrodes 20 times slower than bare nickel, while nickel surfaces coated with four layers of mechanically transferred graphene corroded four times slower than bare nickel, scientists said.|
“Cyclic voltammetry measurements reveal that the graphene coating effectively suppresses metal oxidation and oxygen reduction,” while electrochemical impedance spectroscopy measurements “suggest that while graphene itself is not damaged, the metal under it is corroded at cracks in the graphene film,” the article reports.
How protective is it?
[C]opper films coated with graphene grown via chemical vapor deposition are corroded seven times slower in an aerated Na2SO4 [sodium sulfate] solution as compared to the corrosion rate of bare copper,” the researchers write.
And “nickel with a multilayer graphene film grown on it corrodes 20 times slower, while nickel surfaces coated with four layers of mechanically transferred graphene corrode four times slower than bare nickel.”
1 Ounce, 28 Football Fields
Moreover, that protection is packed into a material so thin that one ounce could be stretched in one transparent layer to cover 28 football fields. A single layer of graphene provides the same corrosion protection as conventional organic coatings that are more than five times thicker, the scientists say.
That could hold enormous potential for electronics, sophisticated components, implantable devices and other applications that require thin coatings, says the team, which concludes:
“These findings establish graphene as the thinnest known corrosion-protecting coating.”