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‘Atomically Thin’ is In, For Graphene Protective Coatings

Thursday, February 23, 2012

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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.

ACS Nano

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.”

Comment from ivor williams, (2/24/2012, 6:25 AM)

One is delighted with progress but how would this coating be applied in ashipbuilding enviroment

Comment from Malcolm McNeil, (2/24/2012, 5:08 PM)

Has it been tested on mild carbon steel and, if so, what were the results?

Comment from Mary Chollet, (2/24/2012, 5:25 PM)

You may contact co-author Dr. Kirill Bolotin, of Vanderbilt University, at kirill.bolotin@vanderbilt.edu.

Comment from Jay Dillon, (9/9/2012, 4:11 PM)

can you coat Aerogel with Graphene or Graphene invisible paint/coating?

Comment from Jay Dillon, (9/9/2012, 5:38 PM)

Not to be too picky, but don't you agree that "slowness" of corrosion speed should be expressed as, for example: "...corrodes 5 percent as fast as untreated nickel..." or "... corrodes at 1/20th the speed of untreated nickel..". Technical writers may be aware of this, but popular writers often make this mistake. This is done in almost every popular science TV show, in describing various similar situations (comparative size, weight, velocity, and so forth). The problem here is that there is no measure of "slowness" per se. Speed, rate of change, is a measured value, but slowness is not, or should not be, I think, for sake of clarity.

Comment from Mary Chollet, (9/10/2012, 12:14 PM)

Jay, the relative slowness references are drawn from the study authors. As the abstract (linked in the story) says: "These results indicate that copper films coated with graphene grown via chemical vapor deposition are corroded 7 times slower in an aerated Na2SO4 solution as compared to the corrosion rate of bare copper. Tafel analysis reveals that 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 4 times slower than bare nickel."

Comment from Larry Stephans, (9/11/2012, 10:34 AM)

The use of graphene in coatings and in other technologies holds great promise as demonstrated by the progress made in the laboratory. Having considerable experience in moving technologies from the lab into practical application, I suggest that getting graphene based corrosion resistant coatings produced economically, on a surface economically in a configuration to perform over the long haul is going to be as much or more of a challenge than proving it demonstrates corrosion control properties in the lab.

Comment from Tom Schwerdt, (9/12/2012, 8:20 AM)

Larry, you are absolutely right.