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Army, Tesla Pioneer Carbon Nanocoating

Wednesday, August 31, 2011

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Super strong, electrically conductive, wear resistant and offering electrostatic discharge protection, carbon nanotubes (CNTs) have long held major potential for structural materials.

Now, an Ohio company and the U.S. Army Corps of Engineers have developed the first commercially available corrosion-resistant coating for steel made with fullerene CNTs.

Saperaud / Wikimedia Commons

Carbon nanotubes—the research focus of Nobel Laureate Richard Smalley—are long, hollow structures with walls formed by one-atom-thick sheets of graphene.

Teslan Carbon Nanocoating was jointly developed by Tesla NanoCoatings Ltd., of Massillon, OH, and the U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL), of Champaign, IL.

Zinc Content Halved

The epoxy polyamide product features about half the zinc content of traditional zinc-rich primers, which protect steel surfaces through the sacrificial action of the zinc dust.

Zinc particles are anodic to steel, and this corrosion protects the steel substrate from corrosion. However, experts say, the high volume of zinc dust pigment (up to 90% by weight) reduces the strength of the coating, increases permeability, and makes delamination of the paint film more likely.

Adding CNTs—long, hollow structures with walls formed by one-atom-thick sheets of graphene—to the formulation allows zinc particles to remain in electric contact, providing as much corrosion protection as before, but without the harmful effects of higher pigment volume content (PVC), researchers say.

The lower pigment load means better adhesion and a stronger barrier film that outperforms barrier-only technology, the developers say. The barrier film is reinforced by the carbon nanotubes and provides corrosion protection via the electrically conductive nanotubes and an optimized amount of anodic metal dust.

Tank Testing

Developers call the nanocoating “the innovative foundation of a complete coating system,” which also includes a compatible polyurethane topcoat.

Army Corps of Engineers ERDC CERL

A fuel tank at Fort Bragg is shown before (left) and after application of Teslan, an epoxy and polyurethane coating formulated with carbon nanotubes.

The first test panels were coated at ERDC in 2005, and the coating was first evaluated last year in the field when it was applied to the exterior surfaces of a 200,000-gallon fuel storage tank at Fort Bragg, NC.

Stronger than Steel

In a presentation on the coating, the Corps of Engineers reports that carbon nanotubes can carry 1,000 times the current of copper and boast tensile strength 50 times greater than steel.

CNT research was pioneered by Nobel Laureate Richard Smalley, of Rice University.

The new coating was named a 2011 R&D 100 Winner by R&D Magazine (formerly, Industrial Research).

Comment from B. BRYCE, (9/2/2011, 4:08 AM)

Does anyone know if there are additional health & welfare requiremets when using these materials eg can the very small nano particles pass through traditioanl PPE & human membranes?

Comment from Richard McLaughlin, (9/6/2011, 9:52 AM)

Bryce, the short answeris "yes", there are health concerns with nano-sized particles, but that concern should be greatly reduced or eliminated once the particles are placed in a suspension, like a coating, or in a finished product. Concerns about worker exposure to nanoparticles come up on several safety email list I read, like the one hosted be the University of Vermont. Some nanoparticles can pass through most PPE and in some cases right straight through a worker’s skin due to the particle’s size. Many can pose a danger to a worker’s internal organs, with lung damage being the most common concern. By the way, man-made nanoparticles are nothing new, just the variety is. We’ve been making carbon black and fumed silica for a very long time and they fall into the “nanoparticle” category. You’ve safely interacted with nanoparticle containing products every time you’ve changed a tire or dealt with a reinforced plastic product. Like I said, once in a suspension or finished product, nanoparticles are normally safe.