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.
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).