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Cathodic Nanocoating Technology for Corrosion Control of Steel Structures

Todd Hawkins, Susan Drozdz

Abstract


Traditional organic coatings which provide cathodic protection such as zinc-rich coatings exhibit several major drawbacks. To achieve electrical conductivity zinc-rich coatings rely on tangential contact between zinc dust particles. This results in over pigmentation of the binder exceeding the critical pigment volume concentration of the resin system. This results in an inferior coating with poor physical and mechanical properties. In addition, Zinc-rich coatings limit the amount of corrosion protection they can provide. The utilization of carbon nanotechnology overcomes the issues noted above. Lower zinc loading levels produce a strong and stable coating film optimized well under the critical pigment volume concentration of the resin. The strong and conductive network of carbon nanotube ropes strengthens and stiffens the film while building an electron path through the binder system. Essentially less zinc provides more availability for cathodic protection to damaged coating areas via the carbon nanotube ropes. Extending service life has a positive environmental and economic impact on waste reduction, energy and raw material consumption. Lowering zinc levels correspondingly lowers the levels of toxic heavy metals such as cadmium and lead that are always present with zinc. High-solids and low VOC coating systems are easy to formulate.

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