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Delaware-based AnCatt Inc. has unveiled a heavy-duty, three-layer coating system that purportedly functions as a corrosion barrier for metal substrates without using chromate or other heavy-metal pigment.
The company says the system—a primer, two-component aliphatic urethane top layer, and optional interlayer—has withstood more than 10,000 hours of Salt Fog (ASTM B 117) testing on steel without rusting or blistering. Coated aluminum panels have been tested for more than 7,000 hours, the company says. (ASTM standards require a maximum of 5,000 testing hours.)
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Photos: AnCatt Inc. |
| The coating system is designed to protect a variety of metals from corrosion in severe environments. |
AnCatt says the test panels showed no visible changes in appearance, including cracking, flaking, and chalking.
The tests were conducted by KTA-Tator Inc. of Pittsburgh, AnCatt reports.
Corrosive Environments
The system uses conductive polymer (polyaniline) composites as anti-corrosion pigments. The system is designed to be used in severe conditions to protect a wide range of metals, including structural steel, pipeline, tanks, bridges, offshore platforms, marine hulls, superstructures and decks.
The primer “serves as an excellent heavy-metal-free replacement for existing heavy-metal-based vinyl wash primers with even better performance,” says the company, which also offers a low-VOC anti-corrosion system.
Selected Features and Performance
AnCatt’s primer contains no zinc chromate, hexavalent chromium, lead or other heavy-metal pigments, the manufacturer reports.
AnCatt says the system provides very good adhesion, with tensile adhesion (pull-off strength) of 700-800 psi on samples following 1,000 hours cyclic weathering exposure. The self-healing formulation features low-cost raw materials and is easy to manufacture, says AnCatt, which is seeking licensing partnerships.
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P7 after 8,372 hours Salt Fog Exposure (coated CRS panel) |
P8 Adhesion Test after 8,372 hours Salt Fog Exposure. |
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• Pull-Off Test: (the three circles)
• Tape Adhesion Test (the three cross marks)
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| The photos show results of salt fog testing (ASTM B 117) over 8,372 hours, according to AnCatt. |
“Since the reporting of anti-corrosion effect of polyaniline in 1981, hundreds of papers and patents have been published or issued on polyaniline anti-corrosion coatings as an environmentally friendly alternative,” says Sue Wang, the company’s Business Development Manager. “Still, there is no such product on the market today.”
She adds: “Today’s alternatives, such as hexavalent chromate (chromium VI), are highly toxic, carcinogenic, and under tightening regulations. Even the less-toxic zinc falls short, since it cannot protect aluminum or galvanized steels and is less effective in severe corrosion as a sacrificial antidote.”
More information: http://www.ancatt.com.
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