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.)
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.
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.
P7 after 8,372 hours Salt Fog Exposure (coated CRS panel)
P8 Adhesion Test after 8,372 hours Salt Fog Exposure.
||• Pull-Off Test: (the three circles)|
• Tape Adhesion Test (the three cross marks)
|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.