28th March 2020

ANTI-CORROSION COATING USES SILICON

Researchers at Brock University in St. Catharines, ON, working with Vanchem Performance Chemicals (Burlington, ON), have created and  patented a new coating system that protects metals against corrosion. Organic chemistry instructor Paul Zelisko and Vanchem produced technology they named Greencoat, which uses silicon rather than heavy metals to bind coatings to both metal surfaces and paint.

"It’s a water-based system that, for all intents and purposes, has reactive sand in it,” says Zelisko. "If the material happens to get flushed out or it leaks, you’re effectively releasing sand and water into the environment.”

Sheets made out of steel or other metals need to be pre-treated. Traditional coating systems use heavy metals ­– such as zinc phosphate, iron phosphate or chrome – to enable the inorganic and organic substances to adhere. But there are concerns over emissions with these.

The new system involves a two-step process. First, water mixed with silica is sprayed onto the metal, creating a chemical bond with the metal. This cleans the metal but also deposits silica onto the surface. This coating not only protects the metal but acts as a primer for the second layer, which is designed to bond well to paint.

The second layer contains polysilicates, the basis of which is silicon. Silicates can be modified to stick to both metals and paints.

For testing effectiveness, treated metal sheets are put into salt-spray chambers, where a fine mist of salt water is continually sprayed onto the metal until it starts to show corrosion. The industry standard is around one thousand hours, says Zelisko. "Our coatings ranged anywhere from 1,800 to 3,000 hours, in some cases almost three times as good as what the industry requires.”

The team received the patent for Greencoat silane-based pretreatment on Aug. 2 in US, with Canadian and European patents pending.

www.vanchem.com