BURLINGTON, Ont.—A partnership between a university chemist and a chemical company has culminated in a green coating system that reportedly protects metals against corrosion. Paul Zelisko, an organic chemistry instructor at Brock University in St. Catharines, Ont., and Burlington, Ont.-based Vanchem Performance Chemicals worked together on a technology called Greencoat, which uses silicon rather than heavy metals to bind coatings to metal surfaces and paint.
What makes the system green is that it is a water-based system that has reactive sand in it. If the material happens to get flushed out or it leaks, you’re effectively releasing sand and water into the environment. The team received a patent for the silane-based pretreatment in the US, with Canadian and European patents pending.
When it comes to protecting steel and other metals from rust and salt damage, traditional coating systems use heavy metals such as zinc phosphate, iron phosphate, or chrome to enable the inorganic substance (metal) and organic substance (paint) to stick to one another. However, phosphates released into the environment can cause algal blooms in lakes and rivers, damaging aquatic plant and animal life.
Zelisko and Vanchem’s system varies from conventional methods by way of its two-step process. First, a base layer of water mixed with silica is sprayed onto the metal, creating a chemical bond with the metal. This not only cleans the metal, but also deposits silica onto the surface. This coating protects the metal while also acting as a primer for the second layer, which was 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.