Performance evaluation of metallic zinc based coating systems through accelerated testing

摘要

Hot dip galvanizing (HDG) has a highly successful long track record of providing effective corrosion protection in a wide range of environments. Recently, it has become popular for architects to specify HDG top coated with an organic resin based system, such as acrylics, epoxies or polyurethanes as a corrosion resistant finish with decorative properties. Engineers also have been specifying HDG for steel in more severe environments, specifying epoxy and polyurethane based top coats to prevent the rapid consumption of the underlying pure zinc layer. The increasing use of paint coatings on galvanized surfaces has led to an increase in the incidence of adhesion failures between the galvanized surface and the paint system. This has usually been attributed to the use of saponifiable resin coatings such as alkyd enamels or primers. However, there is evidence that non-saponifiable resin systems have also suffered adhesion problems over galvanized surfaces.