Zinc powder coating is zinc-rich. That means it has a metallic zinc content above a certain level. It is a form of epoxy zinc paint where, besides zinc, there are two key elements; epoxy resin and a hardener. Epoxy has a proven chemical resistance which makes it ideal for sealing steel, concrete and other industrial materials. Zinc powder may be applied as a stand-alone coating, but only for internal use, but typically it works as an undercoat, providing additional protection from corrosion beneath a topcoat.
Zinc forms zinc patina, which is a by-product of the metal that acts as a protective barrier when applied to metal surfaces. This barrier keeps out the moisture which can speed up the corrosion process. That is because zinc corrodes significantly more slowly than other metals. Normally, oxidation occurs when steel or iron come into contact with moisture in the air. Those metals are especially prone to oxidation, which causes corrosion. A zinc powder coating will act as a metallic barrier, preventing moisture from reaching metal surfaces.