Zinc Coating

Zinc has a number of characteristics that make it a well-suited corrosion protective coating for iron and steel products in most environments. Th e excellent fi eld performance of zinc coatings results from its ability to form dense, adherent corrosion product fi lms and a rate of corrosion considerably below that of ferrous materials (some 10 to 100 times slower depending upon the environment). While a fresh zinc surface is quite reactive when exposed to the atmosphere, a thin fi lm of corrosion products develops rapidly, greatly reducing the rate of further corrosion. In addition to creating a barrier between steel and the environment, zinc also has the ability to cathodically protect the base metal. Zinc, which is anodic to iron and steel, will preferentially corrode and protect the iron or steel against rusting when the coating is damaged (see Figure 1, below).