Zinc metal has a number of characteristics that
make it well-suited for use as a coating for protecting
iron and steel products from corrosion. Its
excellent corrosion resistance in most environments
accounts for its successful use as a protective coating
on a variety of products and in many exposure
conditions. The excellent field performance of zinc
coatings results from their ability to form dense,
adherent corrosion product films and a rate of corrosion
considerably below that of ferrous materials,
some 10 to 100 times slower, depending upon the
environment.

INTRODUCTION

Zinc metal has a number of characteristics that
make it well-suited for use as a coating for protecting
iron and steel products from corrosion. Its
excellent corrosion resistance in most environments
accounts for its successful use as a protective coating
on a variety of products and in many exposure
conditions. The excellent field performance of zinc
coatings results from their ability to form dense,
adherent corrosion product films 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
film of corrosion products develops rapidly, greatly
reducing the rate of further corrosion. Figure 1
shows the expected service life to first maintenance
(5% red rust) of iron and steel based on the zinc
coating thickness and the environment.