Page 4 - Corrosion & Harsh Environment Protection

4 Corrosion & Harsh Environment Protection
Causes of Corrosion
Corrosion is the deterioration of metal caused by a chemical reaction to its
surrounding environment. In most cases this means electrochemical oxidation of
metals in reaction with an oxidant such as oxygen. Corrosion can be accelerated
by the presence of dust, moisture, high relative humidity, high temperatures, salt,
acids, solvents and chemicals. How quickly corrosion occurs depends not only on
the environment, but also on the specific type of metal. Cast iron, for example,
rapidly oxidizes and forms red rust if left in its raw state, simply from exposure
to the air, so it requires some form of protective finish. Other metals, such as
stainless steel, have an inherently higher resistance to corrosion without the need
for special coating.
If left in its raw state, cast iron
rapidly oxidizes, forming red rust.
What Corrosion Looks Like
When we think of corrosion, red rust that forms on iron or steel typically comes to mind, but corrosion may also appear in other forms, depending on the
metal. White rust is corrosion of the zinc that is typically used as a protective coating over iron or steel. The natural green patina on the Statue of Liberty
and on copper roofs is also a form of corrosion.
Oxidized Copper White Rust Red Rust