TB 43-0213
OXIDATION-REDUCTION REACTION
The corrosion process called "rusting"
It begins with water on a metal surface
It begins with moisture on metal. This moisture
polarizes the iron atoms in the metal. Purer
portions of the iron become positive areas. Those
parts of the metal containing more impurities
become negative areas.
The positive charged iron atoms begin to attract
electrons from the weaker negatively charged iron
atoms. These electrons are pulled from the
negative iron atoms and migrate toward the positive
areas.
At the same time, the weakened iron atoms in
negative areas of the metal migrate toward the
surface of the metal where they begin to dissolve
into the moisture on the surface.
The electrons pulled into the positive areas of the
metal now come into contact with the oxygen
atoms found in the moisture on the metal surface.
These oxygen atoms seize upon the electrons. In
turn, the electron charged oxygen atoms now
merge with the weakened iron atoms dissolving on
the surface. This merging forms a new molecule -
the molecule of iron-hydroxide, a crusty, flaky
form of metal commonly known as rust.
TA504742
Figure 2-1. Oxidation-Reduction Reaction.
2-2
