2: Formation of an Oxide Layer
The difference in oxidation rates depends on the conductivity of the oxides because the ions have to move through the oxide layer.
Oxidation occurs much more rapidly as temperature increases because the mobility of ions within the oxide layer increases.
In some cases, dry corrosion is actually encouraged. The formation of an oxide layer on the surface of a metal will, in some instances, lead to a reduction in the rate of corrosion.
When a metal oxidises and forms an outer layer, this layer can remain on the surface of the metal and limit further corrosion by inhibiting the ability of oxygen or other corrodents to reach the metal surface. This is known as passivation.