**9. Factors controlling corrosion rate**

Certain factors tend to accelerate the action of a corrosion cell which includes the establishment of well-defined locations on the metal surface for the anodic

and cathodic reactions. Metals having a more positive (noble) potential in the galvanic series will tend to extract electrons from a metal which is in a more negative (base) position in the series and hence accelerate its corrosion when in contact with it [23]. Aggressive ions such as chloride tend to prevent the formation of protective oxide films on the metal surface and thus increase corrosion.
