**1. Introduction**

Corrosion is the primary means by which metals deteriorate. Corrosion introduces itself into many parts of our lives [1, 2]. The great majority of us have personal feeling for the importance of corrosion. Far too many have cringed at the emergence of rust holes in the body panels of relatively new automobiles [3]. The outdoor rusting of steel, household and garden appliances is a common fact of life. All have seen the strains on cooking utensils from hot foods or experienced the metallic taste in acid foods stored too long on open cans. That these effects are caused by corrosion is well known [4]. The glaring example related to corrosion is the appearance of cracks in certain portions of Taj Mahal, was due to steel dowels embedded inside had extensively corroded and rusted leading to fractures in the stoned [5]. However, corrosion is just as common in other material classes such as ceramics, plastics and rubber. Since, practically all environments are corrosive to some degree and are major contributing causes of material failure and also are a large economic cost to the society [6].
