CORROSION
CORROSION Corrosion is the destruction of metals and alloys by the chemical or electrochemical reaction with the environment. During corrosion, metals are converted to metallic compounds at the surface and these compounds wear away as corrosion products. The corrosion of iron is known as rusting. Examples of corrosion are: Rusting of iron in the moist atmosphere form Fe2O3.2H2O Formation of basic CuCO3 (green film) on the surface of copper. The reaction of chlorine gas with Mg or Sn. Rate of corrosion It is expressed in Milligrams per year (mpy). mpy= 534W/DAT Where W=weight loss in mg, D= the density of the material in g/cm2, A= the area of the material in sq. inch, T= exposure time in an hour. Mechanism of Corrosion They are of two types Direct chemical corrosion or dry corrosion (oxidation, corrosion due to other gases, liquid metal corrosion) and Electrochemical corrosion or wet corrosion.0 Electrochemical or WET corrosion This type of corrosion takes place when...