Galvanic Corrosion:

Galvanic corrosion is the corrosion which results while two dissimilar metals along with different potentials are placed within electrical contact in an electrolyte.

Of all the various categories of corrosion, galvanic corrosion corresponds most nearly to the electrochemical cells defines previously within this module since galvanic corrosion occurs while two electrochemically dissimilar metals are joined together (in electrical contact) within a conducting medium (electrolyte). It might additionally take place along with one metal within heterogeneities (dissimilarities) (for instance, impurity inclusions, grains of different sizes, differences in mechanical stress, difference in composition of grains,); abnormal levels of pH; and high temperatures. A variations in electrical potential exists among the different metals and serves as the driving force for electrical current flow by the corrodant or electrolyte. This is current result within corrosion of one of the metals.  The larger the potential difference, a greater the probability of galvanic corrosion. Galvanic corrosion just causes deterioration of single of the metals. The fewer resistant, active metal becomes the anodic corrosion site.  The tough, nobler metal is cathodic and protected. There are two metals that would be uniformly attacked through the corrosive medium if there were no electrical contact as if the other metal were absent.  Two locations susceptible to galvanic corrosion is a piping transition from one metal to another and a sacrificial anode (such as zinc).