Fuel
cells are pollution free and in view of their future importance, a variety
of fuel cells have been fabricated and tried Corrosion slowly coats the surfaces of metallic objects with oxides or
other salts of the metal The rusting of iron, tarnishing of silver,
development of green coating on copper and bronze are some of the
examples of corrosion It causes enormous damage to
buildings, bridges, ships and to all objects made of
metals especially that of iron