PASSIVATION

"The formation of a thin adherent film or layer on the surface of a metal or mineral that acts as a protective coating to protect the underlying surface from further chemical reaction, such as corrosion, electrodissolution, or dissolution. The passive film is very often, though not always, an oxide. A passivated surface is often said to be in a ""passive state."" The surface oxidation can result from chemical or electrochemical (anodic) oxidation. During anodic passivation, in the current-potential plots, the current, instead of increasing with potential, falls to a very small value. See passivation potential. See also an Encyclopedia Article. "