Corrosion Inhibition and the Role of Films

Abstract

Corrosion inhibitors are chemical agents that effectively reduce corrosion of a metal surface by reacting with the metal surface directly, called interface inhibition, by reacting with or modifying a preexisting corrosion product film, called interphase inhibition, or by scavenging constituents from the solution before they react with the metal. The latter group of inhibitors will not be dealt with in this chapter. Moreover, only the mechanisms of chemical inhibition in conjunction with corrosion films will be discussed. Neither the chemistry of the inhibitors themselves, nor such molecular factors as geometrical dimensions and molecular structure, cross-sectional area, π and σ bonding, ionization potential and electron affinity, spatial relationships between different functional groups, dipole moments, etc., are discussed. All of these factors and others are important to the mechanisms and theories of inhibition by inhibitors; however, they represent another aspect of corrosion inhibition not germane to this text.