Periodic Phenomena During the Anodic Dissolution of Iron in Sodium Chloride Solutions

Periodic phenomena related to unstable surface films have been previously observed for a wide variety of metal electrode systems. These films may be the pre-passive salt films formed prior to true passivation by an oxide film (1) or may be the thicker films present during electropolishing (2) or other high-rate dis-solution processes imilar to these encountered in elec-trochemical machining (3). This note describes the periodic potential oscillations that have been observed durin ~ the galvanostatic anodic dissolution or iron in 20 weight per cent (w/o) NaC1 solution. This work was part of a study aimed at a better understanding of the factors controlling the electrode processes asso-ciated with "wild-cutting, " which occurs in NaC1 solu-tions during electrochemical machining at the low CD