The anodic dissolution kinetics of iron in chloride containing solutions (LiCI) has been studied as a function of peripheral velocity by using a rotating cylinder electrode. The results obtained may be summarized as follows:

  1. Under stationary conditions, iron exhibits an activation controlled dissolution behavior over two decades of applied current density. Rotation at 1600 rpm induces a pronounced active/passive transition similar to that observed in stainless alloys in dilute acid media.

  2. The passivation kinetics under rotating conditions can be described with a Mueller type equation derived for simultaneous overlapping dissolution mechanisms.

  3. Passivity breakdown occurs above −550 mV versus a saturated calomel electrode to produce pronounced pitting corrosion. The pitting potential (Ec) is not a function of chloride ion concentration, pH, or rotational velocity in contrast to the behavior of stainless alloys in halide media.

  4. The mechanism of passivation under rotating conditions involves changes in the diffusion layer thickness and the ease of diffusion of ions to and from the dissolving surface resulting in passivation by oxide film formation.

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© 1979 National Association of Corrosion Engineers
1979
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