Radiochemical study of the mechanism of passivation of iron

✍ Scribed by V.M. Novakovski; Y.A. Likhachev

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 692 KB
• Volume: 12
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(67)80005-7

✦ Synopsis

The automatic registration of potentiostaticcurrent/time diagrams was carried out, together with radiometric control of the true metal dissolution rate. The sensitivity attained permits fairly accurate measurement of the real dissolution rate of the passive tracer iron anode, not only in the stationary state, but also in non-stationary periods after abrupt potential changes.

The changes in the external anodic current, registered in such periods, are shown to take place almost entirely at the expense of the true metal dissolution rate. The quantity of electricity connected with deposition or removal of additional quantities of passivating oxygen is shown to be negligible.

Since there are some proofs for electrochemical equilibrium between the solution and the passivating oxide surface, the effects discovered show that the usual electrode kinetic laws are not valid for cations that pass through the film into the solution.

The peculiarities of such a process are analysed and some new considerations concerning the mechanism of the stationary dissolution rate of the film thickness regulation are suggested.