Use of a glass-carbon rotating disk electrode for the identification of corrosion products of steels
- Karpenko Physicomechanical Institute, L`viv (Ukraine)
It is known that the interaction of steel with aqueous media is a complex multistage process resulting in the appearance of a variety of products of metal oxidation, some of which facilitate the dissolution of iron, while others passivate the metal surface. The composition of the corrosion products is governed by the pH of the medium, its chemical composition, i.e., the presence of various ions, and the testing conditions (temperature, constant or variable mechanical loads, etc.). Thus, in acid media, water dissociates intensely on the metal surface and the released OH{sup -} ions react with iron, forming a layer of hydroxides near the electrode. In this case, the process has four successive stages and Fe(OH){sub 2} plays the role of a surfactant that speeds up the dissolution of iron in an autocatalytic way. One may also consider some other mechanisms of the dissolution of iron. Thus, under certain conditions, the oxidation FeOH {yields} FeOH{sup +} + e may be the slowest stage of the process; one may also assume that iron monohydroxide adsorbed on the surface exists in the form of dimers, liberates an electron in the limiting stage of the process, and transforms, as a result, into Fe{sub 2} (OH){sub 2}{sup +}. At pH > 2, the combining of hydroxyl ions OH{sup -} with adsorbed iron monohydroxide with the formation of dihydroxide is assumed to be the limiting stage of the process. Under other testing conditions, the mechanism of the dissolution of iron may differ from those described above. This paper describes the use of glass-carbon rotating disk electrodes for the determination of corrosion products.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 273945
- Journal Information:
- Materials Science, Journal Name: Materials Science Journal Issue: 4 Vol. 30; ISSN MSCIEQ; ISSN 1068-820X
- Country of Publication:
- United States
- Language:
- English
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