| Activation and mass transfer process was studied using rotating cylinder electrode regarding the flow-accelerated corrosion of low alloy steel (ASME SA106 Grade C) in room temperature alkaline solution. The reducing agent diffused easily as rotating speed increased, and caused corrosion potential to shift upward. Passive film formed from pH 9.8 according to the mechanism of oxidation and subsequent precipitation of ferrous species. Above pH 10.4, film formation process was active and stable. Corrosion current showed increment with rotating velocity in pH 6.98, while it soon saturated in above pH 9.8. On the other hand the limiting current, which governs pure mass transfer phenomenon of reducing species, increased with the rotating speed regardless of pH value. This indicates that activation reactions, which constitute oxidation of ferrous ion and formation of passive film on the bare metal surface, controls the entire corrosion process. |
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