Localized Dissolution Kinetics of Low Carbon Steel
Aljana Petek* and Valter Doleček
Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor
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Localized dissolution of low carbon steel in saturated calcium hydroxide with different amount of sodium chloride has been investigated, using a dc technique. Potentiokinetic polarization curves indicated that pitting potentials (Epit) decrease linearly with the log of chloride concentration. The rate of pit nucleation (1/ti), and the rate of pits growth increases with increasing concentration of Cl- ions. Initiation of pitting attack could be ascribed to the adsorption of Cl- ions on the oxide surface. Adsorption of Cl- ions is physisorption and follow the Langmuir isotherm with ∆adsG0 = –21.1 kJ/mol.
Keywords: Pitting corrosion; adsorption isotherm; low carbon steel; simulated interstitial solution.