The beneficial effect of ruthenium additions on the passivation of duplex stainless steel corrosion in sodium chloride solutions

• Published in: Corrosion science Vol. 51; no. 6; pp. 1364 - 1371
• Main Authors: Sherif, El-Sayed M., Potgieter, J.H., Comins, J.D., Cornish, L., Olubambi, P.A., Machio, C.N.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2009; Elsevier
• Subjects: Applied sciences; B. EIS; C. Passive films; Corrosion; Corrosion environments; Corrosion prevention; Corrosion protection; Duplex stainless steel; Exact sciences and technology; Metals. Metallurgy; Salt water; Salt water; Duplex stainless steel; C. Passive films; B. EIS; Corrosion protection; Ruthenium addition; Austenitic ferritic steel; Surface layer; Composition effect; Sodium chloride; Passivity; Corrosion; Stainless steel; Impedance; Dual phase steel; Passivation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2009.03.022

The effect of varying ruthenium contents of 0.00, 0.14, 0.22, and 0.28% on the corrosion of 22%Cr–9%Ni–3%Mo duplex stainless steel (DSS) after different immersion intervals in 3.5% NaCl solutions has been investigated. The study was carried out using open-circuit potential, potentiodynamic cyclic polarization, chronoamperometry, electrochemical impedance spectroscopy, and weight-loss measurements. Particular attention was paid to the effect of Ru on the pitting corrosion of DSS in the chloride solutions. Electrochemical measurements indicated that the presence of Ru passivates the DSS alloy by decreasing its corrosion parameters. Furthermore, it shifts the corrosion and pitting potentials to more positive values. This effect was found to increase with increasing Ru content and also with increased immersion time of the alloy in the chloride solution before measurements. Weight-loss time data after varied exposure periods (4–20
days) showed that the weight-loss and corrosion rate of DSS significantly decrease with increasing Ru contents.