Effect of intentional convection on the passivity of an Fe–6Cr surface in pH 4.5 Na2SO4 solution. (20th June 2020)

• Record Type: Journal Article
• Authors: Fushimi, K.; Kanazawa, T.; Fujimura, A.; Kitagawa, Y.; Hasegawa, Y.; Doi, T.
• Is Part Of: Electrochimica acta. Volume 346(2020)
• Publication Date: 2020-06-20
• Subjects: Mass-transport -- Passivity -- Fe–6Cr -- Ellipso-microscopy; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2020.136237
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The anodic oxidation behavior of Fe–6Cr during potentio-dynamic polarization in pH 4.5 Na2 SO4 solution was investigated by electrochemical ellipso-microscopy. Active, passive, and trans-passive states of the Fe–6Cr surface showed heterogeneous oxidation behaviors depending on the substrate micro-structure, electrode potential and solution convection. Enhancement of mass-transport by solution injection in the latter half of the active state resulted in acceleration of passivation of the Fe–6Cr surface. The passivity-current density of the surface passivated by intentional convection was reduced to almost half of the current density of the surface that had been in the passive state in a stagnant solution, and the surface passivated by intentional convection showed better resistance against pitting in a chloride-containing solution. The improvement of passivity of the surface was attributed to the formation of a Cr-enriched passive film by a decrease in the thickness of the diffusion layer in the latter half of the active state.