Investigation of the effects of the magnetic field on the anodic dissolution of alloy 690 in SO42− + SCN− solution using digital holography

Abstract

Digital holography has been employed for in situ observation of dynamic processes occurring at the electrode|electrolyte interface during the anodic dissolution of Alloy 690 in solutions containing SO42− + SCN− with or without magnetic field (MF). It was found that MF increased the anodic current of Alloy 690 in 0.5 M Na2SO4 + 5 mM KSCN solution but showed a decreased value when evaluated in 0.5 M H2SO4 + 5 mM KSCN solution. For each solution, as a result of the stirring effect due to Lorentz force, MF showed a decreased localized damage further preventing pitting corrosion. The content of nickel and iron at grain boundaries is higher than that on the grain body, in accordance with the Cr-depletion theory. MF increased the anodic dissolution of nickel and iron, which in turn increased the anodic dissolution at grain boundaries. In situ inline digital holography revealed that IGC begins at one grain boundary and progresses to adjacent grain boundaries with or without MF.

Keywords

• Alloy 690
• Magnetic field
• Digital holography
• Anodic dissolution
• SO42− + SCN−