Contact Area Dependence of the Dissolution of Ferrous Ions from Pure Iron Wires into Freeze-Concentrated Solutions Revealed by a Combination of Microscopy and Image Processing

Abstract

Abstract Despite extensive studies on the mechanical deterioration of steel materials under polar/cryogenic conditions, the chemical corrosion therein has been generally overlooked. This is because conventional analytical and electrochemical tools have limited accessibility to microscopic transitions in frozen media for in situ measurements. In this study, we employed image-processing-based microscopy to investigate the effect of the contact area of freeze-concentrated solutions (FCSs) with iron wires. We observed three dissolution behaviors of ferrous ions depending on the contact area of the FCS with the iron surface, indicating that the diffusion process in an FCS is critical to the corrosion process. A general understanding of corrosion processes under cryogenic conditions may accelerate the elucidation of the mechanisms by which unique chemical reactions occur in systems wherein the diffusion of competitive molecules is limited.