| Stainless steels are designed to be corrosion-resistant. Nevertheless they can undergo localized pitting corrosion, which may rapidly lead to their failure. Catastrophic events could be the consequences. To study the initial steps of metastable pit formation in situ and in real time we adapted our ellipso-microscope for surface imaging (EMSI) and a high resolution, contrast-enhanced optical microscope to the electrolyte - stainless steel interface. Utilizing these methods we have been able to explain the sudden corrosion onset by an explosive autocatalytic growth in the number of metastable pits [1]. Recently by applying those different imaging methods simultaneously the correlation between oxide film weakening and the nucleation of individual pits was examined. The existence of front propagation as a component of the transition to pitting corrosion shows that characteristics of this process are consistent with the behavior of stochastic reaction-diffusion systems [2]. Several videos will elucidate our in situ real-time observations of the interplay between initial pits, oxide film weakening, and the spreading of pitting corrosion across the surface of stainless steel in an electrolytic solution. -- [1] C. Punckt et al., Science 305, 1133-1136 (2004) [2] M. Dornhege et al., J. Electrochem. Society 154, C24-C27 (2007) |
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