Pitting corrosion, stainless steels current fluctuations

Balkwill, R, Stewart, J., Westcott, C. et al. (1989) Noise signals from corrosion processes -current fluctuations associated with the early stages of pitting and stress-corrosion cracking of stainless-steel, in Instationary Processes and Dynamic Experimental Methods in Catalysis, Electrochemistry and Corrosion, DechemaMonographs, vol. 120 (eds G. Sandstede, G. Kreysa), VCH, Weinheim, pp. 229-238. 

SECM was also used to initiate pitting on steel and aluminum and to examine the pit growth and corrosion products (112a, 112b). In these studies, the UME tip was used to generate aggressive Cl ions in close proximity to stainless steel and aluminum surfaces. The tip and substrate current were then monitored to detect corrosion events. Fluctuations in the tip and substrate current were observed, which were indicative of the breakdown of the passive film and pit initiation on the metal. SECM and CV measuranents provided evidence that the large tip current fluctuations observed were caused by the reduction of Fe, which was released from the iron surface in the breakdown of the passive film of iron. 

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