MICROELECTRODES FOR STUDIES OF LOCALIZED CORROSION PROCESSES

Electrochemical techniques using microcapillaries as electrochemical c ells allow the study of local processes on passive metal surfaces. Due to the enhanced current resolution down to pA and fA, processes in th e micro- and nanometer range can be studied. The results obtained on h igh-molybdenum containing stainless steel indicate that pit initiation is caused by active MnS inclusions. Molybdenum as alloying element ha s only a minor effect on the initiation process. The superior corrosio n resistance of the high-molybdenum containing alloy has to be attribu ted to a considerably improved repassivation tendency. Noise measureme nts revealed that the current noise is largely caused by the dissoluti on of small inclusions. Furthermore microelectrochemical noise measure ments allow evaluation of the experimental data with respect to their statistical relevance. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.