TY - GEN A1 - Hampel, Marco T1 - Combination of SECM with a multi-electrode analyzer for resolving local processes during microbiologically influenced corrosion N2 - Electrochemically active bacteria such as iron oxidizing bacteria (IOB) or iron reducing bacteria (IRB) accelerate the corrosion of stainless steel via the oxidation and reduction of iron oxides in the passive layer. The exposure to medium containing IOB and IRB leads to pitting corrosion with deep pits on stainless steel surfaces. Improving corrosion control via a better understanding of localized corrosion processes is highly relevant especially for reasons of safety or environmental protection since advancing pitting corrosion can easily lead to unpredictable material failure. Classic electrochemical methods however, provide insufficient information about the spatial heterogeneity of a corroding sample and fall short in detecting localized corrosion. The aim of this work is to develop methods for the analysis of localized corrosion, on stainless steel surfaces induced by IRB and IOB biofilms. It is quite challenging to address the complexity of the variations in the passive layer composition and microstructure as well as the biofilm’s complexity with its local differential aeration cells and electrochemical parameters both at the same time. Thus in this study, agarose artificial biofilms mimicking the physical properties of a natural biofilm have been used as model systems to be able to differentiate between individual effects. This artificial biofilm is applied on a multi-electrode stainless steel sample to identify local anodic sites during exposure experiments. For more detailed analysis of active sites, a scanning electrochemical microscopy (SECM) has been applied. Using the SECM as an amperometric sensor, we have investigated concentration gradients of iron ions or oxygen within the biofilm and its immediate vicinity on actively corroding electrodes. The presented analytical approach delivers promising results in clarifying how localized corrosion of stainless steels develops chronologically and spatially in the presence of IRBs and IOBs. Our results on model systems do also provide the basis for the investigation of natural biofilms in the future. T2 - EUROCORR 2017 & 20thICC CY - Prague, Czech Republic DA - 04.09.2017 KW - Scanning electrochemical microscope (SECM) KW - Stainless steel KW - Microbiologically influenced corrosion (MIC) KW - Local electrochemistry KW - Corrosion PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/43406 AN - OPUS4-43406 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany