TY - CONF A1 - Dimper, Matthias A1 - Hampel, Marco A1 - Schenderlein, Matthias A1 - Özcan Sandikcioglu, Özlem T1 - Multielectrode array probes for early detection of corrosion processes N2 - Sensors for the detection of general corrosion are well established. However, the detection of early phases of localized corrosion still remains a challenging task since the initiation steps can proceed without showing significant contribution to the electrochemical signal of a macroscopic surface. Along with electrochemical noise based methods, utilization of multielectrode arrays can be used to address this problem. The aim of this study is to develop and test multielectrode arrays for early detection of corrosion processes. By means of a multielectrode analyser the current flow, potential and impedance spectra on each single electrode can be measured as a function of time. Thus, maps of the probe can be generated with real time information for instance showing individual electrodes persistent anodic or cathodic signals. This approach has been utilized in combination with scanning electrochemical techniques such as scanning electrochemical microscope or scanning vibrating electrode to select active electrodes for detailed investigation. As the sensitivity is strongly dependent on the wire diameter and array configuration, a systematical investigation has been performed to optimize the preparation procedures and probe geometry. Stainless steel X5CrNi18-10 (1.4301) wires of different diameters have been embedded in a carrier material made of epoxy resin providing electrical insulation. The multielectrode probes consisting of at least 3 x 3 and a maximum of 10 x 10 single electrodes have been tested in corrosive media, with different chloride concentrations, as well as in the presence of metal reducing bacteria to assess their applicability in the detection of the onset of corrosion. This contribution will summarize our optimization study and the evaluation of the sensor performance. T2 - EUROCORR 2017 & 20thICC CY - Praha, Czech Republic DA - 04.09.2017 KW - Corrosion KW - Multielectrode array sensors KW - Stainless steel KW - Corrosion monitoring PY - 2017 AN - OPUS4-43420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dimper, Matthias A1 - Hampel, Marco A1 - Schenderlein, Matthias A1 - Özcan Sandikcioglu, Özlem T1 - Multielectrode array probes for early detection of corrosion processes N2 - Multielectrodes are arrays of single electrodes arranged in a particular geometry. In our work, all the single electrodes are identical stainless steel X5CrNi18-10 (1.4301) wire electrodes. Using a multielectrode analyser all single electrodes are connected via zero resistance ammeters, simulating a galvanically coupled single electrode surface. The advantage of the multielectrode analyser (MMA) is that the currents flowing between single electrodes can be measured. Thus, real-time maps can be generated indicating where anodic and cathodic areas lie on the surface of the multielectrode and how they behave. The combination of the multielectrode analyser with the scanning electrochemical microscopy (SECM) enables the identification of corrosion sites and the detailed electrochemical analysis. T2 - DECHEMA/GfKORR-Fachgruppe "Mikrobielle Materialzerstörung und Materialschutz" CY - Berlin, Germany DA - 04.10.2017 KW - Scanning electrochemical microscope (SECM) KW - Multielectrode array sensors KW - Corrosion PY - 2017 AN - OPUS4-43461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hampel, Marco A1 - Özcan Sandikcioglu, Özlem T1 - Application of localized electrochemical methods to the analysis of microbiologically influenced corrosion N2 - The corrosion of stainless steel components is a problem of global scale, economically as well as in regards to the safety of industrial equipment and facilities. With microorganisms involved (microbial influenced corrosion, MIC), the problem becomes more complex. Iron reducing bacteria (IRB) for example accelerate the corrosion of iron based materials like stainless steel via the reduction of iron oxides in the passive layer. When co-cultivated with iron oxidizing bacteria, IRBs can induce deep, heterogeneously distributed pits on stainless steel surfaces. The analysis of localized corrosion – or pitting corrosion – is of great relevance since it can lead to unpredictable material failure. In general, macroscopic electrochemical methods are not capable of providing information about the spatial heterogeneity of a sample and thus need to be complemented by multi-electrode based techniques or scanning electrochemical methods. The aim of this work is to develop methods for the analysis of localized corrosion, on stainless steel surfaces induced by IRB biofilms. The greatest challenge is to address the complexity of two heterogeneous systems at the metal/biofilm interface. First there is the variation in the passive layer composition and microstructure. Secondly, the microbial biofilm with its heterogeneous tree-dimensional structure resulting in local differential aeration cells and electrochemical parameters. To be able to differentiate between individual effects, artificial biofilms mimicking the physical properties of a natural biofilm are used in this study as model systems. This artificial biofilm is applied on a multi-electrode probe to identify local anodic sites during exposure experiments. The detailed analysis of active sites by means of scanning electrochemical microscopy (SECM) allows the investigation of local properties within the biofilm and its immediate vicinity. The presented analytical approach delivers promising results in clarifying how localized corrosion of stainless steels develops chronologically and spatially in the presence of IRBs. Furthermore, our results on model systems provide the basis for the application of the methodology for the investigation of natural or multi-species biofilms in the future. T2 - Electrochemistry 2016 CY - Goslar, Germany DA - 26.09.2016 KW - MIC KW - Microbiologically influenced corrosion KW - Scanning electrochemical microscope KW - Multielectrode assemblies PY - 2016 AN - OPUS4-38198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hampel, Marco A1 - Dimper, Matthias A1 - Schenderlein, Matthias A1 - Özcan Sandikcioglu, Özlem 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 AN - OPUS4-43406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hampel, Marco A1 - Dimper, Matthias A1 - Schenderlein, Matthias A1 - Özcan Sandikcioglu, Özlem T1 - A new approach for high-resolution analysis of early-stage corrosion processes N2 - The poster presentation summarizes the recent developments on the combination of scanning electrochemical microscopy with multielectrode arrays for the investigation of local corrosion processes. T2 - GfKORR Jahrestagung 2017 CY - Frankfurt am Main, Germany DA - 07.11.2017 KW - Scanning electrochemical microscope (SECM) KW - Multielectrode array sensors KW - Corrosion PY - 2017 AN - OPUS4-43459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hampel, Marco A1 - Schenderlein, Matthias A1 - Schary, Christian A1 - Dimper, Matthias A1 - Özcan Sandikcioglu, Özlem T1 - Efficient detection of localized corrosion processes on stainless steel by means of scanning electrochemical microscopy (SECM) using a multi-electrode approach N2 - High resolution analysis of corrosion processes on stainless steels is a challenging task. The application of local electrochemical techniques such as scanning electrochemical microscopy (SECM) has opened new possibilities for the detection of corrosion products and activity on metallic surfaces. However, due to its stochastic nature, the analysis of pitting corrosion requires being at the right place at the right time. Scanning over large areas at a high resolution not only leads to long scan durations but also leaves many short-lived processes undetected. In this paper we present the combined automated operation of SECM and wire multi-electrodes connected to a multi-electrode analyzer (MMA). The inter-electrode currents between 25 wire electrodes connected via zero resistance ammeters (ZRA) are measured by the MMA at open circuit potential (OCP) and the electrodes reporting anodic currents are detected automatically to be analyzed by means of SECM. The results demonstrate the successful application of this methodology for the detection of unstable and stable pitting processes on 304 stainless steel in a corrosive aqueous environment. KW - Scanning electrochemical microscope (SECM) KW - Localised corrosion KW - Corrosion monitoring PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-478646 VL - 101 SP - 52 EP - 55 PB - Elsevier B.V. AN - OPUS4-47864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -