TY - CONF A1 - Aristia, Gabriela A1 - Bäßler, Ralph T1 - A Coating System for Corrosion Protection of Carbon Steel as an Alternative for High Alloyed Materials N2 - Corrosive geothermal brines are a major challenge to geothermal power-plants. For cost reasons, plant designers favorize low alloyed steels, e.g., carbon steel, which are susceptible to uniform and localized corrosion when exposed to geothermal brines having acidic and saline properties. To solve such problem, coatings or inhibitors would be a protective solution as an alternative to the use of high alloyed materials. This study investigated a coating system consisting of polyaniline/silicon dioxide basing on locally available resources. Protection against corrosion of carbon steel is shown by long-term exposure and electrochemical tests of coated carbon steels, performed in an artificial acidic and saline geothermal brine, comparable to real conditions at a site in Indonesia. Therefore, an integrated coating system is presented for corrosion protection, combining the electro-chemical functionality of polyaniline and the physical advantages of silica. T2 - European Geothermal Congress CY - Berlin, Germany DA - 17.10.22 KW - Corrosion KW - Geothermal KW - Coatings KW - Polyaniniline KW - Silicate PY - 2022 SP - 1 EP - 7 CY - Berlin AN - OPUS4-56085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph A1 - Stoljarova, A. A1 - Regenspurg, S. T1 - Influence of Precipitating Brine Components on Materials Selection for Geothermal Applications N2 - Since geothermal wells are a feasible energy source to replace fossil fuel supply, many technologies have been developed to take advantage of geothermal energy. Nevertheless, service conditions in geothermal facilities are in many cases extreme in terms of corrosion due to the chemical composition of hydrothermal fluids and temperatures. Therefore, materials selection based on preliminary material qualification is essential to guarantee a secure and reliable operation of the facilities. During operation of a geothermal research facility in Groß Schönebeck copper and lead effects have been found downhole. Occurring mechanisms and measures to prevent precipitation or scaling needed to be investigated as well as potential influences of such precipitates on corrosion resistance of metallic materials used for equipment. This contribution deals with the evaluation of the corrosion behavior of carbon steel and corrosion resistant alloys in copper and/or lead containing artificial geothermal water, simulating the conditions in the Northern German Basin. The behavior of these materials in an artificial geothermal water obtained by electrochemical measurements and exposure tests are presented. While carbon steel exhibits precipitation and deposition, higher alloyed material shows different response to such species and a higher resistance in saline geothermal water. Basing on these results the suitability of the investigated corrosion resistant alloy is given for use in such conditions, whereas carbon steel creates difficulties due to its susceptibility to Cu- and Pb-precipitation. T2 - World Geothermal Congress CY - Online meeting DA - 30.03.2021 KW - Copper KW - Lead KW - Corrosion KW - Steel KW - Geothermal energy PY - 2021 SP - 1 EP - 11 AN - OPUS4-52828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosemann, Paul A1 - Müller, C. A1 - Kauss, N. A1 - Halle, T. T1 - Einfluss der Wärmebehandlung auf Mikrostruktur und Korrosionsverhalten kohlenstoffhaltiger nichtrostender Stähle N2 - Das Korrosionsverhalten von kohlenstoffhaltigen martensitischen nichtrostenden Stählen variiert in Abhängigkeit der Wärmebehandlung (WB) und der damit eingestellten Mikrostruktur deutlich stärker als bei kohlenstoffarmen ferritischen und austenitischen nichtrostenden Stählen. Bei erhöhtem Kohlenstoffgehalt bestimmt die diffusionsgesteuerte Bildung und Auflösung von Chromkarbiden die Verteilung von Chrom und Kohlenstoff im Gefüge. Bisher lag der Fokus von Forschungsarbeiten zum Einfluss der WB auf dem Anlassen im allgemein bekannten Sensibilisierungsbereich dieser Werkstoffgruppe zwischen 200 °C und 700 °C und der dort auftretenden Chromverarmung. Mit der gezielten WB des X46Cr13 (1.4034) wird gezeigt, dass Temperatur und Dauer beim Austenitisieren sowie die anschließende Abkühlung beim Härten das Korrosionsverhalten schon vor dem Anlassen signifikant beeinflussen. Auf der Basis von thermodynamischen Berechnungen wurden definierte WB ausgewählt, um gezielt unterschiedliche Volumengehalte von Chromkarbiden im Gefüge und somit auch unterschiedliche Chrom bzw. Kohlenstoffgehalte im Mischkristall zu erzeugen. Anschließend wurden die resultierenden Gefügezustände hinsichtlich Chromkarbidanteil und Härte verglichen und das Korrosionsverhalten mit der elektrochemisch potentiodynamischen Reaktivierung (EPR) sowie durch einen Schnelltest mit der KorroPad-Prüfung untersucht. Dabei konnte ein direkter Zusammenhang zwischen WB, Mikrostrukturänderungen und Korrosionsverhalten festgestellt werden. Mit steigender Austenitisierungstemperatur wird der Anteil an Chromkarbiden reduziert und der Kohlenstoff- und Chromgehalt der Matrix erhöht, bis eine vollständige Auflösung der Chromkarbide gegeben und die chemische Nennzusammensetzung der Legierung im Mischkristall erreicht ist. In der direkten Folge wird die Ausbildung der für nichtrostende Stähle charakteristischen Passivschicht erleichtert und das Lochkorrosionsverhalten verbessert. Die Abkühlrate hat neben den Austenitisierungsparametern ebenfalls einen großen Einfluss auf das Korrosionsverhalten. So führt eine langsame Abkühlung an Luft zu einer Chromverarmung im Gefüge, die eine deutlich erhöhte Lochkorrosionsanfälligkeit zur Folge hat. In Abhängigkeit der WB von kohlenstoffhaltigen nichtrostenden Stählen können Mikrostruktur, Härte und Korrosionsbeständigkeit in einem weiten Bereich variieren. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - Nichtrostender Stahl KW - Wärmebehandlung KW - EPR KW - KorroPad KW - Korrosionsbeständigkeit KW - ThermoCalc KW - Sensibilisierung KW - Martensitischer nichtrostender Stahl KW - Passivschicht PY - 2018 SN - 978-3-00-058901-0 SN - 1439-1597 VL - 72 SP - 711 EP - 720 PB - Eigenverlag CY - Chemnitz AN - OPUS4-44559 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heyn, A. A1 - Müller, Thoralf A1 - Balzer, M. A1 - Fenker, M. A1 - Kappl, H. T1 - Corrosion protection mechanisms of TiMgN hard coatings on steel N2 - . Hard coated steel components are used in a wide application range, mostly for protective, wear resistant and decorative purposes. Despite of these coatings being regarded as relatively dense, there is always a high risk of localized corrosion when a coated low alloyed steel component encounters a surrounding high humidity atmosphere or even an aqueous medium. An approach to enhance the corrosion properties is the addition of magnesium to physical vapor deposited hard coatings, like TiN. It has been found that there is a remarkable increase in corrosion resistance in dependence of magnesium content of the TiMgN coating and its surface properties. In this work the authors will explain the underlying corrosion protection mechanisms by means of electrochemical and analytical studies. The positive impact of magnesium in the coating relates on its preferred dissolution vs. steel. This causes the potential to shift to more negative direction with respect to the steel substrate and additionally leads to a temporarily passivation of the steel due to alkalization of the surrounding electrolyte by formation of magnesium hydroxide. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - Corrosion KW - Titanium nitride KW - PVD hard coating KW - Magnesium PY - 2018 SN - 978-3-00-058901-0 SN - 1439-1597 VL - 72 SP - 74 EP - 83 PB - Eigenverlag CY - Chemnitz AN - OPUS4-44526 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rosemann, Paul A1 - Kauss, N. T1 - Visualisierung werkstoffbedingter Lochkorrosionsanfälligkeit durch die KorroPad-Prüfung N2 - Mit der KorroPad-Prüfung können lochkorrosionsanfällige Oberflächenbereiche einfach, schnell und kostengünstig nachgewiesen werden. Das KorroPad ist damit für Hersteller, Verarbeiter, Anwender und Forscher eine interessante Alternative zu zeitintensiven Auslagerungsversuchen und elektrochemischen Untersuchungsmethoden, die normalerweise bei der Charakterisierung nichtrostender Stähle zur Anwendung kommen. Mit der KorroPad-Prüfung können auch werkstoff- und gefügebedingte Einflussfaktoren sichtbar gemacht werden, die Lochkorrosionsanfälligkeit verursachen. Um dies zu veranschaulichen, wird die Nachweisgrenze des KorroPads an Referenzlegierungen mit abgestuftem Chromgehalt aufgezeigt. Darauf aufbauend wird dargestellt, wie die Sensibilisierung nichtrostender Stähle durch Chromverarmung mit einer gezielten Verschärfung der KorroPad-Prüfung nachgewiesen werden kann. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - KorroPad KW - Korrosion KW - Nichtrostender Stahl KW - Lochkorrosion KW - Korrosionsbeständigkeit KW - Korrosionsschutz KW - Passivschicht PY - 2018 SN - 978-3-00-058901-0 SN - 1439-1597 VL - 72 SP - 67 EP - 73 PB - Eigenverlag CY - Chemnitz AN - OPUS4-44557 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kauss, N. A1 - Rosemann, Paul T1 - Age-hardening behaviour, microstructure and corrosion resistance of the copper alloyed stainless steel 1.4542 N2 - The copper alloyed stainless steel 1.4542 (X5CrNiCuNb16-4) is used in different areas due to its good mechanical properties and corrosion resistance. Strength and corrosion resistance can be adjusted by the heat treatment, which is of importance for the application of this alloy. The mechanical properties (strength and hardness) are attributed to the dispersive precipitation of the copper rich ε–Phase. The additional precipitation of chromi-um carbides can reduce the corrosion resistance. Different ageing states were produced to investigate the precipitation behaviour with various methods. Furthermore, the influence of cold-rolling on the precipitation behaviour was studied in comparison to a solution annealed state without deformation. The microstructure was studied by SEM and the variations of hardness and magnetic proportion were characterised. The electrochemical potentiodynamic reactivation (EPR) was used to determine the corrosion resistance and detect chromium depletion in all heat-treated states. The results show that a work hard-ening accelerates the precipitation rate, while ageing at 600 °C reduces the corrosion resistance due to chromium depletion. T2 - 20. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 14.03.2018 KW - Corrosion KW - Corrosion resistance KW - Corrosion testing KW - EPR KW - Heat treatment KW - Stainless steel PY - 2018 SN - 978-3-00-058901-0 SN - 1439-1597 VL - 72 SP - 277 EP - 284 PB - Eigenverlag CY - Chemnitz AN - OPUS4-44558 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Babutzka, Martin A1 - Burkert, Andreas A1 - Heyn, A. T1 - Corrosion investigations on zinc coatings by using gel-type electrolytes N2 - A new approach to the assessment of the corrosion behaviour of zinc coatings under atmospheric conditions can be achieved using gel-type electrolytes as an alternative to standard aqueous test electrolytes. Gel-type electrolytes allow minimally invasive corrosion investigations on zinc coatings. They also provide the possibility to carry out corrosion investigations onsite. By using gel-type electrolytes corrosion-relevant characteristic values such as corrosion currents and polarization resistances can be determined. These allow to describe the formation and the stability of the formed corrosion product layers under various climatic conditions. With this knowledge, a prediction of the zinc coating life cycle is possible. In this contribution, the value of gel-type electrolytes for corrosion research on zinc coatings is presented. T2 - Intergalva 2018 CY - Berlin, Germany DA - 17.06.2018 KW - Deckschichtbildung KW - Layer formation KW - Gelartige Elektrolyte KW - Gel-type electrolytes KW - Korrosionsprüfung KW - Corrosion testing KW - Zinkdeckschichten KW - Zinc coatings PY - 2018 SP - 385 EP - 392 AN - OPUS4-45245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dieck, S. A1 - Ecke, M. A1 - Rosemann, Paul A1 - Halle, T. T1 - Reversed austenite for enhancing ductility of martensitic stainless steel N2 - Quenching and partitioning (Q&P) heat Treatment increases the deformability of high-strength martensitic steels. Therefore, it is necessary to have some metastable austenite in the microstructure, which transforms in martensite during plastic deformation (TRIP effect). The austenitic-martensitic microstructure is gained by an increased austenitization temperature, water quenching and additional partitioning. The partitioning enables local carbon diffusion, which stabilizes retained austenite and leads to partial reversion of martensite to austenite. The influence of partitioning time was studied for the martensitic stainless steel AISI 420 (X46Cr13, 1.4034). In line with these efforts, metallographic, XRD and EBSD measurements were performed to characterize the microstructural evolution. The mechanical properties were tested using tension and compression loading. Additional corrosion investigations showed the benefits of Q&P heat treatment compared to conventional tempering. The reversion of austenite by the partitioning treatment was verified with EBSD and XRD. Furthermore, the results of the mechanical and corrosion testing showed improved properties due to the Q&P heat treatment. T2 - International Conference on Martensitic Transformations CY - Chicago, IL, USA DA - 09.07.2017 KW - Heat treatment KW - High ductility KW - Martensitic stainless steels KW - Quenching and partitioning KW - Transformation induced plasticity KW - KorroPad KW - EBSD KW - Mechanical testing PY - 2018 SN - 978-3-319-76968-4 U6 - https://doi.org/10.1007/978-3-319-76968-4_19 SP - 123 EP - 128 PB - Springer AN - OPUS4-44689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lee, Jun-Seob A1 - Radnik, Jörg A1 - Bäßler, Ralph T1 - Electrochemical behavior of UNS N08031 in Green-Death-solution N2 - The electrochemical behavior of UNS(1) N08031 was investigated as a function of electrode potential in Green-Death(2) solution at 40 °C. The UNS N08031 surface is in a stable passive state during cyclic potentiodynamic polarization without an initiation and/or propagation of localized corrosion. In potentiostatic polarization of UNS N08031 for 3600 s, passive current density increases with an increase in the passivation potential from 0.7 to 1.0 VSSE (silver/silver chloride reference electrode in saturated potassium chloride) Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis showed that a more defective n-type semiconductive passive film forms as the potential increases. X-ray photoelectron spectroscopy (XPS) revealed that passive film consists of mainly chromium and minor iron and nickel oxides. The mechanism of the defective passive film formation is discussed. The increase of the applied potential is considered to be a reason for the change in passive film stability. T2 - NACE International Annual Corrosion Conference CY - Phoenix, AZ, USA DA - 15.04.2018 KW - Steel KW - Passive film KW - X-ray photoelectron spectroscopy PY - 2018 SP - 10631, 1 EP - 9 PB - Omnipress CY - Houston AN - OPUS4-44915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Aristia, Gabriela A1 - Bäßler, Ralph A1 - Roth, C. T1 - Polyaniline/silicon dioxide containing coating for use in artificial geothermal brines N2 - Geothermal brine is a complex system containing a wide variety of dissolved salts resulting from the condition s in a geothermal well. These fluids lead to corrosion in pipes and other parts of geothermal system construction and necessitate intense research efforts in finding new suitable materials. Carbon steel is susceptible to corrosion in geothermal brine especially when it is exposed to a high temperature and high-pressure medium, which is considered to be an aggressive environment. An artificial geothermal water, bas ed on a brine composition found in Indonesia, was used to investigate the performance of high alloyed materials. The electrolyte has pH 4 and contains 1,500 mg/l Cl-, 20 mg/l SO4 2-, 15 mg/l HCO3 -, 200 mg/l Ca 2+, 250 mg/l K+, and 600 mg/l Na+. In order to protect the bare material in geothermal application, it is necessary to either use high alloyed material s or coatings. In this research, a coating system consisting of polyaniline and silicon dioxide was investigated regarding its behavior to protect carbon steel. In detail, the effect of SiO2 and polyaniline (PANi) addition was evaluated by exposure and electrochemical tests for 7 days, i.e. electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP ) at room temperature and 150 °C with 1 MPa pressure . T2 - NACE International Annual Corrosion Conference CY - Phoenix, AZ, USA DA - 15.04.2018 KW - Geothermal KW - Coating KW - SiO 2 KW - Polyaniline KW - Corrosion PY - 2018 SP - 10708, 1 EP - 14 PB - Omnipress CY - Houston AN - OPUS4-44916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -