TY - CONF A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Kranzmann, Axel A1 - Schorr, S. T1 - Performance of Protection Coatings during Oxyfuel Combustion Condition T2 - DMG-Sektionstreffen "Angewandte Mineralogie in Technik und Umwelt" (AMITU) und "Physik, Chemie und Kristallographie der Minerale" (PCKM) CY - Bad Münster, Germany DA - 2011-02-23 PY - 2011 AN - OPUS4-25592 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Kranzmann, Axel A1 - Schorr, S. T1 - Alumina Coating on X20CrMoV12-1 against Oxidation and Carburization T2 - DMG-Sektionstreffen "Angewandte Mineralogie in Technik und Umwelt" (AMITU) und "Physik, Chemie und Kristallographie der Minerale" (PCKM) CY - Wolfersdorf, Germany DA - 2012-02-22 PY - 2012 AN - OPUS4-25593 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Kranzmann, Axel A1 - Dörfel, Ilona T1 - Alumina Coatings for Protection of X20CrMoV12-1 T2 - Eurocorr 2011 CY - Stockholm, Sweden DA - 2011-09-04 PY - 2011 AN - OPUS4-24410 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Alumina Coatings under Oxyfuel Condition T2 - The 4th WMRIF (World Materials Research Institutes Forum) CY - Shenyang, China DA - 2011-05-22 PY - 2011 AN - OPUS4-24411 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Saliwan Neumann, Romeo A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Preparation of alumina layers on commercial power plant steels T2 - 2nd Oxyfuel Combustion Conference CY - Yeppoon, Australia DA - 2011-09-12 PY - 2011 AN - OPUS4-24412 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Dörfel, Ilona A1 - Dressler, M. A1 - Feigl, M. A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Overview of protective action of sol-gel alumina coatings on Ni-base alloys and steels in steam-containing atmospheres T2 - Particoat Workshop CY - Costa Teguise, Spain DA - 2012-10-15 PY - 2012 AN - OPUS4-27422 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Nofz, Marianne A1 - Kranzmann, Axel A1 - Schorr, S. T1 - Sol-Gel Alumina Coatings for Power Plant Applications T2 - CMCEE 2012 CY - Dresden, Germany DA - 2012-05-22 PY - 2012 AN - OPUS4-27424 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Feigl, Michael A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Kranzmann, Axel T1 - Corrosion of uncoated and alumina coated steel X20CrMoV12-1 in H2O-CO2-O2 and air at 600 °C N2 - Future coal power plants will in case of oxyfuel combustion be operated with altered atmospheres. Hence, corrosion attack might become more severe and steels have to be protected. An alumina-sol was used to coat X20CrMoV12-1 (X20) with alumina to test the protection. Testing was performed at 600 °C in flowing H2O–CO2–O2 and static laboratory air for 1000 h. Oxidation under air is minor compared to exposure in oxyfuel atmosphere. In both cases a multilayered oxide (hematite, magnetite, spinel) was formed on uncoated steels. Carburization appeared on uncoated X20 in H2O–CO2–O2. The coating demonstrates a high protection. KW - A. Steel KW - B. SEM KW - B. STEM KW - C. Carburization KW - C. High temperature corrosion KW - C. Oxide coatings PY - 2013 U6 - https://doi.org/10.1016/j.corsci.2012.10.031 SN - 0010-938X VL - 68 SP - 44 EP - 50 PB - Elsevier Ltd. CY - Orlando, Fla. AN - OPUS4-27636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kranzmann, Axel A1 - Hünert, Daniela A1 - Rooch, Heidemarie A1 - Urban, Ingrid A1 - Schulz, Wencke A1 - Österle, Werner T1 - Reactions at the interface between steel and oxide scale in wet CO2 containing atmospheres N2 - The resistance of structural steels against corrosion in CO2-H2O and CO2-H2O-O2 atmospheres at temperatures above 550°C was observed with high magnification methods. The test atmosphere is the basic composition of an oxyfuel coal combustion atmosphere. The analytical information base was applied to develop reaction schemes for the oxidation of steels. It was demonstrated that the formation of phases and the kinetics of oxidation reactions in this atmospheres is affected by the formation of intermediate iron hydroxide and a high carbon activity. In the temperature regime above 550°C the thermal equilibrium between H2O, CO2 and Fe reacted and formed CO. CO triggers the formation of FeO and carbides and increases the reaction kinetics. Porosity at the interface is established by gaseous phases such as Fe(OH)2 or H2O. H2 formation is not limited to the steel - oxide interface but can occur in the whole oxide scale. Examples of the experimental results were compared with a thermodynamic approach. The objective of the work was to derive qualitative rules of the basic corrosion reactions. T2 - NACE International corrosion conference 2009 CY - Atlanta, Georgia, USA DA - 2009-03-22 KW - High temperature corrosion KW - Corrosion gases KW - Mild steels KW - 9-12% Cr-steels KW - Hydrogen transport KW - Oxyfuel combustion PY - 2009 SP - 1 EP - 10 (Paper 09265) AN - OPUS4-22334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hünert, Daniela A1 - Schulz, Wencke A1 - Nitschke, Heike A1 - Saliwan Neumann, Romeo A1 - Oder, Gabriele A1 - Kranzmann, Axel T1 - Corrosion behaviour of ferritic and martensitic power plant steels under conditions of dual atmospheres N2 - The most efficient construction materials for boiler water walls and superheaters in steam power plants are ferritic and martensitic steels. In practical operation tubes are simultaneously exposed to combustion gas and air/steam on their opposite surfaces. The corrosion behaviour of ferritic-martensitic steels under such dual atmospheres is nondistinctive and has therefore been investigated in a special designed test equipment between 500 and 620°C. The power plant conditions were simulated wi th a flowing and pressurised (80 bar) combustion gas on the inner side of the tube which mainly consists of H2O and/or CO2. On the outer side, the tube material was exposed to air. It was discovered that under similar temperatures the oxides formed on the air side under dual atmosphere conditions were significantly different to the oxide scales formed when the alloy was exposed to air only. It is assumed that the anomalous corrosion behaviour during the dual atmosphere exposure is due to the hydrogen transport through the bulk alloy from the combustion gas side to the air side. T2 - NACE International corrosion conference 2009 CY - Atlanta, Georgia, USA DA - 2009-03-22 KW - High temperature corrosion KW - Dual atmosphere KW - Corrosive gases KW - Mild steels KW - 9-12% Cr-steels KW - Hydrogen transport PY - 2009 SP - 1 EP - 10 (Paper 09263) AN - OPUS4-22335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hünert, Daniela A1 - Schulz, Wencke A1 - Kranzmann, Axel T1 - Corrosion behavior of ferritic and martensitic power plant steels under conditions of dual atmospheres N2 - The most efficient construction materials for boiler water walls and superheaters in steam power plants are ferritic and martensitic steels. In practical operation, tubes are exposed simultaneously to combustion gas and air/steam on their opposite surfaces. The corrosion behavior of ferritic-martensitic steels under such dual atmospheres is nondistinctive and has been investigated in a specially designed test equipment between 500°C and 620°C. The power plant conditions were simulated with a flowing and pressurized (80 bar) combustion gas on the inner side of the tube, which contains water (H2O) and carbon dioxide (CO2). On the outer side, tube material was exposed to air. Oxides that formed on the air side under dual atmosphere conditions were significantly different from the oxide scales formed when the alloy was exposed to air only. It is assumed that the anomalous corrosion behavior during the dual atmosphere exposure is due to hydrogen and carbon diffusion through the bulk alloy from the combustion gas side to the air side. Both species are produced when the material reacts with the gas phase. Because of its high diffusivity, hydrogen is thought to affect the corrosion process on the air side from the beginning of the corrosion exposure, whereas carbon reaches the opposite side after a considerably longer time period. KW - Chromium steels KW - Corrosive gases KW - Dual atmosphere KW - High-temperature corrosion KW - Hydrogen transport KW - Mild steel PY - 2010 SN - 0010-9312 SN - 1938-159X VL - 66 IS - 12 SP - 126001-1 - 126001-7 PB - National Association of Corrosion Engineers CY - Houston, Tex. AN - OPUS4-23217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Wencke A1 - Feigl, Michael A1 - Dörfel, Ilona A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Influence of a sol-gel alumina coating on oxidation of X20CrMoV12-1 in air up to 650 °C N2 - The need for a more efficient coal power plant generation (e.g. oxyfuel technology) results in modified process parameters and enhanced corrosion. To reach the necessary service life of high temperature parts protective coatings may be a sufficient technical solution. A modified Yoldas sol (Al2O3 based) was used to coat X20CrMoV12-1 by spin coating. After appropriate heat treatments transition alumina coatings being about 400 nm thick were obtained. Oxidation studies were carried out in laboratory air at temperatures up to 650 °C for up to 500 h exposure time. In case of the uncoated sample a rough oxide layer formed on the surface and a remarkable weight gain (2.62 mg/cm²) were detected. The sol–gel alumina layer (mainly δ-Al2O3) demonstrated a high protection, i.e. a very low weight gain (0.05 mg/cm²). Diffusion of alloying elements into the coating was observed. No indication of spallation of the coating occurred. Local defects (2 µm–30 µm) in the coating led to the formation of iron-oxide islands. KW - X20CrMoV12-1 KW - Sol-gel deposition KW - Alumina KW - Air oxidation KW - Transmission electron microscopy KW - Chromium KW - Diffusion KW - Manganese PY - 2013 U6 - https://doi.org/10.1016/j.tsf.2013.04.132 SN - 0040-6090 VL - 539 SP - 29 EP - 34 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-29162 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hünert, Daniela A1 - Schulz, Wencke A1 - Kranzmann, Axel ED - Roland Span, ED - Ingo Weber, T1 - Corrosion of steels in H2O-CO2 atmospheres at temperatures between 500°C and 700°C N2 - The introduction of carbon capture technology into thermal power plants benefits from combustion of fuel and pure oxygen due to high partial pressures of CO2 in the flue gas. The consumption of energy for carbon capture devices and oxygen production plants has to be compensated by higher efficiencies of the power plant. Consequently IGCC plants with 80 bar reactors and high temperature turbine equipment, boilers with 700 °C steam raising units will be the next generation power plants. All plants have in common locally in the process gas compositions with high CO2 partial pressure and steam. In our test we applied a gas composition with 30% H2O and 70% CO2 an composition in between the water content of coal burned in pure oxygen and Methane-oxygen combustion. Additional gas fractions such as SO2 will be added in coming experiments. In this paper we discuss the attack of our model gas composition on different typical power plant construction steels with chromium contents in the range of 1 to 24%. The test conditions were annealing time up to 1000 h, 80 bar pressure, fast flowing gas and temperatures between 500 and 700°C depending on the maximum working temperature of the individual steel. Dependent on the test parameters and in particular the chromium content the oxide scale growth mechanism, the scale thickness, the scale microstructure and phase sequences differed. In particular we observe the growth of FeO at temperatures lower than 570°C which is the eutectic decomposition temperature in the Oxygen-iron phase diagram. Iron carbides are primarily formed in low alloyed steels near the oxide steel interface. The steels studied containing more then 9% chromium the growth of Fe3O4 and Fe-Cr-Spinel was typical. Co and W influenced the reaction in 9 - 12% Cr-steel. The attrition of Mn and other alloying additions was monitored. In no case a dense and protective Cr2O3 or an other Metal-Cr-oxide layer was observed. The oxide scale thickness increases strongly with temperature and decrease with raising chromium content. Data of oxide scale thickness up to corrosion time of 1000 h will be presented. A model will be presented, which deals with possible reactions paths during the corrosion processes in flowing CO2 and water. The steels can be arranged according the reaction with gas and their alloying elements such as Mn, Co and W. In the test environment the maximum working temperature of the steels decreased 50K compared to working temperature in current power plant environment. T2 - 15th International Conference on the Properties of Water and Steam (ICPWS XV), "Water, Steam, and Aqueous Solutions - Advances in Science and Technology for Power Generation" CY - Berlin, Germany DA - 2008-09-07 KW - High temperature corrosion KW - 9-12% Cr-steels KW - H2O-CO2 PY - 2008 SN - 978-3-931384-64-7 IS - Session 06: Electro-12 SP - 1 EP - 7 AN - OPUS4-19061 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hünert, Daniela A1 - Schulz, Wencke A1 - Kranzmann, Axel T1 - Simultaneous oxidation and carburization under oxyfuel conditions N2 - The combustion of coal in CO2-reduced Oxyfuel power plants requires creep resistant and corrosion resistant materials, which can withstand high temperatures up to 600°C and CO2 rich atmospheres. Among the heat resistant materials, the 9-12% chromium steels are proven to resist high wall temperatures in conventional power plants and are suitable as membrane wall, superheaters and steam piping. During Oxyfuel combustion a flue gas is generated, which consists mainly of H2O (30 mol %) and CO2 (70 mol %). The present paper is focused on the corrosion of 9-12% chromium steels under oxyfuel conditions in a temperature range between 550 and 625°C. Depending on Chromium content of the 9-12%chromium steels, carburization of the base material, perlite formation and carbide formation were observed. Alloys with lower chromium content form a non protective oxide scale with perlite at the scale-alloy interface. Steels with 12% chromium have a small growing oxide scale with enlarged M23C6-particles at the scale-alloy interface. The carburization of the base material is found to be increased for the 9% Cr-steel. Higher pressure of the flue gas results in the formation of less resistant scales and cause accelerated carburization of the base materials. However, the carburization has an impact on the mechanical properties at the surface and leads to an embrittlement, which is deleterious during thermal cycling. Oxidation kinetics, phase analysis of the scale (transmission electron microscope) and carburization depths (microprobe) of the base materials are presented. T2 - EUROCORR 2009 CY - Nice, France DA - 2009-09-06 KW - High-temperature corrosion KW - Carburization KW - 9-12 % Cr-steel KW - M23C6-particles KW - Power plant steels PY - 2010 IS - Paper 7805 SP - 1 EP - 11 AN - OPUS4-22500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Hünert, Daniela A1 - Kranzmann, Axel T1 - Material loss of superheater tubes in atmospheres containing high CO2 T2 - Dechema-Workshop CY - Frankfurt am Main, Germany DA - 2009-09-30 PY - 2009 AN - OPUS4-22677 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Performance on Protection Coatings during Oxyfuel Combustion Condition T2 - 3rd Oxyfuel Young Researchers Forum CY - Stuttgart, Germany DA - 2010-10-04 PY - 2010 AN - OPUS4-22659 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Hünert, Daniela A1 - Nitschke, Heike A1 - Saliwan Neumann, Romeo A1 - Kranzmann, Axel T1 - Comparision of the corrosion behaviour of 9-12 % Cr steels in H2O, H2O-CO2 and H2O-CO2-O2 T2 - NACE CORROSION 2009 CY - Atlanta, GA, USA DA - 2009-03-22 PY - 2009 AN - OPUS4-22674 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Hünert, Daniela A1 - Kranzmann, Axel T1 - Corrosion behaviour of 9-12% Cr steels under oxyfuel conditions T2 - Eurocorr 2009 CY - Nice, France DA - 2009-09-06 PY - 2009 AN - OPUS4-22675 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Feigl, Michael A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Piedra Gonzalez, Elsa Maria A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Alumina Coatings against Carburization and Oxidation under Oxyfuel Conditions T2 - Materials for Energy 2010 CY - Karlsruhe, Germany DA - 2010-07-05 PY - 2010 AN - OPUS4-24013 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Feigl, Michael A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Nofz, Marianne A1 - Kranzmann, Axel T1 - Alumina coatings against carburization and oxidation under oxyfuel conditions T2 - 1st International conference on materials for energy CY - Karlsruhe, Germany DA - 2010-07-04 PY - 2010 SN - 978-3-89746-117-8 SP - 1012 AN - OPUS4-24179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Hünert, Daniela A1 - Nitschke, Heike A1 - Saliwan Neumann, Romeo A1 - Kranzmann, Axel T1 - Comparison of the corrosion behaviour of 9-12 % Cr steels in H2O, H2O-CO2 and H2O-CO2-O2 T2 - NACE International corrosion conference 2009 CY - Atlanta, Georgia, USA DA - 2009-03-22 KW - 9-12%Cr-steels KW - Steam KW - CO2 KW - O2 KW - High-temperature corrosion KW - Evaporation of chromium PY - 2009 SP - 1 EP - 10 (Paper No. 09264) AN - OPUS4-19464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Kranzmann, Axel T1 - Aluminiumoxid als Schutzschicht für kommerzielle Kraftwerksstähle (Teil 1) N2 - In Kohlekraftwerken mit Oxyfuel-Technologie erfolgt die Verbrennung unter Zufuhr von reinem Sauerstoff. Damit steht für die Abscheidung und Speicherung von CO2 ein Rauchgas mit hohem CO2-Anteil zur Verfügung (CCS-Technologie). Aufgrund dieses Verbrennungsprozesses ändert sich im Wesentlichen die Rauchgaszusammensetzung hin zu hohem H2O- und SO2 -Anteil. Deshalb wurden in verschiedenen Laboratorien kommerzielle Kraftwerksstähle unter den entsprechenden korrosiven Bedingungen getestet. Im Vergleich zur herkömmlichen Verbrennungsmethode zeigten die ferritisch-martensitischen Stähle schon nach 1000 h Auslagerungszeit unter Oxyfuel-Bedingungen eine durch einen deutlich erhöhten Materialverlust gekennzeichnete Korrosion. Eine Möglichkeit um dennoch die Lebensdauer dieser Stähle zu gewährleisten, besteht im Aufbringen geeigneter Schutzschichten auf die Stahloberfläche. Die vorliegende Arbeit befasst sich mit der Herstellung und Bewertung von Sol-Gel-Aluminiumoxidschichten als Schutz vor Korrosion in Oxyfuel-Rauchgas-Atmosphäre. Diese wurden auf den warmfesten Stahl X20CrMoV12-1 (X20) mittels der Tauchmethode aufgebracht. Anschließend erfolgte eine Auslagerung der beschichteten Proben für 1000 h bei 600 °C in einer H2O-CO2-O2-SO2 -Atmosphäre. Im Vergleich zum unbeschichteten Stahl X20 war der Materialverlust des beschichteten Stahls deutlich geringer. Insbesondere konnte durch die Aluminiumoxidschicht der Transport von CO2 und SO2 zur Stahloberfläche verhindert werden. KW - Stahl KW - Korrosion KW - Aluminiumoxid KW - Sol-Gel PY - 2016 SN - 0016-4232 VL - 107 IS - 9 SP - 1900 EP - 1903 PB - Leuze Verlag CY - Bad Saulgau AN - OPUS4-38148 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Wencke A1 - Nofz, Marianne A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo A1 - Kranzmann, Axel ED - Leuze-Reichert, Sylvia T1 - Aluminiumoxid als Schutzschicht für kommerzielle Kraftwerksstähle (Teil 2) N2 - In Kohlekraftwerken mit Oxyfuel-Technologie erfolgt die Verbrennung unter Zufuhr von reinem Sauerstoff. Damit steht für die Abscheidung und Speicherung von CO2 ein Rauchgas mit hohem CO2-Anteil zur Verfügung (CCS-Technologie). Aufgrund dieses Verbrennungsprozesses ändert sich im Wesentlichen die Rauchgaszusammensetzung hin zu hohem H2O- und SO2 -Anteil. Deshalb wurden in verschiedenen Laboratorien kommerzielle Kraftwerksstähle unter den entsprechenden korrosiven Bedingungen getestet. Im Vergleich zur herkömmlichen Verbrennungsmethode zeigten die ferritisch-martensitischen Stähle schon nach 1000 h Auslagerungszeit unter Oxyfuel-Bedingungen eine durch einen deutlich erhöhten Materialverlust gekennzeichnete Korrosion. Eine Möglichkeit um dennoch die Lebensdauer dieser Stähle zu gewährleisten, besteht im Aufbringen geeigneter Schutzschichten auf die Stahloberfläche. Die vorliegende Arbeit befasst sich mit der Herstellung und Bewertung von Sol-Gel-Aluminiumoxidschichten als Schutz vor Korrosion in Oxyfuel-Rauchgas-Atmosphäre. Diese wurden auf den warmfesten Stahl X20CrMoV12-1 (X20) mittels der Tauchmethode aufgebracht. Anschließend erfolgte eine Auslagerung der beschichteten Proben für 1000 h bei 600 °C in einer H2O-CO2-O2-SO2 -Atmosphäre. Im Vergleich zum unbeschichteten Stahl X20 war der Materialverlust des beschichteten Stahls deutlich geringer. Insbesondere konnte durch die Aluminiumoxidschicht der Transport von CO2 und SO2 zur Stahloberfläche verhindert werden. KW - Stahl KW - Korrosion KW - Aluminiumoxid KW - Sol-Gel PY - 2016 SN - 0016-4232 VL - 107 IS - 10 SP - 2098 EP - 2102 PB - Leuze-Verlag CY - Bad Saulgau AN - OPUS4-38149 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Schulz, Wencke T1 - Abscheidung und Charakterisierung von Sol-Gel-Aluminiumoxidschichten auf kommerziellen Kraftwerksstählen zum Schutz gegen Korrosion bei Oxyfuel-Verbrennung N2 - The objective of the present work was the investigation and demonstration of the potential of sol-gel alumina layers as corrosion protection of commercial power plant steels under oxyfuel conditions. The starting points of this work were modified Yoldas-sols which were developed in the BAM-department 5.6. These sols were suitable for the spin-coating method only. The application of coatings on tubes by spin-coating is impossible. Therefore, the chemical composition of the modified Yoldas-sol had to be adapted to the dip- and spray-coating techniques. Exclusively the sol with the composition s-0.52-6-1.5 with a nitrate/aluminium ratio of 0.52; a solid content of 6 wt.% and a PVP (binder) content of 1.5 wt.% could fulfill the necessary criteria: long-term stability; formation of a dense, crack-free and well adhered layer on polished metal surfaces; as well as high protective abilities against corrosion in H2O-CO2-O2-SO2. The commercial power plant steel X20CrMoV12-1 (X20) and the steel X12Cr13 were successfully coated with the sol s-0.52-6-1.5 by means of the dip-coating method. An at least 400 nm thick alumina layer (δ-Al2O3) is necessary to ensure the corrosion protection of these steels. The corrosion of the coated samples compared to that of the uncoated ones was significantly reduced, even after 1000 h of exposure in a H2O-CO2-O2-SO2 atmosphere at 600°C. Sulfur and carbon were not detected at the substrate surface or beneath the coating. Hence the transport of the flue gas components SO2 and CO2 into as well as through the alumina layer could be hindered. The diffusion of the alloying elements (Cr, Mn, Si) into the alumina layer resulted in the formation of mixed oxides like δ-(Al,Cr)2O3. Formation of such phases considerably contributed to the corrosion protection. The long-term stability of the sol s-0.52-6-1.5 and the high protective abilities of the alumina layer on commercial power plant steels provide a good basis for an industrial application. KW - TEM KW - Alumina KW - Coating KW - Oxyfuel KW - Steel KW - High-Temperature Corrosion PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:188-fudissthesis000000102280-0 SP - 0 EP - 179 PB - Freie Universität CY - Berlin AN - OPUS4-50310 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eh Hovsepian, P. A1 - Ehiasarian, A. P. A1 - Purandare, Y. P. A1 - Mayr, P. A1 - Abstoss, K. G. A1 - Mosquera Feijoo, Maria A1 - Schulz, Wencke A1 - Kranzmann, Axel A1 - Lasanta, M. I. A1 - Trujillo, J. P. T1 - Novel HIPIMS deposited nanostructured CrN/NbN coatings for environmental protection of steam turbine components N2 - To increase efficiency, modern steam plants are pushing their operational regime from super-critical (600 °C/300 bar) to ultra-super-critical (740/760 °C/350 bar) stretching existing turbine materials to their limits. The focus is on new generation functional materials and technologies which complement the inherent properties of existing materials. Current work proposes a novel High Power Impulse Magnetron Sputtering (HIPIMS) Deposition technology, for the first time, for deposition of a ceramic based CrN/NbN coating with a nanoscale multilayer structure (bi-layer thickness Δ = 1.9 nm) with superior adhesion (LC2 = 80 N) to protect low Chromium P92 steel widely used in steam power plants. Thermodynamic calculations predict the equilibrium phases and aggressive gaseous compounds generated by the interaction of steam with the coating. CrN/NbN coated P92 steel samples oxidised at 600 °C in a high pressure (50 bar) 100% steam atmosphere for up to 1000 h reveal the coating's superior oxidation resistance and protective mechanisms, especially against the detrimental effect of Hydrogen. High temperature (650 °C) Tensile Strength, Low Cycle Fatigue and Creep tests confirm that, unlike other state-of-the-art PVD technologies, HIPIMS is not detrimental to the mechanical properties of the substrate material. Water droplet erosion tests confirm no measurable weight loss after 2.4 X 10⁶ impacts. KW - Hipims KW - CrN/NbN KW - Nanoscale multilayers KW - Steam oxidation resistance KW - Water droplet erosion resistance PY - 2018 U6 - https://doi.org/10.1016/j.jallcom.2018.02.312 SN - 0925-8388 SN - 1873-4669 VL - 746 SP - 583 EP - 593 PB - Elsevier AN - OPUS4-44800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nofz, Marianne A1 - Dörfel, Ilona A1 - Sojref, Regine A1 - Wollschläger, Nicole A1 - Mosquera Feijoo, Maria A1 - Schulz, Wencke A1 - Kranzmann, Axel T1 - Thin Sol-Gel Alumina Coating as Protection of a 9% Cr Steel Against Flue Gas Corrosion at 650 °C N2 - Samples of sol-gel alumina coated and uncoated P92 steel were exposed to flue gas at 650 °C for 300 h. As result of this treatment a 50 µm thick bi-layered oxide scale had formed on the surface of the uncoated sample. Below the scale a 40 µm thick inner oxidation zone was detected. In contrast, the porous, micron thick alumina coating enabled the formation of a chromium oxide scale with a thickness of some nanometers at the interface between steel substrate and coating. In this case high temperature corrosion of the steel was prevented so far. KW - Steel KW - Oxide coatings KW - High-temperature corrosion KW - TEM KW - SEM PY - 2018 U6 - https://doi.org/10.1007/s11085-017-9799-0 SN - 0030-770X SN - 1573-4889 VL - 89 IS - 3-4 SP - 453 EP - 470 PB - Springer AN - OPUS4-44472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wollschläger, Nicole A1 - Nofz, Marianne A1 - Dörfel, Ilona A1 - Schulz, Wencke A1 - Sojref, Regine A1 - Kranzmann, Axel T1 - Exposition of sol-gel alumina-coated P92 steel to flue gas: Time-resolved microstructure evolution, defect tolerance, and repairing of the coating N2 - Technically relevant P92 steel (9% Cr) was coated with a micron-thick porous alumina layer prepared by sol-gel technique and treated with flue gas (60 CO2-30 H2O-2 O2-1 SO2-7 N2 (mole fraction in %)) at 650 ° to mimic an oxyfuelcombustion process. Local defects in the coating were marked using focused ion beam (FIB) technique and were inspected after exposition to hot flue gas atmosphere at 300, 800, and 1300 h, respectively. Local defects like agglomerated alumina sol particles tend to spall off from the coating uncovering the underlying dense chromia scale. Re-coating was found to restore the protection ability from oxidation when repeatedly treated with hot flue gas. Cracks and voids did not promote the local oxidation due to the formation of crystalline Mn/S/O species within and on top of the coating. The protective character of the steel-coating system is a result of (i) the fast formation of a dense chromia scale at the surface of sol-gel alumina-coated P92 steel bars in combination with (ii) the porous alumina coating acting as diffusion barrier, but also as diffusion partner in addition with (iii) fast Mn outward diffusion capturing the S species from flue gas. KW - Alumina coatings KW - Oxyfuel KW - Steel P92 KW - High temperature corrosion PY - 2018 U6 - https://doi.org/10.1002/maco.201709712 SN - 1521-4176 SN - 0947-5117 SN - 0043-2822 VL - 69 IS - 4 SP - 492 EP - 502 PB - Wiley-VCH Verlag GmbH&Co. KGaA CY - Weinheim AN - OPUS4-45300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Manzoni, Anna Maria A1 - Stephan-Scherb, Christiane T1 - Corrosion induced alloy sulfidation in a high-entropy alloy (HEA) N2 - To apply high-entropy alloys (HEA) of the CrMnFeCoNi family in challenging atmospheres, their degradation behavior under harsh environments needs to be investigated. Oxidation studies to HEAs have not been extensively investigated and most of them are concentrated on environments like synthetic air, laboratory air, CO/CO2, O2 and H2O atmospheres. Main corrosion products which were identified after aging times of up to 100 h are Mn2O3 (≤800°C) and Mn3O4 (≥800°C). Another corrosive medium in high temperature applications is SO2, which preferentially forms sulfides on commercial steels for example. These can be occurred both in the oxide layer and at the oxide/metal interface. For instance, on Fe-Cr based alloys sulfides (Cr5S6) were detected along grain boundaries and their number increases with exposure time and Cr-content in the alloy. These sulfides show an increased hardness, compared to the bulk alloy, and cause an embrittlement of the grain boundaries. This is a serious material degradation phenomenon, now addressed for the case of HEAs. In the present study metal sulfides were identified after corrosion of the HEA CrMnFeCoNi alloy in an Ar-0.5vol.%SO2 atmosphere at 800°C for 24 h, 48 h, 96 h and 192 h exposure time. After all three duration times, a thin non-protective Cr2O3 layer has formed at the oxide/alloy interface. At the gas side a thick Mn3O4 layer with local voids containing sulfur could be detected by SEM-EDS analysis. Furthermore, S precipitates could be detected in the bulk material near the surface. These sulfides were characterized in detail by scanning and transmission electron microscopy. Based on these results, a model for grain boundary sulfidation of high-entropy alloy CrMnFeCoNi is discussed. T2 - EUROMAT 2021 EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES CY - Online meeting DA - 13.09.2021 KW - High-entropy alloys KW - High-temperature corrosion KW - Sulfidation KW - Chromium oxide KW - Manganese oxide PY - 2021 AN - OPUS4-53455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Laplanche, G. A1 - Schneider, M. A1 - Stephan-Scherb, Christiane T1 - Effect of corrosive atmosphere on the oxidation behavior of CrMnFeCoNi and CrCoNi alloys N2 - High- and medium-entropy alloys (HEAs and MEAs) constitute a new class of materials. Those with a face-centered cubic (fcc) structure from the Cr-Mn-Fe-Co-Ni system have excellent mechanical properties and are considered for high-temperature applications since diffusion in these alloys was reported to be sluggish. However, their corrosion resistance at high temperatures must still be evaluated to further qualify them for such kinds of applications. Various groups studied the oxidation behavior of HEAs and MEAs under (dry) laboratory and artificial air as well as CO2/CO mixtures in different temperature ranges. Adomako et al. carried out oxidation tests in dry air between 800 °C and 1000 °C for 24 h in equiatomic CrCoNi, CrMnCoNi, and CrMnFeCoNi alloys. The authors showed that CrCoNi exhibits the best corrosion resistance at 800 °C due to the formation of a protective Cr2O3 layer. The matrix below the oxide scale was reported to be correspondingly depleted in Cr. It was further shown that the addition of Mn and Fe to CrCoNi changes the phase composition of the oxide scale at 800 °C. A Mn2O3 layer was grown during oxidation on CrMnCoNi and CrMnFeCoNi and a Cr2O3 scale was formed at the matrix/oxide scale interface. Beneath these oxide layers, Mn- and Cr-depleted zones were detected. These phase morphologies demonstrate the inward diffusion of oxygen and outward diffusion of Cr and Mn resulting in the formation of Cr2O3 and Mn2O3. In the present study, the corrosion resistance of CrMnFeCoNi and CrCoNi were confirmed and additionally characterized under further oxidizing atmospheres at 800 °C including Ar-2 Vol.% O2, Ar-2 Vol.% H20, and Ar-2 Vol.% SO2 mixtures. T2 - 10th International Symposium on High-Temperature Corrosion and Protection of Materials CY - Online meeting DA - 28.03.2021 KW - High-entropy alloys KW - High-temperature corrosion KW - Chromium oxide KW - Manganese oxide PY - 2021 AN - OPUS4-53143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stephan-Scherb, Christiane A1 - Schulz, Wencke A1 - Schneider, M. A1 - Karafiludis, Stephanos A1 - Laplanche, G. T1 - High-Temperature Oxidation in Dry and Humid Atmospheres of the Equiatomic CrMnFeCoNi and CrCoNi High- and Medium-Entropy Alloys N2 - Surface degradation phenomena of two model equiatomic alloys from the CrMnFeCoNi alloy system were investigated in 2% O2 and 10% H2O (pO2 = 0.02 and 10−7 atm, respectively) at 800 °C for times up to 96 h. The crystallographic structures, morphologies, and chemical compositions of the corrosion layers developing on CrMnFeCoNi and CrCoNi were comparatively analyzed by mass gain analysis, X-ray diffraction, and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. The oxidation resistance of CrMnFeCoNi is relatively poor due to the fast growth of porous Mnoxide(s). CrCoNi forms an external chromia layer that is dense and continuous in a dry 2% O2 atmosphere. This layer buckles and spalls off after exposure to 10% H2O atmosphere. Beneath the chromia layer, a Cr-depleted zone forms in the CrCoNi alloy in both environments. As the oxide scale spalls off in the H2O-containing atmosphere, a secondary chromia layer was observed and correspondingly enlarges the Cr-depleted zone. In contrast, as the chromia layer remains without significant spallation when CrCoNi is exposed to a dry oxidizing atmosphere, the region depleted in Cr is narrower. KW - High temperature oxidation KW - High entropy alloys KW - Medium entropy alloys KW - CrMnFeCoNi KW - CrCoNi KW - Mn-oxides PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-517859 SN - 0030-770X VL - 95 IS - 1-2 SP - 105 EP - 133 PB - Springer AN - OPUS4-51785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Stephan-Scherb, Christiane A1 - Laplanche, Guillaume T1 - High temperature corrosion phenomena of HEAs and MEAs N2 - High- and medium-entropy alloys (HEAs and MEAs) constitute a new class of materials. Those with a face-centered cubic (fcc) structure from the Cr-Mn-Fe-Co-Ni system have excellent mechanical properties and are considered for high-temperature applications since diffusion in these alloys was reported to be sluggish. However, their corrosion resistance at high temperatures must still be evaluated to further qualify them for such kinds of applications. Various groups studied the oxidation behavior of HEAs and MEAs under (dry) laboratory and artificial air as well as CO2/CO mixtures in different temperature ranges. CrCoNi exhibits the best corrosion resistance at 800 °C due to the formation of a protective Cr2O3 layer. The matrix below the oxide scale was reported to be correspondingly depleted in Cr. It was further shown that the addition of Mn and Fe to CrCoNi changes the phase composition of the oxide scale at 800 °C. A Mn2O3 layer was grown during oxidation on CrMnCoNi and CrMnFeCoNi and a Cr2O3 scale was formed at the matrix/oxide scale interface. Beneath these oxide layers, Mn- and Cr-depleted zones were detected. These phase morphologies demonstrate the inward diffusion of oxygen and outward diffusion of Cr and Mn resulting in the formation of Cr2O3 and Mn2O3. In the present study, the corrosion resistance of CrMnFeCoNi and CrCoNi were confirmed and additionally characterized under further oxidizing atmospheres at 800 °C including Ar-2 Vol.% O2, Ar-2 Vol.% H20, and Ar-2 Vol.% SO2 mixtures. T2 - Symposium on Advanced Mechanical and Microstructural Characterization of High-Entropy Alloys CY - Ruhr-Universität Bochum, Germany DA - 03.02.2020 KW - Mn3O4 KW - High-entropy alloy KW - Medium-entropy alloy KW - High-temperature corrosion KW - Chromia PY - 2020 AN - OPUS4-50984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Stephan-Scherb, Christiane A1 - Karafiludis, Stephanos A1 - Schneider, Mike A1 - Laplanche, Guillaume T1 - High temperature corrosion of high (HEA) and medium (MEA) entropy alloys N2 - The high-temperature corrosion behavior of the medium-entropy alloy Cr33Co33Ni33 (MEA) and the high-entropy alloy Fe20Cr20Co20Ni20Mn20 (HEA) in a mixed gas atmosphere of 10% H2O-2% O2 -0.5% SO2 + Ar as carrier gas [Vol.%] at 800 °C with duration times of t = 24h, 48h and 96h was investigated. Both alloys have a single-phase fcc microstructure. The oxidation kinetics of the HEA-CrMnFeCoNi roughly followed a linear rate law and a slow oxide growth was observable for the MEA-CrCoNi. The scale thickness of the corrosion layer in the quinary alloy increased with exposure time, while the scale thickness in the ternary alloy remained constant at around 1 µm. The MEA-CrCoNi developed a protective Cr2O3 layer with minor buckled parts. Co,Ni-chromite (Co,Ni)Cr2O4 was detected by XRD in minor amounts. The scale on HEA-CrMnFeCoNi displayed a triplex structure of a thin, continuous, inner Cr2O3 layer, a dense, intermediate Mn3O4 layer, and a thick, outer, porous layer consisting of Mn3O4 and MnSO4. Sulphides were only identified in the matrix of HEA-CrMnFeCoNi. Thermodynamic equilibrium calculations with FactSage (Log(S2) vs. Log(O2), ΔG of reactions) are in good agreement with these observations. The intense diffusion of Cr in the ternary alloy leads to an immediate formation of a protective Cr2O3 layer. The fast diffusion of Mn through the bulk HEA material and through the formed Cr2O3 layer compared to the other alloying elements is considered as the rate-limiting process. T2 - DMG Sektionstreffen Angewandte Mineralogie und Kristallographie CY - Online meeting DA - 25.02.2021 KW - Cr2O3 KW - High-Temperature Corrosion KW - HEA KW - MEA PY - 2021 AN - OPUS4-52164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schulz, Wencke A1 - Stephan-Scherb, Christiane A1 - Laplanche, Guillaume T1 - High temperature oxidation behavior of CrMnFeCoNi and CrCoNi in various atmospheres N2 - The study presented here focusses on a systematic analysis of oxidation mechanisms of the well-known Cr20Mn20Fe20Co20Ni20 alloy and one of its ternary sub-system Cr33.3Co33.3Ni33.3 which were reported in the literature to exhibit attractive mechanical properties. Both alloys are single phase fcc prior to oxidation and were simultaneously exposed to different oxygen containing atmospheres at 700° C and 800° C for durations up to 288 h. Cr20Mn20Fe20Co20Ni20 showed poor oxidation resistance at high temperatures due to its high amount of manganese leading to the formation of non-protective Mn-oxide scales. In contrast, a relatively homogeneous and protective chromia layer was found to form on CrCoNi at 700° C and 800° C after each exposure time. Mass change-, SEM- and XRD analysis of the oxide layers were performed in the present study and provide a better understanding of the oxidation mechanisms as well as the impact of the alloy composition on oxidation behavior. T2 - World Congress on High Entropy Alloys (HEA 2019) CY - Seattle, WA, USA DA - 17.11.2019 KW - Scanning electron microscopy KW - High-entropy alloys KW - High-temperature corrosion PY - 2019 AN - OPUS4-50309 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -