TY - CONF A1 - Portella, Pedro Dolabella A1 - Krebber, Katerina T1 - Fiber Optic Sensors for SHM - From Laboratory to Industrial N2 - The paper highlights the research activities in Germany and Europe in the development of distributed fiber optic sensor for structural health monitoring (SHM) like the monitoring of geotechnical and civil infrastructures and presents selected results achieved within these projects. T2 - Conaendi & IEV 2021 CY - Online meeting DA - 09.03.2021 KW - Fiber KW - Optic KW - SHM PY - 2021 AN - OPUS4-52254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritsch, Tobias A1 - Sprengel, Maximilian A1 - Evans, Alexander A1 - Farahbod-Sternahl, L. A1 - Saliwan Neumann, Romeo A1 - Hofmann, M. A1 - Bruno, Giovanni T1 - On the determination of residual stresses in additively manufactured lattice structures N2 - The determination of residual stresses becomes more complicated with increasing complexity of the structures investigated. Additive manufacturing techniques generally allow the production of ‘lattice structures’ without any additional manufacturing step. These lattice structures consist of thin struts and are thus susceptible to internal stress-induced distortion and even cracks. In most cases, internal stresses remain locked in the structures as residual stress. The determination of the residual stress in lattice structures through nondestructive neutron diffraction is described in this work. It is shown how two difficulties can be overcome: (a) the correct alignment of the lattice structures within the neutron beam and (b) the correct determination of the residual stress field in a representative part of the structure. The magnitude and the direction of residual stress are discussed. The residual stress in the strut was found to be uniaxial and to follow the orientation of the strut, while the residual stress in the knots was more hydrostatic. Additionally, it is shown that strain measurements in at least seven independent directions are necessary for the estimation of the principal stress directions. The measurement directions should be chosen according to the sample geometry and an informed choice on the possible strain field. If the most prominent direction is not measured, the error in the calculated stress magnitude increases considerably. KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Principal stress components KW - Neutron diffraction KW - Lattice structures PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520663 DO - https://doi.org/10.1107/S1600576720015344 SN - 1600-5767 VL - 54 SP - 228 EP - 236 AN - OPUS4-52066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Fedelich, Bernard A1 - Finn, Monika A1 - Künecke, Georgia A1 - Rehmer, Birgit A1 - Nolze, Gert A1 - Leistner, C. A1 - Petrushin, N. A1 - Svetlov, I. T1 - Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C N2 - The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as during technical accidents which may happen in service (overheating). High reliability of the results was achieved using specimens of different crystallographic orientations, exciting various vibration modes as well as precise measurement of the material density and thermal Expansion required for modeling the resonance frequencies by finite element method. Combining the results measured in this work and literature data the elastic constants of the gamma and gamma' phases were predicted. This prediction was supported by measurement of the temperature dependence of the gamma'fraction. All data obtained in this work are given in numerical or analytical forms and can be easily used for different scientific and engineering calculations. KW - Nickel-base superalloys KW - Single-crystals KW - Characterization KW - Elastic constants PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520972 DO - https://doi.org/10.3390/cryst11020152 VL - 11 IS - 2 SP - 152 PB - MDPI AN - OPUS4-52097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Marschall, Niklas A1 - Alig, I. A1 - Böhning, Martin T1 - A phenomenological criterion for an optical assessment of PE-HD fracture surfaces obtained from FNCT N2 - The full-notch creep test (FNCT) is a common test method to evaluate the environmental stress cracking (ESC) behavior of high-density polyethylene (PE-HD), e.g. for container materials. The test procedure as specified in ISO 16770 provides a comparative measure of the resistance against ESC using the time to failure of PE-HD specimens under constant mechanical load in a well-defined liquid test environment. Since the craze-crack damage mechanism underlying the ESC phenomenon is associated with brittle failure, the occurrence of a predominantly brittle fracture surface is a prerequisite to consider an FNCT measurement as representative for ESC, i.e. a time to failure dominated by craze-crack propagation. The craze-crack propagation continuously reduces the effective residual cross-sectional area of the specimen during the test, which results in a corresponding increase of the effective mechanical stress. Thus, a transition to ductile shear deformation is inevitable at later stages of the test, leading usually to a pronounced central ligament. Therefore, an optical evaluation of FNCT fracture surfaces concerning their brittleness is essential. An enhanced imaging analysis of FNCT fracture surfaces enables a detailed assessment of craze-crack Propagation during ESC. In this study, laser scanning microscopy (LSM) was employed to evaluate whether FNCT fracture surfaces are representative with respect to craze-crack propagation and ESC. Based on LSM height data, a phenomenological criterion is proposed to assess the validity of distinct FNCT measurements. This criterion is supposed to facilitate a quick evaluation of FNCT results in practical routine testing. Its applicability is verified on a sample basis for seven different commercial PE-HD container materials. KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Laser scanning microscopy (LSM) KW - Fracture surfaces KW - Optical criterion of brittleness PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521012 DO - https://doi.org/10.1016/j.polymertesting.2020.107002 VL - 94 SP - 107002 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-52101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Schulz, Bärbel A1 - Rabe, Torsten T1 - Tailoring the spring constant of ceramic helical compression springs N2 - Ceramic springs combine attractive properties for applications in machinery, metrology, and sensor technology. They are electrically insulating, non-magnetic, provide a linear stress-strain behavior, and are stable at high temperatures and in corrosive environments. Generally, the precise dimensioning of a ceramic spring with respect to the spring constant is challenging. Different models are described, but many of these calculations do not match the actual spring properties. We demonstrate a reliable approach for the dimensioning and manufacturing of helical compression springs with a rectangular winding cross-section. Based on the German standard DIN 2090, which is referring to metallic springs, the spring constant can be calculated based on shear modulus, diameter, height, widths, and number of windings. Different ceramic springs were produced by milling of sintered hollow cylinders of zirconia, alumina and silicon nitride. The experimental spring constants are in very good agreement with the calculated values. Spring constants of zirconia springs were varied over three orders of magnitude between 0.02 N/mm and 5 N/mm by purposeful adaption of the spring geometry. The combination of dimensioning based on DIN 2090 and precise hard machining offers a reliable technology for the fabrication of tailored ceramic springs for special applications. T2 - 45th International Conference and Exhibition on Advanced Ceramics and Composites (ICACC 2021) CY - Online meeting DA - 08.02.2021 KW - Ceramics KW - Hard machining KW - Spring constant PY - 2021 AN - OPUS4-52136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Camin, B. A1 - Hansen, L. A1 - Chyrkin, A. A1 - Nolze, Gert T1 - Synchrotron Sub-μ X-ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel-Base Superalloy and Nickel after Annealing at 1250 °C N2 - Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel-base superalloy CMSX-10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening ƴ'-phase ist partially dissolved. The porosity is studied by X-ray sub-μ tomography with a spatial resolution of about 0.35³ μm³ at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. It is found that depending on the distance from the interface the Kirkendall pores take different shapes: octahedral, rounded pyramidal, drop shaped, dendritic, pear shaped, and joint shapes. Such a variety of pore morphologies indicates a complex multistage process of porosity nucleation and growth under vacancy supersaturation of different degrees. The experimental findings are interpreted on the basis of the results of diffusion modeling. It is shown that the kinetics of porosity growth is essentially influenced by the dissolution of the ƴ'-phase. KW - Diffusion KW - Nickel alloys KW - Porous materials KW - Synchrotron radiations KW - Three-dimensional tomographies PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521476 DO - https://doi.org/10.1002/adem.202001220 VL - 23 IS - 4 SP - 1220 PB - Wiley Online Library AN - OPUS4-52147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plarre, Rüdiger A1 - Zocca, Andrea A1 - Spitzer, Andrea A1 - Benemann, Sigrid A1 - Gorbushina, Anna A1 - Li, Y. A1 - Waske, Anja A1 - Funk, Alexander A1 - Wilgig, Janka A1 - Günster, Jens T1 - Searching for biological feedstock material: 3D printing of wood particles from house borer and drywood termite frass N2 - Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer (EHB) and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the EHB Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of woodbased structures in a layer wise fashion using the Binder Jetting printing process. The Quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a Hausner Ratio HR = 1.1 with ρBulk = 0.67 g/cm3 and ρTap = 0.74 g/cm3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing. KW - 3D printing KW - X-ray tomographic KW - SEM micrography KW - Drywood termite PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521517 DO - https://doi.org/10.1371/journal.pone.0246511 VL - 16 IS - 2 SP - e0246511 AN - OPUS4-52151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Nielow, Dustin T1 - Einfluss fertigungsbedingter Imperfektionen auf die Schwingfestigkeit von FKV-Schalenstrukturen in Sandwichbauweise N2 - Rotorblätter von Windenergieanlagen (WEA) weisen häufig nach wenigen Jahren, lange vor dem Erreichen der prognostizierten Lebensdauer von 20 bis 30 Jahren Risse in der Blattschale auf. Die Folge sind aufwendige Reparaturen am installierten und schwer zugänglichen Rotorblatt und der kostenintensive Nutzungsausfall durch den Stillstand der WEA. Als mögliche Initiatoren für die Schäden in der Blattschale der Rotorblätter gelten fertigungsbedingte Imperfektionen. Für die Untersuchung des Einflusses dieser Imperfektionen auf das Ermüdungsverhalten der Rotorblätter wurde an der BAM (Bundesanstalt für Mate-rialforschung und -prüfung) ein Prüfstand für statische und zyklische Versuche von Schalensegmenten im intermediate scale entwickelt und betrieben. Die untersuchten Schalensegmente in Sandwichbauweise sind der Rotorblattschale von WEA im Hinblick auf die Strukturmechanik, die eingesetzten Halbzeuge, den Laminataufbau und dem eingesetzten Fertigungsverfahren ähnlich. Als Imperfektionen wurden verschiedenen Variationen von Lagenstößen in die Hautlagen und Schaumstöße mit Breitenvariation in den Stützkern reproduzierbar eingebracht. Die Überwachung des Schädigungszustandes während der Schwingversuche unter realistischen Lastszenarien erfolgt über eine kombinierte in situ Schädigungsüberwachung mittels passiver Thermografie und Felddehnungsmessung. Mit den durchgeführten Schwingversuchen und der begleitenden Überwachung des Schädigungszustandes ließen sich die Schadensinitiation und die signifikante Herabsetzung der Lebensdauer durch die eingebrachten Imperfektionen zweifelsfrei nachweisen und entsprechende Konstruktionshinweise für die betriebssichere Auslegung von Sandwichstrukturen ableiten. N2 - Wind turbines often exhibit cracks in the blade shells after only a few years in service, significantly before their expected 20 to 30 year design lifespan. This leads to complicated repairs on difficult to reach rotor blades, and can cause a cost-intensive standstill of the turbine. A possible source of these defects in the rotor blade shells are the imperfections which occur during production. In order to investigate the effect of these imperfections on the fatigue behavior of rotor blades, a test rig was developed at the BAM (Bundesanstalt für Materialforschung und -prüfung) upon which intermediate scale static and cyclic-fatigue testing could be performed. The complementary sandwich shell specimens developed and investigated with the test rig are representative of the outer shell of wind turbine rotor blades in terms of materials and manufacturing processes, as well as structural mechanics. The specimens were built with reproducible imperfections, including laminate overlaps in the face sheets and gaps of varying size in the foam core. The damage condition was monitored during cyclic-fatigue testing under realistic load cases using a combination of in-situ passive thermography and strain field measurement. The cyclic testing and parallel non-destructive structural health monitoring of the shell specimens showed the imperfections to significantly influence the damage initiation and decrease the component service life. The results can be used accordingly as recommendations for operationally more reliable design of sandwich structures. T3 - BAM Dissertationsreihe - 170 KW - Erneuerbare Energien KW - Windenergie KW - Verbundwerkstoffe KW - Betriebsfestigkeit KW - Komponentenprüfung KW - Renewable ernergy KW - Wind energy KW - Intermediate scale KW - Composites KW - Fatigue PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546701 SN - 1613-4249 VL - 170 SP - 1 EP - 178 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-54670 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evans, Alexander A1 - Sprengel, Maximilian A1 - Ulbricht, Alexander A1 - Kromm, Arne A1 - Werner, Tiago A1 - Sommer, Konstantin A1 - Kelleher, Joe A1 - Mishurova, Tatiana A1 - Serrano Munoz, Itziar A1 - Fritsch, Tobias A1 - Schröder, Jakob A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - Manufacturing a safer world: Diffraction based residual stress analysis for metal additive manufacturing N2 - Metal Additive Manufacturing (AM) technologies such as Laser Powder Bed Fusion (LPBF) are characterized by layer wise construction, which enable advancements of component design, with associated potential gains in performance and efficiency. However, high magnitude residual stresses (RS) are often a product of the rapid thermal cycles typical of the layerwise process. Therefore, a deep understanding of the formation of RS, the influence of process parameters on their magnitude and the impact on mechanical performance is crucial for widespread application. The experimental characterisation of these RS is essential for safety related engineering application and supports the development of reliable numerical models. Diffraction-based methods for RS analysis using neutrons and high energy X-rays enable non-destructive spatially resolved characterisation of both surface and bulk residual stresses in complex components. This presentation will provide an overview of recent research by the BAM at large scale facilities for the characterization of residual stresses in LPBF metallic alloys as a function of process parameters. In addition, the challenges posed by the textured and hierarchical microstructures of LPBF materials on diffraction-based RS analysis in AM materials will be discussed. This will include the question of the d0 reference lattice spacing and the appropriate choice of the diffraction elastic constants (DECs) to calculate the level of RS in LPBF manufactured alloys. T2 - 11th INternational Conference on Residual Stress (ICRS11) CY - Online meeting DA - 28.03.2021 KW - Residual stress analysis KW - Neutron diffraction KW - X-ray diffraction KW - Additive manufacturing KW - Laser powder bed fusion KW - AGIL PY - 2022 AN - OPUS4-54676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella A1 - Ulbricht, Alexander A1 - Evans, Alexander A1 - Altenburg, Simon A1 - Ehlers, Henrik A1 - Hilgenberg, Kai A1 - Mohr, Gunther T1 - Monitoring additive manufacturing processes by using NDT methods N2 - In this presentation we discuss the online monitoring of metallic AM parts produced by the Laser Powder Bed Fusion (LPBF) process by using optical, thermographic and electromagnetic methods. In a first approach we present the detection of defects generated during the process and discuss how to improve these methods for the optimization of design and production of metallic AM parts. T2 - ABENDI - Workshop CY - Online meeting DA - 19.11.2020 KW - Additive Fertigung PY - 2020 AN - OPUS4-52042 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella A1 - Trappe, Volker A1 - Trappe, Volker A1 - Nielow, Dustin T1 - Non-destructive characterization methods for polymer matrix composites N2 - The mechanical behavior of fiber reinforced composites with polymer matrix is governed by several mechanisms operating at different length scales. In this contribution we describe first non-destructive techniques which are adequate for the characterization of the fiber-matrix interphase at a microscopic level. In a second step we describe on a mesoscopic level the influence of manufacturing related elements on the mechanical properties of rotor blades for wind turbines. We concentrate on thermography, laminography and ultrasound in connection with mechanical testing systems. Finally we present methods for monitoring rotor blades by using embedded optical fibers. T2 - Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ, Brasilien CY - Online meeting DA - 26.11.2020 KW - Polymer matrix composites PY - 2020 AN - OPUS4-52043 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella A1 - Skrotzki, Birgit A1 - Muth, Thilo T1 - Die Digitalisierung der Materialwissenschaft und Werkstofftechnik - ein Überblick N2 - Die Bereitstellung von zuverlässigen Werkstoffdaten stand für die Werkstoffprüfung seit dem 19. Jahrhundert in zentraler Stelle. Mit der zunehmender Digitalisierung unserer Gesellschaft gewinnt das Datenmanagement insbesondere im Hinblick auf die Modellierungs- und Simulationsaktivitäten an Bedeutung. In unserem Beitrag beschreiben wir die gegenwärtigen Aktivitäten in Deutschland – insbesondere die NFDI-MatWerk und die BMBF-Initiative MaterialDigital – sowie in Europa und Übersee. Abschließend heben wir die Auswirkungen auf die technische und akademische Aus- und Weiterbildung. T2 - DVM - Tagung Werkstoffprüfung CY - Online meeting DA - 03.12.2020 KW - Werkstoffdaten KW - Digitalisierung KW - Materialwissenschaft PY - 2020 AN - OPUS4-52044 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella T1 - Charakterisierung metallischer Werkstoffe für Anwendungen bei hohen Temperaturen N2 - In diesem Beitrag werden am Beispiel von Gasturbinen Verfahren zur Charakterisierung des werkstoff-mechanischen Verhaltens sowie der Gefügeentwicklung von Bauteilen für Anwendungen bei hohen Temperaturen aufgezeigt. Gasturbinen sind technisch gesehen sehr interessante Systeme, die in der Energietechnik und in der Luftfahrt von hoher wirtschaftlicher Relevanz sind. Seit Jahrzehnten gelten Gasturbinen als klassische Innovationstreiber, für ihre Entwicklung wurden bereits maßgebliche Erneuerungen im Bereich der Aerodynamik und der Werkstofftechnik hervorgebracht. T2 - Deutsche Physikalische Gesellschaft Senior Expert Netzwerk CY - Online meeting DA - 20.01.2021 KW - Superlegierungen KW - Gasturbinen PY - 2020 AN - OPUS4-52045 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Duarte, Larissa A1 - Andrade, Ana Carolina A1 - Bettge, Dirk T1 - Fractographic Analysis of Fatigue Striations Formation under different Microstructures and Loading Conditions T1 - Fraktographische Untersuchung der Bildung von Schwingstreifen bei unterschiedlichen Gefügezuständen und Belastungsbedingungen N2 - Fatigue failure of a component can occur at service loads considerably lower than the yield strength of the material. Under fatigue loading condition, the material in the vicinity of the tip of a propagating crack repeatedly deforms plastically, leaving microscopic marks on the crack surface, commonly known as fatigue striations. Counting and measuring fatigue striations is a method in estimating the number of loading cycles a component went through until fracture. Some studies suggest a one-to-one relation between the number of fatigue striations and the number of load cycles, but this relation is still debatable, given that there are many factors influencing the formation of those striations. The main purpose of this work is to analyze the influence of microstructure and mechanical strength on the formation of fatigue striations in structural steels, in order to understand how these material properties are related to the fatigue crack behavior. For such, standard Charpy-V samples were subjected to hardness, fatigue and impact testing. Metallography was performed to characterize the microstructure, and a fractographic analysis by using optical and scanning electron microscopy was carried out to investigate the fracture surface. This study shows that steels with higher ductility have a closer one-to-one relation than those with a higher tensile strength. Above a certain level of tensile strength, fatigue striations do form rarely or completely disappear. N2 - Weit unterhalb der Streckfestigkeit des Werkstoffs kann es durch Schwingbruch zum Bauteilversagen kommen. Unter Schwingbeanspruchung wird der Werkstoff in der Nähe der Spitze eines sich ausbreitenden Risses wiederholt plastisch verformt. Dabei entstehen allgemein als Schwingstreifen bekannte mikroskopische Spuren. Das Zählen und Vermessen von Schwingstreifen ist ein Verfahren zum Schätzen der Anzahl von Belastungszyklen, denen ein Bauteil bis zum Bruch ausgesetzt war. Einige Studien legen hier eine 1 : 1-Beziehung zwischen der Anzahl von Schwingstreifen und der Anzahl von Lastspielen nahe. Dies erscheint angesichts der zahlreichen, die Bildung solcher Streifen beeinflussenden Faktoren allerdings fraglich. Hauptziel dieser Arbeit ist die Untersuchung der Auswirkungen des Gefüges und der mechanischen Festigkeit auf die Bildung von Schwingstreifen in Baustählen, um Zusammenhänge zwischen diesen Werkstoffeigenschaften und dem Schwingbruchverhalten verstehen zu können. Dafür wurden an Standard-Charpy-V-Proben Härte- sowie Schwing- und Schlagprüfungen durchgeführt. Zur Gefügecharakterisierung wurden die Proben metallographisch untersucht. Die Bruchfläche wurde zur Analyse fraktographisch licht- und rasterelektronenmikroskopisch untersucht. Die vorliegende Untersuchung zeigt dabei auf, dass Stähle mit einer höheren Duktilität näher an eine solche 1 : 1-Beziehung herankommen als solche mit einer höheren Zugfestigkeit. Oberhalb einer bestimmten Zugfestigkeit bilden sich selten oder gar keine Schwingstreifen. KW - Schwingstreifen KW - Fatigue striations PY - 2020 DO - https://doi.org/10.3139/147.110668 VL - 57 IS - 12 SP - 869 EP - 886 PB - Carl Hanser Verlag CY - München AN - OPUS4-51952 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rockenhäuser, Christian A1 - Rowolt, C. A1 - Milkereit, B. A1 - Darvishi Kamachali, Reza A1 - Kessler, O. A1 - Skrotzki, Birgit T1 - On the long-term aging of S-phase in aluminum alloy 2618A N2 - The aluminum alloy 2618A is applied for engine components such as radial compressor wheels which operate for long time at elevated temperatures. This results in coarsening of the hardening precipitates and degradation in mechanical properties during the long-term operation, which is not taken into account in the current lifetime prediction models due to the lack of quantitative microstructural and mechanical data. To address this issue, a quantitative investigation on the evolution of precipitates during long-term aging at 190 °C for up to 25,000 h was conducted. Detailed transmission electron microscopy (TEM) was combined with Brinell hardness measurements and thorough differential scanning calorimetry (DSC) experiments. The results showthat GPB zones and S-phase Al2CuMg grow up to < 1,000 h during which the GPB zones dissolve and S-phase precipitates form. For longer aging times, only S-phase precipitates coarsen, which can be well described using the Lifshitz–Slyozov Wagner theory of ripening. A thorough understanding of the underlying microstructural processes is a prerequisite to enable the integration of aging behavior into the established lifetime models for components manufactured from alloy 2618A. KW - Long-term aging KW - Transmission electron microscopy (TEM) KW - Differential scanning calorimetry (DSC) KW - Microstructure KW - S-phase KW - Ostwald ripening PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519899 DO - https://doi.org/10.1007/s10853-020-05740-x SN - 0022-2461 VL - 56 IS - 14 SP - 8704 EP - 8716 PB - Springer Nature AN - OPUS4-51989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Orlov, Nikolai A1 - Kiseleva, A. K. A1 - Milkini, P. A. A1 - Evdokimov, P. V. A1 - Putlayev, V. I. A1 - Günster, Jens T1 - Potentialities of Reaction Sintering in the Fabrication of High-Strength Macroporous Ceramics Based on Substituted Calcium Phosphate N2 - Calcium alkali metal (potassium and sodium) double and triple phosphates have been synthesized in different ways. Was for the first time used reaction sintering to produce ceramics based on calcium alkali metal mixed phosphates and investigated the densification behavior of mixed phosphate-based multiphase materials during sintering by this method. Was presented the microstructure of polished surfaces of sintered samples differing in phase composition and determined the density of ceramics prepared using reaction mixtures differing in composition. The effect of reaction sintering on the porosity of the ceramics has been assessed. Using stereolithographic printing and reaction sintering, was produced macroporous mixed Calcium phosphate-based ceramic implants. Their compressive strength has been determined to be 0.78 ± 0.21 MPa for two-phase samples and 1.02 ± 0.13 MPa for three-phase samples. KW - Reaction Sintering KW - Bio Ceramics PY - 2020 DO - https://doi.org/10.1134/s0020168520120146 VL - 56 IS - 12 SP - 1298 EP - 1306 PB - Pleiades Publishing LTD AN - OPUS4-52004 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Bettge, Dirk A1 - Buggisch, E. A1 - Schiller, Bernadette Nicole A1 - Beck, M. T1 - Corrosion Study on Wellbore Materials for the CO2 Injection Process N2 - For reliability and safety issues of injection wells, corrosion resistance of materials used needs to be determined. Herein, representative low-cost materials, including carbon steel X70/1.8977 and low alloyed steel 1.7225, were embedded in mortar to mimic the realistic casing-mortar interface. Two types of cement were investigated: (1) Dyckerhoff Variodur commercial Portland cement, representing a highly acidic resistant cement and (2) Wollastonite, which can react with CO2 and become stable under a CO2 stream due to the carbonation process. Exposure tests were performed under 10 MPa and at 333 K in artificial aquifer fluid for up to 20 weeks, revealing crevice corrosion and uniform corrosion instead of expected pitting corrosion. To clarify the role of cement, simulated pore water was made by dispersing cement powder in aquifer fluid and used as a solution to expose steels. Surface analysis, accompanied by element mapping on exposed specimens and their crosssections, was carried out to trace the chloride intrusion and corrosion process that followed. KW - Carbon capture storage KW - CCS KW - Carbon dioxide KW - Corrosion KW - Carbon steel KW - Aquifer fluid KW - Cement KW - Casing KW - Pitting PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519774 DO - https://doi.org/10.3390/pr9010115 SN - 2227-9717 VL - 9 IS - 1 SP - 115 PB - MDPI CY - Basel AN - OPUS4-51977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cornelsen Sampaio Kling, I. A1 - Pauw, Brian Richard A1 - Agudo Jácome, Leonardo A1 - Archanjo, B. S. A1 - Simão, R. A. T1 - Development and characterization of starch film and the incorporation of silver nanoparticles N2 - Starch is one of the biopolymers being used for bioplastic synthesis. For production, starch can be combined with different plasticizers, starches from different plant sources and even with nanomaterials to improve or to add film properties. The challenge of adding these, e.g. in the form of silver nanoparticles (AgNp) is to determine the concentration so as to avoid impairing the properties of the film, agglomeration or altering the visual characteristics of the film. In this study, a starch film synthesis route and the incorporation of silver nanoparticles has been proposed in order not to alter the properties of the film while maintaining the transparency and a clear colour of the starch film. The results showed that the proposed synthesis route is promising, efficient, reproducible, fast and the film has good mechanical properties. T2 - Semana MetalMat & Painal PEMM 2020 CY - Online meeting DA - 23.11.2020 KW - Biofilm KW - Silver nanoparticle KW - Starch KW - Starch nanoparticle PY - 2020 SP - 1 EP - 2 AN - OPUS4-51940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Mechanical anisotropy of additively manufactured stainless steel 316l: an experimental and numerical study N2 - This work aims for a yield function description of additively manufactured (AM) parts of stainless steel 316L at the continuum-mechanical macro-scale by means of so-called virtual experiments using a crystal plasticity model at meso-scale. T2 - 1st Workshop on In-situ Monitoring and Microstructure Development in Additive Manufacturing CY - BAM, Berlin DA - 10.12.2020 KW - Anisotropy KW - Crystal plasticity KW - Additive manufacturing PY - 2020 AN - OPUS4-51941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nadammal, Naresh A1 - Mishurova, Tatiana A1 - Fritsch, Tobias A1 - Serrano Munoz, Itziar A1 - Kromm, Arne A1 - Haberland, C. A1 - Portella, Pedro Dolabella A1 - Bruno, Giovanni T1 - Critical role of scan strategies on the development of microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing N2 - Laser based powder bed fusion additive manufacturing offers the flexibility to incorporate standard and userdefined scan strategies in a layer or in between the layers for the customized fabrication of metallic components. In the present study, four different scan strategies and their impact on the development of microstructure, texture, and residual stresses in laser powder bed fusion additive manufacturing of a nickel-based superalloy Inconel 718 was investigated. Light microscopy, scanning electron microscopy combined with electron backscatter diffraction, and neutron diffraction were used as the characterization tools. Strong textures with epitaxially grown columnar grains were observed along the build direction for the two individual scan strategies. Patterns depicting the respective scan strategies were visible in the build plane, which dictated the microstructure development in the other planes. An alternating strategy combining the individual strategies in the successive layers and a 67◦ rotational strategy weakened the texture by forming finer microstructural features. Von Mises equivalent stress plots revealed lower stress values and gradients, which translates as lower distortions for the alternating and rotational strategies. Overall results confirmed the scope for manipulating the microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing by effectively controlling the scan strategies. KW - Additive manufacturing KW - Laser powder bed fusion KW - Nickel-based superalloys KW - Scan strategies KW - Residual stresses KW - Microstructure and texture PY - 2021 DO - https://doi.org/10.1016/j.addma.2020.101792 VL - 38 SP - 1792 PB - Elsevier B.V. AN - OPUS4-51944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - da Silva, A. A1 - McEniry, E. A1 - Gault, B. A1 - Neugebauer, J. A1 - Raabe, D. T1 - Segregation-assisted spinodal and transient spinodal phase separation at grain boundaries N2 - Segregation to grain boundaries affects their cohesion, corrosion, and embrittlement and plays a critical role in heterogeneous nucleation. In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries, here, we apply a density-based phase-field model. The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data, while the grain-boundary-density profile is obtained using atomistic simulations. To benchmark the performance of the model, Mn grain-boundary segregation in the Fe–Mn system is studied. 3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions. We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm. The jump corresponds to a spinodal Phase separation at grain boundary. For alloy compositions above the jump, we reveal an interfacial transient spinodal phase separation. The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries. The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries. KW - Grain Boundary Spinodal KW - Densty-based Thermodynamics KW - Microstrucrue Design PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519497 DO - https://doi.org/10.1038/s41524-020-00456-7 VL - 6 IS - 1 SP - 191 PB - Nature AN - OPUS4-51949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Riechers, Birte A1 - Roed, L. A1 - Mehri, S. A1 - Ingebrigtsen, T. A1 - Hecksher, T. A1 - Dyre, J. A1 - Niss, K. T1 - Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time N2 - The noncrystalline glassy state of matter plays a role in virtually all fields of materials science and offers complementary properties to those of the crystalline counterpart. The caveat of the glassy state is that it is out of equilibrium and therefore exhibits physical aging, i.e., material properties change over time. For half a century, the physical aging of glasses has been known to be described well by the material-time concept, although the existence of a material time has never been directly validated. We do this here by successfully predicting the aging of the molecular glass 4-vinyl-1,3-dioxolan-2-one from its linear relaxation behavior. This establishes the defining property of the material time. Via the fluctuation-dissipation theorem, our results imply that physical aging can be predicted from thermal-equilibrium fluctuation data, which is confirmed by computer simulations of a binary liquid mixture. KW - Physical aging KW - Equilibrium relaxation KW - Glass PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546015 DO - https://doi.org/10.1126/sciadv.abl9809 SN - 2375-2548 VL - 8 IS - 11 SP - 1 EP - 8 PB - American Association for the Advancement of Science CY - Washington, DC AN - OPUS4-54601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, A. A1 - Kranzmann, Axel T1 - Understanding the Anomalous Corrosion Behaviour of 17% Chromium Martensitic Stainless Steel in Laboratory CCS-Environment—A Descriptive Approach N2 - To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 ◦C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment. KW - Corrosion KW - Steel KW - High alloyed steel KW - Corrosion mechanism KW - CCS PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545700 DO - https://doi.org/10.3390/cleantechnol4020014 VL - 4 IS - 2 SP - 239 EP - 257 PB - MDPI AN - OPUS4-54570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xing, H. A1 - Jing, H. A1 - Dong, X. A1 - Wang, Lei A1 - Han, Y. A1 - Hu, R. T1 - Cellular growth during rapid directional solidification: Insights from quantitative phase field simulations N2 - In this paper, columnar cellular growth with kinetic effects including kinetic undercooling and solute trapping in rapid directional solidification of alloys was investigated by using a recent quantitative phase-field model for rapid solidification. Morphological transition and primary spacing selection with and without kinetic effects were numerically investigated. Numerical results show that doublon structure is an intermediate state in the primary spacing adjustment of cellular arrays. It was found that the inclusions of kinetic effects result in the increase of the solute in the solid phase and the solute enrichment in the interdendritic liquid channel. Moreover, predicted results indicate that the growth directions of the cellular arrays in rapid directional solidification with and without kinetic effects are independent of the Péclet number. Therefore, the kinetic effects play important roles in numerical simulations of the growth pattern selection and solute distribution during rapid solidification. Neglecting them will result in the inaccurately predicted results. KW - Rapid solidification KW - Phase-field model PY - 2022 DO - https://doi.org/10.1016/j.mtcomm.2022.103170 VL - 30 SP - 103170 PB - Elsevier Ltd. AN - OPUS4-54571 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Suárez Ocano, Patricia A1 - Fries, S. G. A1 - Lopez-Galilea, I. A1 - Darvishi Kamachali, Reza A1 - Roik, J. A1 - Agudo Jácome, Leonardo T1 - The AlMo0.5NbTa0.5TiZr refractory high entropy superalloy: Experimental findings and comparison with calculations using the CALPHAD method N2 - Detailed microstructural characterization of the AlMo0.5NbTa0.5TiZr refractory high entropy superalloy in the as-cast state is reported for first time and compared with the state annealed at 1400 oC for 24 h. The former shows a dendritic structure, with a mixture of A2/B2 phases < 20 nm in both the dendritic and interdendritic regions. A mostly amorphous phase, rich in Al and Zr, is found within the interdendritic region. The annealed state reproduced the combination of A2/B2/Al-Zr-rich phases reported previously. Calculations from two relevant ThermoCalc databases were compared with the experimental results. Equilibrium calculations were compared with results for the annealed alloy, whereas solidification paths calculated using Scheil-Gulliver model were used for comparison with the as-cast alloy. A previously hypothesized spinodal decomposition during cooling as the mechanism responsible for the patterned A2/B2 microstructure is confirmed via the CALPHAD calculations, pointing to its use as an efficient design tool for such alloys. Finally, the comparison between the experimental and computational findings allowed better understanding the solidification path and equilibrium stability of this alloy, giving a base to make better decisions on the field of new refractory superalloy design. KW - CALPHAD database analysis KW - Refractory superalloys KW - Chemically complex alloy KW - Characterization KW - Microstructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545906 DO - https://doi.org/10.1016/j.matdes.2022.110593 SN - 1873-4197 VL - 217 SP - 1 EP - 13 PB - Elsevier CY - Amsterdam AN - OPUS4-54590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Winkelmann, A. A1 - Britton, T. B. A1 - Nolze, Gert T1 - EBSD Kikuchi Pattern Analysis, Silicon 15kV N2 - Supplementary data and images for Si EBSD pattern analysis as presented in: A. Winkelmann, T.B. Britton, G. Nolze "Constraints on the effective electron energy spectrum in backscatter Kikuchi diffraction", Physical Review B (2019). KW - EBSD KW - Electron energy KW - Energy distribution KW - Kikuchi pattern KW - Simulation PY - 2019 DO - https://doi.org/10.5281/zenodo.2565061 PB - Zenodo CY - Geneva AN - OPUS4-51907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dub, S. A1 - Haftaoglu, Cetin A1 - Kindrachuk, Vitaliy T1 - Estimate of theoretical shear strength of C60 single crystal by nanoindentation N2 - The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves. The respective resolved shear stresses were computed for the octahedral slip systems ⟨011¯¯¯⟩{111}, supposing that their activation resulted in the onset of plasticity. A finite element analysis was applied, which reproduced the elastic loading until the first pop-in, using a realistic geometry of the Berkovich indenter blunt tip. The obtained estimate of the C60 theoretical shear strength was about 1/11 of the shear modulus on {111} planes. KW - Finite element analysis KW - Fullerite KW - Nanoindentation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523208 DO - https://doi.org/10.1007/s10853-021-05991-2 VL - 56 IS - 18 SP - 10905 EP - 10914 PB - Springer Nature AN - OPUS4-52320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Skrotzki, Birgit T1 - The long-term ageing process of alloy 2618A N2 - The long-term ageing process of alloy 2618A was introduced and discussed The dark-field transmission electronmicroscopical resilts werde shown and evaluated regarding the precipitate radii. The influence of the precipitate radii regarding ageing was used for a preliminary ageing assessment. T2 - 19th International Microscopy Congress (IMC19) CY - Sydney, Australia DA - 09.09.2018 KW - Alloy 2618A KW - Degradation KW - Coarsening KW - S-phase KW - Dark-field transmission electron microscopy (DFTEM) PY - 2018 AN - OPUS4-46120 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Skrotzki, Birgit T1 - The long-term ageing process of alloy 2618A N2 - The long-term ageing process of alloy 2618A was introduced and discussed The dark-field transmission electronmicroscopical resilts werde shown and evaluated regarding the precipitate radii. The influence of the precipitate radii regarding ageing was used for a preliminary ageing assessment. T2 - 19th International Microscopy Congress (IMC19) CY - Sydney, Australia DA - 09.09.2018 KW - Alloy 2618A KW - Degradation KW - Coarsening KW - S-phase KW - Dark-field transmission electron microscopy (DFTEM) PY - 2018 AN - OPUS4-46123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiel, Erik A1 - Ziegler, Mathias A1 - Ahmadi, Samim A1 - Portella, Pedro Dolabella T1 - Structured heating in active thermography by using laser arrays N2 - Lock-in- and flash thermography are standard methods in active thermography. They are widely used in industrial inspection tasks e.g. for the detection of delaminations, cracks or pores. The requirements for the light sources of these two methods are substantially different. While lock-in thermography requires sources that can be easily and above all fast modulated, the use of flash thermography requires sources that release a very high optical energy in the very short time. By introducing high-power vertical cavity surface emitting lasers (VCSELs) arrays to the field of thermography a source is now available that covers these two areas. VCSEL arrays combine the fast temporal behavior of a diode laser with the high optical irradiance and the wide illumination range of flash lamps or LEDs and can thus potentially replace all conventional light sources of thermography. However, the main advantage of this laser technology lies in the independent control of individual array areas. It is therefore possible to heat not only in terms of time, but also in terms of space. This new degree of freedom allows the development of new NDT methods. We demonstrate this approach using a test problem that can only be solved to a limited extent in active thermography, namely the detection of very thin, hidden defects in metallic materials that are aligned vertically to the surface. For this purpose, we generate destructively interfering thermal wave fields, which make it possible to detect defects within the range of the thermal wave field high sensitivity. This is done without pre-treatment of the surface and without using a reference area to depths beyond the usual thermographic rule of thumb. T2 - ConaEnd&Iev 2018 CY - Sao Paulo, Brazil DA - 27.08.2018 KW - VCSEL KW - Active thermography KW - Laser KW - Structured heating KW - Subsurface defects PY - 2018 AN - OPUS4-45851 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, Anja A1 - Kranzmann, Axel T1 - Local Corrosion of Martensitic Stainless Steels during Exposure to Saline Aquifer Water and CO2 Environment N2 - Carbon Capture and Storage (CCS) is well acknowledged to mitigate climate change. Therefore, pipe Steels suitable for CCS technology require resistance against the corrosive environment of a potential CCS-site, e.g. heat, pressure, salinity of the aquifer, CO2-partial pressure. Samples of different mild and high alloyed stainless injection-pipe Steels partially heat treated: 42CrMo4, X20Cr13, X46Cr13, X35CrMo4 as well as X5CrNiCuNb16-4 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in a CO2-saturated synthetic aquifer environment similar to possible geological on-shore CCS-sites in the northern German Basin. Main corrosion products analysed on pits are FeCO3 and FeOOH. The carbon content does not show significant influence on the pitting behaviour. Generally, higher chromium Content results in better corrosion resistance. Although X35CrMo17-1 and X5CrNiCuNb16-4 show low surface corrosion rates, their resistance against local corrosion in CCS environment is not significantly better compared to the much less costly Steels X20Cr13 and X46Cr13. KW - Corrosion KW - CCS KW - Carbon storage KW - Aquifer KW - Heat treatment PY - 2018 DO - https://doi.org/10.18178/ijcea.2018.9.1.694 SN - 2010-0221 VL - 9 SP - 26 EP - 31 PB - International Association of Computer Science and Information Technology Press CY - Singapore AN - OPUS4-46627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sonntag, Nadja A1 - Cabeza, S. A1 - Kuntner, M. A1 - Mishurova, Tatiana A1 - Klaus, M. A1 - Kling e Silva, L. A1 - Skrotzki, Birgit A1 - Genzel, Ch. A1 - Bruno, Giovanni T1 - Visualisation of deformation gradients in structural steel by macroscopic magnetic domain distribution imaging (Bitter technique) N2 - Abstract While classically used to visualise the magnetic microstructure of functional materials (e.g., for magnetic applications), in this study, the Bitter technique was applied for the first time to visualise macroscopic deformation gradients in a polycrystalline low-carbon steel. Spherical indentation was chosen to produce a multiaxial elastic–plastic deformation state. After removing the residual imprint, the Bitter technique was applied, and macroscopic contrast differences were captured in optical microscopy. To verify this novel characterisation technique, characteristic “hemispherical” deformation zones evolving during indentation were identified using an analytical model from the field of contact mechanics. In addition, near-surface residual stresses were determined experimentally using synchrotron radiation diffraction. It is established that the magnetic domain distribution contrast provides deformation-related information: regions of different domain wall densities correspond to different “hemispherical” deformation zones (i.e., to hydrostatic core, plastic zone and elastic zone, respectively). Moreover, the transitions between these three zones correlate with characteristic features of the residual stress profiles (sign changes in the radial and local extrema in the hoop stress). These results indicate the potential of magnetic domain distribution imaging: visualising macroscopic deformation gradients in fine-grained ferromagnetic material with a significantly improved spatial resolution as compared to integral, mean value-based measurement methods. KW - Bitter technique KW - Deformation KW - Expanding cavity model KW - Indentation KW - Magnetic domain distribution KW - Residual stress PY - 2018 DO - https://doi.org/10.1111/str.12296 SN - 1475-1305 VL - 54 IS - 6 SP - e12296, 1 EP - 15 PB - Wiley AN - OPUS4-46569 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenberg, Rainer A1 - Charmi, Amir T1 - Virtual-lab-based determination of a macroscopic yield function for additively manufactured parts N2 - Diese Arbeit beschreibt eine Methode für die Ermittlung einer Fließfunktion für additiv gefertigte Bauteile des Werkstoffs S316L. Ein Kristallplastizitätsmodell wird zunächst mit experimentellen Daten kalibriert. Anschließend werden mit diesem Modell sogenannte virtuelle Experimente durchgeführt, die die prozeßspezifische Mikrostruktur in Form von kristallographischen und morphologischen Texturen miteinbeziehen. Diese Simulationen werden mit einem representativen Volumenelement (RVE) durchgeführt, das aus EBSD/CT-Scans an additiv gefertigten Proben generiert wurde und daher die Kornstruktur und Kristallorientierungen enthält. Die virtuellen Experimente werden durchgeführt, um anhand der damit erhaltenen Fließpunkte eine anisotrope Barlat-Fließfunktion zu bestimmen. Dieser skalenübergreifende Ansatz ermöglicht die Simulation großer Strukturen, für die die Anwendung eines Kristallplastizitätsmodells numerisch zu teuer wäre. N2 - This work presents a method for the yield function determination of additively manufactured parts of S316L steel. A crystal plasticity model is calibrated with test results and used afterwards to perform so-called virtual experiments, that account for the specific process-related microstructure including crystallographic and morphological textures. These simulations are undertaken on a representative volume element (RVE), that is generated from EBSD/CT-Scans on in-house additively manufactured specimen, considering grain structure and crystal orientations. The results of the virtual experiments are used to determine an anisotropic Barlat yield function, that can be used in a macroscopical continuum-sense afterwards. This scale-bridging approach enables the calculation of large-scale parts, that would be numerically too expensive to be simulated by a crystal plasticity model. T2 - 3. Tagung des DVM-Arbeitskreises Additiv gefertigte Bauteile und Strukturen CY - Berlin, Germany DA - 07.11.2018 KW - Additive manufacturing KW - Scale-bridging KW - Crystal plasticity KW - Virtual experiments KW - Anisotropy PY - 2018 SN - 2509-8772 SP - 153 EP - 158 PB - DVM CY - Berlin AN - OPUS4-46570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karl, D. A1 - Kamutzki, F. A1 - Zocca, Andrea A1 - Görke, O. A1 - Günster, Jens A1 - Gurlo, A. T1 - Towards the colonization of Mars by in-situ resource utilization: Slip cast ceramics from Martian soil simulant N2 - Here we demonstrate that by applying exclusively Martian resources a processing route involving suspensions of mineral particles called slurries or slips can be established for manufacturing ceramics on Mars. We developed water-based slurries without the use of additives that had a 51 wt. % solid load resembling commercial porcelain slurries in respect to the particle size distribution and rheological properties. These slurries were used to slip cast discs, rings and vases that were sintered at temperatures between 1000 and 1130 °C using different sintering schedules, the latter were set-up according the results of hot-stage microscopic characterization. The microstructure, porosity and the mechanical properties were characterized by SEM, X-ray Computer tomography and Weibull analysis. Our wet processing of minerals yields ceramics with complex shapes that show similar mechanical properties to porcelain and could serve as a technology for future Mars colonization. The best quality parts with completely vitrificated matrix supporting a few idiomorphic crystals are obtained at 1130 °C with 10 h dwell time with volume and linear shrinkage as much as ~62% and ~17% and a characteristic compressive strength of 51 MPa. KW - Ceramic KW - Mars PY - 2018 DO - https://doi.org/10.1371/journal.pone.0204025 SN - 1932-6203 VL - 13 IS - 10 SP - e0204025, 1 EP - 7 PB - Public Library of Science CY - San Francisco, Kalifornien, Vereinigte Staaten AN - OPUS4-46612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Fedelich, Bernard A1 - Rehmer, Birgit A1 - Peter, Frauke T1 - Computational methods for lifetime prediction of metallic components under high-temperature fatigue N2 - The issue of service life prediction of hot metallic components subjected to cyclic loadings is addressed. Two classes of lifetime models are considered, namely, the incremental lifetime rules and the parametric models governed by the fracture mechanics concept. Examples of application to an austenitic cast iron are presented. In addition, computational techniques to accelerate the time integration of the incremental models throughout the fatigue loading history are discussed. They efficiently solve problems where a stabilized response of a component is not observed, for example due to the plastic strain which is no longer completely reversed and accumulates throughout the fatigue history. The performance of such an accelerated Integration technique is demonstrated for a finite element simulation of a viscoplastic solid under repeating loading–unloading cycles. KW - Fatigue KW - Incremental lifetime models KW - Finite element analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481215 UR - https://www.mdpi.com/2075-4701/9/4/390 DO - https://doi.org/10.3390/met9040390 SN - 2075-4701 VL - 9 IS - 4 SP - 390, 1 EP - 24 PB - mdpi CY - Basel, Switzerland AN - OPUS4-48121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Reinsch, Stefan A1 - Fechtelkord, M. T1 - Structural investigation of hydrous phosphate glasses N2 - Dissolved water has major impact on the physical and chemical properties of phosphate glasses. In the present study we have investigated the structural response to water incorporation for glasses in the system Li2O–MgO–Al2O3–P2O5. Glasses containing 0–8 wt% H2O were synthesised at 500 MPa confining pressure in internally heated gas pressure vessels at 1323 K (LMP, Al-poor glass) and 1423 K (LMAP, Al-enriched glass). Water contents of glasses were determined by pyrolysis and subsequent Karl-Fischer titration (KFT) and/or by infrared spectroscopy. Density varies nonlinearly with water content implying large structural changes when adding up to 2 wt% H2O to the dry glass. Glass Transition temperatures measured by differential thermal analysis (DTA) continuously decrease with water content. The trend can be explained by depolymerisation of the phosphate network. Near-infrared spectroscopy shows that even in Al poor glasses only a minority of dissolved water is present as H2O molecules, but the largest amount is present as OH Groups formed by hydrolysis of P–O–P bonds. The network is stabilised by aluminium which is predominantly six-coordinated in these glasses as shown by 27Al MAS NMR spectroscopy. With increase of Al in the glasses, breaking up of the Phosphate network through hydrolysis is depressed, i.e. much lower OH Contents are formed at same total water content. Network depolymerisation upon addition of H2O is evident also from 31P MAS NMR spectroscopy. While Phosphate tetraheda are crosslinked by two to three bridging oxygen in dry glasses, diphosphate Groups are dominant in glasses containing 8 wt% H2O. T2 - 2. INT. CONF. ON PHOSPHATE GLASSES CY - Oxford, UK DA - 26.07.2017 KW - water speciation KW - phosphate glasses KW - infrared spectroscopy KW - NMR spectroscopy KW - high pressure PY - 2019 DO - https://doi.org/10.13036/17533562.60.2.041 SN - 1753-3562 VL - 60 IS - 2 SP - 49 EP - 61 PB - Society of Glass Technology CY - Sheffield AN - OPUS4-48122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir A1 - Falkenberg, Rainer A1 - Skrotzki, Birgit T1 - Virtual-lab-based determination of a macroscopic yield function for additively manufactured parts N2 - This work aims for a yield function description of additively manufactured parts of S316L steel at the continuum-mechanical macro-scale by means of so-called virtual experiments using a crystal plasticity (CP) model at meso-scale. Additively manufactured parts require the consideration of the specific process-related microstructure, which prevents this material to be macroscopically treated as isotropic, because of crystallographic as well as topological textures. From virtual experiments, yield loci under various loading conditions are simulated. The scale bridging from meso- to macro-scale is realised by the identification of the simulated yield loci as a modified anisotropic Barlat-type yield model representation. T2 - Workshop on Additive Manufacturing, BAM CY - Berlin, Germany DA - 13.05.2019 KW - Virtual experiments KW - Additive manufacturing KW - Anisotropy KW - Crystal plasticity KW - Scale-bridging PY - 2019 AN - OPUS4-48064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mair, Georg A1 - Gesell, Stephan T1 - Betriebsfestigkeit von Composite-Wasserstoffspeichern – Ansatz zur Simulation der Auswirkung der erstmaligen Prüfung N2 - Druckbehälter werden vor ihrer Inbetriebnahme obligatorisch einer hydraulischen Prüfung bis zum sog. Prüfdruck belastet. Damit sollen fehlerhaft gefertigte Individuen erkannt und ausgesondert werden. Mit dieser Prüfung werden aber auch diejenigen Einzelbehälter ausgesondert, die ohne einem nachvollziehbaren Fertigungsfehler, nur auf Basis der statistischen Streuung ggf. eine Festigkeit unterhalb des Prüfdrucks aufweisen. Da der Prüfdruck im Fall der Wasserstoffspeicher mindestens 20% über dem maximal zulässigem Betriebsdruck liegt, wäre damit ein Versagen im Betrieb ausgenommen, gäbe es die verschiedenen Alterungs- bzw. Ermüdungseffekt nicht. Um den Einfluss der erstmaligen Prüfung auf eine angenommene ausfallfreie Zeit bewerten zu können, wird hier die Alterung und die erstmalige Prüfung in Kombination analysiert. Hierzu wird auf Basis der Restfestigkeitsdaten aus einer umfangreichen Prüfkampagne ein Ansatz für die Beschreibung der Alterung ermittelt und auf andere Lastzustände übertragen. So kann für das Baumuster, das der o.g. Prüfkampagne zugrunde lag, mithilfe einer Monte-Carlo-Simulation gezeigt werden, dass mindestens 10.000 LW vor einem ersten Alterungsversagen mit 1 aus 1 Mio. In Abhängigkeit der Anzahl der Individuen, die bei der erstmaligen Prüfung versagen, und der Streuung der gesamten Population, kann diese Mindestfestigkeit auf realistisch 50.000 Lastwechsel steigen. Damit ist gezeigt, dass aufgrund der erstmaligen Prüfung eine Mindestfestigkeit erzeugt wird, die stark vom Alterungsverhalten abhängt. Im Ergebnis heißt dies, dass in den Vorschriften aktuell die Bedeutung des Mindestberstdrucks in der Baumusterprüfung überschätzt und die möglichst betriebsbegleitende Erfassung der Alterung unterschätzt sind. T2 - 29. Tagung Technische Zuverlässigkeit- 2019 (02TA502019) CY - Nürtingen bei Stuttgart, Germany DA - 07.05.2019 KW - Mindedestberstdruck KW - Alterung KW - Betriebsfestigkeit KW - Restberstfestigkeit KW - Aussonderugnsrate PY - 2019 AN - OPUS4-48023 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Kalinka, Gerhard T1 - Deformation behavior of alumina and zirconia springs at room temperature N2 - At high temperatures and in harsh environments ceramic springs are often superior to metallic springs and allow for innovative solutions. A recently proposed application involves ceramic springs with metallized surfaces as capacitive force sensor. A strictly linear stress-strain characteristic of the spring is a precondition for such a sensor. Helical ceramic springs with rectangular cross-section have been produced from sintered hollow cylinders. Alumina, ATZ, Y-TZP, and Ce-TZP springs with identical dimensions were characterized and compared regarding deformation behavior. Spring deformation was investigated under various load scenarios. Dynamic compression was performed with deformation speeds from 0.3 to 30 mm/min. Spring constants of alumina springs are strain rate independent. By contrast, Y-TZP spring constant increases by approximately 3 % within the experimental framework. A high-precision test facility was developed to characterize spring displacement in nm range under static tensile load over long periods of time. Spring elongation with asymptotic course was observed for zirconia containing materials at room temperature. This effect is particularly strong in the case of Y-TZP. Up to 0.3 % time-dependent elongation was measured after 24 h under constant load. Deformation is completely reversible after unloading. Alumina springs do not show any time-dependent deformation under identical test conditions. Contrary to alumina springs, a non-linear stress-strain behavior of TZP springs at room temperature was proved in both test series. It is supposed, that pseudo-elasticity caused by stress-induced phase transformation from tetragonal to monoclinic is responsible for this special behavior of TZP springs. T2 - D-A-CH Keramiktagung CY - Leoben, Austria DA - 06.05.2019 KW - Phase transformation KW - Ceramic spring KW - Force-distance diagram KW - Deformation behavior PY - 2019 AN - OPUS4-48026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Avila, Luis A1 - Rehmer, Birgit A1 - Skrotzki, Birgit A1 - Graf, B. A1 - Rethmeier, Michael A1 - Ulbricht, Alexander T1 - Low cycle fatigue behavior, tensile properties and microstructural features of additively manufactured Ti-6Al-4V N2 - Despite of the significant advances in additive manufacturing (AM) process optimization there is still a lack of experimental results and understanding regarding the mechanical behavior and its relationship with the microstructural features of AM-parts, especially in loading conditions typical for safety-relevant applications. Within the scope of the presented ongoing investigations, a basic microstructural characterization, tensile tests at room and elevated temperature (400°C) as well as a characterization of the fatigue behavior of additively manufactured Ti-6Al-4V in the low cycle fatigue regime are carried out in the as-built state. After failure, different techniques are used to describe the failure mechanisms of the specimens. The AM-Specimens are provided by the Fraunhofer institute for production systems and design technology and investigated at the BAM following the philosophy of the TF-Project AGIL. T2 - Workshop on Additive Manufacturing: Process, materials, testing, simulation & implants CY - BAM, Berlin, Germany DA - 13.05.2019 KW - High Temperature Testing KW - Titanium KW - Ti-6Al-4V KW - Additive Manufacturing KW - DED-L KW - LMD KW - Computed Tomography KW - Microstructure KW - Tensile Properties KW - Low Cycle Fatigue PY - 2019 AN - OPUS4-48067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit A1 - Avila, Luis A1 - Charmi, Amir A1 - Falkenberg, Rainer A1 - Rehmer, Birgit T1 - Mechanical Testing and Simulations on AM Ti6Al4V and 316L N2 - First experimental results are shown on mechanical properties of additively manufactured alloy Ti6Al4V. A modelling and simulation approach is presented to describe the anisotropic behavior of 316L at the macro-scale. T2 - Workshop on Additive Manufacturing: Process, materials, testing, simulation & implants CY - BAM, Berlin, Germany DA - 13.05.2019 KW - AM KW - Mechanical behavior KW - Microstructure KW - Anisotropy KW - Modeling KW - Simulation PY - 2019 AN - OPUS4-48072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Bettge, Dirk A1 - Kratzig, Andreas A1 - Knauer, S. T1 - Factors Influencing Droplet Corrosion in Dense Phase CO2 N2 - Recent studies have shown that even at a very low concentration of impurities (less than 100 ppmv of SO2, NO2, O2 and H2O) the droplet formation and condensation of sulfuric and nitric acids in dense phase CO2 are possible and observable. To reveal the mechanism of droplet corrosion in dense phase CO2 at high pressure and low temperature, further studies on factors that affect wettability and resulting corrosion behaviors of transport pipeline steels are needed. In this study, effects of surface morphology were investigated by varying surface roughness of carbon steel coupons exposed to CO2 stream containing impurities to measure the wettability by contact angle and to observe the condensation as well as possible droplet corrosion that followed. Other considered factors were: pH of the droplet, temperature, droplet volume, and exposure time. T2 - NACE International Corrosion Conference 2019 CY - Nashville, TN, USA DA - 24.03.2019 KW - CCUS KW - Dense phase KW - CO2 KW - Droplet KW - Corrosion KW - Condensation KW - Carbon steel PY - 2019 SP - 13017-1 EP - 13017-13 PB - NACE International CY - Houston AN - OPUS4-47915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph A1 - Le, Quynh Hoa A1 - Kratzig, Andreas A1 - Bettge, Dirk A1 - Knauer, S. T1 - Factors Influencing Droplet Corrosion in Dense Phase CO2 N2 - This work examined the factors that influence the droplet corrosion of CO2 pipeline steels caused by oxyfuel flue gases in dense phase CO2 at 278 K, simulating the underground transport conditions. The wetting properties were studied by contact angle measurement, revealing pH and time dependency on the reactive wetting behaviors of carbon steel X70. Exposure tests with CO2 saturated water droplet on steel surface showed that the impurities (220 ppmv SO2 and 6700 ppmv O2) diffused into the droplet and then reacted with metal surfaces in dense phase condition, forming the corrosion products. The corrosion rate was confirmed strongly depending on the droplet volume as well as the SO2 concentration. Condensation experiments carried out on freshly polished coupons in CO2 with 200 ppmv H2O, 220 ppmv SO2 and 6700 ppmv O2, showed that the formation and aggregation of droplets is time and temperature dependent. At 278 K, condensation happened stronger and the corrosion products, mainly consisted of dense hydrated FeSO3/FeSO4. While at 288 K, more fluffy corrosion products consisting of iron oxide/hydroxide and hydrated FeSO3/FeSO4 were found. Further exposure tests on carbon steel coupons with different surface roughness did not reveal the difference in weight loss/gain and therefore the corrosion rate. T2 - NACE International Corrosion Conference 2019 CY - Nashville, TN, USA DA - 24.03.2019 KW - Carbon Capture, Utilization and Storage (CCUS) KW - Supercritical/dense phase CO2 KW - Carbon steel KW - Droplet corrosion KW - Condensation PY - 2019 AN - OPUS4-47916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Lüchtenborg, Jörg A1 - Günster, Jens A1 - Mühler, T. T1 - Layerwise Slurry Deposition for the Additive Manufacturing of Ceramics N2 - Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer, which can be used for SLM or for 3DP. This technique offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and is capable of producing parts with physical and mechanical properties comparable to traditionally shaped parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported. T2 - CIMTEC - International Ceramics Congress CY - Perugia, Italy DA - 04.06.2018 KW - Ceramic KW - Additive Manufacturing PY - 2018 AN - OPUS4-46337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Lüchtenborg, Jörg A1 - Günster, Jens A1 - Mühler, T. T1 - Powder-based Additive Manufacturing: beyond the comfort zone of powder deposition N2 - In powder-based Additive Manufacturing (AM) processes, an object is produced by successively depositing thin layers of a powder material and by inscribing the cross section of the object in each layer. The main methods to inscribe a layer are by binder jetting (also known as powder 3D printing) or by selective laser sintering/melting (SLS/SLM). Powder-based AM processes have found wide application for several metallic, polymeric and also ceramic materials, due to their advantages in combining flexibility, easy upscaling and (often) good material properties of their products. The deposition of homogeneous layers is key to the reproducibility of these processes and has a direct influence on the quality of the final parts. Accordingly, powder properties such as particle size distribution, shape, roughness and process related properties such as powder flowability and packing density need to be carefully evaluated. Due to these requirements, these processes have been so far precluded to find commercial use for certain applications. In the following, two outstanding cases will be presented. A first example is that powder-based AM processes are widely used for many metallic and polymeric materials, but they find no commercial application for most technical ceramics. This seemingly contradicting observation is explained by the fact that in powder based AM, a dry flowable powder needs to be used. The processing of technical ceramics in fact typically requires very fine and poorly flowable powder, which makes them not suitable for the standard processes. There have been several approaches to adapt the raw materials to the process (e.g. by granulation), but in order to maintain the superior properties of technical ceramics it seems necessary to follow the opposite approach and adapt the process to the raw materials instead. This was the motivation for developing the Layerwise Slurry Deposition (LSD), an innovative process for the deposition of powder layers with a high packing density. In the LSD process, a ceramic slurry is deposited to form thin powder layers, rather than using a dry powder. This allows achieving high packing density (55-60%) in the layers after drying. It is also important, that standard ceramic raw materials can be used. When coupled with a printing head or with a laser source, the LSD enables novel AM technologies which are similar to 3D printing or selective laser sintering, but taking advantage of having a highly dense powder bed. The LSD -3D printing, in particular, offers the potential of producing large (> 100 mm) and high quality ceramic parts, with microstructure and properties similar to traditional processing. Moreover, due to the compact powder bed, no support structures are required for fixation of the part in the printing process. Figure 1 shows the schematics of the working principle of the LSD-3D print and illustrates some examples of the resolution and features achievable. The second outstanding case here described is the application of powder-based AM in environments with reduced or zero gravity. The vision is to be able to produce repair parts, tools and other objects during a space mission, such as on the International Space Station (ISS), without the need of delivering such parts from Earth or carrying them during the mission. AM technologies are also envisioned to play an important role even for future missions to bring mankind to colonize other planets, be it on Mars or on the Moon. In this situation, reduced gravity is also experienced (the gravitational acceleration is 0.16 g on the Moon and 0.38 g on Mars). These environments cause the use of AM powder technologies to be very problematic: the powder layers need to be stabilized in order to avoid dispersion of the particles in the chamber. This is impossible for standard AM powder deposition systems, which rely on gravitation to spread the powder. Also in this case, an innovative approach has been implemented to face this technological challenge. The application of a gas flow through a powder has a very strong effect on its flowability, by generating a force on each particle, which is following the gas flow field. This principle can be applied in a simple setup such as the one shown in Figure 2. In this setup, the gas flow causes an average pressure on the powder bed in direction of the arrows, generating a stabilizing effect which acts in the same direction of the gravitational force. This effect can be used in addition to normal gravity on Earth to achieve a better stabilization of 3D printed parts in the powder bed. In this case, even a significant increase of packing density of the powder was measured, compared to the same experimental setup without gas flow. This is due to the fact that the force on each single particle follows the gas flow field, which is guiding the particles to settle between the pores of the powder bed, thus achieving an efficient packing. The same principle can be applied in absence of gravitation, where the gas flow acts to stabilize the powder layers. It has been shown that ceramic powder could be deposited in layers and laser sintered in µ-gravity conditions during a DLR (Deutsches Zentrum für Luft- und Raumfahrt) campaign of parabolic flights, as shown in Figure 2. A follow-up campaign is dedicated to the deposition of metallic (stainless steel) powder in inert atmosphere and to study the effects of laser melting in µ-gravity. In conclusion, the description of these two example cases shows how the development of novel technological processes can address some of the limitations of standard powder-based AM, in order to enable the use of new materials, such as technical ceramics, or to tackle the challenges of AM in space. T2 - WMRIF 2018 Early Career Scientist Summit CY - London, NPL, UK DA - 18.06.2018 KW - 3D-printing KW - Additive Manufacturing KW - Powder KW - SLM PY - 2018 AN - OPUS4-46338 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mair, Georg A1 - Becker, B. A1 - Gesell, Stephan A1 - Wang, Bin T1 - Monte-Carlo-analysis of minimum load cycle requirements for composite cylinders for hydrogen N2 - Hydrogen is an attractive energy carrier that requires high effort for safe storage. For ensuring safety, storage cylinders must undergo a challenging approval process. Relevant standards and regulations for composite cylinders used for the transport of hydrogen and for its onboard storage are currently based on deterministic (e.g. ISO 11119-3) or to some respect semi-probabilistic criteria (UN GTR No. 13; with respect to burst strength). This paper provides a systematic analysis of the load cycle properties resulting from these regulations and standards. Their characteristics are compared with the probabilistic approach of the Federal Institute for Materials Research and Testing BAM. The most important aspect of comparing different concepts is the rate for accepting designs with potentially unsafe or critical safety properties. This acceptance rate is analysed by operating Monte-Carlo simulations over the available range of production properties. T2 - ICHS 2017 CY - Hamburg, Germany DA - 11.09.2017 KW - Safety assessment KW - Failure rate KW - Ageing KW - Degradation KW - End of life KW - Production scatter PY - 2018 DO - https://doi.org/10.1016/j.ijhydene.2018.09.185 SN - 0360-3199 VL - 44 IS - 17 SP - 8833 EP - 8841 PB - Elsevier Ltd AN - OPUS4-46341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Peetz, Christoph A1 - Buggisch, Enrico A1 - Bettge, Dirk A1 - Kranzmann, Axel T1 - Electrochemical study on wellbore constellations for CO2 injection N2 - Carbon Capture and Storage (CCS) is identified as an excellent technology to reach the target of CO2 reduction. However, the safety issue and cost effectiveness hinder the future of CCS. For the reliability and safety issues of injection wells the corrosion resistance of the materials used needs to be determined. In this study, representative low cost materials including carbon steel 1.8977 and low alloyed steel 1.7225 were embedded in cement to mimic the realistic casing-cement interface. Electrochemical studies were carried out using these metal-cement specimens in comparison with those made of metal only in CO2 saturated synthetic aquifer fluid, at 333 K, to reveal the effect of cement on the steel performance. The results showed the protective effect of cement on the performance of pipeline metals during polarisation process. However, the corrosion current density was high in all cases, with and without cement, indicating that the corrosion resistance of these materials is low. This conclusion was supported by the surface analysis of the polarized specimens, which revealed both homogenous and pitting corrosions. Furthermore, to reveal the possible protective performance of FeCO3, the pipeline steels were pre-carbonated and then tested in the same condition as freshly polished specimens. T2 - EUROCORR 2018 CY - Krakow, Poland DA - 09.09.2018 KW - CCUS KW - Supercritical/dense phase CO2 KW - Carbon steels KW - Martensitic steel KW - Superaustenite steel KW - Injection KW - Impurities PY - 2018 AN - OPUS4-46279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Peetz, Christoph A1 - Buggisch, Enrico A1 - Bettge, Dirk A1 - Kranzmann, Axel T1 - Electrochemical study on wellbore constellations for CO2 injection N2 - Carbon Capture and Storage (CCS) is identified as an excellent technology to reach the target of CO2 reduction. However, the safety issue and cost effectiveness hinder the future of CCS. For the reliability and safety issues of injection wells the corrosion resistance of the materials used needs to be determined. In this study, representative low cost materials including carbon steel 1.8977 and low alloyed steel 1.7225 were embedded in cement to mimic the realistic casing-cement interface. Electrochemical studies were carried out using these metal-cement specimens in comparison with those made of metal only in CO2 saturated synthetic aquifer fluid, at 333 K, to reveal the effect of cement on the steel performance. The results showed the protective effect of cement on the performance of pipeline metals during polarisation process. However, the corrosion current density was high in all cases, with and without cement, indicating that the corrosion resistance of these materials is low. This conclusion was supported by the surface analysis of the polarized specimens, which revealed both homogenous and pitting corrosions. T2 - EUROCORR 2018 CY - Krakow, Poland DA - 09.09.2018 KW - CCUS KW - Supercritical/dense phase CO2 KW - Carbon steels KW - Martensitic steel KW - Superaustenite steel KW - Injection KW - Impurities PY - 2018 SP - 1 EP - 4 PB - EFC CY - Krakau, Poland AN - OPUS4-46291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Balzer, R. A1 - Kiefer, P. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Sub-critical crack growth in silicate glasses N2 - Environmental conditions are known to influence sub-critical crack growth (SCCG) that are released from microscopic flaws at the glass surface, leading to stress corrosion phenomena at the crack tip. The processes at the crack-tip are complex and water has been identified as a key component governing SCCG at low crack velocities (region I). In particular, the influence of humidity accelerating crack propagation is well studied for industrial soda-lime silicate glasses, which are practically free (< 1000 ppm) of dissolved water. To shed light on the corrosion process, the situation at the crack-tip is reversed in the present study as dissolved water in larger fractions is present in the glass and crack propagation is triggered in dry environment. For this purpose, water-bearing silicate glasses of up to 8 wt% total water were synthesized in an internally heated pressure vessel at 0.5 GPa and compared to dry glasses of standard glass manufacturing. SCCG was measured using the double cantilever beam technique and by Vickers indentation. For dry glasses, three trends in the crack growth velocity versus stress intensity curve were found. The slope in region I limited by environmental corrosion increases in the order sodium aluminosilicate < sodium borosilicate ≲ sodium lead silicate. The velocity range of region II reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among the glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam1/2. For hydrous glasses, it is found that those of low Tg are more prone to SCCG. As water strongly decreases Tg, it promotes SCCG. First results indicate that molecular water has a dominating influence on SCCG. T2 - ICG Annual Meeting 2018 CY - Yokohama, Japan DA - 23.09.2018 KW - DCB KW - Glass KW - Crack growth KW - Water speciation PY - 2018 AN - OPUS4-47164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falkenberg, Rainer T1 - Modelling of environmentally assisted material degradation in the crack phase-field framework N2 - The simulation of crack propagation was conducted with a diffusive crack model in a variational framework. Moreover, the physically sound introduction of mass transport and coupling mechanisms due to environmentally assisted effects could be realised in this framework. The objective consists of the application of the phase-field Approach towards the simulation of environmentally assisted material degradation with the advantage of a non-required predefined crack path and a mesh-independent non-local formulation that facilitates the damage evolution with respect to material softening. The sharp crack is regularised by the introduction of a phase-field order parameter leading to a diffusive crack formulation. Besides the equations originating from the linear momentum balance an additional evolution equation for the crack phase-field is introduced. Furthermore, mass transport is simulated by a Diffusion equation. The description delivered by the variational phase-field framework is able to simulate crack propagation according to published numerical test cases. Additionally, the calculation of stress intensity factors is possible as well as crack resistance curves that describe stable crack propagation. KW - Fracture mechanics KW - Crack propagation KW - Phase-field KW - Mass transport KW - Environmentally assisted cracking PY - 2019 DO - https://doi.org/10.1177/1464420718761220 SN - 1464-4207 VL - 233 IS - 1 SP - 5 EP - 12 PB - SAGE AN - OPUS4-47152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbricht, Jürgen A1 - Jürgens, Maria A1 - Mosquera Feijoo, Maria A1 - Agudo Jácome, Leonardo A1 - Roohbakhshan, Farshad A1 - Saliwan Neumann, Romeo A1 - Nolze, Gert A1 - Fedelich, Bernard A1 - Kranzmann, Axel A1 - Skrotzki, Birgit T1 - Performance of 9-12%Cr steels under cyclic loading and cyclic oxidation conditions N2 - 9-12% Cr ferritic-martensitic stainless steels are widely used as high temperature construction materials in power plants due to their excellent creep and oxidation resistance. The growing share of renewable energy sources in power generation forces many of these plants into more flexible operation with frequent load shifts or shutdowns. These cyclic operation profiles constitute a major lifetime issue. The present contribution reports on current findings obtained in a multidisciplinary project which combines cyclic mechanical and cyclic oxidation testing with detailed microstructural analyses. Mechanical analyses are carried out on P92 and P91 steel grades to give an overview of softening phenomena and lifetimes obtained in isothermal cyclic loading (low cycle fatigue, LCF), non-isothermal cyclic loading (thermo-mechanical fatigue, TMF), and service-like combinations of creep and fatigue periods (creep-fatigue interaction). Oxidation testing focuses on the grades P92 and VM12 with the intention of clarifying the impact of frequent passes through intermediate temperature levels on the kinetics of steam-side oxidation and the characteristics of the evolving oxide scales. An attempt is made to evaluate their composition, strength, integrity and adhesion after up to 250 temperature cycles. Flat coupons as well as curved tube sections are tested to assess the mutual influence of geometry on oxide scale integrity. Complementary microstructural investigations by scanning and transmission electron microscopy plus EBSD are used for phase identification and substrate/oxide interface characterisation. The evolutions of grain size and dislocation density under different test conditions are quantified. T2 - International Conference on Power Plant Operation & Flexibility CY - London, UK DA - 04.07.2018 KW - Ferritic-martensitic steels KW - Low cycle fatigue KW - Thermo-mechanical fatigue KW - Cyclic oxidation PY - 2018 AN - OPUS4-47115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbricht, Jürgen A1 - Jürgens, Maria A1 - Agudo Jácome, Leonardo A1 - Nolze, Gert A1 - Roohbakhshan, Farshad A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - Cyclic loading and creep-fatigue performance of P92 N2 - 9-12% Cr ferritic-martensitic stainless steels are widely used as high temperature construction materials in power plants due to their excellent creep and oxidation resistance. The growing share of renewable energy sources in power generation forces many of these plants into more flexible operation with frequent load shifts or shutdowns. These cyclic operation profiles constitute a major lifetime issue. The present contribution reports on current findings obtained in a multidisciplinary project which combines cyclic mechanical and cyclic oxidation testing of different 9-12% Cr grades with detailed microstructural analyses. Mechanical analyses are carried out on P92 and P91 steel grades to give an overview of softening phenomena and lifetimes obtained in isothermal cyclic loading (low cycle fatigue, LCF), non-isothermal cyclic loading (thermo-mechanical fatigue, TMF), and service-like combinations of creep and fatigue periods. Complementary microstructural investigations by scanning and transmission electron microscopy plus EBSD are used for phase identification, substrate/oxide interface characterization and quantification of the microstructure evolution under cyclic conditions. T2 - 44th MPA-Seminar CY - Leinfelden/Stuttgart, Germany DA - 17.10.2018 KW - Ferritic-martensitic steels KW - Fatigue KW - Creep-fatigue PY - 2018 AN - OPUS4-47116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbricht, Jürgen A1 - Agudo Jácome, Leonardo A1 - Jürgens, Maria A1 - Roohbakhshan, Farshad A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - Cyclic loading performance and related microstructure evolution of ferritic-martensitic 9-12% Cr steels N2 - The current competitive situation on electricity markets forces power plants into cyclic operation regimes with frequent load shifts and starts/shutdowns. In the present work, the cyclic mechanical behavior of ferritic-martensitic 9-12 % Cr steels under isothermal and thermomechanical loading was investigated for the example of grade P92 material. A continuous softening was observed under all loading conditions. The introduction of hold periods to the applied cycles reduced material lifetime, with most prominent effects at technologically relevant small strain levels. The microstructural characterization reveals a coarsening of the original “martensitic” lath-type microstructure to a structure with polygonal subgrains and reduced dislocation density. The microstructural data forms the input for a physically-based modelling approach. T2 - 44th MPA-Seminar CY - Leinfelden/Stuttgart, Germany DA - 17.10.2018 KW - Ferritic-martensitic steels KW - Cyclic loading KW - Microstructure evolution PY - 2018 SP - 259 EP - 265 AN - OPUS4-47118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häusler, Ines A1 - Darvishi Kamachali, Reza A1 - Hetaba, W. A1 - Skrotzki, Birgit T1 - Thickening of T-1 Precipitates during Aging of a High Purity Al–4Cu–1Li–0.25Mn Alloy N2 - The age hardening response of a high-purity Al–4Cu–1Li–0.25Mn alloy (wt. %) during isothermal aging without and with an applied external load was investigated. Plate shaped nanometer size T1 (Al2CuLi) and θ′ (Al2Cu) hardening phases were formed. The precipitates were analyzed with respect to the development of their structure, size, number density, volume fraction and associated transformation strains by conducting transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) studies in combination with geometrical Phase analysis (GPA). Special attention was paid to the thickening of T1 phase. Two elementary types of single-layer T1 precipitate, one with a Li-rich (Type 1) and another with an Al-rich (Defect Type 1) central layer, were identified. The results show that the Defect Type 1 structure can act as a precursor for the Type 1 structure. The thickening of T1 precipitates occurs by alternative stacking of These two elementary structures. The thickening mechanism was analyzed based on the magnitude of strain associated with the precipitation transformation normal to its habit plane. Long-term aging and aging under load resulted in thicker and structurally defected T1 precipitates. Several types of defected precipitates were characterized and discussed. For θ′ precipitates, a ledge mechanism of thickening was observed. Compared to the normal aging, an external load applied to the peak aged state leads to small variations in the average sizes and volume fractions of the precipitates. KW - Al-Cu-Li-alloy KW - Precipitation KW - T1 precipitate KW - Microstructure evolution KW - Thickening KW - Creep KW - Volume fraction KW - Number density KW - Strain difference PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-471207 DO - https://doi.org/10.3390/ma12010030 SN - 1996-1944 VL - 12 IS - 1 SP - 30, 1 EP - 23 PB - MDPI AN - OPUS4-47120 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sommer, Konstantin A1 - Kranzmann, Axel A1 - Reimers, W. T1 - Microstructure characterization of additive produced parts N2 - Due to the advantages of additive manufacturing (AM), it has been increasingly integrated into many industrial sectors. The application of AM materials for safety-critical parts requires the detailed knowledge about their microstructure stability under thermo-mechanical or mechanical load and knowledge on ageing process mechanisms. Ageing processes are characterized by change of the material microstructure that is to be initially investigated. This work deals with the Investigation of 316L stainless steel manufactured by selective laser melting (SLM). Describing Parameters must be defined and applied on the microstructure of these materials in their initial state and after loads were applied. The findings of this work form the basis for the investigation of AM material ageing. T2 - FEMS Junior EUROMAT 2018 CY - Budapest, Hungary DA - 08.07.2018 KW - Additive manufacturing KW - Selective laser melting KW - 316L KW - Material characterization KW - Microstructure PY - 2018 AN - OPUS4-47176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gesell, Stephan T1 - WP8 - RCS standardisation work N2 - The presentation presents a first work premise for the acceptable failrate of a hydrogen pressure vessel. Based on this premise, the basic algorithm for the analysis of given acceptance criteria is presented. T2 - TAHYA PSB Meeting#1 CY - TU Chemnitz, Germany DA - 20.11.2018 KW - FCH JU KW - TAHYA KW - Horizon 2020 KW - Safety assessment PY - 2018 AN - OPUS4-47178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Roohbakhshan, Farshad A1 - Olbricht, Jürgen A1 - Fedelich, Bernard A1 - Skrotzki, Birgit T1 - Dislocation-based modeling of high temperature deformation and fatigue in P92 ferritic-martensitic steels N2 - The employment of renewable energy resources, which are naturally intermittent, for electricity generation has altered the working conditions of conventional power plants from continuous (baseload) to cyclic or flexible operation. For a long time, 9-12% Cr ferritic-martensitic stainless steels have been widely used in power plants due to their favorable characteristics such as high creep strength at high temperatures and oxidation and corrosion resistance. The components of power plants are subjected to long term cyclic loadings including fatigue and creep-fatigue at high temperatures. As ferritic-martensitic steels are known to exhibit cyclic softening when subjected to such loading scenarios, it is crucial to study the material response in such conditions. Since it is impossible to test the material behavior exactly as the operation conditions of power plants, due to technical difficulties and cost issues, it is necessary to develop physically-based material models that can predict the material behavior in more realistic situations. In recent years, many material models have been proposed to describe the behavior of 9-12% Cr ferritic-martensitic stainless steels, which follow phenomenological or physically-based approaches. Phenomenological models provide a stress-strain relation based on empirical observations although they usually lack physical background. To alleviate this drawback and to allow for more flexibility and wider ranges of strain-rate and temperature, physically-based models are suggested. In this approach, microstructural evolution, dislocation movement and/or kinetics of plastic deformation processes are included. The physically-based models allow for a better extrapolation from the experiment results to other operation conditions and their material constants can be interpreted physically. Compared to the former approach, the material behavior can be described more accurately and flexibly and the number of material constants is less in general. In the presented work, the existing micromechanical models developed for P92 steel are compared and extended to allow for new dislocation-based strengthening/cyclic mechanisms. Their performance is assessed in the light of mechanical test data from creep-fatigue and thermo-mechanical fatigue experiments and detailed characterizations of the microstructure evolution in the fatigued material. T2 - 12th International Fatigue Congress CY - Poitiers, France DA - 27.05.2018 KW - 9-12% Cr ferritic-martensitic steels KW - Cyclic softening KW - Micromechanical model KW - Microstructural evolution KW - P92 steels PY - 2018 AN - OPUS4-47101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Klinger, Christian A1 - Bettge, Dirk A1 - Murakami, Y. T1 - Defects as a root cause of fatigue failure of metallic components. I: Basic aspects N2 - According to the definition of the ASM handbook [1,3], a defect is "an imperfection. that can be shown to cause failure by a quantitative analysis and that would not have occurred in the absence of the imperfection". The topic of the present three-part review is a discussion of defects which can cause failure in cyclically loaded structures. The features discussed comprise material defects such as non-metallic inclusions, pores or micro-shrinkages, etc. and geometric defects such as surface roughness and secondary notches which have their origin in manufacturing, and defects such as surface damage due to scratches, impact events or contact fatigue as well as corrosion pits which arise in service. In this first part, the discussion is prefaced by an introduction to basic aspects which are essential for a deeper understanding of the characteristics and mechanisms how the defects influence fatigue crack initiation and propagation. These include the life cycle of a fatigue crack from initiation up to fracture, crack arrest, multiple crack initiation and coalescence, and the material and geometrical properties affecting these. KW - Defects KW - Fatigue crack propagation stages KW - Crack arrest KW - Multiple cracks PY - 2019 DO - https://doi.org/10.1016/j.engfailanal.2019.01.055 SN - 1350-6307 VL - 97 SP - 777 EP - 792 PB - Pergamon-Elsevier Science Ltd CY - Oxford, England AN - OPUS4-47372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Klinger, Christian A1 - Bettge, Dirk A1 - Murakami, Y. T1 - Defects as a root cause of fatigue failure of metallic components. III: Cavities, dents, corrosion pits, scratches N2 - This third part of the review on defects as root cause of fatigue failure addresses cavities (pores, micro-shrinkages, unmelted regions), defective microstructures and microcracks as material defects and defects due to local damage during manufacturing, service and maintenance such as dents, scratches and localized corrosion. In addition, damage due to contact fatigue and the effect of surface roughness are discussed in the context of fatigue failure. Also addressed is the competition between different kinds of defects in controlling the initiation and early growth of fatigue cracks. KW - Pores KW - Micro-shrinkages KW - Impact damage KW - Contact fatigue KW - Corrosion pits KW - Scratches PY - 2019 DO - https://doi.org/10.1016/j.engfailanal.2019.01.034 SN - 1350-6307 VL - 97 SP - 759 EP - 776 PB - Pergamon-Elsevier Science Ltd CY - Oxford, England AN - OPUS4-47373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Sonntag, Nadja T1 - Untersuchung magnetischer Streufelder in einem inhomogen verformten Baustahl mittels passiv-magnetischer Prüfverfahren N2 - Die Metal Magnetic Memory (MMM) Methode ist ein standardisiertes, zerstörungsfreies Prüfverfahren, das für die Detektion von lokal geschädigten Materialbereichen in ferromagnetischen Bauteilen oder Proben verwendet wird. Es basiert auf der Annahme lokaler magnetoelastischer Wechselwirkungen an Spannungskonzentrationsstellen, die schwache magnetische Streufelder an den geschädigten Prüfkörperoberflächen hervorrufen. Die MMM-Methode überträgt dabei die für einachsige und elastische Verformungen entwickelten magnetoelastischen Modellvorstellungen ohne weitere Anpassungen in den Schädigungskontext, der jedoch mehrachsige Beanspruchungen und elastisch-plastische Deformationsprozesse erwarten lässt. Das Ziel der Arbeit ist es daher, die gängigen MMM-Hypothesen zur Signalentstehung fach- und skalenübergreifend und unter stärkerer Berücksichtigung mechanischer und mikrostruktureller Aspekte zu überprüfen. Zu diesem Zweck wurden zum einen gekerbte Flachzugproben aus einem unlegierten Baustahl inhomogen elastisch-plastisch verformt und die entstehenden magnetischen Streufelder an deren Oberflächen mit einem Drei-Achsen-GMR-Magnetometer detektiert. Die so ermittelten Magnetfeld-verteilungen wurden für unterschiedliche Verformungszustände ortsaufgelöst und richtungsabhängig mit gemessenen Dehnungsverteilungen (digitale Bildkorrelation) und mit simulierten Lastspannungs-verteilungen korreliert. Die eingeschnürten Probenbereiche wurden zusätzlich topographisch mittels Streifenlichtprojektion und Weißlichtinterferenzmikroskopie vermessen, um den Magnetisierungs-prozess ebenfalls vor dem Hintergrund geometrischer Effekte diskutieren zu können. Um systematische, verformungsinduzierte Veränderungen der magnetischen Mikrostruktur (magnetischer Domänen) im polykristallinen, quasi-isotropen Material nachzuweisen, wurde zum anderen ein in dieser Arbeit entwickelter statistischer Ansatz der Domänenanalyse angewandt. Hierfür wurde das Material zunächst durch Härteeindrücke mehrachsig elastisch-plastisch verformt, und die verformten Probenbereiche wurden anschließend mit Hilfe der Bitterstreifentechnik hauptsächlich bei niedriger Vergrößerung lichtmikroskopisch untersucht. Die beobachteten makroskopischen Domänen-kontraste wurden über ein analytisches, kontaktmechanisches (ECM-) Modell und über Makro-Eigen-spannungsmessungen (energiedispersive Synchrotron-Beugungsuntersuchungen) charakteristischen Verformungszonen unter den Härteeindrücken zugeordnet. Die Ergebnisse dieser Untersuchungen belegen, dass die Entstehung der Streufelder – entgegen bisheriger Annahmen – nicht allein auf mechanische Spannungs- und Verformungsgradienten im Material zurückzuführen, sondern auch topographisch bedingt ist. Die Vernachlässigung überlagerter geometrischer Effekte kann zu sicherheitsrelevanten Fehlinterpretationen der magnetischen Signale führen. Einachsige magnetoelastische Modellvorstellungen sollten zudem nicht ohne Anpassungen auf komplexe Beanspruchungen übertragen werden, da u. a. sowohl mechanische Größen (wie Spannungen oder Dehnungen) als auch mikrostrukturelle Parameter (wie z. B. Versetzungsdichten) bei komplexen Belastungen als ortsabhängige Variablen behandelt werden müssen. Die in dieser Arbeit beobachteten Domänenkontraste lassen sich zweifelsfrei charakteristischen Verformungszonen zuordnen, mikro-strukturell jedoch nicht allein mit anzunehmenden Gradienten der Versetzungsdichte erklären. Statt-dessen entstehen beispielsweise lokale Verformungstexturen, die zusätzliche magnetische Anisotropien bewirken könnten. Da bisher weder die makroskopischen noch die mikrostrukturellen Ursachen der Streufeldentstehung hinreichend verstanden sind, scheint die MMM-Methode für die quantitative Bewertung des Schädigungszustands derzeit ungeeignet. N2 - The Metal Magnetic Memory (MMM) method is a standardized, nondestructive testing method used for the detection of locally damaged material areas in ferromagnetic components or samples. It assumes local magnetoelastic interactions in stress concentration zones, causing weak magnetic stray fields on the damaged specimen surfaces. The MMM method transfers magnetoelastic model conceptions developed for uniaxial and elastic deformations without further adjustments into the damage context, which is, however, associated with multiaxial stresses and elastic-plastic deformations. The objective of this thesis is therefore to verify prevalent MMM hypotheses concerning the signal generation, putting emphasis on complex mechanical and microstructural aspects of damage while using interdisciplinary and multi-scale approaches. To this end, on the one hand, notched tensile specimens made of an unalloyed structural steel were inhomogeneously (elastically and plastically) deformed and deformation-induced magnetic stray fields were then detected by a three-axis GMR magnetometer. The obtained surface magnetic field distributions were correlated with measured strain distributions (digital image correlation) and with numerically simulated mechanical stress distributions (finite element analysis). To enable discussions on the magnetization process against the background of geometrical effects, the necked specimen regions were additionally investigated using optical profilometry methods (fringe projection and white light interference microscopy). On the other hand, a newly developed meso-scale approach to magnetic domain analysis was applied to prove systematic, deformation-induced changes of the magnetic microstructure within the polycrystalline, quasi-isotropic material: After multiaxial elastic-plastic deformation of coupon specimens by hardness indentation, the deformed sample regions were studied by Bitter technique in optical microscopy, preferably at low magnification. The observed macroscopic domain contrasts were related to characteristic deformation zones below the indents by using an analytical model from the field of contact mechanics (ECM) and macro-residual stress measurements (obtained from energy-dispersive synchrotron diffraction experiments). It is demonstrated that the formation of magnetic stray fields, quite contrary to previous assumptions, results not only from mechanical (e.g. stress) gradients within the material, but is also topographically induced. The neglect of such superimposed geometric effects may also lead to safety-relevant misinterpretations of the magnetic signals. Furthermore, uniaxial magnetoelastic model concepts should not be applied to complex stress/strain conditions without adaptation since both mechanical quantities (such as stresses or strains) and microstructural parameters (such as dislocation densities) must be treated as location-dependent variables. The observed magnetic domain contrasts could clearly be assigned to characteristic deformation zones but cannot be explained solely by hypothesized gradients of the dislocation density. Instead, for example, local deformation textures emerge, which may cause additional magnetic anisotropies. The MMM method currently seems unsuitable for quantitative damage assessments of components or specimens since neither the macroscopic nor the microstructural origins of the stray field formation have yet been sufficiently understood. KW - Magnetoelastischer Effekt KW - Magnetische Domänen KW - Mehrachsige Verformung KW - Schädigung KW - Unlegierter Baustahl KW - Magnetoelastic effect KW - Magnetic domains KW - Multiaxial deformation KW - Damage KW - Structural steel PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484302 DO - https://doi.org/10.14279/depositonce-8524 SP - 1 EP - 117 CY - Berlin AN - OPUS4-48430 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Schönauer-Kamin, D. A1 - Moos, R. A1 - Giovanelli, F. A1 - Rabe, Torsten T1 - Influence of pressure assisted sintering and reaction sintering on microstructure and thermoelectric properties of bi-doped and undoped calcium cobaltite N2 - Calcium cobaltite (Ca3Co4O9) is considered as one of the most promising thermoelectric p-type oxides for energy harvesting applications at temperatures above 500 °C. It is challenging to sinter this material as its stability is limited to 920 °C. To facilitate a practicable and scalable production of Ca3Co4O9 for multilayer generators, a systematic study of the influence of powder calcination, Bi-doping, reaction sintering, and pressure-assisted sintering (PAS) on microstructure and thermoelectric properties is presented. Batches of doped, undoped, calcined, and not calcined powders were prepared, tape-cast, and sintered with and without uniaxial pressure at 900 °C. The resulting phase compositions, microstructures and thermoelectric properties were analysed. It is shown that the beneficial effect of Bi-doping observed on pressureless sintered samples cannot be transferred to PAS. Liquid phase formation induces distortions and abnormal grain growth. Although the Seebeck coefficient is increased to 139 µV/K by Bi-doping, the power factor is low due to poor electrical conductivity. The best results were achieved by PAS of calcined powder. The dense and textured microstructure exhibits a high power factor of 326 µW/mK² at 800 °C but adversely high thermal conductivity in the relevant direction. The figure of merit is higher than 0.08 at 700 °C. KW - Ceramics KW - Calcium cobaltite KW - Thermoelectric properties KW - Calcination KW - Pressure-assisted sintering PY - 2019 DO - https://doi.org/10.1063/1.5107476 SN - 0021-8979 VL - 126 IS - 7 SP - 075102-1 EP - 075102-11 PB - AIP Publishing CY - Melville AN - OPUS4-48708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Feldmann, Titus A1 - Charmi, Amir A1 - Epishin, A. T1 - Simulation of pore shrinkage with crystal plasticity and dislocation transport N2 - Single crystal superalloys usually contain pores of sizes 5-10 micro-m after casting and heat treatment. These pores can be reduced under compression by combined creep and diffusion in a subsequent treatment called Hot Isostatic Pressing (HIP). The paper presents a methodology to simulate pore shrinkage under HIP conditions in two dimensions (2D). At the scale of the pores, which is also the scale of the sub-grains (<50 micro-m) the dislocation sources cannot be assumed to be homogeneously distributed. Thus, the applicability of classical crystal plasticity is questionable. In this case, the transport of dislocations under an applied stress from the location where they are nucleated must be explicitly modelled. This is done by solving the transport equations for the dislocation densities and the elasticity equations in 2D. The dislocations are assumed to be nucleated at Low Angle Boundaries. They glide or climb through the sub-grains with a stress dependent velocity. The transport equations are solved by the Flux-Corrected Transport method, which belongs to the predictor-corrector class of algorithms. In the first step, an artificial diffusion is introduced, which suppresses spurious oscillations of the solution. In a second step, the solution is corrected in such a way that no additional extremes appear and that the extremes do not grow. The algorithm is validated by simulating the transport of simple distributions with a constant velocity field. With the dislocation velocities and the computed dislocation densities, the inelastic shear rate at the slip system level is computed by integrating the Orowan equation. In the 2D-setting, three slip systems are considered. The contributions of these slip systems are summed up to obtain the total inelastic strain rate. Dislocation glide and climb and the coupling of climb with vacancies diffusion are considered. The resolution of the equilibrium equations from the inelastic strains turned out to be prone to numerical instabilities. As an alternative, the stresses are directly computed from the distribution of geometrically necessary dislocations following the method presented in. The resulting boundary value problem is solved by the Least-Square Finite Element method. Examples of simulations are presented for a representative region under creep tension and for a pore shrinking under external pressure. T2 - International Conference on Material Modelling, ICMM 6 CY - Lund, Sweden DA - 26.06.2019 KW - Superalloy KW - Pores KW - Creep KW - Dislocations PY - 2019 AN - OPUS4-48488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kiefer, P. A1 - Balzer, R. A1 - Deubener, J. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Density, elastic constants and indentation hardness of hydrous soda-lime silica glasses N2 - The effect of structural water on density, elastic constants and microhardness of water-bearing soda-lime-silica glasses of up to 21.5 mol% total water is studied. It is found that the Poisson ratio and the water content are positively correlated, while density and the elastic moduli decrease with increasing water content. Vickers hardness decreases by approximately 27% from the dry to the most hydrous glass. For water fractions <3 mol%, the dependencies are non-linear reflecting the non-linear change in the concentrations of OH and H2O molecules dissolved, whereas for water fractions >3 mol% linear dependencies are found. To distinguish the effect of structural water and environmental water, indentations were performed in toluene, nitrogen gas and air. Timedependent softening was evident for testing dry glasses in humid atmospheres as well as for tests of hydrous glasses in dry atmospheres. This indicates that the response times of dissolved water species are effectively equal in both scenarios. KW - Elastic constants KW - Soda-lime-silica KW - Glass KW - Water content KW - Microhardness PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.119480 SN - 0022-3093 SN - 1873-4812 VL - 521 SP - 119480 PB - Elsevier B.V. AN - OPUS4-48758 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Schuth, S. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Fechtelkord, M. A1 - Deubener, J. T1 - The influence of H2O and SiO2 on the structure of silicoborate glasses N2 - To understand the impact of dissolved water on structure and properties, four boron-rich glasses of molar compositions 15-x Na2O x CaO 15 SiO2 70 B2O3 (with x=0, 7.5, 10) and 10 Na2O 15 SiO2 75 B2O3 were prepared and subsequently hydrated (up to 8 wt% H2O). Density measurements show a non-linear trend upon hydration implying large structural changes in particular at water contents<2 wt%. Near-infrared spectroscopy shows hydroxyl groups are the dominant species in all glasses upon the entire range of water content. Molecular H2O is detectable only at total water contents>2 wt%. 11B MAS NMR spectra show that the abundance of BO4 species is mainly controlled by ratio of (Na2O+CaO)/B2O3 while incorporation of water plays a minor role. Compared to borate glasses, the efficiency of formation of BO4 tetrahedra is favored by crosslinking of the network by SiO4-units. The glass transition temperatures, determined by differential thermal analysis, decreases continuously with water content due to breakage of B-O-B bonds by hydrolysis. However, compared to Silicates and aluminosilicates, the effect of dissolved water is less pronounced which can be explained by weaker B-O-B bonds in comparison to Si-O-Si bonds. KW - High pressure KW - Water speciation KW - Silicoborate glasses KW - Infrared spectroscopy KW - NMR spectroscopy PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.05.030 VL - 519 SP - 38 EP - 51 PB - Elsevier B.V. AN - OPUS4-48748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Ou, D. A1 - Ghafafian, Carineh A1 - Zscherpel, Uwe A1 - Trappe, Volker T1 - Wind turbine rotor blade testing by dual-energy laminography N2 - Modern wind turbine rotor blades consist of sandwich shell segments made from glass fiber reinforced polymers. During manufacturing, defects can arise which could lead to failure of the whole component under dynamic mechanical and thermal loads. Hence during operation defects can arise which, if detected, can be repaired locally and in-situ by applying repair patches instead of taking the whole rotor blade down and repair it remotely. This method is much more time and cost effective, since the shut-down time of the energy converter is limited to a minimum. These repair patches can, however, also lead to new defects if not applied optimally. Therefore, it is necessary to control the quality of the repair patches to ensure the best possible restoration of structural integrity of the component. As a rotor blade is an object with a large aspect ratio, X-ray laminography is predestined to provide 3D information of the objective volume. To enhance the amount of information gained from laminographic reconstruction, we use in this study a photon counting and energy discriminating X-ray detector and apply a material decomposition algorithm to the data. By inherently separating the incident spectra within the detection process into two distinct energy bins, the basis material decomposition can provide material resolved images. Choosing glass and epoxy resin as basis materials and numerically solving the inverse dual-energy equation system, the reconstructed laminographic datasets contain highly valuable information about the distribution of the basis materials within the structure. Furthermore, cross- artifacts arising from the limited angle of the projection data can be reduced by this method which allows to investigate structures that were hidden underneath the artefacts. T2 - International Symposium on Digital Industrial Radiology and Computed Tomography – DIR2019 CY - Fürth, Germany DA - 02.07.2019 KW - Laminography KW - Wind energy KW - Fiber reinforced polymer KW - Photon counting detector KW - Repair patch PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484380 UR - https://www.dir2019.com/portals/dir2019/bb/Tu.3.A.1.pdf SN - 978-947971-06-0 SP - 1 EP - 13 AN - OPUS4-48438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Ou, D. A1 - Ghafafian, Carineh A1 - Zscherpel, Uwe A1 - Trappe, Volker T1 - Wind turbine rotor blade testing by dual-energy laminography N2 - Modern wind turbine rotor blades consist of sandwich shell segments made from glass fiber reinforced polymers. During manufacturing, defects can arise which could lead to failure of the whole component under dynamic mechanical and thermal loads. Hence during operation defects can arise which, if detected, can be repaired locally and in-situ by applying repair patches instead of taking the whole rotor blade down and repair it remotely. This method is much more time and cost effective, since the shut-down time of the energy converter is limited to a minimum. These repair patches can, however, also lead to new defects if not applied optimally. Therefore, it is necessary to control the quality of the repair patches to ensure the best possible restoration of structural integrity of the component. As a rotor blade is an object with a large aspect ratio, X-ray laminography is predestined to provide 3D information of the objective volume. To enhance the amount of information gained from laminographic reconstruction, we use in this study a photon counting and energy discriminating X-ray detector and apply a material decomposition algorithm to the data. By inherently separating the incident spectra within the detection process into two distinct energy bins, the basis material decomposition can provide material resolved images. Choosing glass and epoxy resin as basis materials and numerically solving the inverse dual-energy equation system, the reconstructed laminographic datasets contain highly valuable information about the distribution of the basis materials within the structure. Furthermore, cross- artifacts arising from the limited angle of the projection data can be reduced by this method which allows to investigate structures that were hidden underneath the artefacts. T2 - 1st International Symposium on Photon Counting Technologies & Applications CY - München, Germany DA - 05.07.2019 KW - Laminography KW - Wind energy KW - Fiber reinforced polymer KW - Photon counting detector KW - Dual-energy PY - 2019 AN - OPUS4-48440 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit A1 - Uckert, Danilo A1 - Kühn, Hans-Joachim A1 - Matzak, Kathrin A1 - Rehmer, Birgit T1 - Ermüdungsverhalten des warmfesten austenitischen Gusseisens EN-GJSA-XNiSiCr35-5-2 bei hoher Temperatur N2 - Die warmfeste austenitische Gusseisenlegierung EN-GJSA-XNiSiCr35-5-2 (häufig auch als Ni-Resist D-5S bezeichnet) wurde hinsichtlich ihres mechanischen Verhal-tens bei hoher Temperatur charakterisiert. Dazu wurden (isotherme) niederzyklische (LCF-) und (nicht-isotherme) thermomechanische Ermüdungsversuche (TMF) zwischen Raumtemperatur und 900 °C durchgeführt. Diese Ergebnisse dienten (zu-sammen mit weiteren Versuchsdaten) der Kalibrierung werkstoffmechanischer Modelle. Bei den höchsten Prüftemperaturen wurde Schädigung in Form von Kriechen beobachtet und metallographisch dokumentiert. T2 - 41. Vortragsveranstaltung Langzeitverhalten warmfester Stähle und Hochtemperaturwerkstoffe CY - Dusseldorf, Germany DA - 30.11.2018 KW - Ni-Resist KW - LCF KW - TMF KW - Kriechen KW - Lebensdauer KW - Schädigung PY - 2018 AN - OPUS4-46851 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Müller, Alexander T1 - Schädigungscharakterisierung an Faser-Kunststoff-Verbunden im Schwingversuch mittels Röntgenrefraktionstopographie unter Berücksichtigung der Matrixeigenschaften N2 - In der vorliegenden Arbeit wurden verschiedene Epoxidharzsysteme charakterisiert. Zwei Systeme mit großen bruchmechanischen Unterschieden wurden zur Fertigung äquivalenter GFK- und CFK-Laminate mit Faserausrichtungen in 0/90° und ±45° ausgewählt. In quasi-statischen Zugversuchen und Einstufenschwingversuchen mit einem Beanspruchungsverhältnis von R= 0,1 wurden diese Laminate hinsichtlich ihres Schädigungsbeginns und ihrer Schädigungsentwicklung untersucht. Die Detektion der Schädigungen sowie die Dokumentation der Schädigungsentwicklung wurde anhand der Lichtabsorptionsanalyse an GFK-Laminaten und anhand der Röntgenrefraktionsanalyse an CFK-Laminaten umgesetzt. Auf diese Weise konnten Einflüsse der bruchmechanischen Eigenschaften der Matrix auf die Schädigungsentwicklung im Verbund aufgezeigt werden. Zudem wurden für die untersuchten Laminate die Schädigungsgrenzen bei schwingender Beanspruchung ermittelt. Anhand durchgeführter Schwingversuche an CFK-Laminaten im Very High Cycle Fatigue-(VHCF)-Lastwechselbereich bis 108 konnten Rückschlüsse vom Schädigungsverhalten im High Cycle Fatigue-(HCF)-Lastwechselbereich bis 106 auf die Dauerfestigkeit im VHCF-Bereich gezogen werden und damit VHCF-Dauerfestigkeitsgrenzen bestimmt werden. Mit dem Ziel die Ermüdung der Laminate auf die Beanspruchung der Matrix zurückzuführen, wurden die Erweiterte Inverse Laminattheorie, mikromechanikbasierte Mischungsregeln sowie eine Vergleichsspannungshypothese auf die untersuchten Laminate angewendet. Die Schädigungsgrenzen konnten damit in Form der Matrixbeanspruchung wiedergegeben werden. Die Abbildung der Ermüdung verschiedener Laminate anhand einer matrixspezifischen normierten Masterschädigungslinie ist für die behandelten CFK- und GFK-Laminate gelungen. T3 - BAM Dissertationsreihe - 162 KW - CFK KW - GFK KW - Ermüdung KW - Epoxidharz KW - Masterschädigungslinie KW - Röntgenrefraktion KW - ZfP PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-467833 SN - 1613-4249 VL - 162 SP - 1 EP - 204 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-46783 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, Kathrin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Stephan-Scherb, Christiane T1 - A µ‐XANES study of the combined oxidation/sulfidation of Fe–Cr model alloys N2 - The precise analysis of cation diffusion profiles through corrosion scales is an important aspect to evaluate corrosion phenomena under multicomponent chemical load, as during high‐temperature corrosion under deposits and salts. The present study shows a comprehensive analysis of cation diffusion profiles by electron microprobe analysis and microbeam X‐ray absorption near edge structure (µ‐XANES) spectroscopy in mixed oxide/sulfide scales grown on Fe–Cr model alloys after exposing them to 0.5% SO2. The results presented here correspond to depth‐dependent phase identification of oxides and sulfides in the corrosion scales by µ‐XANES and the description of oxidation‐state‐dependent diffusion profiles. Scales grown on low‐ and high‐alloyed materials show both a well‐pronounced diffusion profile with a high concentration of Fe3+ at the gas and a high concentration of Fe2+ at the alloy interface. The distribution of the cations within a close‐packed oxide lattice is strongly influencing the lattice diffusion phenomena due to their different oxidation states and therefore different crystal‐field preference energies. This issue is discussed based on the results obtained by µ‐XANES analysis. KW - X-ray absorption spectroscopy KW - Oxidation KW - Sulfidation PY - 2019 DO - https://doi.org/10.1002/maco.201810644 VL - 70 IS - 8 SP - 1360 EP - 1370 PB - Wiley VCH-Verlag AN - OPUS4-47934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian T1 - Obtaining, validating, and storing material parameters N2 - Several aspects of obtaining, validating, and storing material parameters are presented and discussed pertaining especially to calibration, inter-laboratory testing and statistical validation. T2 - 2019 Summer School Priotrity Program 1713 "Chemomechanics" CY - Ebernburg, Germamy DA - 06.05.2019 KW - Materials science KW - Calibration KW - Data storage PY - 2019 AN - OPUS4-48012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Electrode area dependence of dielectric breakdown strength N2 - Dielectric breakdown of ceramics is widely believed to originate from microstructural defects. Still, there is no commonly accepted model for the origin and process of dielectric failure that covers all observed phenomena and dependencies. In analogy to mechanical strength, the Weibull distribution is commonly used to evaluate dielectric strength data. This works well for a given group of specimens with constant geometry. But unlike mechanical strength, dielectric strength scales with the inverse square root of sample thickness. This cannot be explained by the classic Weibull concept. The Griffith type energy release rate model of dielectric breakdown proposed by Schneider is based on space charge injection and conducting filaments from the sample surface. This model incorporates the distinct thickness dependence and the pronounced influence of surface defects. Based on this model and the classic Weibull probability of failure, Schneider’s group theoretically derived a probability of breakdown that predicts an increase of failure probability with increasing electrode area. In our study we tested this model with dielectric strength data measured on dense alumina samples using different electrode areas. Weibull modulus and characteristic dielectric strength (scale parameter) were determined for a set of measurements using small electrodes. These values were used to calculate the failure probability under large electrodes according to the model. The calculated data excellently fits the measured values. Thus, our experiments substantiate the assumptions made in the breakdown model and the significance of surface defects for dielectric failure. T2 - 94. DKG Jahrestagung CY - Leoben, Austria DA - 05.05.2019 KW - Dielectric strength KW - Breakdown strength KW - Ceramics PY - 2019 AN - OPUS4-48015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra A1 - Lindemann, Franziska A1 - Hodoroaba, Vasile-Dan T1 - Nano Powder - a Challenge for Granulometry N2 - If the particle size decreases, the ratio of surface area to volume increases considerably. This provides benefits for all surface-driven processes that run faster or at lower temperatures than larger particles. However, handling and characterization of the nanopowders are much more difficult. Particularly polydisperse powders with irregular shape, as grinding products, represent a challenge. Granulometry in the submicron and nanoscale often leads to incorrect results without knowledge of particle morphology. This presentation demonstrates potentials of using the volume-specific surface area (SV or VSSA) in the granulometric characterization of nanopowders, for instance, correlations between the volume-specific surface area and the median particle size are discussed considering the particle morphology and the model of the logarithmic normal distribution. Moreover, the presentation deals with the optimal dispersion of nanopowders during sample preparation. Indirect ultrasound device with defined cooling was developed to prevent both contamination by sonotrode abrasion and sample changes by heat. Successful granulometric characterization of nanopowders demands both improved dispersion technology and very often an effective combination of two or more measurement methods. T2 - Jahrestagung der Deutschen Keramischen Gesellschaft CY - Leoben, Austria DA - 06.05.2019 KW - Nano screening KW - VSSA KW - Nano particle KW - Particle size PY - 2019 AN - OPUS4-47976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Jacobasch, Stefan A1 - Duffner, Eric A1 - Goedecke, Thomas A1 - Portella, Pedro Dolabella A1 - Mair, Georg A1 - Schendler, Thomas A1 - Gradt, Thomas A1 - Askar, Enis A1 - Bartholmai, Matthias A1 - Schröder, Volkmar A1 - Maiwald, Michael A1 - Holtappels, Kai A1 - Tschirschwitz, Rico A1 - Neumann, Patrick P. T1 - Unser Beitrag zum Thema Wasserstoff N2 - Die BAM ist nahezu über die gesamte Wertschöpfungskette hinweg wissenschaftlich tätig. Von der sicheren und effizienten Wasserstofferzeugung (POWER-to-GAS), über die (Zwischen-)Speicherung von Wasserstoff in Druckgasspeichern bis hin zum Transport bspw. mittels Trailerfahrzeug zum Endverbraucher. Komplettiert werden die Aktivitäten der BAM durch die sicherheitstechnische Beurteilung von wasserstoffhaltigen Gasgemischen, die Verträglichkeitsbewertung von Werkstoffen bis hin zur Detektion von Wasserstoffkonzentrationen über geeignete Sensorik, auch mittels ferngesteuerter Messdrohnen (sog. UAV-Drohnen). Zudem untersucht die BAM proaktiv Schadensrisiken und Unfallszenarien für die Sicherheitsbetrachtung, um mögliche Schwachstellen aufzeigen und potenzielle Gefährdungen erkennen zu können. KW - Wasserstoff KW - Wasserstofferzeugung KW - Energiespeicherung KW - Gasdetektion KW - Risikoanalyse KW - Power-to-Gas KW - Explosionsschutz KW - Tribologie KW - Druckgasspeicher KW - Glasspeicher KW - Gassensorik KW - Mini-UAV PY - 2019 SP - 1 CY - Berlin AN - OPUS4-47960 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Delorme, F. A1 - Chen, C. A1 - Bektas, M. A1 - Moos, R. A1 - Rabe, Torsten T1 - Influence of Reaction-Sintering and Calcination Conditions on Thermoelectric Properties of Sm-doped Calcium Manganate CaMnO3 N2 - A wide range of solid-state synthesis routes for calcium manganate is reported in the literature, but there is no systematic study about the influence of the solid-state synthesis conditions on thermoelectric properties. Therefore, this study examined the influence of calcination temperature and calcination cycles on the Seebeck coefficient, electrical conductivity, and thermal conductivity. Higher calcination temperatures and repeated calcination cycles minimized the driving force for sintering of the synthesized powder, leading to smaller shrinkage and lower densities of the sintered specimens. As the electrical conductivity increased monotonously with increasing density, a higher energy input during calcination caused deterioration of electrical conductivity. Phase composition and Seebeck coefficient of sintered calcium manganate were not influenced by the calcination procedure. The highest thermoelectric properties with the highest power factors and figures of merit were obtained by means of reaction-sintering of uncalcined powder. KW - Thermoelectric oxides KW - Calcination KW - Solid-state-synthesis KW - Power factor KW - Reaction-sintering PY - 2018 DO - https://doi.org/10.4416/JCST2018-00017 SN - 2190-9385 VL - 9 IS - 3 SP - 289 EP - 300 PB - Göller Verlag AN - OPUS4-46224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhne, Patrick A1 - Mieller, Björn A1 - Rabe, Torsten T1 - Slurry development for spray granulation of ceramic multicomponent batches N2 - The granules commonly yielded by spray drying procedures exhibit a hard shell and an irregular, dimpled shape, which is often described as donut-like morphology. Sintered parts produced from such granules suffer from microstructural defects and reduced mechanical properties resulting from these disadvantageous granule properties. Using the example of alumina, zirconia and zirconia-toughened alumina (ZTA) batches, this paper shows that the morphology of the granules can be tuned by adjusting slurry stability. High zeta potential is essential to optimally disperse the particles. But to achieve spherical and soft granules the electrostatic repulsion forces between the particles should be reduced before spray granulation. Electrostatic repulsion forces were changed with the addition of nitric acid. Measurements of zeta potential and viscosity, as well as sedimentation investigations with an optical centrifuge were used for precise slurry assessment as a major precondition for optimal and reproducible adjustment of slurries before spray drying. Sedimentation analysis using an optical centrifuge was performed to investigate different influences like that of additive composition, solids content or pH-value on the sedimentation behavior. Adequately flocculated slurries lead to homogeneous, soft granules that can be easily deformed and pressed. The fraction of donut-shaped particles and the rigidity of granules were reduced. Consequently, the sintered parts produced from these granulates show improvements regarding porosity, pore size distribution, sintered density and biaxial strength. KW - Slurry optimization KW - Optical centrifugation KW - Destabilization KW - Spray drying KW - Biaxial strength PY - 2018 DO - https://doi.org/10.4416/JCST2018-00022 SN - 2190-9385 VL - 9 IS - 3 SP - 327 EP - 336 PB - Göller Verlag AN - OPUS4-46225 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Häusler, Ines A1 - Darvishi Kamachali, Reza A1 - Heidl, Daniel A1 - Skrotzki, Birgit T1 - Influence of heat treatment and creep loading on an Al-Cu-Li alloy N2 - The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process. T2 - 19th International Microscopy Congress (IMC19) CY - Sydney, Australia DA - 09.09.2018 KW - Aluminium KW - Degradation KW - Coarsening KW - Dark-field transmission electron microscopy PY - 2018 AN - OPUS4-46129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Häusler, Ines A1 - Darvishi Kamachali, Reza A1 - Heidl, Daniel A1 - Skrotzki, Birgit T1 - Influence of heat treatment and creep loading on an Al-Cu-Li alloy N2 - The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process. T2 - 19th International Microscopy Congress (IMC19) CY - Sydney, Australia DA - 09.09.2018 KW - Aluminium KW - Degradation KW - Coarsening KW - Dark-field transmission electron microscopy PY - 2018 AN - OPUS4-46131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falk, Florian A1 - Menneken, Martina A1 - Stephan-Scherb, Christiane T1 - Early oxidation and sulfidation of high temperature model alloys: An EDXRD in situ study N2 - The fundamental impact of sulfur and water on corrosion rates and potential failure of the exposed material is well known. However, the access to the related corrosion mechanism causing material degradation is often a problem to solve. This study investigates the effect of SO2 and water vapor in the initial stages of corrosion of an Fe9Cr0.5Mn model alloy at 650 °C in situ. The analysis was carried out under laboratory conditions using energy-dispersive X-ray diffraction (EDXRD). T2 - Dechema EFC Workshop CY - Frankfurt am Main, Germany DA - 26.09.2018 KW - Sulfidation KW - Model alloy KW - Oxidation PY - 2018 AN - OPUS4-46134 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Hollesch, Martin A1 - Börner, Andreas T1 - Keramikfedern – Herstellung, Eigenschaften und Applikation N2 - Entwickelt wurde eine mehrstufige Fertigungstechnologie (Schruppen, Schlichten, Trennschnitt) zur Herstellung keramischer Federn aus gesinterten Hohlzylindern. Durch Optimierung von Maschinenparametern, Schleifscheiben sowie Werkstück- und Werkzeugaufnahmen ist es gelungen, Federn aus Hochleistungskeramik (Aluminiumoxid und Zirkonoxid) mit hoher Kanten- und Oberflächenqualität reproduzierbar herzustellen. Eine hohe Variabilität bezüglich Außen- und Innendurchmesser, Steigung, Windungsquerschnitt und Abstand zwischen den Windungen ermöglicht es, die Federkonstante über drei Größenordnungen zu variieren. Untersucht wurden Federstabilität und Spannungs-Dehnungs-Verhalten unter konstanter und zyklischer Druckbelastung sowie die thermomechanische Stabilität der Keramikfedern. Aluminiumoxid-Federn können bis etwa 800°C, Zirkonoxid-Federn bis etwa 600°C ohne bleibende geometrische Verformung eingesetzt werden. Unter konstanter Spannung zeigen Federn aus Y-stabilisiertem TZP (Zirkonoxid)-Werkstoffen, von anderen Keramikwerkstoffen abweichend, bei Raumtemperatur eine zeitabhängige, elastische, Verformung (Superelastizität), die nach Entlastung über einen Zeitraum von mehreren Stunden reversibel verläuft. Als Ursache wird eine spannungsinduzierte reversible Phasenumwandlung zwischen austenitischer (tetragonales ZrO2) und martensitischer (monoklines ZrO2) Phase postuliert. Diskutiert wird das Anwendungspotenzial der entwickelten Federn für kapazitive keramische Federsensoren für Gravimeter und Wägetechnik. T2 - AK-Sitzung "Keramikbearbeitung" des Fraunhofer IPK CY - Berlin, Germany DA - 27.09.2018 KW - Keramikfeder KW - Spannungs-Dehnungs-Verhalten KW - Zyklische Belastung KW - Thermomechanische Eigenschaften KW - Fertigungstechnologie PY - 2018 AN - OPUS4-46231 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bettge, Dirk A1 - Kratzig, Andreas A1 - Peetz, Christoph A1 - Kranzmann, Axel T1 - Interaction of Oxidizing and Reductive Impurities in CO2 Streams with Transport Pipeline Steel N2 - A main goal of CLUSTER CCS project at BAM was to study the corrosion behaviour of pipeline steel with dense phase carbon dioxide containing impurities. Depending on the kind of impurities specific corrosion mechanisms and corrosion rates were determined. T2 - CO2 and H2 Technologies for the Energy Transition CY - BAM, Berlin, Germany DA - 28.11.2018 KW - Carbon capture KW - Carbon dioxide KW - Corrosion KW - CCS PY - 2018 AN - OPUS4-47016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kratzig, Andreas A1 - Bettge, Dirk A1 - Peetz, Andreas A1 - Kranzmann, Axel T1 - Interaction of Reactive Components in CO2 Streams with Transport Pipeline Steel X70 N2 - In context of CLUSTER project, impacts of impurities (SO2, NO2, O2, CO, H2S, H2, N2, Ar and H2O) in CO2 streams captured from different sources in a regional cluster on transport, injection and storage were investigated. Corrosion studies of oxidizing, reductive or mixed atmospheres towards transport pipeline steel X70 were carried out applying high pressure (10 MPa) at low temperatures (278 K or 313 K). T2 - GHGT-14 Conference CY - Melbourne, Australia DA - 22.10.2018 KW - Carbon capture KW - CCS KW - Carbon dioxide KW - Corrosion PY - 2018 AN - OPUS4-47017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prasetiadi, A. E. A1 - Jost, M. A1 - Schulz, Baerbel A1 - Quibeldey, M. A1 - Rabe, Torsten A1 - Follmann, R. A1 - Jakoby, R. T1 - Liquid-crystal-based amplitude tuner and tunable SIW filter fabricated in LTCC technology N2 - Tunable microwave devices will play an important role in future wireless systems, in which high-frequency bands, e.g. millimeter waves, will become promising, due to its huge spectrum availability. At such frequency bands, liquid crystals (LCs) exhibit low microwave loss, which is excellent compared with the other tuning elements. In this paper, LC-based microwave components are fabricated by using low temperature co-fired ceramic technology, allowing the integration of the LC into microwave structures. The first component, the Amplitude tuner, controls the signal’s amplitude by using the interference concept, which exhibits a tunable attenuation range from 11 dB to 30 dB at 30 GHz. The second component is a 3-pole tunable bandpass filter, which is realized by using a substrate integrated waveguide topology, enabling a device with comparatively high-quality factors (Q-factors). The measurement results show Q-factors in the range of 68 to 100 for a frequency tuning of 29.4–30.1 GHz, i.e. a tuning range of 700 MHz, accompanied by an insertion loss 2 dB to 4 dB. KW - Passive components and circuits KW - Filters KW - Microwave technology PY - 2018 DO - https://doi.org/10.1017/S1759078718000600 SN - 1759-0787 VL - 10 IS - 5-6 SP - 674 EP - 681 PB - Cambridge University Press AN - OPUS4-46985 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Piechotta, Christian A1 - Goedecke, Caroline A1 - Sojref, Regine T1 - Transformation of the antidiabetic drug metformin N2 - For years there have been more and more reports on the presence of drugs in the aquatic environment. Due to the demographic change, the consumption of pharmaceuticals has risen sharply. After taking the drugs, they are partly metabolized in the human body. However, the metabolism is not complete so that both the metabolites and non-metabolized amounts of the parent compounds are excreted. These compounds reach the waste water and afterwards the sewage treatment plants. In sewage treatment plants transformation products can be formed by the oxidative conditions during wastewater treatment processes. The transformation products may have a higher toxicity than the actual environmental pollutants and are often only partly removed during the waste water treatment. Since a lot of these compounds are still unknown, the transformation products are not detected by target analysis used in sewage treatment plants and are often released undetected in the aquatic ecosystems. The released substances may be subject to additional transformation processes in the environment. Pharmaceuticals produced in high amounts can be already detected in the μg/L range in water bodies worldwide. Metformin and its major transformation product guanylurea are one of the main representatives. Metformin is the drug of choice for treating type 2 diabetes. The drug therapy for diabetes mellitus has increased significantly in recent years. In the year 2015 1500 tons of metformin were prescribed in Germany (for statutory insured persons). Metformin is not metabolized in the human body and is excreted unchanged therefore concentrations between 57 μg/L and 129 μg/L are found in German waste water treatment plants influents. In this work the transformation of the antidiabetic drug metformin is investigated. The degradation of metformin is initialize by commercial water treatment techniques like UV-radiation or noncommercial techniques like heterogenous photocatalysis based on titanium dioxide. The degradation of metformin and resulting transformation products are analyzed by LC-MS/MS and LC-HRMS. T2 - SPEA 10 CY - Almeria, Spain DA - 04.06.2018 KW - Metformin KW - Photocatalysis PY - 2018 AN - OPUS4-47030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Villajos Collado, José Antonio A1 - Jagorel, Noëmie A1 - Reinsch, Stefan T1 - Increasing Exposed Metal Site Accessibility in a Co-MOF-74 Material With Induced Structure-Defects N2 - Metal-organic frameworks (MOFs) are promising nanoporous materials with many practical applications. This owes largely to their remarkable porosity and the presence of specific chemical functionalities, such as exposed metal sites (EMS). The MOF-74 structure is known for exhibiting one of the highest EMS densities among porous materials. Moreover, the inclusion of structural defects has been proposed to enhance activity further. This was previously achieved by mixing the original linker together with a second one, having lower topology. The presence of structural defects was evidenced by the resulting crystalline properties and thermal stability. In this work, different mixtures of tetratopic 2,5-dihydroxyterephthalic acid with up to 60% of the tritopic hydroxyterephtalic acid were used to synthesize crystalline Co-MOF-74-like materials. Materials synthesized from higher proportions than 30% of hydroxyterephtalic acid in the synthesis media collapse upon partial removal of the solvent molecules. This indicates the presence of structural defects and the importance of the solvent molecules in stabilizing the crystalline structures. Electron microscope images show that crystal size reduces with inclusion of hydroxyterephtalic acid as the second linker. The presence of coordinated solvent molecules at the EMS was evaluated by Fourier-transform infrared spectra (FTIR) spectroscopy, so that a higher degree of solvent-exchange was observed during washing for defective structures. Furthermore, TG analysis suggests defective structures exhibit lower desolvation temperatures than the defect-free structures. Finally, N2 adsorption-desorption analyses at −196°C showed an enhanced accessibility of the gas to the inner porosity of the defective structures and therefore, the EMS of the material. All these finding make this pathway interesting to enhance the potential interest of these materials for an industrial application because of both a facilitated activation and a better access to the active sites. KW - MOF-74 KW - Structural defects KW - Mixed-linkers KW - Exposed metal sites KW - Facilitated activation PY - 2019 DO - https://doi.org/10.3389/fmats.2019.00230 VL - 6 SP - 230 PB - Frontiers Media CY - Lausanne AN - OPUS4-49256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fleck, M. A1 - Tielemann, Christopher A1 - Scheffler, F. A1 - Brauer, D. S. A1 - Müller, Ralf T1 - Surface crystallization of BT0.75S (fresnoite) glass in different atmosphere N2 - Fresnoite glass with excess SiO2 exhibits oriented surface crystallization, in contrast to the stoichiometric glass composition. Recent EBSD studies documented that the crystals in BTS (2BaO-TiO2-xSiO2, x=0-3) can occur in a distinct [101]-orientation perpendicular to the surface and claimed that this orientation is not a result of growth selection. During these previous studies, however, the effect of surface preparation and surrounding atmosphere during the crystallization experiments were not considered. As these parameters may influence crystal orientation, we studied the surface crystallization of a BTS glass (2BaO-TiO2–2.75SiO2) under controlled conditions with the help of light, electron and polarisation microscopy as well as EBSD. Heat treatments for one hour at 840°C of fractured BTS glass surfaces in air resulted in a large number of not-separable surface crystals. This large number of crystals can be caused by dust particles, which act as nucleation agents. As crystal growth velocity could further be influenced by humidity, our experiments are performed in a filtered and dried air atmosphere. The crystal morphology and orientation will be analysed in dependence of the sample preparation and a differing surrounding atmosphere. T2 - 93rd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV) CY - Nuremberg, Germany DA - 13.05.2019 KW - BTS KW - Fresnoit KW - Glass ceramic KW - Glass-ceramic KW - Glass PY - 2019 AN - OPUS4-49294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Busch, R. A1 - Tielemann, Christopher A1 - Reinsch, Stefan A1 - Patzig, C. A1 - Höche, T. A1 - Müller, Ralf T1 - Characterization of early crystallization stages in surface-crystallized diopside glass-ceramics N2 - Structure formation in glass-ceramics by means of surface crystallization is a challenging open question and remains elusive to definite answers. In several glass-ceramic systems, oriented crystal layers have been observed at the immediate surface, including diopside and some fresnoite systems. However, it is still open to debate, whether oriented surface crystallization is the result of oriented nucleation or growth selection effects. In the same vein, there is still discussion whether surface nucleation is governed by surface chemistry effects or by defects serving as active nucleation sites. In order to help answer these questions, annealing experiments at 850°C have been performed on a MgO·CaO·2SiO2 glass, leading to the crystallization of diopside at the surface. Different annealing durations and surface treatment protocols (i.a. lapping with diamond slurries between 16 µm and 1 µm grain size) have been applied. Particular focus has been put on earliest crystallization stages, with crystal sizes down to about 200 nm. The resultant microstructure has been analyzed by electron backscatter diffraction (EBSD) and two different kinds of textures have been observed, with the a- or b-axis being perpendicular to the sample surface and the c-axis lying in the sample plane. Even at shortest annealing durations, a clear texture was present in the samples. Additionally, selected samples have been investigated with energy-dispersive x-ray spectroscopy in the scanning transmission electron microscope (STEM-EDX). The diopside crystals have been found to exhibit distinguished submicron structure variations and the glass around the crystals was shown to be depleted of Mg. T2 - 93rd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV) CY - Nuremberg, Germany DA - 13.05.2019 KW - Glass KW - Crystallization KW - Diopside KW - EBSD KW - Orientation PY - 2019 AN - OPUS4-49296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph A1 - Le, Quynh Hoa A1 - Yevtushenko, Oleksandra A1 - Bettge, Dirk T1 - Corrosion Aspects for Materials to be Used in CC(U)S Applications N2 - This contribution provides current findings regarding materials susceptibility for carbon capture, utilization and storage (CCUS) applications. Basing on results gathered in 2 German long-term projects (COORAL and CLUSTER) suitable materials are introduced as well as dominating impurities of the CO2-stream and corrosion mechanisms. Investigations cover the whole CCUS process chain and provide material recommendations for certain parts. T2 - 1st International Conference on Corrosion Protection and Application CY - Chongqing, China DA - 09.10.2019 KW - Carbon KW - Capture KW - Storage KW - Utilization KW - CCS KW - CCU KW - CO2 KW - Corrosion KW - Steel PY - 2019 SP - Paper 31 PB - Chinese Society for Corrosion and Protection CY - Chongqing/China AN - OPUS4-49301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph A1 - Le, Quynh Hoa A1 - Yevtushenko, Oleksandra A1 - Bettge, Dirk T1 - Corrosion Aspects for Materials to be Used in CC(U)S Applications N2 - This contribution provides current findings regarding materials susceptibility for carbon capture, utilization and storage (CCUS) applications. Basing on results gathered in 2 German long-term projects (COORAL and CLUSTER) suitable materials are introduced as well as dominating impurities of the CO2-stream and corrosion mechanisms. Investigations cover the whole CCUS process chain and provide material recommendations for certain parts. T2 - 1st International Conference on Corrosion Protection and Application CY - Chongqing, China DA - 09.09.2019 KW - Carbon KW - Capture KW - Storage KW - Utilization KW - CCS KW - CCU KW - CO2 KW - Corrosion PY - 2019 AN - OPUS4-49302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hemmleb, M. A1 - Bettge, Dirk T1 - In-situ Messung der 3D-Topografie von Bruchflächen im REM N2 - Die Abbildung von Bruchflächen im REM liefert hochaufgelöste Bilddaten, die für die mikrofraktografische Bewertung von Bruchmechanismen unerlässlich sind. Durch den Abbildungsprozess im REM gehen räumliche Informationen im Normalfall größtenteils verloren. Mit der Verwendung eines segmentierten Rückstreudetektors ist dagegen die Erzeugung eines 3D-Oberflächenmodells während der Bildaufnahme praktisch in Echtzeit möglich. Die hier beschriebene Untersuchung soll die Anwendbarkeit des Verfahrens auf Bruchflächen zeigen. Zukünftig können Topografiedaten dazu beitragen, Bruchflächen besser zu interpretieren. T2 - Metallographietagung 2019 CY - Dresden, Germany DA - 18.09.2019 KW - Fraktografie KW - Schadensanalyse KW - Topografie KW - 3D PY - 2019 AN - OPUS4-49330 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hemmleb, M. A1 - Bettge, Dirk ED - Petzow, G. T1 - In-situ Messung der 3D-Topografie von Bruchflächen im REM N2 - Die Abbildung von Bruchflächen im Rasterelektronenmikroskop (REM) liefert hochaufgelöste Bilddaten, die für die mikrofraktografische Bewertung von Bruchmechanismen unerlässlich sind. Die Ermittlung von Bruchmechanismen ist oft ein wichtiger Teil von Schadensanalysen zur Ermittlung der Bruchursache. Durch den Abbildungsprozess im REM gehen räumliche Informationen im Normalfall größtenteils verloren und können daher nicht zur Präzisierung des Bruchmechanismus herangezogen werden. Um räumliche Informationen von Probenoberflächen im REM zu erfassen, gibt es verschiedene Methoden. Die für die Ermittlung der 3D-Topografie bereits länger eingeführten Verfahren mittels Proben- oder Strahlkippung können die Berechnung des Oberflächenmodells erst nach der seriellen Aufnahme mehrerer Bilder vornehmen. Mit der Verwendung eines segmentierten Rückstreudetektors ist dagegen die Erzeugung eines 3D-Oberflächenmodells während der Bildaufnahme praktisch in Echtzeit möglich. Die Probentopografie wird gleichzeitig mit dem Bildeinzug dargestellt und gespeichert. T2 - Metallographietagung 2019 CY - Dresden, Germany DA - 18.09.2019 KW - Fraktografie KW - Schadensanalyse KW - Topografie KW - 3D KW - REM PY - 2019 SN - 978-3-88355-417-4 VL - 2019/53 SP - 175 EP - 180 PB - DGM AN - OPUS4-49332 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Suárez Ocano, Patricia A1 - Fries, S. A1 - Agudo Jácome, Leonardo T1 - Thermodynamic study of a refractory complex concentrated alloy using the CALPHAD method N2 - Introduction/purpose: Multi-principal-element alloys (MPEAs), also known as complex concentrated alloys (CCAs), have recently come to the attention of the scientific community due to some interesting and unexpected microstructures, and their potential for improving properties such as, e.g. mechanical strength and oxidation resistance in high temperature structural applications. The AlMo0.5NbTa0.5TiZr refractory (r)CCA is one such candidate, showing a two-phase microstructure after a two-stage heat treatment under argon atmosphere at a controlled cooling rate. Since the application conditions intended for this alloy require a long-term high temperature (> 700 °C) mechanical and oxidation resistance, it becomes necessary to assess the possible phase development in this regime. Methods: In this contribution, the CALPHAD method is used to calculate phase equilibria for the AlMo0.5NbTa0.5TiZr CCA in the presence and absence of oxygen. Equilibrium phase amount evolution with temperature and Scheil Model for solidification (e.g. Fig.1a and Fig.1b, respectively) are analyzed, which are obtained using the databases TCNI9 and TTNI7 and the Gibbs energy minimizer in the Thermo-Calc software. Results: The diagrams reveal that two BCC-based phases could form during alloy solidification, where one phase would be enriched with Mo, Nb and Ta while the other phase, with Al, Ti and Zr. Activity oxides diagrams show that a stable form of aluminum oxide (α-Al2O3, Pearson symbol: hR10, corundum) can be formed. Results obtained by both databases, as well as discrepancies between property phase and Scheil approaches are discussed on the base of experimental results. Conclusions: A modeling tool is used to support alloy characterization and development, providing also the possibility to feedback information to improve existing thermodynamic databases. T2 - EUROMAT 2019 CY - Stockholm, Sweden DA - 01.09.2019 KW - CALPHAD databases analysis KW - Thermodynamic analysis KW - Complex concentrated alloy (CCA) PY - 2019 AN - OPUS4-49345 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholz, Philipp A1 - Wachtendorf, Volker A1 - Elert, Anna Maria A1 - Falkenhagen, Jana A1 - Becker, Roland A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Tschiche, Harald A1 - Reinsch, Stefan A1 - Weidner, Steffen ED - Scholz, Philipp T1 - Analytical toolset to characterize polyurethanes after exposure to artificial weathering under systematically varied moisture conditions N2 - Polyether and -ester urethanes (PU) were exposed to artificial weathering at 40 °C and artificial UV radiation in a weathering chamber. In 3 parallel exposures, humidity was varied between dry, humid, and wet conditions. Material alteration was investigated by various analytical techniques like size exclusion chromatography (SEC), liquid chromatography-infrared spectroscopy (LC-FTIR), thermal-desorption gas chromatography-mass spectrometry (TD-GC-MS), fluorescence mapping and dynamic mechanical analysis (DMA). Our results show that depending on the weathering conditions, different degradation effects can be observed. By means of SEC an initial strong decrease of the molar masses and a broadening of the mass distributions was found. After a material dependent time span this was followed by a plateau where molar mass changes were less significant. A minor moisture-dependent degradation effect was only found for polyester PU. Fluorescence measurements on two materials revealed an increase in the luminescence intensity upon weathering process reaching a saturation level after about 500 h. The changes in the optical properties observed after different exposure conditions and times were very similar. The TD-GC-MS data showed the fate of the stabilizers and antioxidant in the course of weathering. LC-FTIR measurements revealed a change in peak intensities and the ratio of urethane and carbonyl bands. KW - Polyurethane KW - Artificial weathering KW - Moisture KW - Crosslinking KW - Degradation PY - 2019 UR - https://www.sciencedirect.com/science/article/pii/S0142941819303708 DO - https://doi.org/10.1016/j.polymertesting.2019.105996 SN - 0142-9418 VL - 78 SP - 105996, 1 EP - 9 PB - Elsevier CY - Amsterdam AN - OPUS4-48625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert A1 - Saliwan Neumann, Romeo A1 - Reith, F. A1 - Etschmann, B. A1 - Kilburn, M. R. A1 - Brugger, J. T1 - Unravelling the formation histories of placer gold and platinum-group mineral particles from Corrego Bom Successo, Brazil: A window into noble metal cycling N2 - Gold and platinum-group-metals (PGM) are cycled through Earth's environments by interwoven geological, physical, chemical and biological processes leading to the trans/neoformation of metallic particles in placers. The placer deposit at Corrego Bom Successo (CBS, Brazil) is one of the few localities worldwide containing secondary gold- and PGM-particles. Placer gold consists of detrital particles from nearby hydrothermal deposits that were transformed in the surface environment. Processes that have affected these particles include shortdistance transport, chemical de-alloying of the primary Gold silver, and (bio)geochemical dissolution/reprecipitation of Gold leading to the formation of pure, secondary gold and the Dispersion of gold nanoparticles. The latter processes are likely mediated by non-living organic matter (OM) and bacterial biofilms residing on the particles. The biofilms are largely composed of metallophillic β- and γ-Proteobacteria. Abundant mobile gold and platinum nanoparticles were detected in surface waters, suggesting similar mobilities of these metals. Earlier hydrothermal processes have led to the formation of coarsely-crystalline, arborescent dendritic potarite (PdHg). On potarite surfaces, biogeochemical processes have then led to the formation of platinum- and palladium-rich micro-crystalline layers, which make up the botryoidal platinum palladium aggregates. Subsequently potarite was dissolved from the core of many aggregates leaving voids now often filled by secondary anatase (TiO2) containing biophilic elements. The presence of fungal structures associated with the anatase suggests that fungi may have contributed to ist formation. For the first time a primary magmatic PGM-particle comprising a mono-crystalline platinum palladium-alloy with platinum iridium osmium inclusions was described from this locality, finally defining a possible primary source for the PGM mineralisation. In conclusion, the formation of modern-day placer gold- and PGM-particles at CBS began 100s ofmillions of years ago bymagmatic and hydrothermal processes. These provided the metal sources for more recent biogeochemical cycling of PGEs and gold that led to the trans/neoformation of gold- and PGM-particles. KW - Gold KW - Platinum-group-metals KW - Biogeochemical cycling KW - Magmatic and hydrothermal processes KW - Biomineralisation PY - 2019 DO - https://doi.org/10.1016/j.gr.2019.07.003 SN - 1342-937X VL - 76 SP - 246 EP - 259 PB - Elsevier AN - OPUS4-48657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blaeß, Carsten A1 - Müller, Ralf T1 - Effects of microstructure on crack healing in glass matrix composites N2 - Crack healing in glass ceramic solid oxide fuel cell (SOFC) sealants is of utmost importance as cracks caused by thermal cycling remain a bottleneck in developing durable SOFC. Whereas no or low crystal volume fraction seems most favorable for viscous crack healing, it does not for load bearing and undesired diffusion. On the other hand, crystals or filler particles can make the sealant less prone to these disadvantages but it could increase the effective composite viscosity and retard crack healing. Against this background, the influence of crystal volume fraction, phi, on viscous crack healing in glass matrix composites prepared from soda lime silicate glass and zirconia filler particles was studied. Vickers indention induced radial cracks were healed isothermally during interrupted annealing steps and monitored with optical microscopy. Due to the slow crystallization of the glass under study, phi could be kept constant during crack healing. For bulk glass samples (phi = =), the decrease in radial crack length was retarded by an initial increase in crack width due to crack rounding. Up to phi = 0.15 the increase in effective viscosity retarded this crack broadening thereby yielding faster crack healing. For phi > 0.15, crack broadening was progressively suppressed but the same was true for crack healing, which was fully prevented above phi = 0.3. Results indicate that optimum micro structures can prevent crack broadening limited by the global effective composite viscosity and this way promote crack healing limited by local glass viscosity. T2 - 93. Glastechnische Tagung CY - Nürnberg, Germany DA - 12.05.2019 KW - Crack healing KW - Glass matrix composite KW - Vickers indentation PY - 2019 AN - OPUS4-48543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf A1 - Poologasundarampilai, G. A1 - Brauer, D. S. T1 - Sintering and concomitant crystallization of bioactive glasses N2 - The sintering of bioactive glasses allows for the preparation of complex structures, such as three‐dimensional porous scaffolds. Such 3D constructs are particularly interesting for clinical applications of bioactive glasses in bone regeneration, as the scaffolds can act as a guide for in‐growing bone cells, allowing for good Integration with existing and newly formed tissue while the scaffold slowly degrades. Owing to the pronounced tendency of many bioactive glasses to crystallize upon heat treatment, 3D scaffolds have not been much exploited commercially. Here, we investigate the influence of crystallization on the sintering behavior of several bioactive glasses. In a series of mixed‐alkali glasses an increased CaO/alkali metal oxide Ratio improved sintering compared to Bioglass 45S5, where dense sintering was inhibited. Addition of small amounts of calcium fluoride helped to keep melting and sintering temperatures low. Unlike glass 13‐93, these new glasses crystallized during sintering but this did not prevent densification. Variation in bioactive glass particle size allowed for fine‐tuning the microporosity resulting from the sintering process. KW - Bioactive glass KW - Crystallization KW - Scaffolds KW - Sintering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485458 DO - https://doi.org/10.1111/ijag.13477 SN - 2041-1286 VL - 10 IS - 4 SP - 449 EP - 462 PB - Wiley AN - OPUS4-48545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lima, P. A1 - Diener, S. A1 - Katsikis, N. A1 - Günster, Jens T1 - Additive manufacturing of SiSiC by layerwise slurry deposition and binder jetting (LSD-print) N2 - The current work presents for the first time results on the Additive Manufacturing of SiSiC complex parts based on the Layerwise Slurry Deposition (LSD) process. This technology allows to deposit highly packed powder layers by spreading a ceramic slurry and drying. The capillary forces acting during the process are responsible for the dense powder packing and the good joining between layers. The LSD process can be combined with binder jetting to print 2D cross-sections of an object in each successive layer, thus forming a 3D part. This process is named LSD-print. By LSD-print and silicon infiltration, SiSiC parts with complex geometries and features down to 1mm and an aspect ratio up to 4:1 could be demonstrated. The density and morphology were investigated for a large number of samples. Furthermore, the density and the mechanical properties, measured by ball-on-three-balls method, were in all three building directions close to isostatic pressed references. KW - Silicon Carbide KW - Additive Manufacturing KW - 3D printing KW - Layerwise slurry deposition KW - LSD print PY - 2019 DO - https://doi.org/10.1016/j.jeurceramsoc.2019.05.009 VL - 2019 IS - 39 SP - 3527 EP - 3533 PB - Elsevier Ltd. AN - OPUS4-48546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mieller, Björn T1 - Influence of test procedure on dielectric breakdown strength of alumina N2 - Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV/mm were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations (< 2 kV/mm) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization. KW - Ceramic KW - High-voltage testing KW - Dielectric breakdown KW - Alumina PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483852 DO - https://doi.org/10.1007/s40145-018-0310-4 SN - 2226-4108 SN - 2227-8508 VL - 8 IS - 2 SP - 247 EP - 255 PB - Springer AN - OPUS4-48385 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Knauer, S A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Jaeger, P T1 - Contact angle and corrosion of a Water – CO2 system on X70 and S41500 at 278 K and pressures up to 20 MPa N2 - Interfacial properties related to wettability and corrosion in CO2 transport pipelines are experimentally determined by the sessile and the pendant drop methods. The contact angle of a water drop in a compressed CO2 atmosphere is analyzed on an X70 pipeline carbon steel and compared to that on a martensitic steel S41500 to elucidate the effect of corrosion process on active wetting behaviour. The measurements are performed with liquid CO2 at 278 K and pressures ranging from 5 to 20 MPa. The results show that the contact angle (CA) increases with pressure from 132 ° to 143 ° for S41500 and from 117 ° to 137 ° for X70 and decreases with drop age by 20 ° to 24 ° regardless of the pressure and of the fact that corrosion only occurs on X70, which is confirmed by scanning electron microscopy, element mapping and energy dispersive x-ray spectrometry (EDS) analysis. At higher pressure, the contact angles on both materials converge. Further, related properties like density and interfacial tension were determined. CO2 - saturated water has a higher density than pure water: At 5 MPa saturated water reaches a density of 1017 kg⋅m^(-3) and at 20 MPa 1026 kg⋅m^(-3) compared to pure water with a density of 1002 kg⋅m^(-3) and 1009 kg⋅m^(-3), respectively. In this pressure range the IFT drops from 33 mN⋅m^(-1)at 5 MPa to 23 mN⋅m^(-1) at 20 MPa. KW - Carbon capture KW - Utilization, and storage (CCUS) technology KW - Contact angle KW - Wetting KW - Corrosion KW - Condensate KW - Impurities KW - Carbon steel PY - 2019 UR - https://www.sciencedirect.com/science/article/pii/S1750583618309472?dgcid=author DO - https://doi.org/10.1016/j.ijggc.2019.06.021 SN - 1750-5836 SN - 1878-0148 VL - 89 SP - 33 EP - 39 PB - Elsevier, ScienceDirect AN - OPUS4-48601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Paulick, C. T1 - Development of ceramic helical springs for sensor applications N2 - At high temperatures and in harsh environments ceramic springs are often superior to metallic ones and allow for innovative solutions. A further application was proposed by using ceramic springs as capacitive force sensor. Lower and upper coil surfaces are coated by electrically conducting layers. Deformation of such spring results in a change of capacity. Sensor application calls for helical springs with rectangular cross-section, a linear stress-strain characteristic over entire deformation range and low manufacturing tolerances relating to inner and outer diameter, coil cross section and spring pitch. Furthermore, complex spring design with integrated connecting elements has to be realized. Alumina, zirconia (Y-TZP) and silicon nitride springs were produced by hard machining starting from sintered hollow cylinders. After external and internal cylindrical grinding the hollow cylinders were filled with hard wax, followed by multi-stage cutting of spring coils with custom-made cutting discs. Finally, hard wax was removed by melting and burnout. Best surface and edge qualities of springs were reached using Y-TZP material and hot isostatic pressed alumina. Y-TZP springs produced with material-specifically selected cutting discs and optimized process parameters show sharp coil edges without spallings and mean roughness values of inner surfaces < 0.2 μm. Manufacturing tolerances of spring diameters, spring pitch, height and width of coil cross section are in the range of ± 10 microns. Good reproducibility of spring geometry by optimized hard machining technology allows for production of Y-TZP springs with spring constants differing less than ± 1 % within a series. According to DIN 2090 spring constant for rectangular coil cross section is proportional to the square of height and width of coil cross section and indirectly proportional to number of active coils and to the cube of the mean spring diameter. Hence, spring constants can be tailored over a range of many orders of magnitude by changing the spring dimensions. Good agreement was reached between calculated target spring constants and measured values on produced springs. Alumina and zirconia springs were characterized relating to deformation behavior under dynamic compression load with various deformation speeds and under static tensile loads over long periods of time. Contrary to alumina springs, a non-linear stress-strain behavior of TZP springs was proved in both test series. It is supposed, that pseudoelasticity caused by stress-induced transformation of tetragonal to monoclinic phase is responsible for this special feature of TZP springs. Therefore, TZP material cannot be used for capacitive spring sensors. T2 - European Ceramic Society Conference (ECerS) CY - Torino, Italy DA - 16.06.2019 KW - Ceramic spring KW - Sensor KW - Spring constant KW - Failure test KW - Microstructure PY - 2019 AN - OPUS4-48610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Bestimmung der Partikelgrößenverteilung mittels Zentrifugen-Sedimentationsverfahren nach ISO 13318-2 (Küvette) N2 - Im Vortrag werden das Messprinzip des Zentrifugen-Sedimentationsverfahrens erläutert und die Anforderungen der zugrundeliegenden Normen diskutiert. Es schließen sich umfangreiche Ausführungen zur praktischen Durchführung der Messung, insbesondere auch zu den vorbereitenden Arbeiten, sowie zur Auswertung der Rohdaten an. Nach einem Vergleich der Ergebnisse mit anderen Messverfahren, wird das Verfahren in einer Zusammenfassung bewertet. T2 - Rheologie und Stabilität von dispersen Systemen CY - Potsdam, Germany DA - 03.06.2019 KW - Nanomaterial KW - Partikelgrößenverteilung KW - Analytische Zentrifuge PY - 2019 AN - OPUS4-48286 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -