TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai A1 - Mohr, Gunther A1 - Gumenyuk, Andrey A1 - Straße, Anne A1 - Pittner, Andreas A1 - Günster, Jens A1 - Gornushkin, Igor B. A1 - Pelkner, Matthias A1 - Ehlers, Henrik A1 - Heckel, Thomas A1 - Zscherpel, Uwe A1 - Seeger, Stefan A1 - Bruno, Giovanni T1 - ProMoAM - Verfahrensentwicklung für das Prozessmonitoring in der additiven Fertigung N2 - Verfahren zum in-situ Monitoring der Prozess- und Bauteilparameter sollen Fehlstellen und Inhomogenitäten bereits während der Fertigung nachweisen und zukünftig auch die Regelung der Prozessparameter ermöglichen. T2 - Challenges in Additive Manufacturing: Innovative Materials and Quality Control, Berlin Partner Workshop CY - Berlin, Germany DA - 12.09.2018 KW - Additive Fertigung KW - Prozessmonitoring KW - ProMoAM PY - 2018 AN - OPUS4-46300 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Swaraj, Sufal A1 - Müller, Anja A1 - Sparnacci, Katia A1 - Unger, Wolfgang T1 - Core-shell nanoparticles investigated with scanning transmission X-ray microscopy N2 - A scanning transmission x-ray microscopy (STXM) based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core-shell nanoparticles which exhibit a strong x-ray absorption contrast and a sharp interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less x-ray beam induced damage of the sample is achieved by recording STXM images only at two predetermined energies of maximum absorption contrast instead of recording a stack of images across the whole absorption edge. A model core-shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, investigated at the HERMES beamline is presented for demonstration. This STXM based methodology yields particle dimensions in good agreement with the scanning electron microscopy (SEM) results (deviation equal or less than 10%). Extension of this methodology to core-shell nanoparticles with inorganic core and organic shell will also be presented and the challenges encountered will be highlighted. T2 - 13th SOLEIL Users' Meeting CY - Saint-Aubin, France DA - 18.01.2018 KW - STXM KW - SEM KW - PTFE KW - PS KW - Core-shell nanoparticles KW - Polymers PY - 2018 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. AN - OPUS4-43883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinrich, Thomas A1 - Müller, Anja A1 - Schneider, Markus A1 - Sparnacci, K. A1 - Unger, Wolfgang T1 - Chemical Analysis of Core-Shell Nanoparticles using ToF-SIMS and XPS N2 - The analysis of nanomaterials is currently an important task - especially in case of risk assessment – as the properties of these material class are not well understood. The rather high surface area of these objects renders their interactions significantly different to their corresponding bulk. Thus, the surface’s chemical composition must be investigated to get a better understanding and prediction of the nanomaterials’ behavior. ToF-SIMS and XPS have proven to be powerful tools to determine the general chemical composition. The superior surface sensitivity of ToF-SIMS furthermore allows us to study mainly the utmost atomic layer and thus gives us an idea of the interactions involved. Here, we present initial data on the analysis of Hyflon®-polystyrene core-shell nanoparticles which can be used as a model system due to the known preparation and a rather good chemical as well as physical separation of core and shell. Furthermore, principle component analysis (PCA) will be used to detect the influence of sample preparation and for a better separation of different samples. ToF-SIMS imaging is desired to be implemented for single particle detection as well. T2 - RSC-NPL Symposium: Nanoparticle concentration – critical needs and state-of-the-art measurement CY - London, UK DA - 24.04.2018 KW - XPS KW - ToF-SIMS KW - Nanoparticles PY - 2018 AN - OPUS4-44795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Unger, Wolfgang A1 - Böllinghaus, Thomas T1 - Use of time-of-flight secondary ion mass spectrometry for the investigation of hydrogen-induced effects in austenitic steel AISI 304L N2 - During the energy transformation from fossil fuels to renewable energy sources, the use of hydrogen as fuel and energy storage can play a key role. This presents new challenges to industry and the scientific community alike. The storage and transport of hydrogen, which is nowadays mainly realized by austenitic stainless steels, remains problematic, which is due to the degradation of mechanical properties and the possibility of phase transformation by hydrogen diffusion and accumulation. The development of materials and technologies requires a fundamental understanding of these degradation processes. Therefore, studying the behavior of hydrogen in austenitic steel contributes to an understanding of the damage processes, which is crucial for both life assessment and safe use of components in industry and transportation. As one of the few tools that is capable of depicting the distribution of hydrogen in steels, time-of-flight secondary ion mass spectrometry was conducted after electrochemical charging. To obtain further information about the structural composition and cracking behavior, electron-backscattered diffraction and scanning electron microscopy were performed. Gathered data of chemical composition and topography were treated employing data fusion, thus creating a comprehensive portrait of hydrogen-induced effects in the austenite grade AISI 304L. Specimens were electrochemically charged with deuterium instead of hydrogen. This arises from the difficulties to distinguish between artificially charged hydrogen and traces existing in the material or the rest gas in the analysis chamber. Similar diffusion and permeation behavior, as well as solubility, allow nonetheless to draw conclusions from the experiments. T2 - 21st International Conference on Secondary Ion Mass Spectrometry CY - Kraków, Poland DA - 10.09.2017 KW - AISI 304L KW - Hydrogen KW - ToF-SIMS KW - Austenitic stainless steel PY - 2018 DO - https://doi.org/10.1116/1.5013931 SN - 1071-1023 VL - 36 IS - 3 SP - Article 03F103, 1 EP - 6 PB - American Vacuum Society (AVS) AN - OPUS4-44840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Anja A1 - Lippitz, Andreas A1 - Swaraj, Sufal A1 - Sparnacci, Katia A1 - Unger, Wolfgang T1 - Progress Talk 3 / Investigating the dimensions of core|shell nanoparticles using scanning transmission X-ray microscopy (STXM) N2 - This presentation deals with the progress between month twelve and nineteen of my PhD thesis. I prepared it, in order to update my supervisor Prof. Kemnitz and my colleagues from the department of chemistry at the Humboldt-Universität zu Berlin (HU). T2 - Working Group Meeting of Prof. Erhard Kemnitz CY - Humboldt-Universität zu Berlin (HU), Germany DA - 30.01.2018 KW - Core-shell nanoparticles KW - Metrology KW - PS KW - PTFE KW - Polymers KW - SEM KW - STXM PY - 2018 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. AN - OPUS4-43981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Anja A1 - Swaraj, S. A1 - Sparnacci, K. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Determining the shell thickness of core-shell nanoparticles using scanning transmission X-ray microscopy (STXM) N2 - A scanning transmission x-ray microscopy (STXM) based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core-shell nanoparticles which exhibit a strong x-ray absorption contrast and a well-defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less x-ray beam induced damage of the sample is achieved by recording STXM images only at two predetermined energies of maximum absorption contrast, instead of recording a stack of images across the whole absorption edge. A model core-shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near edge x-ray absorption fine structure (NEXAFS) spectroscopy confirms the significant difference in x-ray absorption behavior between PTFE and PS. Additionally, due to the insolubility of styrene in PTFE a well-defined interface between particle core and shell is expected. In order to validate the STXM results, both the naked PTFE cores as well as the complete core-shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM based methodology yields particle dimensions in agreement with the SEM results and provides additional information such as the position of the particle core which cannot be extracted from a SEM micrograph. T2 - Innanopart open day CY - London, UK DA - 25.04.2018 KW - STXM KW - SEM KW - PTFE KW - PS KW - Polymer KW - Core-shell nanoparticles PY - 2018 AN - OPUS4-44841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Metrology for spatially resolved chemical analysis at the micro and nanometre scales Surface Analysis Working Group (SAWG) - Report for 16th Meeting (2017/18) N2 - Following the 2017 meeting, progress with the Key Comparison CCQM-K153 related to the BET specific surface lead by UNIIM and the Pilot Study P-190 “Thickness Measurement of nm HfO2 Films” lead by KRISS will be discussed. The 16th meeting of SAWG will focus on •survey on CMC claims submitted with reference to K-129 and K-136. •the overall and SAWG specific aspects of the CCQM Strategy process, •a consideration of comparisons on convention methods as recommended by the CCQM Plenary Meeting 2017, •the 2019 CCQM Workshop and paper(s) for Metrologia’s Special Issue, •discussion of future comparisons. T2 - 24th meeting of the CCQM 2018 CY - Paris, France DA - 19.04.2018 KW - Surface chemical analysis KW - Metrology KW - Inter-laboratory comparisons PY - 2018 AN - OPUS4-44998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Anja A1 - Swaraj, Sufal A1 - Sparnacci, Katia A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Investigation of core-shell nanoparticles using scanning transmission x-ray microscopy (STXM) N2 - A scanning transmission x-ray microscopy (STXM) based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core-shell nanoparticles which exhibit a strong x-ray absorption contrast and a well-defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less x-ray beam induced damage of the sample is achieved by recording STXM images only at two predetermined energies of maximum absorption contrast, instead of recording a stack of images across the whole absorption edge. A model core-shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near edge x-ray absorption fine structure (NEXAFS) spectroscopy confirms the significant difference in x-ray absorption behavior between PTFE and PS. Additionally, due to the insolubility of styrene in PTFE a well-defined interface between particle core and shell is expected. In order to validate the STXM results, both the naked PTFE cores as well as the complete core-shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM based methodology yields particle dimensions in good agreement with the SEM results (deviation equal or less than 10%) and provides additional information such as the position of the particle core which cannot be extracted from a SEM micrograph. T2 - DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS CY - Berlin, Germany DA - 11.03.2018 KW - STXM KW - SEM KW - PS KW - PTFE KW - Core-shell nanoparticles PY - 2018 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. AN - OPUS4-44654 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Uwe A1 - Griepentrog, Michael A1 - Hertwig, Andreas A1 - Sahre, Mario A1 - Unger, Wolfgang A1 - Hodoroaba, Vasile-Dan A1 - Krüger, Jörg T1 - Plasma Germany, Fachausschuss Normung, Berichtszeitraum Herbst 2017 – Frühjahr 2018 N2 - Der Vortrag gibt den aktuellen Stand der Normung im Bereich der Oberflächen-technik insbesondere der Oberflächenanalytik und der Oberflächenmess- und -prüftechnik wider. Vorgestellt wird der Status technischer Berichte, Normenentwürfe und Normen u.a. zur Charakterisierung von funktionellen Glasoberflächen für bioanalytische Anwendungen, zur Messung der Schichtdicke von Nanomaterialien mittels Ellipsometrie, zur Kalibrierung von Interferometern und Interferenzmikroskopen für die Formmessung, zur Rockwelleindringprüfung zur Bewertung der Schicht-haftung, zu den Grundlagen der Ellipsometrie, zur Messung der Schichtdicke mittels Wirbelstromverfahren, zur Schichtpotentialmessung von Mehrfach-Nickelschichten, zu Filtern und Augenschutzgeräten gegen Laserstrahlung sowie zur Bestimmung der Schichthaftung mittels Zugversuch. T2 - Plasma Germany, Fachausschuss Normung, Frühjahrssitzung CY - Kiel, Germany DA - 17.04.2018 KW - Stand der Normung KW - Oberflächentechnik KW - Oberflächenanalytik KW - Oberflächenmesstechnik KW - Oberflächenprüftechnik PY - 2018 AN - OPUS4-44729 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinrich, Thomas A1 - Sparnacci, K. A1 - Unger, Wolfgang A1 - Schneider, Markus A1 - Müller, Anja T1 - Chemical Analysis of Core-Shell Nanoparticles using ToF-SIMS and XPS N2 - The analysis of nanomaterials is current an important task - especially in case of risk assessment, as the properties of these material class are not well understood currently. The rather high surface area of these objects renders their interactions significantly different to their corresponding bulk. Thus, the surfaces chemical composition has to be investigated to get a better understanding and prediction of the nanomaterials' behavior. ToF-SIMS has proven as a powerful tool to determine said chemical composition. Its superior surface sensitivity allows us to study mainly the utmost atomic layer and therefore gives us an idea of the interactions involved. Here, we show first result from the validation of the method for the analysis of polystyrene and gold nanoparticles. ToF-SIMS will be compared to other methods like XPS, T-SEM or REM. Furthermore, principle component analysis (PCA) will be used to detect the influence of different sample preparation performed by an innovative microfluidic device. ToF-SIMS imaging is desired to be implemented for single particle detection as well. T2 - DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS CY - Berlin, Germany DA - 11.03.2018 KW - XPS KW - ToF-SIMS KW - Nanoparticles PY - 2018 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. AN - OPUS4-44790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinrich, Thomas A1 - Hupatz, H. A1 - Lippitz, Andreas A1 - Schalley, C. A. A1 - Unger, Wolfgang T1 - Switchable Rotaxanes operating in multilayers on solid supports N2 - Interfaces provide the structural basis for function as, for example, encountered in nature in the membrane-embedded photosystem or in technology in solar cells. Synthetic functional multilayers of molecules cooperating in a coupled manner can be fabricated on surfaces through layer-by-layer self-assembly. Ordered arrays of stimuli-responsive rotaxanes undergoing well-controlled axle shuttling are excellent candidates for coupled mechanical motion. Such stimuli-responsive surfaces may help integrating synthetic molecular machines in larger systems exhibiting even macroscopic effects or generating mechanical work from chemical energy through cooperative action. The present work demonstrates the successful deposition of ordered mono- and multilayers of chemically and photochemically switchable rotaxanes on gold surfaces. Two substrates are investigated – silicon and gold. Of these materials, only gold showed to be suitable for the development of highly preferential oriented rotaxane layers. XPS indicates for both substrates that our layer-by-layer approach worked and a layer growth with every deposition step is present. NEXAFS showed that both stimuli cause an increase of the multilayer's preferential orientation and that the switching is reversible. However, these effects are only observed for the multilayers on gold surfaces. T2 - DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS CY - Berlin, Germany DA - 11.03.2018 KW - XPS KW - NEXAFS KW - Rotaxanes KW - Multilayers PY - 2018 AN - OPUS4-44794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Coelho Lima, Isabela A1 - Unger, Jörg F. T1 - Variational Bayesian Inference for structural model update N2 - Appropriate monitoring of transportation infrastructures (e.g. bridges) is of utmost importance to ensure safe operation conditions. Accurate and reliable assessment of such structures can be achieved through the integration of data from non-destructive testing, advanced modeling and model updating techniques. The Bayesian framework has been widely used for updating engineering and mechanical models, due to its probabilistic description of information, in which the posterior probability distribution reflects the knowledge, over the model parameters of interest, inferred from the data. For most real-life applications, the computation of the true posterior involves integrals that are analytically intractable, therefore the implementation of Bayesian inference requires in practice some approximation methods. This paper investigates the application of Variational Bayesian Inference for structural model parameter identification and update, based on measurements from a real experimental setup. The Variational Bayesian method circumvents the issue of evaluating intractable integrals by using a factorized approximation of the true posterior (mean field approximation) and by choosing a family of conjugate distributions that facilitates the calculations. Inference in the Variational Bayesian framework is seen as solving an optimization problem with the aim of finding the parameters of the factorized posterior which would minimize its Kullback-Leibler divergence in relation to the exact posterior. The Variational Approach is an efficient alternative to sampling methods, such as Markov Chain Monte Carlo, since the latter’s accuracy depends on sampling from the posterior distribution a sufficient amount of times (and therefore requiring an equivalent number of computations of the forward problem, which can be quite expensive). T2 - ECCM - ECFD 2018 CY - Glasgow, Scotland, UK DA - 11.06.2018 KW - Variational Bayesian KW - Structural monitoring KW - Bayesian inference PY - 2018 AN - OPUS4-45603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang A1 - Ehlert, Christopher A1 - Donskyi, Ievgen A1 - Girard-Lauriault, P.-L. A1 - Lippitz, Andreas A1 - Illgen, Rene A1 - Haag, R. A1 - Adeli, M. T1 - Chemical modification of graphene and carbon nano tubes as viewed by xps and nexafs spectroscopies with dft spectra simulation N2 - Graphene is a two-dimensional carbon network with unique properties. However, its low solubility, poor reactivity and the limited accessibility of a well-defined basal plane are major challenges for applications. An ideal method to overcome these problems is the covalent attachment of functional molecules to its surface which enable further reactive modifications for specific applications. There are several technologies for surface functionalization of graphene and related CNT materials. To get control on the functionalization process and to optimize the performance of the modified surfaces analytical tools for surface chemical characterization are required. X-ray absorption (NEXAFS) and photoelectron spectroscopy (XPS) have been identified to be rather powerful here [1-3]. Specifically, NEXAFS spectroscopy underpinned by quantum chemical spectrum simulations [4] is unique in a way to address changes of aromaticity and defect formation at the graphene surface during functionalization. For relevant surface modification technologies, we present examples on how NEXAFS and XPS can do a good job. All presented modifications aim on the production of platforms for defined functional 2D nanomaterials, as for example multifunctional hybrid architectures. In detail, we investigated: • A wet chemical method for covalent functionalization of graphene sheets by a one-pot nitrene [2+1] cycloaddition reaction under mild conditions. Here a reaction between 2,4,6-trichloro-1,3,5-triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine-functionalized graphene sheets. • Graphene and carbon nanotube functionalized by Vacuum-Ultraviolet (VUV) induced photochemical or r.f. cw low pressure plasma processes to introduce amino, hydroxy or brominated functionalities. To underpin finger-print information delivered by C K-edge NEXAFS we studied the effects of selected point and line defects as well as chemical modifications for a single graphene layer model by density functional theory based spectrum simulations. References [1] P.-L. Girard-Lauriault et al., Appl. Surf. Sci., 258 2012 8448-8454, DOI: 10.1016/j.apsusc.2012.03.012 [2] A. Lippitz et al., Surf. Sci., 611 2013 L1-L7, DOI: 10.1016/j.susc.2013.01.020 [3] A. Faghani et al., Angew. Chemie (International ed.), 56 2017 2675-2679, DOI:10.1002/anie.201612422 [4] C. Ehlert, et al., Phys.Chem.Chem.Phys., 16 2014 14083-14095, DOI: 10.1039/c4cp01106f T2 - AVS 65th INTERNATIONAL SYMPOSIUM CY - Long Beach, CA, USA DA - 21.10.2018 KW - Graphene KW - Plasma KW - Nitrene [2+1] cycloaddition KW - XPS KW - NEXAFS PY - 2018 AN - OPUS4-46468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Jörg F. A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas T1 - Concrete under cyclic loading a continuum damage model and a temporal multiscale approach N2 - The durability of concrete structures and its performance over the lifetime is strongly influenced by many interacting phenomena such as e.g. mechanical degradation due to fatigue loading, loss of prestress, degradation due to chemical reactions or creep and shrinkage. Failure due to cyclic loading is generally not instantaneous, but characterized by a steady damage accumulation. Many constitutive models for concrete are currently available, which are applicable for specific loading regimes, different time scales and different resolution scales. A key limitation is that the models often do not address issues related to fatigue on a structural level. Very few models can be found in the literature that reproduce deterioration of concrete under repeated loading-unloading cycles. The objective of this paper is the presentation of numerical methods for the simulation of concrete under fatigue loading using a temporal multiscale method. First, a continuum damage model for concrete is developed with a focus on fatigue under compressive stresses. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. Second, a multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach. This evolution equation is then solved on the long time scale using different time integration schemes. T2 - 6th European Conference on Computational Mechanics (ECCM 6) CY - Glasgow, UK DA - 11.06.2018 KW - Cycle jump KW - Fatigue damage KW - Concrete PY - 2018 AN - OPUS4-45696 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Dietrich, P. A1 - Thissen, A. A1 - Schwibbert, Karin A1 - Unger, Wolfgang T1 - Investigations of biofilms in various conditions by near-ambient pressure XPS N2 - X-ray photoelectron spectroscopy (XPS) provides elemental and chemical information from the outermost ~10 nm of the sample surface. This is in the same order of magnitude as the thickness of the outer bacterial membrane of gram-negative bacteria, as well as outer membrane molecules as exopolysaccharides and lipopolysaccharides, commonly attached to the cell surface. With the development of near-ambient pressure (NAP)-XPS, bacteria can be analysed with minimal sample preparation. EnviroESCA is a laboratory based NAP-XPS instrument, equipped with a monochromated Al Kα radiation source and a differentially pumped energy analyser connected to an exchangeable sample environment. It allows for measurements in various gas-atmospheres, including water vapor, which makes it possible to characterise bacteria and other biological samples close to their natural, hydrated state. Artificial model-biofilms of exopolysaccharides, planktonic Pseudomonas Fluorescens and biofilms of Escherichia Coli have been characterised in hydrated and dried state. High-resolution XPS-spectra from carbon, oxygen, nitrogen and phosphorous can be assigned to carbohydrates, lipids and proteins in general agreement with literature. Especially the carbon 1s peak is of interest. A series of measurements of an E. coli biofilm from 11 mbar in humid environment to 1 mbar air reveal changes in the C1s peak, which suggests that the bacterial surface undergo substantial Change. T2 - BAM PhD-retreat CY - Warnemünde, Germany DA - 28.09.2018 KW - Biofilms KW - E. coli KW - NAP-XPS PY - 2018 AN - OPUS4-46132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang A1 - Kjaervik, Marit T1 - New work item proposal for a technical report for ISO/TC 201 WG 4 “Surface characterization of biomaterials”: Surface chemical analysis – Surface chemical analysis of cells and biofilms N2 - The proposed ISO Technical Report provides a description of a variety of physical methods of analytical chemistry by which bacteria and biofilms can be analysed. The state of the art, sample requirements and strengths associated with each method are identified. T2 - 27th Plenary Meeting of ISO/TC 201 CY - Cancun, Mexico DA - 2018-09-20 KW - Surface chemical analysis of biofilms KW - XPS KW - Fourier-Transform Infrared Spectroscopy KW - 3D nano SIMS KW - Raman-spectroscopy PY - 2018 AN - OPUS4-46214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Coelho Lima, Isabela A1 - Unger, Jörg F. T1 - Variational bayesian inference for structural model updating N2 - Appropriate monitoring of transportation infrastructures (e.g. bridges) is of utmost importance to ensure safe operation conditions. Accurate and reliable assessment of such structures can be achieved through the integration of data from non-destructive testing, advanced modeling and model updating techniques. The Bayesian framework has been widely used for updating engineering and mechanical models, due to its probabilistic description of information, in which the posterior probability distribution reflects the knowledge, over the model parameters of interest, inferred from the data. For most real-life applications, the computation of the true posterior involves integrals that are analytically intractable, therefore the implementation of Bayesian inference requires in practice some approximation methods. This paper investigates the application of Variational Bayesian Inference for structural model parameter identification and update, based on measurements from a real experimental setup. The Variational Bayesian method circumvents the issue of evaluating intractable integrals by using a factorized approximation of the true posterior (mean field approximation) and by choosing a family of conjugate distributions that facilitates the calculations. Inference in the Variational Bayesian framework is seen as solving an optimization problem with the aim of finding the parameters of the factorized posterior which would minimize its Kullback-Leibler divergence in relation to the exact posterior. The Variational Approach is an efficient alternative to sampling methods, such as Markov Chain Monte Carlo, since the latter’s accuracy depends on sampling from the posterior distribution a sufficient amount of times (and therefore requiring an equivalent number of computations of the forward problem, which can be quite expensve). T2 - 6th European Conference on Computational Mechanics (ECCM 6) CY - Glasgow, UK DA - 11.06.2018 KW - Structural monitoring KW - Bayesian inference KW - Variational Bayesian PY - 2018 AN - OPUS4-45693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sobol, Oded A1 - Röhsler, Andreas A1 - Nolze, Gert A1 - Unger, Wolfgang A1 - Böllinghaus, Thomas T1 - Sputtering derived artefacts in austenitic steel during Time-of-Flight Secondary Ion Mass Spectrometry analyses N2 - Among the very few techniques to localize hydrogen (H) at the microscale in steels, Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was proven to be a reliable tool. The necessity to detect hydrogen stems from its deleterious effects in metals, that are often used as structural components and to obtain better understanding of the underlying metallurgical mechanisms of hydrogen embrittlement (HE) which are still unclear. Austenitic stainless steels are nowadays commonly used in a wide variety of application, from hydrogen transport and storage facilities to petrochemical and offshore applications where they are exposed to aggressive environments and therefore prone to HE. One of the greater risks in the austenitic class is the embrittlement of the material due to the instability of the γ austenite and its transformation into a brittle α martensitic phase. This transformation takes place due to the local stresses that are induced by the uptake of hydrogen during service. Nonetheless, it was shown that this transformation can occur as an artefact during SIMS analysis itself where Cs-sputtering is necessary not only to remove surface contaminations but mainly to enhance H/D secondary ion yield. In the following contribution we show the influence of different sputtering conditions on AISI 304L austenitic stainless steel in order to distinguish the artefact from the hydrogen induced transformation. The material was charged electrochemically in a deuterium based electrolyte. Deuterium (D) must be in these experiments as a replacement for hydrogen which cannot be used because adsorbed hydrogen superimposes hydrogen originating from charging the sample in the SIMS images. ToF-SIMS analyses were conducted by ToF SIMS IV (IONTOF GmbH, Münster, Germany). The experiments were carried out on deuterium charged and non-charged samples. The structural characterization was carried out by SEM and EBSD examinations before and after charging, both with a Leo Gemeni 1530VP field-emission scanning electron microscope and a Zeiss Supra 40 instrument (Carl Zeiss Microscopy GmbH, Oberkochen, Germany). The results showed that the use of 1keV Cs+ beam induces stacking faults while higher sputter beam energies results in γ→α transformation. T2 - SIMS Europe 2018 CY - Münster, Germany DA - 16.09.2018 KW - Austenitic steel KW - Hydrogen KW - ToF-SIMS KW - Artefact PY - 2018 AN - OPUS4-46701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Anja A1 - Radnik, Jörg A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Progress Talk 3 / Non-destructive depth profiling of core-shell nanoparticles by ER-XPS N2 - This presentation deals with the progress between month twenty and twenty-nine of my PhD thesis. I prepared it, in order to update my supervisor Prof. Kemnitz and my colleagues from the department of chemistry at the Humboldt-Universität zu Berlin (HU). T2 - Working Group Meeting of Prof. Erhard Kemnitz CY - Humboldt-Universität zu Berlin (HU), Germany DA - 20.11.2018 KW - ER-XPS KW - Synchrotron KW - Core-shell nanoparticles KW - Depth-profiling PY - 2018 AN - OPUS4-46676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Hirthammer, Volker A1 - Unger, Jörg F. T1 - A continuum damage model for the simulation of concrete under cyclic loading N2 - A continuum damage model for concrete is developed with a focus on fatigue under compressive stresses. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. The model is designed to represent failure under static loading as a particular case of fatigue failure after a single loading cycle. As a consequence, most of the material parameters can be deduced from statictests. Only a limit set of additional constitutive parameters is required to accurately describe the evolution under fatigue loading. Another advantage of the proposed model is the possibility to directly incorporate other multi-physics effects such as creep and shrinkage or thermal loading on the constitutive level. A multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach. This evolution equation is then solved on the long time scale using different implicit and explicit time integration schemes. Their performance and some limitations for specific loading regimes is discussed. T2 - Computational Modelling of concrete and concrete Structures Euro-C, March 1st 2018 CY - Bad Hofgastein, Austria DA - 26.02.2018 KW - Continnum damage model KW - Simulation of concrete KW - Under cyclic loading PY - 2018 UR - https://euro-c.tuwien.ac.at/home/ AN - OPUS4-48399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Unger, Wolfgang A1 - Böllinghaus, Thomas T1 - In-situ observation of the hydrogen behaviour in austenitic stainless steel by time-of-flight secondary ion mass spectrometry during mechanical loading N2 - The reduction of harmful emissions to the environment is one of the most urgent challenges of our time. To achieve this goal, it is inevitable to shift from using fossil fuels to renewable energy sources. Within this transition, hydrogen can play a key role serving as fuel in transportation and as means for energy storage. The storage and transport of hydrogen using austenitic stainless steels as the infrastructure, as well as the use of these grades in hydrogen containing aggressive environments, remains problematic. The degradation of the mechanical properties and the possibility of phase transformation by ingress and accumulation of hydrogen are the main drawbacks. Advanced studies of the behaviour of hydrogen in austenite is necessary to fully understand the occurring damage processes. This knowledge is crucial for the safe use of components in industry and transportation facilities of hydrogen. A powerful tool for depicting the distribution of hydrogen in steels, with high accuracy and resolution, is time-of-flight secondary ion mass spectrometry (ToF-SIMS). We here present a comprehensive research on the hydrogen degradation processes in AISI 304L based on electrochemical charging and subsequent ToF-SIMS experiments. To obtain furthermore information about the structural composition and cracking behaviour, electron-backscattered diffraction (EBSD) and scanning electron microscopy (SEM) were performed afterwards. All the gathered data was treated employing data fusion, thus creating a thorough portrait of hydrogen diffusion and its damaging effects in AISI 304L. Specimens were charged with deuterium instead of hydrogen. This necessity stems from the difficulty to separate between artificially charged hydrogen and traces existing in the material or adsorbed from the rest gas in the analysis chamber. Similar diffusion and permeation behaviour, as well as solubility, allow nonetheless to draw onclusions from the experiments. T2 - International Conference on Metals and Hydrogen; Steely Hydrogen 2018 CY - Ghent, Belgium DA - 29.05.2018 KW - Hydrogen KW - Deuterium KW - ToF-SIMS KW - AISI 304L PY - 2018 AN - OPUS4-45079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tan, K. H. A1 - Sattari, S. A1 - Donskyi, Ievgen A1 - Cuellar-Camacho, J. L. A1 - Cheng, C. A1 - Schwibbert, Karin A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Gorbushina, Anna A1 - Adeli, M. A1 - Haag, R. T1 - Functionalized 2D nanomaterials with switchable binding to investigate graphene–bacteria interactions N2 - Graphene and its derivatives have recently attracted much attention for sensing and deactivating pathogens. However, the mechanism of multivalent interactions at the graphene–pathogen interface is not fully understood. Since different physicochemical parameters of graphene play a role at this interface, control over graphene’s structure is necessary to study the mechanism of these interactions. In this work, different graphene derivatives and also zwitterionic graphene nanomaterials (ZGNMs) were synthesized with defined exposure, in terms of polymer coverage and functionality, and isoelectric points. Then, the switchable interactions of these nanomaterials with E. coli and Bacillus cereus were investigated to study the validity of the generally proposed “trapping” and “nano-knives” mechanisms for inactivating bacteria by graphene derivatives. It was found that the antibacterial activity of graphene derivatives strongly depends on the accessible area, i.e. edges and basal plane of sheets and tightness of their agglomerations. Our data clearly confirm the authenticity of “trapping” and “nano-knives” mechanisms for the antibacterial activity of graphene sheets. KW - XPS KW - Graphene KW - Graphene–bacteria interaction PY - 2018 DO - https://doi.org/10.1039/c8nr01347k SN - 2040-3364 SN - 2040-3372 VL - 10 IS - 20 SP - 9525 EP - 9537 PB - RSC CY - London AN - OPUS4-45084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Busch, I. A1 - Unger, Wolfgang A1 - Bütefisch, S. A1 - Lenck, O. A1 - Koenders, L. A1 - Weimann, T. A1 - Weinert, M. T1 - Analytical and topographical Reference Material for the Nanoscale N2 - Reliable standards are required to support research and development as well as end-user in application. Appropriate standards have to fulfill three requirements: small uncertainty, easy to use and low overall costs of application. For calibration of microscopes at nanoscale and/or element analysis special requirements for standards are given, which are challenging in manufacture. T2 - Workshop on Reference Nanomaterials CY - Berlin, Germany DA - 14.05.2018 KW - XPS KW - Imaging KW - Reference material KW - NoStep Standards PY - 2018 AN - OPUS4-45156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Hirthammer, Volker A1 - Unger, Jörg F. ED - Meschke, G. ED - Pichler, B. ED - Rots, J.G. T1 - A continuum damage model for the simulation of concrete under cyclic loading N2 - Lifetime aspects including fatigue failure of concrete structures were traditionally only of minor importance. Because of the growing interest in maxing out the capacities of concrete, its fatigue failure under compression has become an issue. A variety of interacting phenomena such as e.g. loss of prestress, degradation due to chemical reactions or creep and shrinkage influence the fatigue resistance. Failure due to cyclic loads is generally not instantaneous, but characterized by a steady damage accumulation. Therefore, a reliable numerical model to predict the performance of concrete over its lifetime is required, which accurately captures order effects and full three-dimensional stress states. Many constitutive models for concrete are currently available, which are applicable for specific loading regimes, different time scales and different resolution scales. However, a key limitation of those models is that they generally do not address issues related to fatigue on a structural level. Very few models can be found in the literature that reproduce deterioration of concrete under repeated loading-unloading cycles. This is due to the computational effort necessary to explicitly resolve every cycle which exceeds the currently available computational resources. The limitation can only be overcome by the application of multiscale methods in time. The objective of the paper is the development of numerical methods for the simulation of concrete under fatigue loading using temporal multiscale methods. First, a continuum damage model for concrete is developed with a focus on fatigue under compressive stresses [1]. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. The model is designed to represent failure under static loading as a particular case of fatigue failure after a single loading cycle. As a consequence, most of the material parameters can be deduced from static tests. Only a limit set of additional constitutive parameters is required to accurately describe the evolution under fatigue loading. Another advantage of the proposed model is the possibility to directly incorporate other multi-physics effects such as creep and shrinkage or thermal loading on the constitutive level. Second, a multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach [2]. This evolution equation is then solved on the long time scale using different implicit and explicit time integration schemes. Their performance and some limitations for specific loading regimes is discussed. Finally, the developed methods will be validated and compared to experimental data. [1] Vitaliy Kindrachuk, Marc Thiele, Jörg F. Unger. Constitutive modeling of creep-fatigue interaction for normal strength concrete under compression, International Journal of Fatigue, 78:81-94, 2015 [2] Vitaliy Kindrachuk, Jörg F. Unger. A Fourier transformation-based temporal integration scheme for viscoplastic solids subjected to fatigue deterioration, International Journal of Fatigue, 100:215-228, 2017 T2 - Conference on Computational Modelling of concrete and concrete structures (EURO_C 2018') CY - Bad Hofgastein, Austria DA - 26.02.2018 KW - Fatigue KW - Concrete KW - Damage PY - 2018 SN - 978-1-138-74117-1 DO - https://doi.org/10.1201/9781315182964-19 SP - 155 EP - 164 PB - CRC Press, Taylor & Francis Group CY - Boca Raton, Lodon, New York, Leiden AN - OPUS4-47999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Unger, Wolfgang T1 - Summary of ISO/TC 201 technical report: ISO/TR 19693 surface chemical analysis—characterization of functional glass substrates for biosensing applications N2 - ISO/TR 19693:2018—Surface chemical analysis—Characterization of functional glass substrates for biosensing applications gives an overview of methods, strategies, and guidance to identify possible sources of problems related to substrates, device production steps (cleaning, activation, and chemical modification), and shelf life (storage conditions and aging). It is particularly relevant for surface chemical analysts characterizing glass‐based biosensors, and developers or quality managers in the biosensing device production community. Based on quantitative and qualitative surface chemical analysis, strategies for identifying the cause of poor Performance during device manufacturing can be developed and implemented. A review of measurement capabilities of surface analytical methods is given to assist readers from the biosensing community. KW - Bio sensing device KW - Surface chemical analysis KW - XPS KW - SIMS KW - Standardization PY - 2018 DO - https://doi.org/10.1002/sia.6481 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 8 SP - 835 EP - 838 PB - John Wiley & Sons, Ltd. AN - OPUS4-45829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinrich, Thomas A1 - Müller, Anja A1 - Schneider, Markus A1 - Sparnacci, Katja A1 - Unger, Wolfgang T1 - Chemical characterisation and classification of (Core-Shell) nanoparticles using PCA assisted ToF-SIMS N2 - The analysis of nanomaterials is currently an important task - especially in case of risk assessment – as the properties of these material class are not well understood and their growing use in everyday life. The rather high surface area of these objects renders their interactions significantly different to their corresponding bulk. Thus, the surface’s chemical composition must be investigated to get a better understanding and prediction of the nanomaterials’ behaviour. ToF-SIMS and XPS have proven to be powerful tools to determine the general chemical composition. The superior surface sensitivity of ToF-SIMS furthermore allows us to study mainly the utmost atomic layers and thus gives us an idea of possible interactions involved. Supported by multivariate data analysis such as principal component analysis (PCA), the method can also be used for sub-classification of different materials using slight differences in surface chemistry. Here, we present data of the analysis of Hyflon®-polystyrene core-shell nanoparticles which can be used as a model system due to the known preparation and a rather good chemical as well as physical separation of core and shell. Principle component analysis (PCA) will be used to detect the influence of sample preparation and for a better separation of different samples. This is achieved by measurement of a statistically relevant set of samples for every particle sample. We acquired surface spectra under static SIMS conditions with Bi32+ and analysed the resulting spectra by PCA. The carefully selected and refined peaks allow a reasonable categorization and further a reliable allocation of blank feeds. In detail, the fluorine containing, organic fragments are an indication for a heterogeneous shell that has errors. Furthermore, results on Au nanoparticles with and without an antibody shell are presented. ToF-SIMS imaging is desired to be implemented for single particle detection as well. T2 - SIMS-Europe CY - Münster, Germany DA - 16.09.2018 KW - Nanoparticles KW - ToF-SIMS KW - XPS KW - PCA KW - Titania KW - Core-Shell PY - 2018 AN - OPUS4-46249 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cant, D. A1 - Shard, A. A1 - Müller, Anja A1 - Clifford, C. A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Surface chemical analysis – Electron spectroscopies – Measurement of the thickness and nature of nanoparticle coatings N2 - Recent years have seen increasing development of nanoparticles for applications in a wide range of fields, including but not limited to areas of great impact such as catalysis, medicine, energy, optoelectronics, cosmetics, and many others. In particular, nanoparticles bearing some form of coating layer, whether by design or due to incidental processes such as contamination or oxidation, are among the most commonly studied and utilised. In the characterisation of nanoparticles, the surface properties are of great importance, because a large proportion of the particle forms a part of the surface or interface. In the case of coated nanoparticles, the thickness of the coating is significant in determining the properties of the nanoparticle, and defines its interactions with its environment. Measurement of surface chemistry and coating thickness of nanoparticles is a challenge to which electron spectroscopies are well suited, due to high surface sensitivity, well-understood physical principles and accessibility. T2 - Annual Meeting of ISO/TC 201/SC7 CY - Cancun, Mexico DA - 21.09.2018 KW - Nanoparticle characterization KW - X-ray Photoelectron Spectroscopy (XPS) KW - Auger Electron Spectroscopy (AES) KW - Core-shell nanoparticles PY - 2018 AN - OPUS4-46259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Li, Wei T1 - Crack propagation in filled and unfilled polymers: Separation of surface energy and irreversible deformation energy N2 - Fiber-reinforced-polymers (FRPs) are in current research focus in the lightweight construction industry, because of their extraordinary characteristics (stiffness and strength-to-density relation). The structure of polymer matrix and the interaction with reinforcement are crucial for optimization of the mechanical and thermal properties of FRPs. Due to the macromolecular chain structure, the mechanical properties of a polymer strongly vary with temperature: Below the glass transition, the chain segments of a polymer are “frozen”. Regarding fracture, the total changed energy during fracture if only dissipates for the generation of the new surfaces. However, in the region of the glass transition, the polymer chain segments start to get “unfrozen”, and the energy is not only required for generating new surfaces, but also for irreversibly deformation. This irreversible deformation is affected by the global temperature and the local temperature near the crack tip, which is affected by the local strain rate and crack propagation velocity. Hence, in this research project, the irreversible deformation of neat and reinforced polymers will be controlled by changing the global temperature as well as the local temperature. With using different fracture experiments, the amount of energy required for creating new surfaces and for the irreversible deformation will be separated. The fracture tests include the conventional tensile test, the macroscopic peel test and the single fiber peel – off test. T2 - PhD Day 2018 of BAM CY - Berlin, Germany DA - 31.05.2018 KW - Crack Propagation KW - Polymer PY - 2018 AN - OPUS4-48471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Streeck, C. A1 - Wirth, Thomas A1 - Unger, Wolfgang A1 - Beckhoff, B. T1 - Qualifying calibration samples for advanced thin film materials characterisation N2 - In this article the question of the certification of calibration samples for the characterisation of advanced thin film materials is addressed within the framework of reliable process control or quality management purposes. Reference measurement techniques can be used in order to address the gap in appropriate certified reference materials (CRMs) for thin film analyses. They allow for qualifying out-of-production samples originating from an operating production line as calibration samples. As a template for this procedure, CIGS [Cu(In,Ga)Se2] layers, that are absorber layers for high efficiency thin-film solar cells, have been used for establishing and validating reference-free X-ray fluorescence (XRF) analysis and Auger-electron spectroscopy (AES) as reference measurement techniques. The focus was on determining the average mole fractions in the CIGS layers obtaining results traceable to the SI unit system. Reference-free XRF is physically traceable and is based upon radiometrically calibrated instrumentation and knowledge of atomic fundamental data. Sputter-assisted AES can be established as a chemically traceable method after careful calibration using a certified reference material (CRM) based on a total number counting method. KW - CIGS KW - X-ray fluorescence (XRF) KW - Auger-electron spectroscopy (AES) PY - 2018 UR - https://www.spectroscopyeurope.com/article/qualifying-calibration-samples-advanced-thin-film-materials-characterisation VL - 30 IS - 1 SP - 11 EP - 14 PB - John Wiley & Sons Ltd CY - Chichester, West Sussex PO19 8SQ, UK AN - OPUS4-44260 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinen, S. A1 - Rackow, S. A1 - Cuellar-Camacho, J. L. A1 - Donskyi, Ievgen A1 - Unger, Wolfgang A1 - Weinhart, M. T1 - Transfer of functional thermoresponsive poly(glycidyl ether) coatings for cell sheet fabrication from gold to glass surfaces N2 - Thermoresponsive polymer coatings can facilitate cell sheet fabrication under mild conditions by promoting cell adhesion and proliferation at 37 1C. At lower temperatures the detachment of confluent cell sheets is triggered without enzymatic treatment. Thus, confluent cell sheets with intact extracellular matrix for regenerative medicine or tissue engineering applications become available. Herein, we applied the previously identified structural design parameters of functional, thermoresponsive poly(glycidyl ether) brushes on gold to the more application-relevant substrate glass via the self-assembly of a corresponding block copolymer (PGE-AA) with a short surface-reactive, amine-presenting anchor block. Both, physical and covalent immobilization on glass via either multivalent ionic interactions of the anchor block with bare glass or the coupling of the anchor block to a polydopamine (PDA) adhesion layer on glass resulted in stable coatings. Atomic force microscopy revealed a high degree of roughness of covalently attached coatings on the PDA adhesion layer, while physically attached coatings on bare glass were smooth and in the brush-like regime. Cell sheets of primary human dermal fibroblasts detached reliably (86%) and within 20 ± 10 min from physically tethered PGE-AA coatings on glass when prepared under cloud point grafting conditions. The presence of the laterally inhomogeneous PDA adhesion layer, however, hindered the spontaneous temperature-triggered cell detachment from covalently grafted PGE-AA, decreasing both detachment rate and reliability. Despite being only physically attached, self-assembled monolayer brushes of PGE-AA block copolymers on glass are functional and stable thermoresponsive coatings for application in cell sheet fabrication of human fibroblasts as determined by X-ray photoelectron spectroscopy. KW - X-ray photoelectron spectroscopy KW - Thermoresponsive poly(glycidyl ether) coatings KW - Cell sheet fabrication KW - Nm film thickness PY - 2018 DO - https://doi.org/10.1039/c7tb03263c SN - 2050-750X SN - 2050-7518 VL - 6 IS - 10 SP - 1489 EP - 1500 PB - The Royal Society of Chemistry AN - OPUS4-44600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Unger, Jörg F. T1 - A Fourier transformation-based method for gradient-enhanced modeling of fatigue N2 - A key limitation of the most constitutive models that reproduce a Degradation of quasi-brittle materials is that they generally do not address issues related to fatigue. One reason is the huge computational costs to resolve each load cycle on the structural level. The goal of this paper is the development of a temporal Integration scheme, which significantly increases the computational efficiency of the finite element method in comparison to conventional temporal integrations. The essential constituent of the fatigue model is an implicit gradient-enhanced formulation of the damage rate. The evolution of the field variables is computed as amultiscale Fourier series in time.On a microchronological scale attributed to single cycles, the initial boundary value problem is approximated by linear BVPs with respect to the Fourier coefficients. Using the adaptive cycle jump concept, the obtained damage rates are transferred to a coarsermacrochronological scale associated with the duration of material deterioration. The performance of the developedmethod is hence improved due to an efficient numerical treatment of the microchronological problem in combination with the cycle jump technique on the macrochronological scale. Validation examples demonstrate the convergence of the obtained solutions to the reference simulations while significantly reducing the computational costs. KW - Accelerated temporal integration KW - Fourier series KW - Gradient-enhanced fatigue model PY - 2018 DO - https://doi.org/10.1002/nme.5740 SN - 1097-0207 SN - 0029-5981 VL - 114 IS - 2 SP - 196 EP - 214 PB - Wiley AN - OPUS4-44008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Near-ambient pressure XPS of hydrated Escherichia coli samples with EnviroESCA N2 - This application note presents how EnviroESCA can be used to analyze E. coli biofilms on silicon under near ambient pressure conditions in various states of hydration. Such investigations of the outer bacterial cell surface in their hydrated state are essential for studying biological interfaces at work. KW - Biofilms KW - E. coli KW - NAP-XPS PY - 2018 UR - http://www.enviroai.com/uploads/1/0/2/8/102861712/nap_xps_of_escherichia_coli_samples.pdf IS - Application Note #000400 SP - 1 EP - 4 CY - Berlin, Germany AN - OPUS4-45720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang T1 - Analysis of deuterium in austenitic stainless steel AISI 304L by Time-of-Flight Secondary Ion Mass Spectrometry N2 - Due to their excellent combination of ductility, strength and corrosive resistance, austenitic stainless steels (ASS) are widely used in many industrial applications. Thus, these steel grades can be found as structural components in the (petro-)chemical industry, in offshore applications and more recent for storage and transport of hydrogen fuel. Steels employed for these applications are exposed to aggressive environments and hydrogen containing media. The ingress and accumulation of hydrogen into the microstructure is commonly observed during service leading to a phenomenon called “hydrogen embrittlement”. A loss in ductility and strength, the formation of cracks and phase transformations are typical features of this hydrogen-induced degradation of mechanical properties. Although, great efforts are made to understanding hydrogen embrittlement, there is an ongoing debate of the underlying mechanisms. This knowledge is crucial for the safe use and durability of components on the one side and the development of new materials on the other. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was proven to be a powerful tool for depicting the distribution of the hydrogen isotope deuterium in the microstructure of austenitic and duplex steels. The combination with imaging techniques such as electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM), delivering structural and morphological information, creates a comprehensive picture of the hydrogen/deuterium-induced effects in the materials. All the gathered data is treated with principal component analysis (PCA) and data fusion to enhance the depth of information. The mobility of hydrogen and deuterium in a steel microstructure is affected by external mechanical stress. To investigate the behaviour of deuterium in a strained microstructure, a new in situ experimental approach was developed. This gives the possibility of analysing samples in the SIMS instrument simultaneously to four-point-bending-tests. Specimens made from ASS AISI 304L were electrochemically charged with deuterium instead of hydrogen. This necessity stems from the difficulty to separate between artificially charged hydrogen and hydrogen existing in the pristine material or adsorbed from the rest gas in the analysis chamber. Nonetheless, similar diffusion, permeation and solubility data allow to draw qualitative conclusions from the experiments, which are relevant for the application addressed. T2 - SIMS Europe 2018 CY - Münster, Germany DA - 16.09.2018 KW - Hydrogen KW - Deuterium KW - Austenitic stainless steel KW - SIMS PY - 2018 AN - OPUS4-46029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Jörg F. A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Hirthammer, Volker T1 - A continuum damage model for the simulation of concrete under cyclic loading N2 - Lifetime aspects including fatigue failure of concrete structures were traditionally only of minor importance. Because of the growing interest in maxing out the capacities of concrete, its fatigue failure under compression has become an issue. A variety of interacting phenomena such as e.g. loss of prestress, degradation due to chemical reactions or creep and shrinkage influence the fatigue resistance. Failure due to cyclic loads is generally not instantaneous, but characterized by a steady damage accumulation. Therefore, a reliable numerical model to predict the performance of concrete over its lifetime is required, which accurately captures order effects and full three-dimensional stress states. Many constitutive models for concrete are currently available, which are applicable for specific loading regimes, different time scales and different resolution scales. However, a key limitation of those models is that they generally do not address issues related to fatigue on a structural level. Very few models can be found in the literature that reproduce deterioration of concrete under repeated loading-unloading cycles. This is due to the computational effort necessary to explicitly resolve every cycle which exceeds the currently available computational resources. The limitation can only be overcome by the application of multiscale methods in time. The objective of the paper is the development of numerical methods for the simulation of concrete under fatigue loading using temporal multiscale methods. First, a continuum damage model for concrete is developed with a focus on fatigue under compressive stresses. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. The model is designed to represent failure under static loading as a particular case of fatigue failure after a single loading cycle. As a consequence, most of the material parameters can be deduced from static tests. Only a limit set of additional constitutive parameters is required to accurately describe the evolution under fatigue loading. Another advantage of the proposed model is the possibility to directly incorporate other multi-physics effects such as creep and shrinkage or thermal loading on the constitutive level. Second, a multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach. This evolution equation is then solved on the long time scale using different implicit and explicit time integration schemes. Their performance and some limitations for specific loading regimes is discussed. Finally, the developed methods will be validated and compared to experimental data. T2 - Conference on Computational Modelling of concrete and concrete structures (EURO_C 2018') CY - Bad Hofgastein, Austria DA - 26.02.2018 KW - Fatigue KW - Concrete KW - Damage PY - 2018 AN - OPUS4-48001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinrich, Thomas A1 - Schneider, Markus A1 - Schäpe, Kaija A1 - Unger, Wolfgang A1 - Stockmann, Jörg M. T1 - Classification of engineered Titania nanomaterials via surface analysis using principal component analysis (PCA) assisted Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) N2 - Due to the growing number of engineered nanomaterials (NM) the need for a reliable risk assessment for these materials is today bigger than ever before. Especially the nanomaterial’s surface or shell directly interacts with its environment and therefore is a crucial factor for NM’ toxicity or functionality. Especially, titania is one of the NM with the greatest technological importance. It is used for a large number of applications and can be found in food, cosmetics, glasses, mirrors, paints to mention only a few. In 2012, experts estimate[d] the annual European nano-titania production or utilization at an amount of more than 10,000 t. Great progress has been achieved in the area of NM investigation and characterization during the past decade. A variety of publications provide information about technological innovation as well as hazard potential, which means the potential risk on human health and ecosystems. However, enhanced data harmonization and well-defined standards for nanomaterial analysis, could significantly improve the reliability of such studies which often suffers from varying methods, parameters and sample preparations. To develop a suitable approach for the NM’s risk assessment, the ACEnano project aims at establishing a toolbox of verified methods. The size of this well-structured European project allows to handle even those big challenges like data harmonization and standardization. Due to its powerful combination of superior surface sensitivity and lateral resolution down to the Nano regime, ToF-SIMS could become one of these toolbox methods. Supported by multivariate data analysis such as principal component analysis (PCA), the method can be used for sub-classification of nanomaterial families using slight differences in surface chemistry. Here, we show a PCA supported classification of titania nanoparticles from various sources (NIST, JRC, BAM) with ToF-SIMS. Parameters like size, shell, pre-preparation and crystal system cause variance in the data and allow us to distinguish the species from each other. Moreover, this variance in the data also occurs and can be used for investigation when we compare our measurements of particle ensembles with those of grown titania films. The carefully selected and refined peaks allow a reasonable particle categorization and further a reliable allocation of blank feeds, which introduces a promising approach for NM characterization in the context of NM risk assessment. T2 - SIMS-Europe CY - Münster, Germany DA - 16.09.2018 KW - Nanoparticles KW - ToF-SIMS KW - XPS KW - PCA KW - Titania PY - 2018 AN - OPUS4-46250 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Dietrich, P. A1 - Thissen, A. A1 - Schwibbert, Karin A1 - Unger, Wolfgang T1 - Depth-dependent analysis of model biofilms by combining laboratory- and synchrotron-based X-ray photoelectron spectroscopy N2 - Synchrotron XPS in the soft-X-ray regime is suitable for the detection of light elements commonly found in biological samples. Various model systems of biofilms have been developed and characterised at synchrotron- and lab-based facilities. By obtaining the chemical composition at various information depths, the vertical distribution of iodine in an artificial biofilm have been determined. T2 - Tenth Joint BER II and BESSY II User Meeting CY - Berlin, Germany DA - 05.12.2018 KW - Biofilms KW - HAXPES KW - XPS KW - Iodine KW - Synchrotron-XPS PY - 2018 AN - OPUS4-46929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nehring, Grzegorz A1 - Targowski, P. A1 - Rabin, Ira T1 - Can an inkwell leak into ink? N2 - X-ray fluorescence analysis, due to its non-destructive nature and ist suitability to work with historic objects in situ, quickly became one of the most important methods for the evaluation of iron-gall ink. The main advantage of this qualitative and semi-quantitative method is that it makes it easy to differentiate between inks, based on the assumption that the differences result from the manufacture of the ink. This work explores the question whether the ink ‘fingerprint’ results strictly from the elemental composition of the basic ink ingredients even if it is stored in vessels made of metals or metal alloys. In addition, we tested and compared the performance of three different XRF spectrometers. We prepared various lab-grade inks according to historical ink recipes and measured the metal content of the ink deposited on sized cotton Linters paper with three types of XRF spectrometers: a simple hand-held device with an interaction spot of 4 mm and two devices equipped with poly-capillary Xray optics for line scanning and imaging. Since the exact elemental mass composition of the non-aged ink samples was known, we were able to evaluate the accuracy of the research procedure. Lab-grade inks were then aged in the metal jars imitating inkwells. The aging of the inks in the metal containers resulted in the significant change of the primary inks fingerprint as opposed to that of the control inks stored in glass containers. This effect was independently confirmed by the measurements conducted with every instrument we used. We will present a brief comparison of the results 43 achieved when using different spectrometers and a possible hypothesis explaining the processes that occurred. T2 - Konferenz -7th Meeting X-ray and other techniques in investigations of the objects of cultural heritage CY - Krakow, Poland DA - 17.05.2018 KW - Iron-gall ink KW - XRF KW - Inkwells KW - Ink composition KW - Performance comparison PY - 2018 AN - OPUS4-49157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabin, Ira A1 - Kohl, Anka A1 - Bicchieri, M. A1 - Sodo, A. A1 - Piantanida, G. T1 - New results in Dead Sea Scrolls non-destructive characterisation. Evidence of different parchment manufacture in the fragments fromReed collection N2 - This work presents the non-destructive spectroscopic characterisation of original Dead Sea Scrolls (DSS)parchment fragments from Ronald Reed collection. The fragments are of paramount importance becausethey have never been subjected to any treatment of preservation and restoration, this allows to investi-gate the manufacturing method of real original Jewish parchments. The manufacture of “sacred” Jewishparchments, in fact, is traditionally supposed to use a superficial tannin treatment. To study the DSS frag-ments, it was necessary both to analyse mock-up samples, especially manufactured in order to reproduceancient Oriental Jewish ritual parchments, and to compare the results with those obtained in the analysisof modern and ancient Western Jewish ritual parchments, in order to test the effectiveness of the selectedspectroscopic techniques. Traditionally, the main difference between Oriental and Western traditionalparchment preparation consisted in the dehairing method: enzymatic for Oriental and lime-based forWestern. Moreover, a finishing treatment with tannin was supposed to be applied on ritual Jewish parch-ments. The need of reference samples derives from the knowledge that each parchment preparation,treatment and degradation can induce structural modifications that affect the spectral features. FourierTransform Infrared Spectroscopy by Attenuated Total Reflection (ATR-FTIR), FT-Raman and m-Ramanwere used in this study. The experimental results allowed us to recognise, with different sensitivity, thepresence of tannin by using m-Raman and IR spectroscopies and to prove that not all the archaeologicalsamples were manufactured in the same way with vegetal extracts. Many salts (tschermigite, dolomite,calcite, gypsum and iron carbonate) were found on the surface of DSS fragments. They can derive fromthe degradation processes and storage environment before the discovery or from the manufacture. More-over, the different sensitivities and instrumental characteristics of the used techniques permitted us toestablish an analytical protocol, useful for further studies of similar materials. KW - ATR-FTIR KW - Tannins KW - Dead Sea Scrolls KW - Raman KW - FT-Raman PY - 2018 DO - https://doi.org/10.1016/j.culher.2018.01.014 VL - 32 SP - 22 EP - 29 PB - Elsevier Masson SAS AN - OPUS4-49533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Surface characterisation of biofilms by nearambient pressure X-ray photoelectron spectroscopy N2 - The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. T2 - Royal Society of Chemistry Twitter Conference CY - Worldwide (online conference) DA - 06.03.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Maierhofer, Christiane T1 - Numerical 2D model to quantify defects in semitransparent materials by pulsed thermography N2 - Pulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for evaluation of material defects. Material defects are often simulated by flat-bottom holes (FBH) or grooves. Typically, analytical 1D models are used to determine the defect depth of FBHs, grooves or delaminations. However, these models cannot take into account lateral heat flows, or only to a limited extent (semi-empirical model). Their applicability is therefore limited by the FBHs aspect ratio (diameter to remaining wall thickness), to ensure that the heat flow above the defect can still be described one-dimensionally. Additionally, the surfaces of semi-transparent materials have to be blackened to absorb the radiation energy on the surface of the material. Without surface coatings, these models cannot be used for semi-transparent materials. Available 1D analytical models for determination of sample or layer thicknesses also do not take into account lateral heat flows. Here, we present an approach for quantitative determination of the geometry of FBHs or grooves in semi-transparent materials by considering lateral heat flow. For this purpose, the results of a numerical 2D model are fitted to experimental data, e.g., to determine simultaneously the defect depth of a FBH or groove and its diameter or width, respectively. The model considers semi-transparency of the sample within the wavelength range of the excitation source as well as of the IR camera and thermal losses at its surfaces. Heat transport by radiation within the sample is neglected. It supports the use of an arbitrary temporal shape of the heating pulse to properly describe the measurement conditions for different heat sources. T2 - Progress in Photoacoustic & Photothermal Phenomena CY - Erice, Italy DA - 06.09.2018 KW - Pulse thermography KW - Numerical modelling KW - 2D model KW - Data reconstruction KW - Flat bottom holes KW - Notches KW - Semitrasnparent materials PY - 2018 AN - OPUS4-46105 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maiwald, Michael A1 - Emmerling, Franziska A1 - Villajos Collado, José Antonio A1 - Maierhofer, Christiane A1 - Thiel, Erik A1 - Altenburg, Simon T1 - Already producing or still assembling? – Perspectives towards modular production and quality control in a digitized process industry N2 - The CLEAN ENERGY Flagship is an initiative designed to utilize recent game changing developments in digital, materials and manufacturing technologies to catalyze a radical paradigm shift towards clean, reliable, efficient and cost-optimal energy. Unifying and drastically accelerating radically new energy material design, processing and integration across the entire value chain addressing energy production, conversion, storage and systems. CLEAN ENERGY participants are all distinguished research organisations that each benefit from their own industry networks and contacts with regions and state-level activities and have a long history of collaborating with each other (for 10 years now under the umbrella of EERA) within a European collaborative framework. Through EERA, CLEAN ENERGY aims to become a crucial partner in the SET-Plan, supporting long-lasting approaches through its established networks and internal collaborations. T2 - Clean Energy Workshop on Autonomous Materials Development Platforms CY - Brussels, Belgium DA - 02.10.2018 KW - Digitization KW - Energy production KW - Energy storage KW - Energy systems KW - Clean energy technology PY - 2018 AN - OPUS4-46135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Franz, Philipp A1 - Metz, Christian A1 - Brackrock, Daniel A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Zerstörungsfreie Charakterisierung und Qualitätssicherung der Materialeigenschaften und Beständigkeit additiv gefertigter Kunststoffteile N2 - Mit additiven Fertigungsverfahren hergestellte Bauteile und Produkte aus Kunststoffen werden zunehmend nicht mehr nur als Prototypen, sondern als voll funktionsfähige Bauteile und Produkte gefertigt. Bedingt durch die Fertigungsprozesse und den schichtweisen Aufbau resultieren physikalische Materialeigenschaften, die stark von den Fertigungsparametern abhängen und zudem anisotrop sind. Von den Fertigungsparametern werden auch die Oberflächeneigenschaften beeinflusst, sodass zu erwarten ist, dass sich die Beständigkeit gegenüber äußeren Umwelteinflüssen bei additiv gefertigten Bauteilen von der konventionell gefertigter unterscheiden kann. Nachfolgend wird daher die Entwicklung eines Qualitätssicherungskonzeptes basierend auf spektroskopischen und zerstörungsfreien Prüfverfahren vorgestellt, in dem der Alterungsprozess von mittels Fused Deposition Modelling (FDM) und mittels Lasersintering (LS) hergestellten Probekörpern untersucht wird. T2 - DGZfP-Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Additive Fertigung KW - Kunststoffe KW - Zerstörungsfreie Prüfung PY - 2018 AN - OPUS4-44896 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Franz, Philipp A1 - Metz, Christain A1 - Brackrock, Daniel A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Zerstörungsfreie Charakterisierung und Qualitätssicherung der Materialeigenschaften und Beständigkeit additiv gefertigter Kunststoffteile N2 - Mit additiven Fertigungsverfahren hergestellte Bauteile und Produkte aus Kunststoffen werden zunehmend nicht mehr nur als Prototypen, sondern als voll funktionsfähige Bauteile und Produkte gefertigt. Bedingt durch die Fertigungsprozesse und den schichtweisen Aufbau resultieren physikalische Materialeigenschaften, die stark von den Fertigungsparametern abhängen und zudem anisotrop sind. Von den Fertigungsparametern werden auch die Oberflächeneigenschaften beeinflusst, sodass zu erwarten ist, dass sich die Beständigkeit gegenüber äußeren Umwelteinflüssen bei additiv gefertigten Bauteilen von der konventionell gefertigter unterscheiden kann. Nachfolgend wird daher die Entwicklung eines Qualitätssicherungskonzeptes basierend auf spektroskopischen und zerstörungsfreien Prüfverfahren vorgestellt, in dem der Alterungsprozess von mittels Fused Deposition Modelling (FDM) und mittels Lasersintering (LS) hergestellten Probekörpern untersucht wird. T2 - DGZfP-Jahrestagung 2018 CY - Leipzig, Germany DA - 07.05.2018 KW - Additive Fertigung KW - Kunststoffe KW - Zerstörungsfreie Prüfung PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449016 SN - 978-3-940283-92-4 VL - DGZfP BB 166 SP - Mo.2.A.1, 1 EP - 9 AN - OPUS4-44901 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Quantification of impact damages in CFRP and GFRP structures with thermography and ultrasonics N2 - The extent of damage caused by impacts in fibre reinforced composites depends on the energy of the impacts, on the velocity and the shape of the impacting body, on the material and structure of the composite and on the geometry of the structure. Here, mainly the thickness of the component is essential. The non-destructive evaluation of these damages can be carried out using both ultrasound and active thermography methods. A comparison of the detection sensitivity of these methods for the different damages is carried out in this paper depending on the fibre composite material used (CFRP and GFRP), the thickness of the material and the impact energy. The NDT methods used after the damage are supplemented by thermographic measurements with high temporal resolution, which were already recorded during the impact. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Active thermography KW - Passive thermography KW - Ultrasonics KW - CFRP KW - GFRP KW - Impact PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454952 UR - http://www.qirt.org/archives/qirt2018/papers/126.pdf DO - https://doi.org/10.21611/qirt.2018.126 SP - 933 EP - 940 PB - DGZfP e. V. AN - OPUS4-45495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane A1 - Fischer, Christian T1 - Additiv gefertigte Polymerbauteile: Untersuchung der Beständigkeit durch künstliche Bewitterung und zerstörungsfreie Charakterisierung (PolyMatAM) N2 - Es wird ein Verfahren zur Charakterisierung der Beständigkeit und Langzeitstabilität von additiv gefertigten Kunststoff-Bauteilen vorgestellt. Dabei sollen die Prüfkörper über 2000 Stunden künstlich bewittert und währenddessen die Änderungen der Eigenschaften der Bauteile zerstörungsfrei untersucht werden. T2 - 47. Jahrestagung der Gesellschaft für Umweltsimulation e.V. (GUS) CY - Stutensee, Germany DA - 21.03.2018 KW - Additive Fertigung KW - Künstliche Bewitterung KW - Thermografie PY - 2018 AN - OPUS4-46545 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Verfahrensentwicklung für das Prozessmonitoring in der additiven Fertigung von Metallen - Thermografie N2 - Aktuell werden Prozessmonitoringsysteme in der additiven Fertigung (AM) zur Überwachung der Energiequelle, des Bauraums, des Schmelzbades und der Bauteilgeometrie zumindest im metallbasierten AM schon kommerziell angeboten. Weitere Verfahren aus den Bereichen der Optik, Spektroskopie und zerstörungsfreien Prüfung werden in der Literatur als geeignet für die in-situ Anwendung bezeichnet, es finden sich aber nur wenige Berichte über konkrete Umsetzungen in die Praxis. Die Bundesanstalt für Materialforschung und -prüfung hat ein neues Projekt gestartet, dessen Ziel die Entwicklung von Verfahren des Prozessmonitorings zur in-situ Bewertung der Qualität additiv gefertigter Bauteile in AM-Prozessen mit Laser- bzw. Lichtbogenquellen ist. Verschiedene Verfahren der zerstörungsfreien Prüfung, wie Thermografie, optische Tomografie, optische Emissionsspektroskopie, Wirbelstromprüfung und Laminografie werden in verschiedenen AM-Prozessen zum Einsatz gebracht und die Ergebnisse fusioniert. Die evaluierten Ergebnisse werden mit Referenzverfahren wie Computertomografie und Ultraschall-Tauchtechnik verglichen. Ziel ist eine deutliche Reduzierung aufwändiger und zeitintensiver, zerstörender oder zerstörungsfreier Prüfungen nach der Fertigung des Bauteiles und zugleich eine Verringerung von Ausschussproduktion. Hier wird das Projekt als Ganzes vorgestellt und der Fokus auf verschiedene Methoden der Temperaturmessung mit Hilfe der Thermografie gelegt. Anforderungen an die Messtechnik für verschiedene AM-Systeme werden diskutiert und erste experimentelle Ergebnisse werden präsentiert. T2 - 3. Tagung des DVM-Arbeitskreises Additiv gefertigte Bauteile und Strukturen CY - Berlin, Germany DA - 07.11.2018 KW - Additive Fertigung KW - Prozessmonitoring KW - ProMoAM KW - Thermografie PY - 2018 AN - OPUS4-46562 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Maierhofer, Christiane A1 - Wachtendorf, Volker A1 - Fischer, C. T1 - Active thermography for quality assurance of 3D-printed polymer structures N2 - Active thermography with flash and halogen light excitation is used as a method for non-destructive testing of 3D-printed polymer components. Test specimens with artificial defects have been generated, using laser sintering and fused layer modeling. These test specimens have been investigated in different measurement configurations with both excitation methods. Afterwards, the different measurement conditions were compared regarding their capability to detect the defects. Furthermore, advanced analysis methods are used, to fully exploit the capabilities of these techniques. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Active thermography KW - Artificial weathering PY - 2018 AN - OPUS4-45387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Thermography in metal AM: Comparison of high-speed NIR thermography and MWIR thermography N2 - Additive manufacturing (AM) opens the route to a range of novel applications.However, the complexity of the manufacturing process poses a challenge for the production of defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields, thermography is a valuable tool for process surveillance. The high process temperatures in metal AM processes allow one to use cameras usually operating in the visible spectral range to detect the thermally emitted radiation from the process. In our work, we compare the results of first measurements during the manufacturing processes of a commercial laser metal deposition (LMD) setup and a laser beam melting (LBM) setup using a MWIR camera with those from a VIS high-speed camera with band pass filter in the NIR range. T2 - Additive Manufacturing Benchmarks 2018 CY - Gaithersburg, MA, USA DA - 18.06.2018 KW - Thermography KW - Additive manufacturing KW - Laser metal deposition KW - Laser beam melting KW - ProMoAM PY - 2018 AN - OPUS4-45401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Ahmadi, Samim A1 - Thiel, Erik A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane T1 - Benefits & peculiarities of using highpower lasers for lock-in thermography N2 - Optical lock-in thermography is a completely contactless and very sensitive NDE technique. As an optical source of energy, incandescent (i.e. halogen) lamps are most commonly used because they are relatively inexpensive, do not need any work safety measures and offer high irradiances at the test site. However, they are strongly restricted by their low modulation bandwidth with a maximum modulation frequency of only about 1 Hz. The use of high-power kilowatt-class laser sources, e.g. diode laser arrays, pushes this constraint beyond 100 Hz. This allows for the exploration of the near-surface region of metals and layer systems with better and more accurate penetration depth and depth resolution. Moreover, these lasers are virtually free of any additional thermal radiation that could interfere with the “true” thermal response emitted from the heated sample. In turn, they can be easily used in a one-sided test configuration. Altogether using lasers considerably increases the application range of lock-in thermography, since especially for metals with a high reflectance and high thermal diffusivity a high irradiance is vitally important to allow for lock-in testing [1, 2]. We report on the mentioned benefits of using such high-power lasers and analyze the range of materials to be tested using lock-in thermography in dependence on the laser irradiance, the modulation frequency, the infrared camera as well as the optical and thermal material parameters. In this context, we also address a number of systematic errors caused by the use of ideal and non-ideal heat sources. For example, the measured phase angle in lock-in thermography depends on the irradiance and the modulation bandwidth of the source. This in turn has a decisive influence on the uncertainty in the quantification of, e.g. layer thicknesses. T2 - INTERNATIONAL SCHOOL OF QUANTUM ELECTRONICS, 62nd Course, Progress in Photoacoustic & Photothermal Phenomena CY - Erice, Italy DA - 06.09.2018 KW - Thermography KW - Laser thermography KW - Lock-in thermography KW - NDT PY - 2018 AN - OPUS4-46282 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Ziegler, Mathias A1 - Maierhofer, Christiane T1 - Systematic errors in the evaluation of uncorrected data from thermographic lock-in measurements N2 - Lock-in thermography (LT) is based on the correct evaluation of phase differences between the temperature oscillations at different surface regions of the object under test during periodic heating. Since the usual heating procedures contain a DC component, the actual heating pattern achieved is not harmonic. This causes systematic deviations when phase differences are determined by means of harmonic analysis, e.g. with FFT analysis. The resulting errors depend clearly on the ratio between DC and AC amplitude, which is demonstrated at simulated and experimentally recorded temperature transients. Further experimental LT data obtained by different oscillating energy inputs showed a variety of possible shapes of transients with different DC components. T2 - 14th QIRT Conference CY - Berlin, Germany DA - 26.6.2018 KW - Lock-in thermography KW - Non-destructive testing KW - FFT PY - 2018 AN - OPUS4-45377 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiel, Erik A1 - Altenburg, Simon A1 - Mohr, Gunther A1 - Thiede, Tobias A1 - Maierhofer, Christiane A1 - Bruno, Giovanni A1 - Rethmeier, Michael A1 - Hilgenberg, Kai A1 - Mishurova, Tatiana A1 - Straße, Anne T1 - AM activities at BAM with focus on process monitoring N2 - The presentation gives an overview of current projects in additive manufacturing at BAM. In particular, the results of the ProMoAm project were presented. T2 - VAMAS - Materials Issues in Additive Manufacturing CY - Berlin, Germany DA - 25.06.2018 KW - Additive Manufacturing KW - Laser Metal Deposition KW - Thermography KW - Data Fusion KW - In-situ monitoring PY - 2018 AN - OPUS4-45620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Ziegler, Mathias A1 - Maierhofer, Christiane ED - Maldague, X. T1 - Systematic errors in the evaluation of uncorrected data from thermographic lock-in measurements N2 - Lock-in thermography (LT) is based on the correct evaluation of phase differences between the temperature oscillations at different surface regions of the object under test during periodic heating. Since the usual heating procedures contain a DC component, the actual heating pattern achieved is not harmonic. This causes systematic deviations when phase differences are determined by means of harmonic analysis, e.g. with FFT analysis. The resulting errors depend clearly on the ratio between DC and AC amplitude, which is demonstrated at simulated and experimentally recorded temperature transients. Further experimental LT data obtained by different oscillating energy inputs showed a variety of possible shapes of transients with different DC components. T2 - 14th QIRT Conference CY - Berlin, Germany DA - 26.06.2018 KW - NDT KW - Lock-in Thermography KW - FFT PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-453768 SP - 539 EP - 547 PB - QIRT Council AN - OPUS4-45376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Maierhofer, Christiane T1 - Iterative numerical 2D-modeling for quantification of material defects by pulsed thermography N2 - Pulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for examination of material defects. Typically, analytical 1D models are used to determine the defect depth of flat-bottom holes (FBH), grooves or delamination. However, these models cannot take into account lateral heat flows, or only to a limited extent. They are therefore limited by the FBHs aspect ratio (diameter to remaining wall thickness), to ensure that the heat flow above the defect can still be described one-dimensionally. Here, we present an approach for quantitative determination of the geometry for FBH or grooves. For this purpose, the results of a numerical 2D model are fitted to experimental data, e.g., to determine simultaneously the defect depth of a groove or FBH and its diameter of width. The model takes lateral heat flows into account as well as thermal losses. Figure 1 shows the temperature increase of a pulsed thermography measurement at three different locations on the sample. The numerical model is fitted to the experimental data (red lines) to quantify the groove. The numerical simulation matches the experimental data well. T2 - 45th Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Burlington, VT, USA DA - 15.07.2018 KW - Opaque materials KW - Pulse thermography KW - Numerical modelling KW - 2D model KW - Data reconstruction KW - Flat bottom holes KW - Notches PY - 2018 AN - OPUS4-46353 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. A1 - Knazowicka, L. A1 - Blahut, A. T1 - Evaluation of different techniques of active thermography for quantification of artificial defects in fiber-reinforced composites using thermal and phase contrast data analysis N2 - For assuring the safety and reliability of components and constructions in energy applications made of fiber-reinforced polymers (e.g., blades of wind turbines and tidal power plants, engine chassis, flexible oil and gas pipelines) innovative non-destructive testing methods are required. Within the European Project VITCEA complementary methods (shearography, microwave, ultrasonics and thermography) have been further developed and validated. Together with partners from the industry, test specimens have been constructed and selected on-site containing different artificial and natural defect artefacts. As base materials, carbon and glass fibers in different orientations and layering embedded in different matrix materials (epoxy, polyamide) have been considered. In this contribution, the validation of flash and lock-in thermography to these testing problems is presented. Data analysis is based on thermal contrasts and phase evaluation techniques. Experimental data are compared to analytical and numerical models. Among others, the influence of two different types of artificial defects (flat bottom holes and delaminations) with varying diameters and depths and of two different materials (CFRP and GFRP) with unidirectional and quasi-isotropic fiber alignment is discussed. KW - Active thermography KW - CFRP KW - GFRP KW - Delaminations KW - Flash excitation KW - Lock-in excitation PY - 2018 DO - https://doi.org/10.1007/s10765-018-2378-z SN - 0195-928X SN - 1572-9567 VL - 39 IS - 5 SP - Article 61, 1 EP - 37 PB - Springer AN - OPUS4-44687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernegger, Raphael A1 - Altenburg, Simon A1 - Roellig, Mathias A1 - Maierhofer, Christiane T1 - Applicability of a 1D analytical model for pulse thermography of laterally heterogeneous semitransparent materials N2 - Pulse thermography (PT) has proven to be a valuable non-destructive testing method to identify and quantify defects in fiber-reinforced polymers. To perform a quantitative defect characterization, the heat diffusion within the material as well as the material parameters must be known. The heterogeneous material structure of glass fiber-reinforced polymers (GFRP) as well as the semitransparency of the material for optical excitation sources of PT is still challenging. For homogeneous semitransparent materials, 1D analytical models describing the temperature distribution are available. Here, we present an analytical approach to model PT for laterally inhomogeneous semitransparent materials.We show the validity of the model by considering different configurations of the optical heating source, the IR camera, and the differently coated GFRP sample. The model considers the lateral inhomogeneity of the semitransparency by an additional absorption coefficient. It includes additional effects such as thermal losses at the samples surfaces, multilayer systems with thermal contact resistance, and a finite duration of the heating pulse. By using a sufficient complexity of the analytical model, similar values of the material parameters were found for all six investigated configurations by numerical fitting. KW - Absorption coefficient KW - Analytical model KW - GFRP KW - Heterogeneous KW - Pulse thermography KW - Semitransparent PY - 2018 DO - https://doi.org/10.1007/s10765-018-2362-7 SN - 0195-928X SN - 1572-9567 VL - 39 IS - 3 SP - Article 39, ICPPP 19, 1 EP - 17 PB - Springer International Publishing AG AN - OPUS4-44003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Sobol, Oded T1 - Hydrogen assisted cracking and transport studied by ToF-SIMS and data fusion with HR-SEM N2 - For almost 150 years it is known that hydrogen has a deleterious effect on the mechanical properties of metallic components. Nowadays, the problem of hydrogen assisted degradation is highly relevant in energy related fields due to the massive use of steel as a structural component in these applications and its sensitivity to hydrogen. Since the discovery of hydrogen assisted cracking (HAC), researchers studied intensively and suggested possible explanations and mechanisms in order to define how hydrogen is affecting the material. In general, it is considered that hydrogen changes the mechanical properties more in terms of ductility (deformation capacities) than in strength (load capacities). Hydrogen concentration is one of three crucial factors in the degradation process, together with the microstructure of the material and the internal/external mechanical load. The relatively high concentration of hydrogen resulting in this loss of ductility can originate during production or before service (e.g. welding processes) and during service (i.e. catholically protected systems to eliminate corrosion processes in sour environments). In parallel to the theoretical work, tremendous efforts were, and are still, invested in searching for a proper method to elucidate, map and quantify the hydrogen in the microstructure, which is the basis for this work. For steels, the focus is mainly on the observations of diffusion processes and the interaction of hydrogen with the microstructure in regions with high local stresses/strains (for example around evolving cracks). The challenge for reaching this goal arises from the fact that accurate indication of hydrogen by means of position, unlike heavier atoms, can be made only by mass spectrometry or by interaction with another element (e.g. silver decoration, special coating and resonant nuclear reaction by nitrogen). In addition to this, the difficulty recording the hydrogen behavior while it rapidly diffuses through the material, leaving only the unpredicted failure, should be taken into account. Although using powerful characterization methods, models and computational simulations, the key to defining the mechanisms behind HAC is still under debate and not fully understood. The relationship between material and hydrogen is determined by three factors, i.e., the material structure and microstructure – determining the physical properties, the mechanical load applied on the material and the hydrogen concentration. It is well known that in order to have a complete definition of HAC these three factors must be examined locally with the minimal scale and the maximal resolution reachable. The major gap is the lack in such a characterization method or a technique by which one has the ability to detect and observe the hydrogen in the metallic microstructure. The commonly used techniques nowadays are capable of characterization of the microstructure without the ability to observe the hydrogen distribution. Global hydrogen concentration and localized hydrogen observation are possible by some techniques which are incapable of indicating a change in the structure or microstructure therefore a comprehensive overview can be gained only by combining several methods. In the presented research, secondary ion mass spectrometry (SIMS) was adopted as the main tool to detect and locally map the hydrogen distribution in two types of duplex stainless steel grades: EN 1.4462 (standard 2205 duplex stainless steel) and EN 1.4162 (2101 lean duplex stainless steel). The term duplex stainless steel (DSS) refers to the austenitic-ferritic microstructure of the steel where the combination of physical and mechanical properties of the two phases is achieved. The DSS was selected as a case study for this work due to the wide use of this grade in many energy and the lack of knowledge on hydrogen behavior in two-phase containing microstructures. ToFSIMS was exploited in-situ and ex-situ in three experimental approaches during or following an electrochemical charging procedure. This type of hydrogen charging was selected as it simulated a procedure of cathodic protection of most sub-water oil and gas extraction and delivery systems. The experimental procedures were: 1. Ex-situ charging followed by ToF-SIMS imaging for basic understanding of hydrogen distribution. 2. Ex-situ charging followed by in-situ mechanical loading to obtain information on hydrogen behavior around a propagating crack. 3. In-situ permeation of hydrogen through a steel membrane inside the ToF-SIMS to obtain information on diffusion behavior of hydrogen in a two-phase microstructure. The comprehensive view of the effect of hydrogen on steel was gained by using supplementary methods, such as high resolution scanning electron microscopy (HR-SEM), focused ion beam (FIB) and electron back-scattered diffraction (EBSD). The state of the art in this work lies in applying both: in-situ experimental approaches and data treatment of the ToF-SIMS raw data. The data treatment includes the combination of data from several sources (data fusion). The results for the ex-situ charging followed by static sample imaging and data fusion showed that when the analyzed surface is directly exposed to the electrolyte the degradation is pronounced differently in the ferrite, austenite and interface. The degradation mechanisms in the ferrite and austenite were reflected by the formation of cracks on the surface of both, where a high concentration of hydrogen was obtained. This result supports the assumption that hydrogen is attracted to highly deformed regions. The advantage of using in-situ charging/permeation in comparison to ex-situ charging is that the effect of hydrogen on the ferrite and austenite phases when the hydrogen is evolving from within the microstructure is realized, in comparison to when the analyzed surface is initially exposed directly to the electrolyte. In both experiments the ferrite was observed as a fast diffusion path for the hydrogen. The faster diffusion of hydrogen through the ferrite is expected due to the higher diffusion coefficient, however, a direct proof for the diffusion sequence in this scale was never shown. Most significant results were achieved by the ‘core’ experiments of this research. These experiments included the design of a novel dynamic mechanical loading device to apply an external load during SIMS imaging of a hydrogen precharged-notched sample. For the first time it was shown that plastic deformation induced by applying a mechanical load is resulting in a redistribution of hydrogen locally around the notch. T3 - BAM Dissertationsreihe - 160 KW - Duplex stainless steels KW - Hydrogen assisted cracking KW - Time-of-Flight secondary ion mass spectrometry KW - Data fusion PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-447331 SN - 1613-4249 VL - 160 SP - I EP - 180 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-44733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Anja A1 - Swaraj, S. A1 - Sparnacci, K. A1 - Unger, Wolfgang T1 - Shell thickness determination for PTFE‐PS core‐shell nanoparticles using scanning transmission X‐ray microscopy (STXM) N2 - A scanning transmission X‐ray microscopy (STXM)‐based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core‐shell nanoparticles, which exhibit a strong X‐ray absorption contrast and a well‐defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less X‐ray beam‐induced damage of the sample is achieved by recording STXM images only at 2 predetermined energies of maximum Absorption contrast, instead of recording a stack of images across the whole absorption edge. A model core‐shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near‐edge X‐ray absorption fine structure spectroscopy confirms the significant difference in X‐ray absorption behavior between PTFE and PS. Additionally, because of the insolubility of styrene in PTFE a well‐defined interface between particle core and shell is expected. To validate the STXM results, both the naked PTFE cores as well as the complete core‐shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM‐based methodology yields particle dimensions in agreement with the SEM results and provides additional information such as the position of the particle core, which cannot be extracted from a SEM micrograph. T2 - European conference on applications of surface and interface analysis (ECASIA'17) CY - Montpellier, France DA - 24.09.2017 KW - Core-shell nanoparticles KW - Polymers KW - PS KW - PTFE KW - SEM KW - STXM PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449700 DO - https://doi.org/10.1002/sia.6464 SN - 1096-9918 SN - 0142-2421 VL - 50 IS - 11 SP - 1077 EP - 1082 PB - John Wiley & Sons CY - Hoboken, New Jersey, USA AN - OPUS4-44970 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS N2 - Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing. This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface. T2 - European conference on applications of surface and interface analysis (ECASIA'17) CY - Montpellier, France DA - 24.09.2018 KW - Bacteria KW - E. coli KW - NAP-XPS PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454047 DO - https://doi.org/10.1002/sia.6480 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 11 SP - 996 EP - 1000 PB - John Wiley & Sons CY - Hoboken, New Jersey, USA AN - OPUS4-45404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Donskyi, Ievgen A1 - Guday, G. A1 - Lippitz, Andreas A1 - Adeli, M. A1 - Haag, R. A1 - Unger, Wolfgang T1 - Gram-scale production of high quality nanographene under mild conditions and doping via non-destructive covalent functionalization N2 - We report a new method for top-down one-pot, gram-scale production of high-quality nanographene from graphite under mild conditions. The nanographene sheets had a very low oxygen content, comparable to that of nanographene grown by chemical vapor deposition. This method is easily scalable and comparatively mild, opening the door to an environmentally friendly process to produce high-quality nanographenes. Nanographene sheets were further covalently functionalized using a non-destructive [2+1] cycloaddition reaction that left the π-conjugated system intact. T2 - 10th Joint BER II and BESSY II User Meeting CY - Berlin, Germany DA - 05.12.2018 KW - Nano graphene KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS KW - Raman spectroscopy PY - 2018 AN - OPUS4-47086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Surface characterisation of bacteria and biofilms by NAP-XPS N2 - The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. In this contribution, the latest progress on biofilm characterisation by NAP-XPS will be presented, and measurement capabilities and limitations will be discussed. T2 - Die Frühjahrstagung der Deutsche Physikalische Gesellschaft CY - Berlin, Germany DA - 12.03.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Dietrich, P. A1 - Thissen, A. A1 - Schwibbert, Karin A1 - Defedov, A. A1 - Wöll, C. A1 - Unger, Wolfgang T1 - Exploring the capabilities of NAP-XPS: Application to metal-organic frameworks, nanoparticles and biofilms N2 - Near-ambient pressure XPS makes it possible to characterise samples not compatible to ultra-high vacuum, and enables the study of liquid-solid, gas-liquid and gas-solid interfaces. NAP-XPS meas-urements of biofilms, suspended nanoparticles and metal-organic frameworks were performed with EnviroESCA developed by SPECS. An interesting application is surface characterisation of biofilms, which are bacterial communities embedded in a self-produced polysaccharide matrix. Various model systems ranging from pure polysaccharides of alginate to biofilms harvested directly from the growth medium have been char-acterised in humid conditions[1]. NAP-XPS also makes it possible to characterise nanoparticles in solution. Silver nanoparticles in aqueous solution were characterised and the Ag 3d-spectrum compared to spectra obtained of dried nanoparticles in UHV-conditions[2]. The binding energy of the Ag 3d-core level peak was shifted by 0,6 eV towards higher binding energy for suspended nanoparticles compared to the dried sample measured in UHV. This can be assigned to a change in surface potential at the water-nanoparticle interface. Metal-organic frameworks (MOFs) are suitable materials for gas storage of small molecules due to their nanoporous, crystalline structure. However, instability in humidity remains an issue for many types of MOFs. XPS-measurements of the MOF-structure HKUST-1 were performed in various NAP-conditions to assess the stability of the sample and its interaction with the gas molecules as water, methanol and pyridine. T2 - 5th AP-XPS Workshop CY - Berlin, Germany DA - 11.12.18 KW - Biofilms KW - E. coli KW - NAP-XPS KW - Metal organic frameworks KW - Nanoparticles PY - 2018 AN - OPUS4-47060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Unger, Wolfgang A1 - Thissen, A. A1 - Dietrich, P. T1 - Progress on characterisation of biofilms by NAP-XPS N2 - Progress talk on characterisation of biofilms by NAP-XPS in the framework of the MetVBadBugs EURAMET-project T2 - MetVBadBugs 24 M project meeting CY - Turin, Italy DA - 06.02.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Comparison of MWIR thermography and high-speed NIR thermography in a laser metal deposition (LMD) process N2 - Additive manufacturing (AM) offers a range of novel applications. However, the manufacturing process is complex and the production of defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal AM processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid-wavelength-IR camera with those from a visual spectrum high-speed camera with band pass filter in the near-IR range. T2 - Conference QIRT 2018 CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Laser metal deposition KW - ProMoAM KW - Thermography PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454993 UR - http://www.qirt.org/archives/qirt2018/papers/p35.pdf DO - https://doi.org/10.21611/qirt.2018.p35 SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-45499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane T1 - Corrigendum to "Measurement of the radiative energy output of flash lamps by means of thermal thin probes" [Infrared Phys. Technol. 67 (2014) 363-370] N2 - This is a corrigendum to the original article "Measurement of the radiative energy output of flash lamps by means of thermal thin probes" that was published in the journal "Infrared physics & technology", vol. 67 (2014), pp. 363-370. PY - 2018 DO - https://doi.org/10.1016/j.infrared.2017.11.011 SN - 1350-4495 VL - 91 SP - 278 PB - Elsevier CY - Amsterdam AN - OPUS4-50505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, Sebastian A1 - Unger, Jörg F. T1 - Probabilistic traffic load identification for concrete bridges N2 - In this work, a probabilistic framework for identification of traffic loads on concrete Bridge structures is presented using data from a FE structural model in combination with a finite volume approach for traffic load modelling. The identification approach uses Bayesian Inference to identify traffic loads from measured sensor data from travelling load experiments performed at BAM. The work focuses on the load identification part of the Framework utilizing global structural response measurements only. The obtained information on traffic loads can be forwarded to further analysis such as fatigue and structure state estimation or model updating. T2 - IRF2018, Proceedings of the 6th International Conference on Integrity-Reliability-Failure CY - Lisbon, Portugal DA - 22.07.2018 KW - Concrete bridges KW - Traffic loads KW - FE modelling KW - Risk analysis PY - 2018 SN - 978-989-20-8313-1 VL - 06 SP - Paper 7121, 521 EP - 522 PB - INEGI-Instituto de Ciência e Inovação em Engenharia Mecânica e Gestão Industrial CY - Portugal AN - OPUS4-48981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Drüke, M. A1 - Silberreis, K. A1 - Lauster, D. A1 - Ludwig, K. A1 - Kühne, C. A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Herrmann, A. A1 - Dernedde, J. A1 - Adeli, M. A1 - Haag, R. T1 - Interactions of fullerene-polyglycerol sulfates at viral and cellular interfaces N2 - Understanding the mechanism of interactions of nanomaterials at biointerfaces is a crucial issue to develop new antimicrobial vectors. In this work, a series of water-soluble fullerene-polyglycerol sulfates (FPS) with different fullerene/polymer weight ratios and varying numbers of polyglycerol sulfate branches are synthesized, characterized, and their interactions with two distinct surfaces displaying proteins involved in target cell recognition are investigated. The combination of polyanionic branches with a solvent exposed variable hydrophobic core in FPS proves to be superior to analogs possessing only one of these features in preventing interaction of vesicular Stomatitis virus coat glycoprotein (VSV-G) with baby hamster kidney cells serving as a model of host cell. Interference with L-selectin-ligand binding is dominated by the negative charge, which is studied by two assays: a competitive surface plasmon resonance (SPR)-based inhibition assay and the leukocyte cell (NALM-6) rolling on ligands under flow conditions. Due to possible intrinsic hydrophobic and electrostatic effects of synthesized compounds, pico- to nanomolar half maximal inhibitory concentrations (IC50) are achieved. With their highly antiviral and anti-inflammatory properties, together with good biocompatibility, FPS are promising candidates for the future development towards biomedical applications. KW - Fullerene-Polyglycerol Sulfates KW - Fullerene KW - Biointerfaces KW - XPS PY - 2018 DO - https://doi.org/10.1002/smll.201800189 SN - 1613-6829 SN - 1613-6810 VL - 14 IS - 17 SP - 1800189, 1 EP - 7 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-44573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Dietrich, P. A1 - Beblo-Vranesevic, K. A1 - Kjærvik, Marit A1 - Unger, Wolfgang A1 - Schwibbert, Karin A1 - Hardie, K. A1 - Brown, J. T1 - XPS surface analysis of bacterial samples N2 - This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work. The use of innovative near-ambient pressure (NAP-)XPS instrumentation allows the detailed analysis of irregularly-surfaced biofilms. NAP-XPS enables the surface analysis of bacterial samples in their natural hydrated state without complex sample preparation techniques such as freeze-drying or fast-freezing, which are needed for XPS analysis in ultrahigh vacuum. KW - Near ambient pressure XPS KW - Biofilms PY - 2018 UR - http://www.enviroai.com/uploads/1/0/2/8/102861712/xps_surface_analysis_of_bacillus_subtilis_biofilms_final.pdf IS - Application Note #000399 SP - 1 EP - 5 CY - Berlin AN - OPUS4-44588 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kindrachuk, Vitaliy ED - Titscher, Thomas ED - Hirthammer, Volker ED - Unger, Jörg F. T1 - A continuum damage model for the simulation of concrete under cyclic loading N2 - A continuum damage model for concrete is developed with a focus on fatigue under compressive stresses. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. The model is designed to represent failure under static loading as a particular case of fatigue failure after a single loading cycle. As a consequence, most of the material parameters can be deduced from statictests. Only a limit set of additional constitutive parameters is required to accurately describe the evolution under fatigue loading. Another advantage of the proposed model is the possibility to directly incorporate other multi-physics effects such as creep and shrinkage or thermal loading on the constitutive level. A multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach. This evolution equation is then solved on the long time scale using different implicit and explicit time integration schemes. Their performance and some limitations for specific loading regimes is discussed. T2 - Euro-C, March 1st 2018 CY - Bad Hofgastein, Austria DA - 26.02.2018 KW - Continnum damage model KW - Simulation of concrete KW - Under cyclic loading PY - 2018 UR - https://euro-c.tuwien.ac.at/home/ SN - 978-1-315-18296-4 SN - 978-1-138-74117-1 VL - 2018 SP - 155 EP - 164 PB - CRC Press, Taylor & Francis Group CY - Leiden, The Netherland AN - OPUS4-48400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Uwe A1 - Griepentrog, Michael A1 - Hertwig, Andreas A1 - Sahre, Mario A1 - Unger, Wolfgang A1 - Hodoroaba, Vasile-Dan A1 - Krüger, Jörg T1 - Plasma Germany, Fachausschuss Normung, Berichtszeitraum Frühjahr 2018 - Herbst 2018 N2 - Der Vortrag gibt den aktuellen Stand der Normung im Bereich der Oberflächen-technik insbesondere der Oberflächenanalytik und der Oberflächenmess- und -prüftechnik wider. Vorgestellt wird der Status technischer Berichte, Normenentwürfe und Normen u.a. zur Charakterisierung von funktionellen Glasoberflächen für bioanalytische Anwendungen, zur Messung der Schichtdicke von Nanomaterialien mittels Ellipsometrie, zur Kalibrierung von Interferometern und Interferenzmikroskopen für die Formmessung, zur Rockwelleindringprüfung zur Bewertung der Schicht-haftung, zu den Grundlagen der Ellipsometrie, zur Messung der Schichtdicke mittels Wirbelstromverfahren, zur Schichtpotentialmessung von Mehrfach-Nickelschichten, zu Filtern und Augenschutzgeräten gegen Laserstrahlung sowie zur Bestimmung der Schichthaftung mittels Zugversuch. T2 - Fachausschuss Normung, Herbstsitzung CY - Jena, Germany DA - 06.11.2018 KW - Stand der Normung KW - Oberflächentechnik KW - Oberflächenanalytik KW - Oberflächenmesstechnik KW - Oberflächenprüftechnik PY - 2018 AN - OPUS4-48894 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Adamczyk, Burkart A1 - Schraut, Katharina A1 - Adam, Christian ED - Thiel, S. ED - Thomé-Kozmiensky, E. ED - Friedrich, B. ED - Pretz, T. ED - Quicker, P. ED - Senk, D. G. ED - Wortruba, H. T1 - Nachbehandlung von Stahlwerksschlacken und deren Verwertung als Klinkermaterial T1 - Post-treatment of steelmaking slags and their utilisation as cement clinker N2 - Steelmaking slags produced using the Linz-Donawitz method (LD slags) are widely used as building and construction materials in road, earth and water works. Because the legal conditions become more and more re-strictive , this application is uncertain in the future. LD slags contain high amounts of mineral bound iron (in form of Fe2O3), which must be considered as a waste of resources. Except for the Iron the chemical composition is quite similar to that of Portland cement clinker. However, due to the high content of Fe2O3 the mineralogical composition differs significantly, resulting in a low hydraulic reactivity. A post-treatment of the liquid LD slag in an electric arc furnace under reducing conditions enables the reduction of the iron compounds to metallic iron, which separates from the mineral phase due to its higher density. The remaining solidified mineral fraction mainly contains typical crystalline phases of cement clinker in similar ratios: Alite (Ca3SiO5; > 60%) as main phase, Belite (Ca2SiO4, 10%), Tricalciumaluminate (Ca3Al2O6; 5%) and Brownmillerite (Ca2(Al,Fe)2O5, 1%) as secondary phases. Alite, which usually decomposes to Belite and free lime under slow cooling conditions, is stabilized in the Fe-reduced slag probably by integration of foreign ions into the lattice and is stable even if the slag is cooled down very slowly. Furthermore, the particularly large Alite crystals do not exhibit the typical decomposition edge of Belite and lime, found in Alite from ordinary ce-ment clinker. Technological tests for building materials show a high hydraulic reactivity and a compressive strength after 28 days comparable or even slightly higher to reference cement. Nevertheless, because of the increasing viscosity with decreasing Fe2O3 content, the treatment requires a temperature higher than the slag decanted from the LD converter. Furthermore, during the reduction of the bound Iron huge amounts of carbon monoxide are released, resulting in foaming of the slag. Both aspects make it difficult to manage the process. In addition, for economic reasons the treatment has to be carried out immediately after casting the slag from the LD converter to avoid the solidification, which is a logistical challenge for most steel plants. Otherwise the separation of the mineral bound iron as metallic phase and the utilisation of the mineral fraction as cement clinker will both save resources and lower the global CO2-output. For these reasons further initiatives should be considered in the medium term. N2 - LD-Schlacken weisen eine große chemische Ähnlichkeit zu Protlandzementklinker auf. Sie enthalten jedoch noch bis zu 30% Eisen, das mineralisch in oxidischer Form gebunden vorliegt. Dadurch kann sich bei der Erstarrung die wichtigste Klinkerphase "Alit" nicht ausbilden. Durch eine reduzierende Schmelzbehandlung der Schlacke kann des mineralisch gebundene Eisen als Metall separiert werden. Dadurch wird auch die Mineralogie der Schlacke so verändert, dass auch sie nun praktisch einem Portlandzementklinker entspricht. Entsprechende Versuche wurden am kleintechnischen Lichtbogenofen der BAM durchgeführt. Es werden Ergebnisse vorgestellt und auf Grenzen und Möglichkeiten eines derartigen Prozesses im Hinblick auf eine industrielle Umsetzung eingegangen. T2 - Berliner Konferenz Mineralische Nebenprodukte und Abfälle CY - Berlin, Germany DA - 11.06.2018 KW - Zementklinker KW - Stahlwerksschlacke KW - LD-Schlacke KW - Lichtbogenofen KW - Alit PY - 2018 SN - 978-3-944310-41-1 VL - 5 SP - 282 EP - 296 PB - Thomé-Kozmiensky Verlag GmbH CY - Neuruppin AN - OPUS4-45199 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koerdt, Andrea A1 - An, Biwen Annie A1 - Kleinbub, Sherin T1 - Microbial corrosion coupled to methanogenesis by strains from different environments N2 - Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms, either chemically (formation of hydrogen sulfide) or electrically (direct electron uptake). Methanogenetic Archaea are also known to be involved in iron corrosion, forming a multi-species biofilm on corroding metallic structures. However, mechanistic details and kinetics of the overall process in methanogen-induced MIC are poorly understood. T2 - Beirat Material CY - Berlin, Germany DA - 26.04.2018 KW - Corrosion KW - Methanogens KW - Archaea KW - Implants KW - Biofilm PY - 2018 AN - OPUS4-45112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Christian A1 - Hermann, P. A1 - Kästner, B. A1 - Adamczyk, Burkart A1 - Hoehl, A. A1 - Ulm, G. A1 - Adam, Christian T1 - Air and chlorine gas corrosion of different silicon carbides analyzed by nano-Fourier-transform infrared (nano-FTIR) spectroscopy N2 - The present study shows the potential of high-resolution imaging and nano-Fourier-transform infrared (nano-FTIR) spectroscopy for corrosion science. The protective oxidation layers of different chlorine-gas treated silicon carbides (SiCs) were characterized with these techniques. A nitrified SiC showed the highest resistant strength against chlorine corrosion at 1000 °C compared to the other SiCs. Nano-FTIR spectroscopy with a lateral resolution below 40 nm detected differences in the crystallinity of the bulk-SiC and in the transitional region to the protective layer. Furthermore, high-resolution imaging provides deep insight in the interfacial layer between bulk-SiC and the protective oxidation layer on sub-micrometer scale. KW - Nano-Fourier-transform infrared spectroscopy KW - Scattering-type scanning near-field optical microscopy (s-SNOM) KW - Synchrotron radiation KW - Corrosion KW - Silicon carbide KW - Chlorine PY - 2018 DO - https://doi.org/10.1016/j.corsci.2017.12.002 SN - 0010-938X VL - 131 SP - 324 EP - 329 PB - Elsevier AN - OPUS4-43648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taube, Mareike Carolin A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Schulenburg, F. A1 - Bartmann, U. A1 - Beckmann, T. A1 - Michalik, K. A1 - Reuter, M. A1 - Stelter, M. T1 - Optimisation of a Pyrometallurgical Niobium and Tantalum Recyling Process with on-line-LIBS N2 - Tantalum and niobium are essential for the development of electronics towards a more and more compact design, but without reducing their performance today. Especially in smart phones and tablets, tantalum and niobium capacitors with high charge densities have already become almost indispensable. However, tantalum as a critical raw material is still a problem for the sustainable production of electronics. Due to this fact, the existence of efficient recycling processes especially in Europe is becoming even more important nowadays. The Bundesanstalt für Materialforschung und -prüfung (BAM) is currently working on the optimisation of an existing pyrometallurgical tantalum recycling process. Optimisation of this industrial process is carried out in a small-scale electric arc furnace (480 kVA, capacity approx. 150 kg/h) at BAM using a new and innovative equipment for on-line analysis of high temperature processes. The aim of this project is to identify the best timing for an optimum slag tapping, when the slag is lower than minimum targeted tantalum concentration. Hence, LIBS (Laser induced breakdown spectroscopy) is used to identify the chemical composition of the slag layer and during slag tapping. The on-line-LIBS prototype of BAM enables an in-situ measurement of the element distribution in the melt after calibration on the slag system. First results of this joint research project will be presented including LIBS-measurements and thermodynamic and kinetic aspects of the process. T2 - European Mineral Processing & Recycling Congress (EMPRC 2018) CY - Essen, Germany DA - 25.06.2018 KW - Laser-induced breakdown spectroscopy KW - On-line analysis KW - Tantalum KW - Niobium KW - Pyrometallurgy PY - 2018 SN - 978-3-940276-84-1 SP - 347 EP - 362 PB - GDMB Verlag GmbH CY - Clausthal-Zellerfeld AN - OPUS4-47040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Simon, Sebastian A1 - von Werder, Julia A1 - Meng, Birgit A1 - Stephan, D. A. A1 - Adam, Christian T1 - Zementklinker durch Nachbehandlung von Stahlwerksschlacken N2 - Die Klinkerphasenbildung durch Sinterung in Drehrohröfen bei der Herstellung von Portlandzementklinker (PZK) ist gründlich erforscht und optimiert. Im Hinblick auf mögliche ökonomische und ökologische Vorteile befassen sich aktuelle Forschungsvorhaben darüber hinaus mit der Herstellung von Klinkermineralen aus Stahlwerksschlacken, die eine vergleichbare chemische Zusammensetzung aufweisen. Neuste Untersuchungen zeigen, dass nach der reduzierenden Behandlung schmelzflüssiger Linz-Donawitz-(LD)-Schlacken und Abscheidung des gebildeten metallischen Eisens eine mineralische Schlacke entsteht, die unabhängig von ihren Abkühlbedingungen ca. 50–60 Gew.% des wichtigsten Klinkerminerals Alit (C3S) enthält und eine hohe hydraulische Reaktivität aufweist. Die Stabilität des Alits auch nach langsamer Abkühlung deutet auf eine Stabilisierung des Minerals durch Nebenelemente aus den LD-Schlacken hin. Ein sinkender Anteil an LD-Schlacke durch Zusatz synthetischer Schlackemischung, die sich hinsichtlich ihrer Hauptkomponenten wie eine ausreduzierte LD-Schlacke zusammensetzt, führt zu einem Rückgang des Alitgehaltes und dem Zerfall der Schlacke beim Erstarren. T2 - 5. Schlacken-Symposium CY - Meitingen, Germany DA - 25.10.2018 KW - LD-Schlacke KW - Zement KW - Tricalciumsilikat PY - 2018 SP - 219 EP - 229 PB - Max Aicher Unternehmensgruppe AN - OPUS4-46412 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Simon, Sebastian A1 - von Werder, Julia A1 - Meng, Birgit A1 - Stephan, Dietmar Aloys A1 - Adam, Christian T1 - Zementklinker durch Nachbehandlung von Stahlwerksschlacken N2 - Die Klinkerphasenbildung durch Sinterung in Drehrohröfen bei der Herstellung von Portlandzementklinker (PZK) ist gründlich erforscht und optimiert. Im Hinblick auf mög-liche ökonomische und ökologische Vorteile befassen sich aktuelle Forschungsvorha-ben darüber hinaus mit der Herstellung von Klinkermineralen aus Stahlwerksschla-cken, die eine vergleichbare chemische Zusammensetzung aufweisen. Neuste Untersuchungen zeigen, dass nach der reduzierenden Behandlung schmelz-flüssiger Linz-Donawitz-(LD)-Schlacken und Abscheidung des gebildeten metallischen Eisens eine mineralische Schlacke entsteht, die unabhängig von ihren Abkühlbedin-gungen ca. 50–60 Gew.% des wichtigsten Klinkerminerals Alit (C3S) enthält und eine hohe hydraulische Reaktivität aufweist. Die Stabilität des Alits auch nach langsamer Abkühlung deutet auf eine Stabilisierung des Minerals durch Nebenelemente aus den LD-Schlacken hin. Ein sinkender Anteil an LD-Schlacke durch Zusatz synthetischer Schlackemischung, die sich hinsichtlich ihrer Hauptkomponenten wie eine ausreduzierte LD-Schlacke zusammensetzt, führt zu einem Rückgang des Alitgehaltes und dem Zerfall der Schlacke beim Erstarren. T2 - 5. Schlacken-Symposium CY - Meitingen, Germany DA - 25.10.2018 KW - Zement KW - LD-Schlacke KW - Tricalciumsilikat PY - 2018 AN - OPUS4-46409 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taube, Mareike Carolin A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Schulenburg, F. A1 - Reuter, M. A1 - Stelter, M. T1 - Optimierung eines pyrometallurgischen Tantal- und Niob- Recyclingprozesses mithilfe von On-Line LIBS N2 - Die Entwicklung von Hochleistungselektronik zu immer kleineren Bauformen ohne Leistungseinbußen ist ohne den Einsatz von Technologiemetallen wie Niob und Tantal heute praktisch nicht mehr realisierbar. Besonders in technischen Geräten wie Smartphones und Tablets sind Tantal- und Niobkondensatoren aufgrund ihrer hohen Leistungsdichten bereits unverzichtbar geworden. Für die nachhaltige Produktion von Elektronik stellt jedoch vor allem das Tantalerz Coltan als sogenanntes „conflict mineral” ein großes Problem dar. Um den Wirtschaftsstandort Europa unabhängiger von Primärrohstoffimporten aus Krisenregionen zu machen, ist die Entwicklung von effizienten Recyclingverfahren heute wichtiger denn je. An der Bundesanstalt für Materialforschung und -prüfung (BAM) findet daher zurzeit die Optimierung eines pyrometallurgischen Industrieprozesses zur Niob- und Tantalrückgewinnung statt, welchem hauptsächlich niedrigkonzentrierte metallurgische Rückstände aus der Tantal- und Niob- bzw. der Zinngewinnung als Einsatzstoffe dienen. Zu diesem Zweck werden im kleintechnischen Lichtbogenofen der BAM (480 kVA, max. Materialdurchsatz ca. 150 kg/h) Versuche mit einem neuen innovativen Messgerät durchgeführt, welches eine On-Line Analyse von Hochtemperaturprozessen ermöglicht. Der eingesetzte Prototyp nutzt das Verfahren der laserinduzierten Plasmaspektroskopie (LIBS), um die chemische Zusammensetzung der Schlackephase noch im Schmelzbad und während eines Schlackeabgusses zu bestimmen. Nach einer Kalibrierung auf das vorliegende Stoffsystem ermöglicht dieser On-Line-LIBS Prototyp der BAM daher eine in-situ Bestimmung der Elementverteilung in der Schmelze. Die hier gewonnenen Daten sollen helfen, die aktuelle Prozessführung zu verbessern und die Tantal- und Niobausbeute noch weiter zu erhöhen. T2 - Jahrestreffen Bremen 2018 der ProcessNet-Fachgruppen Hochtemperaturtechnik (HTT), Abfallbehandlung und Wertstoffrückgewinnung (AuW) CY - Bremen, Germany DA - 06.03.2018 KW - Laser-induced breakdown spectroscopy KW - Tantal KW - On-Line Analyse KW - Recycling KW - Pyrometallurgie PY - 2018 AN - OPUS4-45612 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taube, Mareike Carolin A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Schulenburg, F. A1 - Bartmann, U. A1 - Beckmann, T. A1 - Michalik, K. A1 - Reuter, M. A1 - Stelter, M. T1 - Optimisation of a Pyrometallurgical Niobium and Tantalum Recyling Process with on-line-LIBS N2 - Tantalum and niobium are essential for the development of electronics towards a more and more compact design, but without reducing their performance today. Especially in smart phones and tablets, tantalum and niobium capacitors with high charge densities have already become almost indispensable. However, tantalum as a critical raw material is still a problem for the sustainable production of electronics. Due to this fact, the existence of efficient recycling processes especially in Europe is becoming even more important nowadays. The Bundesanstalt für Materialforschung und -prüfung (BAM) is currently working on the optimisation of an existing pyrometallurgical tantalum recycling process. Optimisation of this industrial process is carried out in a small-scale electric arc furnace (480 kVA, capacity approx. 150 kg/h) at BAM using a new and innovative equipment for on-line analysis of high temperature processes. The aim of this project is to identify the best timing for an optimum slag tapping, when the slag is lower than minimum targeted tantalum concentration. Hence, LIBS (Laser induced breakdown spectroscopy) is used to identify the chemical composition of the slag layer and during slag tapping. The on-line-LIBS prototype of BAM enables an in-situ measurement of the element distribution in the melt after calibration on the slag system. First results of this joint research project will be presented including on-line-LIBS-measurements and thermodynamic and kinetic aspects of the process. T2 - European Mineral Processing & Recycling Congress (EMPRC 2018) CY - Essen, Germany DA - 25.06.2018 KW - Laser-induced breakdown spectroscopy KW - Process control KW - Tantalum KW - In-situ analysis KW - Pyrometallurgy PY - 2018 AN - OPUS4-45614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -