TY - CONF A1 - Trappe, Volker A1 - Sachs, Patrick T1 - Dynamic mechanical analysis of epoxy-matrix cross linking measured in-situ using an elastomer container N2 - A new patented dynamic mechanical analysis (DMA) is presented, where the tensile, bending- or torsional stiffness of a media can be characterized in-situ during the phase transition from liquid to solid. An epoxy system, e.g. Hexion L285/H287, is filled into an elastomer container, such as a silicone tube. This can be mounted into a conventional DMA and, based on a linear viscoelastic approach, the storage modulus (E’;G’), the loss modulus (E’’;G’’) and the loss angle tan(delta) can be measured at constant temperature as a function of time in order to investigate the liquid to sol-gel to solid transition. With this new method, the stiffness increase as a result of the cure process can be directly measured more precisely than with a rheometer in a shear plate set-up, because using an elastomer container gives a defined cross section for calculating the Young’s modulus. T2 - 20th European Conference on Composite Materials, ECCM20 CY - Lausanne, Switzerland DA - 26.06.2022 KW - Dynamic mechanical analysis (DMA) KW - Thermoset polymers KW - Cure process KW - Cross linking PY - 2022 AN - OPUS4-55213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit A1 - von Hartrott, P. T1 - Interlinking Structured Data about Aging and Fattigue of an Aluminum Alloy N2 - In typical material oriented research projects numerous types and sources of data need to get connected to form the final outcome. The data-structures have to be described in a manner semantically concise enough so that all participants share the meaning and at the same time flexible enough to allow connecting findings and facts that have not been connected before. The present contribution describes the approach that is being taken in a public funded research project with two cooperating research institutes. The aim of the data-management solution is to describe and interlink three main entity types: material entities like a test specimen that is under observation, immaterial entities like a fatigue life model and processes that generate and transform the immaterial and material entities. The shared understanding of what is described by the data is achieved by referring to existing linked data resources. In addition a common thesaurus that is subject to ongoing discussion is used for concepts and terms that need precision beyond publicly available concept descriptions. The data associated with the entities and processes and entities is rather small and well structured. The entities and processes covered by the vocabularies are typical to laboratories performing fatigue testing and microstructure analysis. Through the interlinking of the entities and processes it becomes possible to intuitively understand the knowledge that is accumulating in the database. For example it is easy to trace the history of a creep test specimen starting from the chemical composition that has been analyzed for the heat, continuing with the heat treatment of the material, going into the creep test itself with the associated creep data and finally finding the transmission electron microscopy images that have been taken from the crept sample. The presented approach is prototypical way to tackle the sustainable management of structured open research data. Open questions remain for example with the management of attributions, the acceptance of an increased effort in data creation and the access control to specific regions of the data. On the other hand the approach sketches what added value can be created, if the community adopts and contributes to the linked data principles. T2 - LCF9 CY - Berlin, Germany DA - 21.6.2022 KW - Data management KW - Data linking KW - Thesaurus PY - 2022 AN - OPUS4-55159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis Alexander A1 - Rehmer, Birgit A1 - Graf, B. A1 - Ulbricht, Alexander A1 - Skrotzki, Birgit A1 - Rethmeier, Michael T1 - Low cycle fatigue behavior of DED-L Ti-6AL-4V N2 - Laser powder-based directed energy deposition (DED-L) is a technology that offers the possibility for 3D material deposition over hundreds of layers and has thus the potential for application in additive manufacturing (AM). However, to achieve broad industrial application as AM technology, more data and knowledge about the fabricated materials regarding the achieved properties and their relationship to the manufacturing process and the resulting microstructure is still needed. In this work, we present data regarding the low-cycle fatigue (LCF) behavior of Ti-6Al-4V. The material was fabricated using an optimized DED-L process. It features a low defect population and excellent tensile properties. To assess its LCF behavior two conventionally manufactured variants of the same alloy featuring different microstructures were additionally tested. The strain-controlled LCF tests were carried out in fully reversed mode with 0.3 % to 1.0 % axial strain amplitude from room temperature up to 400°C. The LCF behavior and failure mechanisms are described. For characterization, optical microscopy (OM), scanning electron microscopy (SEM), and micro-computed tomography (µCT) were used. The low defect population allows for a better understanding of the intrinsic material’s properties and enables a fairer comparison against the conventional variants. The fatigue lifetimes of the DED-L material are nearly independent of the test temperature. At elevated test temperatures, they are similar or higher than the lifetimes of the conventional counterparts. At room temperature, they are only surpassed by the lifetimes of one of them. The principal failure mechanism involves multiple crack initiation sites. T2 - Ninth International Conference on Low Cycle Fatigue (LCF9) CY - Berlin, Germany DA - 21.06.2022 KW - AGIL KW - Additive Manufacturing KW - Ti-6Al-4V KW - Low-Cycle-Fatigue KW - Microstructure PY - 2022 AN - OPUS4-55123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Han, Ying A1 - Kruse, Julius A1 - Madia, Mauro A1 - Radners, Jan A1 - von Hartrott, Philipp A1 - Skrotzki, Birgit T1 - The influence of aging and mean stress on fatigue of Al-alloy EN AW-2618A N2 - In this study, the influence of aging and mean stress on fatigue of the aluminium-alloy EN AW-2618A is investigated. Therefore axial fatigue tests are carried out on smooth specimens. The experiments show that the fatigue life decreases with increasing mean stress. Furthermore, the tests with the overaged specimens demonstrate that the number of cycles to failure is decreasing with increasing aging time. T2 - LCF9 CY - Berlin, Germany DA - 21.06.2022 KW - Fatigue KW - Aluminium alloy KW - EN AW-2618A KW - Damage Behavior PY - 2022 AN - OPUS4-55125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Han, Ying A1 - Radners, J. A1 - von Hartrott, P. A1 - Skrotzki, Birgit T1 - Aluminium High Temperature Fatigue N2 - The studied aluminium alloy is EN AW-2618A (2618A). It is very widely used for exhaust gas turbo-charger compressor wheels. Due to long operating times, high cycle fatigue (HCF) and material aging under the influence of temperatures up to 230 °C is particularly relevant for the wheels. The wheels are typically milled from round wrought blanks. From such round blanks, different testpieces are extracted and a comprehensive series of HCF tests is conducted at room temperature. The tests investigate the materials fatigue performance in the T61 state for two load-ratios, namely R = -1 and R = 0.1. Additionally, two overaged material states are tested, accounting for the aging process the material undergoes during long operating times at high temperatures. The experimental results are evaluated and compared to each other. Furthermore, the design process of notched specimens is presented. With the notched specimens, it is aimed to quantify the notch sensitivity of the material. Relating thereto, two potential model parameters for the fatigue lifetime model are introduced. T2 - FVV Frühjahrstagung 2022 CY - Würzburg, Germany DA - 31.03.2022 KW - High Cycle Fatigue KW - Aluminium Alloy KW - EN AW-2618A PY - 2022 AN - OPUS4-54886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blaeß, Carsten A1 - Wilbig, Janka A1 - Müller, Ralf A1 - Nawaz, Q. A1 - Boccaccini, A.R. T1 - 3D printing of crystallizing bioactive glasses N2 - Artificial bone replacement by individual customized three-dimensional resorbable bioactive glass has not yet been widely established in the clinical use. This is mainly due to the antagonism of sintering ability and suitable bioactivity. Competitive crystallization often prevents the generation of dense sintered bodies, especially for additive manufactured 3D structures. Previous studies of the fluoride-containing glass F3 have shown its potential to combine both sintering ability and suitable bioactivity. Furthermore, the occurring sintering blockade by surface crystallization of Na2CaSi2O6 was tunable by glass particle size. In this study the glasses F3, F3-Cu with 1 mol% CuO added at the expense of CaO and the well-known 13-93 were chosen to determine the influence of surface crystallization on 3D printed sinter bodies. For this purpose, grain size fractions in range of smaller 32 µm to 315 µm in fraction size of 6-20 µm were sieved from jaw crushed glass frit as well as glass cubes were cut from casted blocks for all glasses. Sintering behavior of both pressed and printed powder compacts was observed via heating microscopy. Crystallization was determined by DTA and crystallization progress was monitored on fractured sinter bodies and polished cubes via electron and laser scanning microscopy as well as with diffractometry. Depending on grain size the formation of crystalline support framework along former grain boundaries shows the capability to stabilize fully densified sinter bodies before softening. Beside of this, the generation of complex hierarchic porosity was possible as well. T2 - ICG Berlin 2022 CY - Berlin, Germany DA - 03.07.2022 KW - Bioactive Glass KW - Crystallization KW - Sintering KW - 3D printing PY - 2022 AN - OPUS4-55253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beygi Nasrabadi, Hossein A1 - Chen, Yue A1 - Hanke, T. A1 - von Hartrott, P. A1 - Skrotzki, Birgit T1 - Domain-level ontology formulation based on the Platform Material Digital (PMD) ontology: case study Brinell hardness N2 - A large amount of publicly available data is reproduced every day in the field of materials science, while these kind of material data can have different formats and types like paper-type publications, standards, datasheets or isolated datasets in repositories. However, gathering a specific library from such extensive and diverse material data is always challenging for the materials scientists and engineers, since the time-related limitations are not allowed to fully access the large publicly available databases; search across these disparate databases, manage the large volumes of heterogeneous datasets, and integrate data from multiple sources. To address these challenges and make data findable, accessible, interoperable, and reusable (FAIR), an efficient data management system is necessary to build comprehensive, documented, and connected data spaces in the future. A formal standardized knowledge representation through an ontology can address such problems and make data more available and interoperable between related domains. Ontology can also rich machine processable semantic descriptions that increases the performance of scientific searches. In this regard, the Platform MaterialDigital (PMD) is currently working on developing a high-level ontology for the materials and material related processes. For example, in one of the PMD projects of “KupferDigital”, we will try to develop a data ecosystem for digital materials research based on ontology-based digital representations of copper and copper alloys. As a case study, this paper describes the methodology for ontology development of Brinell hardness, based on PMD core ontology. The methodology we describe includes the following steps; gathering the required domain terminology from different resources like standards (DIN EN ISO 6506-1) and test reports, representing the performance of a standard-conformant hardness test and the treatment of the recorded values up to a “reportable” hardness value for a material, designing the process chain according to the semantic technologies, and developing a domain-level ontology of Brinell hardness based on PMD ontology semantic formalization. Apart the mentioned methodology, some interesting tools and methods were introduced and ontology design challenges and possible solutions for modelling materials and processes were discussed. Furthermore, a dataset from the Brinell hardness measurement of cast copper samples is prepared for testing the query process. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Copper KW - Materials Science KW - Ontology KW - Platform MaterialDigital (PMD) KW - Brinell hardness PY - 2022 AN - OPUS4-56092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kilo, M. A1 - Diegeler, A. A1 - Müller, Ralf A1 - Waurischk, Tina A1 - Reinsch, Stefan T1 - Glass Screening for the systematic development of new glasses N2 - Die technischen Möglichkeiten der robotischen Glasschmelzanlage der BAM werden vorgestellt. T2 - 26th International Conference on Glass CY - Berlin, Germany DA - 04.07.2022 KW - Material Digital PY - 2022 AN - OPUS4-56280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Tielemann, Christopher A1 - Müller, Ralf A1 - Busch, R. A1 - Patzig, C. A1 - Höche, T. T1 - Surface-Initiated Microstructure Formation in Glass Ceramics N2 - Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. For silicate glasses we found a good correlation between the calculated surface energy of crystal faces and oriented surface nucleation. Surface energies were estimated assuming that crystal surfaces resemble minimum energy crack paths along the given crystal plane. This concept was successfully applied by Rouxel in calculating fracture surface energies of glasses. Several oriented nucleation phenomena can be herby explained assuming that high energy crystal surfaces tend to be wetted by the melt. This would minimize the total interfacial energy of the nucleus. Furthermore, we will discuss the evolution of the microstructure and its effect on the preferred crystal orientation. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Glass KW - Oriented surface crystallization KW - Surface energy KW - Bond energy KW - Nucleation mode PY - 2022 AN - OPUS4-56070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick A1 - Kuchenbecker, Petra A1 - Lindemann, Franziska A1 - Rabe, Torsten T1 - Optimized spray granules for dry pressing by means of slurry destabilization and ultrasonic atomization N2 - The homogeneous introduction of organic additives is a prerequisite for good processability of ceramic powders during dry pressing. The addition of organic additives by wet route via ceramic slurries offers advantages over dry processing. The organic content can be reduced and a more homogeneous distribution of the additives on the particle surface is achieved. In addition to the measurements of zeta potential and viscosity, sedimentation analysis by optical centrifugation was also tested and successfully used to characterize the ceramic slurries and accurately evaluate of the suitability of different types, amounts, and compositions of organic additives. Spray drying of well-stabilized slurries usually results in mostly hollow granules with a hard shell leading to sintered bodies with defects and reduced strength and density. By purposefully degrading the slurry stability after dispersion of the ceramic powder, the drying behavior of the granules in the spray drying process and thus the granule properties can be influenced. Destabilization of the slurry and thus partial flocculation was quantified by optical centrifugation. Spray drying of the destabilized alumina slurries resulted in "non-hollow" granules without the detrimental hard shell and thus improved granule properties. Further improvement of the granules was achieved by installing ultrasonic atomization in the spray dryer. A narrower granule size distribution was achieved, which had a positive effect on, among other things, the flowability of the granules. Specimens produced from this granules had fewer defects of smaller size, leading to better results for the density and strength of the sintered bodies. The observations made for alumina could be transferred to zirconia and as well to ZTA with 20 wt% zirconia. T2 - Ceramics in Europe 2022 CY - Krakau, Poland DA - 10.07.2022 KW - Ultrasound KW - Spray drying KW - Slurry PY - 2022 AN - OPUS4-56171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eisenbart, M. A1 - Bauer, F. A1 - Klotz, U. A1 - Weber, M. A1 - Beygi Nasrabadi, Hossein A1 - Skrotzki, Birgit A1 - Klengel, R. A1 - Steinmeier, L. A1 - Parvez, A. A1 - Hanke, T. A1 - Dziwis, G. A1 - Meissner, R. A1 - Tikana, L. A1 - Heisterkamp, J. T1 - Development of an ontology for the lifecycle of copper and copper alloys N2 - Efforts towards digitalization in the material science and technology community have enhanced in the last years. In 2019 the German digitalization initiative platform „MaterialDigital“1 (MD) has been started. Numerous projects concerning digitalization, including the copper related project „KupferDigital“ (copper digital) have been initiated under the umbrella of MD. The initiative strives to address numerous issues concerning data access, exchange, security, provenance and sovereignty. Heterogeneous data origin, storage and evaluation often result in problems concerning comparability and reproducibility of scientific and technological results. In many cases material data are recorded, but the methods of testing are insufficiently described, or such information is not communicated along with the raw data. The material data can also have numerous different formats such as paper printouts, pdfs, excel sheets or csv-files. Hence, gathering and integrating material data from different sources is challenging for potential users like materials scientists and engineers, especially if there are contradictory data where the reasons for contradictions is not clear due their vague description. In order to address these problems, data should comply to the so called „FAIR“ principle which calls for data to be findable, accessible, interoperable, and reusable (FAIR)2 and hence be accessible via so-called decentralized but interconnected data spaces. By using knowledge representation withontologies, data can be enriched with meaning and the methods of the testing procedures can be accurately provided. In this presentation we want to introduce our approach to such knowledge representation based on a high-throughput alloy development process for Cu-based alloys³ along with characterization techniques such as hardness testing and microstructural characterization (e.g. EBSD – Electron Backscattered Diffraction). T2 - Copper Alloys Conference CY - Dusseldorf, Germany DA - 22.11.2022 KW - Copper KW - Life cycle KW - Ontology PY - 2022 AN - OPUS4-56406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Rouxel, T. A1 - Behrens, H. A1 - Deubener, J. T1 - Vacuum crack growth in silicate glasses N2 - Although the slow crack growth in glass is dominated by stress-corrosion phenomena, it also should reflect the underlaying intrinsic fracture behavior controlled by glass chemistry and structure. To investigate such underlaying phenomena, crack growth velocity in alkali silicate glasses was measured in vacuum across 10 orders of magnitude with double cantilever beam technique. Measured and literature crack growth data were compared with calculated intrinsic fracture toughness data obtained from Young’s moduli and theoretical fracture surface energy. Data analysis reveals slight correlation with the packing density and significant deviations from the intrinsic brittle fracture behavior. These deviations do not follow simple compositional trends. Two opposing processes may explain this finding: a decrease in the apparent fracture surface energy due to stress-induced chemical changes at the crack tip and its increase due to energy dissipation during fracture. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Oxide glass KW - Fracture toughness KW - Fracture surface PY - 2022 AN - OPUS4-56485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena A1 - Brandić Lipińska, M. A1 - Davenport, R. A1 - Imhof, A. B. A1 - Waclavicek, R. A1 - Fateri, M. A1 - Gines-Palomares, J. C. A1 - Zocca, Andrea A1 - Makaya, A. A1 - Günster, Jens T1 - How will we explore, work, and live on the moon? N2 - 3D-printed landing pads on the moon: Paving the road for large area sintering of lunar regolith. A prerequisite for lunar exploration and beyond is the manufacturing of objects directly on the moon, given the extreme costs involved in the shipping of material from Earth. Looking at processes, raw materials, and energy sources, equipment will certainly have to be brought from Earth at the beginning. Available on the moon are lunar regolith as raw material and the sun as an energy source. One of the first steps towards the establishment of a lunar base is the creation of infrastructure elements, such as roads and landing pads. We’ll introduce you to the ESA-project PAVER that demonstrates the sintering and melting of lunar regolith simulant material to produce large scale 3D printed elements that could be used during human and robotic lunar explorations. T2 - Berlin Science Week CY - Online meeting DA - 09.11.2022 KW - Additive manufacturing KW - Lunar regolith simulant KW - EAC-1A KW - Space exploration PY - 2022 UR - https://www.youtube.com/watch?v=StfLuVhKkUE AN - OPUS4-56377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Meyer, Lena T1 - Laser beam melting additive manufacturing at μ-gravity N2 - At the Workshop "Neutron and Synchrotron Monitoring in Aerospace Advanced Manufacturing" at the Institute of Materials Physics in Space, German Aerospace Center (DLR) in Cologne, we presented on the opportunities and our experiences of using a powder based additive manufacturing process for in-space manufacturing applications in microgravity. T2 - Workshop 'Neutron and Synchrotron Monitoring in Aerospace Advanced Manufacturing' CY - Cologne, Germany DA - 11.08.2022 KW - Additive manufacturing KW - In-space manufacturing KW - Microgravity KW - μ-gravity KW - Laser beam melting KW - Advanced manufacturing KW - Aerospace KW - Process monitoring PY - 2022 AN - OPUS4-56521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Schubert, Hendrik A1 - Günster, Jens T1 - Combination of layerwise slurry deposition and binder jetting (lsd-print) for the additive manufacturing of advanced ceramic materials N2 - Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. Powder bed fusion and binder jetting especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders. In this context, the “layerwise slurry deposition” (LSD) has been developed as a layer deposition method which enables the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder layer. This offers high flexibility in the ceramic feedstock used, especially concerning material and particle size. The LSD technology can be combined with binder jetting to develop the so-called “LSDprint” process for the additive manufacturing of ceramics. The LSDprint technology combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing. In this presentation, the LSD process will be introduced and several examples of application ranging from silicate to high-performance ceramics will be shown. Recent developments towards the scale-up and industrialization of this process will be discussed, alongside future perspectives for the multi-material additive manufacturing. T2 - Shaping 8 CY - Dübendorf, Switzerland DA - 14.09.2022 KW - Additive Manufacturing KW - 3D printing KW - Ceramics PY - 2022 AN - OPUS4-56523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandić Lipińska, M. A1 - Davenport, R. A1 - Imhof, A. B. A1 - Waclavicek, R. A1 - Fateri, M. A1 - Meyer, Lena A1 - Gines-Palomares, J. C. A1 - Zocca, Andrea A1 - Makaya, A. A1 - Günster, Jens T1 - PAVER - Contextualizing laser sintering within a lunar technology roadmap N2 - The Global Exploration Strategy of the International Space Exploration Coordination Group (ISECG) describes a timeframe of 2020 and beyond with the ultimate aim to establish a human presence on Mars towards the 2040ies. The next steps lie on the Moon with a focus on the coming 10 years. Early lunar surface missions will establish a capability in support of lunar science and prepare and test mission operations for subsequent human exploration of Mars and long-duration human activities on the Moon. Given the extreme costs involved in the shipping of material from Earth, a prerequisite for future human exploration is the manufacturing of elements directly on the Moon’s surface. Unlike the equipment, which at the beginning will have to be brought from Earth, raw materials and energy could be available following the concept of In-Situ Resource Utilization. The ESA OSIP PAVING THE ROAD (PAVER) study investigates the use of a laser to sinter regolith into paving elements for use as roadways and launch pads thus mitigating dust issues for transport and exploration vehicles. The ESA-funded study examines the potential of using a laser (12 kW CO2 laser with spot beam up to 100 mm) for layer sintering of lunar and martian regolith powders to manufacture larger 3D elements and provide know-how for the automatic manufacture of paving elements in the lunar environment. The project contributes to the first step toward the establishment of a lunar base and will lead to the construction of equipment capable of paving areas and manufacturing 3D structures. PAVER project sets the starting point for an examination of the larger context of lunar exploration. Mission scenarios will look at different phases of lunar exploration: Robotic Lunar Exploration, Survivability, Sustainability, and Operational Phase. A proposed Technology Roadmap investigates the mission scenario and analyses how, and to which extent, laser melting/sintering will play a role in the various phases of exploration. The paper contextualizes laser sintering within selected mission scenarios and discusses the different kinds of infrastructure that can be produced at each phase of the mission. The outcome of the study includes the detailing of the TRL steps in the project and an outline of a timeline for the different elements. Covered aspects include terrain modelling such as operation pads, roadways, or towers, non-pressurized building structures to protect machinery, and habitat envelopes, to protect and shield humans against dust, micrometeoroids, and radiation. T2 - 73rd International Astronautical Congress (IAC) CY - Paris, France DA - 18.09.2022 KW - Additive manufacturing KW - ISRU KW - Infrastructure KW - Lunar habitat KW - Paving KW - Solar sintering PY - 2022 AN - OPUS4-56529 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena A1 - Zocca, Andrea A1 - Wilbig, Janka A1 - Kolsch, Nico A1 - Günster, Jens T1 - Laser beam melting additive manufacturing at μ-gravity N2 - In-space manufacturing (ISM) provides the opportunity to manufacture and repair critical components on future human spaceflight missions. For explorations to Mars and beyond, ISM is a key strategy not only due to the long travel distances and high costs of supply from earth but also to be able to safely work in space for years. Human spaceflight is still dependent on shipments from earth that can fail for several reasons. ISM is a valuable alternative to ensure the timely and safe resupply of space missions. With additive manufacturing (AM) technologies, components are built directly from a 3D computer-aided-design (CAD) model which offers the advantages of freedom of design and the production of complex and ready-to-use parts. A virtual tool box with 3D models in space or the supply of information instead of components from earth to space can strongly benefit future missions. For industrial use, most research has focused on laser based additive manufacturing processes such as laser beam melting (LBM) where metallic powder particles are spread into a uniform powder bed and melted by a laser to the desired shape. In the absence of gravity, the handling of metal powders, which is essential for the process, is challenging. We present an evolution of an AM system, where a gas flow throughout the powder bed is applied to stabilize the powder bed. This is needed to compensate for the missing gravitational forces in microgravity experiments on parabolic flight campaigns. The system consists of a porous building platform acting as a filter for the fixation of metal particles in a gas flow. It is driven by reduced pressure established by a vacuum pump underneath the platform. The system creates a drag force that directs the particles towards the porous building platform, similar to the effect of the gravitational force. The AM system with its gas-flow-assisted powder deposition has been tested in several parabolic flight campaigns, and stainless-steel powder has successfully been processed during microgravity conditions. Different powder recoating mechanisms have been investigated to assess the homogeneous distribution of the powder as well as the attachment of the next layer to the powder bed. These mechanisms included different container designs with parallel double blades and with a V-shape at the bottom, and a roller recoating system. The samples presented are the first metal parts ever manufactured using LBM in μ-gravity. In addition to manufacturing in a μ-gravity environment, the experiments have shown the feasibility to manufacture components at different accelerations during the parabolic flight: hyper gravity (1.8 g), μ-gravity (< 0.01 g) and 1 g. Recent results will also be presented describing the application of this LBM setup in a parabolic flight campaign with mixed lunar, martian and µ-gravity acceleration, during which the processing of a lunar regolith simulant powder was tested. For ISM, the development and testing of the proposed AM system demonstrates that LBM can be considered a viable technology for the manufacturing of metal and ceramic parts in a μ-gravity or reduced-gravity environment. T2 - International Conference on Advanced Manufacturing CY - Online meeting DA - 07.03.2022 KW - μ-gravity KW - In-space manufacturing KW - Additive manufacturing KW - Laser beam melting KW - Microgravity KW - Stainless steel KW - Lunar regolith simulant PY - 2022 AN - OPUS4-54450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Viguier, B. A1 - Epishin, A. A1 - Fedelich, Bernard T1 - Creep of single-crystals of nickel-base gamma-alloy at high temperatures N2 - Porosity in single-crystal nickel-base superalloys is removed by hot isostatic pressing (HIP) at temperatures above gamma’-solvus where the material is very soft and ductile. For example, single-crystal nickel-base superalloy CMSX-4 is HIPed at temperature 1288 °C, which is slightly higher than the gamma’-solvus temperature of this alloy equal to about 1280 °C. It is assumed that pore shrinking during HIP is mostly due to dislocation creep. Such a modelling of HIP of CMSX-4 was started in our group on the base of results of creep tests of [001] single-crystals at 1288 °C [1]. However, it was found later [2] that the alloy CMSX-4 shows very strong creep anisotropy at 1288 °C. Therefore, for calibration of the creep law, creep tests of different orientations under different stress levels are required at the HIP temperature. This was the main task of present work. Single-crystals of CMSX-4 of axial orientations [001], [011], [123] and [111] were cast by VIAM Moscow and tested by BAM Berlin under creep conditions at 1288 °C and stress levels between 4 MPa and 16 MPa. At all stress levels, the creep rate increases by an order of magnitude when changing the orientation from [001] to [111] with [011] and [123] orientations in between. Such a character of creep anisotropy corresponds to the orientation dependence of the Schmid factor for octahedral glide. The crystal viscoplasticity model developed in [1] was improved to better represent the time induced softening observed during creep. The creep tests for different stresses and orientations as well as pore closure were simulated. The results of pore closure simulation are compared with measurements of porosity decrease during Hiping. T2 - 15th International Conference on Creep and Fracture of Engineering Materials and Structures CY - Online meeting DA - 14.06.2021 KW - Nickel-base superalloys KW - Creep KW - Single-Crystal PY - 2021 AN - OPUS4-53935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Current and future technological advancement in polymer matrix composites enabled through fundamental discoveries N2 - This presentation is a summary of the work from the past 20 years’ development of PMC-testing at the BAM-FB 5.3 with respect to safety-relevant design of advanced light weight structures in aircraft, wind turbine and automotive applications. The talk begins with wood as an example from nature, and emphasizes that load case, fiber architectural design and the production process and quality have to go hand in hand to generate an advanced light weight structure. Since PMC-relevant basic findings of mankind span across hundreds of years, high-performance composite applications today are based more on long term experiences than on breakthrough inventions of modern days. In the second part of the talk, future plans and projects of FB-5.3 are presented, specifically addressing H2-safety, circular economy, recycling by design and digitalization of PMC-technologies. T2 - Abteilungsseminar CY - Online meeting DA - 07.09.2021 KW - Polymer Matrix Composites KW - Thermo mechanical fatigue PY - 2021 AN - OPUS4-54150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Agea-Blanco, Boris A1 - Blaeß, Carsten A1 - Reinsch, Stefan A1 - Behrens, H T1 - Sintering and Foaming of Silicate Glass Powders N2 - The lecture focuses on the mechanisms of non-desired gas bubble formation and foaming during the sintering of glass powder compacts. It is shown that foaming is driven by carbon gases and that carbonates, encapsulated in micropores or mechaniacally dissolved beneath the glass surface, provide the major foaming source. T2 - Sandanski Workshop Sinter crystallization 27th-29th September 2021 PROJECT “THEORY AND APPLICATIONS OF SINTER-CYSTALLIZATION” DN 19/7 CY - Online meeting DA - 27.10. 2021 KW - Sintering KW - Non-desired foaming PY - 2021 AN - OPUS4-53772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abel, Andreas A1 - Zapala, P. A1 - Michels, H. A1 - Skrotzki, Birgit T1 - Microstructure-Property-Correlation of a Mo-Ti-B alloyed iron aluminide N2 - Iron aluminides depict a sustainable and light-weight material class which could be employed in many applications requiring high strength at intermediate to high temperatures. According to first results, the alloy Fe-26Al-4Mo-0.5Ti-1B surpasses conventional materials in wet corrosion resistance and creep resistance up to 650 °C. For these reasons, the AiF research project “WAFEAL – Materials applications for iron aluminides” was initiated to transfer these findings into a standardised materials dataset and to derive best practices for processing. In the first place, a set of different microstructures adjusted by varying casting methods, wall thicknesses and heat treatments was investigated and correlated with hardness on macro and micro scale. Correlations were drawn between solidification rates and resulting grain sizes and hardness. The effect of vacancy hardening was only verified for wall thickness as low as 2.5 mm. Moreover, a common decrease of macrohardness after a heat treatment at 1000 °C for 100 h was observed irrespective of casting process or wall thickness. This effect was linked with an unexpected decrease of the complex boride phase fraction which acts as a hardening phase. T2 - Intermetallics 2021 CY - Bad Staffelstein, Germany DA - 04.10.2021 KW - Fe-Al alloys KW - Intermetallics KW - Iron aluminides KW - Heat treatment KW - Wall thickness KW - Centrifugal casting KW - Die casting KW - Investment casting KW - Microstructure KW - Hardness KW - Complex borides PY - 2021 AN - OPUS4-53617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Kraus, David T1 - Thermo-mechanical fatigue of glass fiber reinforced polymer N2 - Glass fiber reinforced polymer (GFRP) materials in practical applications have to endure cyclic mechanical loading in a wide temperature range (e.g. aircraft applications, automotive, wind turbine blades). In this study the static strength and fatigue behavior of GFRP was investigated in a temperature range from 213 K to 343 K. Therefor the coefficients of thermal expansion of the composite as well as the matrix are measured in this temperature interval. The inverse laminate theory was extended and used to calculate the inter fiber-failure effort for a virtual UD-layer according to the layer wise strength approach. The experimentally determined results are compared with the micro-mechanical model according to Krimmer, which has been enhanced to include the effect of temperature and fiber-perpendicular failure modes. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve, as it was similar done for the fatigue behavior of CFRP and GFRP to very high load cycles at room temperature. T2 - ICFC8 - The 8th International Conference on the Fatigue of Composites CY - Online meeting DA - 23.06.2021 KW - Glass fibre reinforced plastics KW - Fatigue KW - Thermo-mechanical-loading PY - 2021 AN - OPUS4-52910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Nofz, Marianne A1 - Müller, Ralf A1 - Deubener, J. T1 - Sintering of silver‑alkali zinc borate glass‑composites N2 - Since decades electric contacts based on silver metallization pastes are key components of photovoltaics and advanced microelectronics. For the metallization of commercial Si solar cells, high conductive silver glass pastes are cost effectively applicated by screen printing. Nevertheless, silver pastes are still one of the most crucial and expensive none Si materials in solar cells. Ever shorter time to market as well as increasing demands on reduced Ag consumption and line width require the targeted development of silver-glass-pastes with increased sinter ability and electrical conductivity. As a main difficulty, however, the liquid phase sintering of silver glass pastes is poorly understood so far. In the present study, the influence of different network modifier in alkali-zinc-borate paste glasses on liquid phase sintering of silver-glass-pastes was investigated. Low melting X2O-ZnO-B2O3 glasses with X = Na, Li and Rb (abbr. LZB, NZB, and RZB) were utilized to prepare silver-glass-composites containing 30 %Vol glass. Shrinkage behavior of the silver-glass-composites compared with that of pure silver and pure glass powder compacts was studied with heating microscopy. The powder compacts were uniaxially pressed and heated at 5 K/min to the glass softening temperature. Glass transformation temperature and viscosity of the glasses were respectively measured with dilatometry and rotational viscometry. The thermal behavior of the pure glasses was analyzed with thermal analysis. Additionally, the contact angle of glass on pure silver foil was determined by means of heating microscopy between room temperature and 830 °C. Thermal analysis of the alkali-zinc-borate-glasses under study has shown transformation temperatures between 450 °C (RZB), 460 °C (LZB) and 465 °C (NZB). For all glasses crystallization was found to start approximately at about 550 °C. However, different peak areas hint on a different degree of crystallization. Conformingly, the sintering behavior, measured in terms of area shrinkage, significantly differed for the silver-pastes under study. For silver-pastes with NZB or LZB-glass, sintering starts at 464 °C for NZB Ag pastes and at 451 °C for LZB Ag pastes and ends at 597 °C for NZB Ag paste and at 594 °C for LZB Ag paste. The sintering of the RZB Ag paste proceeds between 426 °C and 703 °C. The final densification was retarded possibly due to crystallization or swelling. The low sinter onset at 426 °C seems to correlate with the good wetting behavior of the RZB glass. Thus, the lowest apparent contact angle between the just densified powder compact sintered at a silver substrate was found for this glass. Moreover, microstructure analyses of the various composites indicate differences in silver dissolution and reprecipitation. T2 - Technology Crossover Extravaganza, HiTEC/CICMT/APEPS CY - Online meeting DA - 26.04.2021 KW - Silver-glass-metallization-paste KW - Sintering KW - Crystallization KW - Alkali ions KW - Sintering atmosphere PY - 2021 AN - OPUS4-52872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus A1 - Bayerlein, Bernd A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit T1 - Towards digitalization of materials in PMD: An application ontology of the tensile test N2 - Due to the diversity of materials and the processes associated with their production and use, the complexity of the lifecycles of materials and the multitude of academic and industrial researchers participating in generation of data for material design impose a huge challenge. The topical goal of digitalizing materials and processes can only be adequately addressed by consolidating the efforts of all stakeholders in this field. There are many scattered activities, but there is a demand for an elimination of redundancies as well as an advance in acceptance and a common basis in the digitalization of materials. Furthermore, data analysis methods play an important role in both, the experimental and simulation-based digital description of materials, but they have been poorly structured so far. Therefore, the two joint projects Platform Material Digital (PMD, materialdigital.de) and Materials open Laboratory (Mat-o-Lab, matolab.de) aim to contribute to a standardized description of data processing methods in materials research. Besides stimulating the formation of a collaborative community in this respect, their main technical goals are the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications. In this regard, data management in accordance with the FAIR (findability, accessibility, interoperability, reuseability) principles is addressed. There is a common agreement in the scientific community following current discussions that data is supposed to be conform to these principles. This includes storage, processing and querying of data in a preferably standardized form. To meet the challenge to contextualize material data in a way that is consistent with all stakeholders, all necessary information on the condition of the material including production and application-related changes have to be made available via a uniform, machine-readable description. For this purpose, ontologies are to be used since they allow for machine-understandable knowledge representations and conceptualizations that are needed for data management and the digitalization in the field of materials science. As first efforts in PMD and Mat-o-Lab, application ontologies are created to explicitly describe processes and test methods. Thereby, the well-known tensile test of metals at room temperature was described ontologically in accordance with the respective ISO standard 6892-1:2019-11. The efforts in creating this tensile test application ontology are shown in this presentation. Especially, the path of ontology development based on standards to be pursued is focused, which is in accordance with the generic recommendations for ontology development and which is supposed to be exemplary for the creation of other application ontologies. T2 - VirtMet: 1st International Workshop on Metrology for Virtual Measuring Instruments and Digital Twins CY - Online meeting DA - 21.09.2021 KW - Platform Material Digital (PMD) KW - Ontology KW - Tensile test KW - Standard KW - Ontology development PY - 2021 AN - OPUS4-53481 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thuy, Maximilian A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Damage progression of environmental stress cracking affected by manufacturing process-induced microstructural orientation N2 - Currently, the Full Notch Creep Test (FNCT) [1] method is used by material suppliers and end users in industry for the approval of container and pipe materials based on high-density polyethylene (PE-HD). The resistance to environmental stress cracking (ESC) of the material is evaluated using the time to failure of the specimen in an aqueous solution of a detergent [2, 3]. Usually specimens made of sheets with isotropic material properties, manufactured by hot pressing, are employed in order to obtain intrinsic properties of the material in terms of ESC failure. In contrast, the processes used in manufacturing to form containers and pipes, such as extrusion blow molding or extrusion, impose anisotropic properties to the material. These are mostly due to a microstructural orientation (polymer chains or crystallites) [4]. Furthermore, the different cooling conditions significantly affect the size distribution of crystallites as well as the overall morphology. It is therefore essential to understand the influence of process-induced material characteristics on failure due to ESC. A large number of studies on material properties as a function of microstructural preferential orientation have already been conducted [5-7]. However, effects on ESC as the major failure mechanism of containers and pipes are still rather unexplored [8, 9]. The most important factor is whether primarily intramolecular high-strength covalent bonds or the substantially weaker intermolecular van der Waals forces are predominantly loaded. In addition to the widely established classification by time to failure, the strain or crack opening displacement (COD) provides valuable information about the evolution and progression of damage as a function of time [10, 11]. Optical strain measurement using digital image correlation allows the differences in COD for isotropic and different angles of orientation of anisotropic specimens to be discussed. Also, a post-fracture surface analysis provides clarification on the craze-crack mechanism of the ESC. These different ESC-related properties of extruded and hot-pressed specimens have been investigated at different environmental medium temperatures and different initial stresses to provide a broad characterization of the fracture behavior of PE-HD. T2 - 36th International Conference of the Polymer Processing Society CY - Montreal, Canada DA - 26.09.2021 KW - Environmental stress cracking KW - High-density polyethylene KW - Fracture behavior KW - Microstructural orientation PY - 2021 AN - OPUS4-53400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus T1 - Tensile Test Ontology used in Platform Material Digital (PMD) N2 - Data analysis methods play an important role in both the experimental and simulation-based digital description of materials but have so far been poorly structured. The platform Material Digital (PMD) is supposed to contribute to a standardized description of data processing methods in materials research. The goal is the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications. Therefore, application ontologies are created to explicitly describe processes and test methods. In this presentation, the first efforts within the joint project PMD in creating a tensile test application ontology in accordance with the ISO standard 6892-1:2019-11 are shown. Especially, the path of ontology development to be pursued based on standards was focused. Furthermore, the presentation includes a live demonstration of queries possibly performed to query data that was uploaded in the PMD triple store. T2 - Online Workshop: An introduction to the semantic web and ontologies CY - Online meeting DA - 23.04.2021 KW - Ontology KW - Tensile Test KW - Platform Material Digital KW - PMD KW - Knowledge Graphs KW - Semantic Web PY - 2021 AN - OPUS4-52949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abram, Sarah-Luise A1 - Mrkwitschka, Paul A1 - Prinz, Carsten A1 - Rühle, Bastian A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan A1 - Resch-Genger, Ute T1 - Monodisperse iron oxide nanoparticles as reference material candidate for particle size measurements N2 - In order to utilize and rationally design materials at the nanoscale the reliable characterization of their physico-chemical properties is highly important, especially with respect to the assessment of their environmental or biological impact. Furthermore, the European Commission’s REACH Regulations require the registration of nanomaterials traded in quantities of at least 1 ton. Powders or dispersions where 50% (number distribution) of the constituent particles have sizes ≤ 100 nm in at least one dimension are defined as nanomaterials. This creates a need for industrial manufacturers and research or analytical service facilities to reliably characterize potential nanomaterials. Currently, BAM is developing reference nanoparticles, which shall expand the scarce list of worldwide available nano reference materials certified for particle size distribution and will also target other key parameters like shape, structure, porosity or functional properties. In this respect, materials like iron oxide or titanium dioxide are considered as candidates to complement the already available silica, Au, Ag, and polystyrene reference nanoparticles. The thermal decomposition of iron oleate precursors in high boiling organic solvents can provide large quantities of iron oxide nanoparticles that can be varied in size and shape.[1, 2] The presence of oleic acid or other hydrophobic ligands as capping agents ensures stable dispersion in nonpolar solvents. Such monodisperse, spherical particles were synthesized at BAM and pre-characterized by electron microscopy (TEM, SEM including the transmission mode STEM-in-SEM) and dynamic light scattering comparing cumulants analysis and frequency power spectrum. 1. REACH regulations and nanosafety concerns create a strong need for nano reference materials with diverse properties. 2. Iron oxide nanoparticles are under development as new candidate reference material at BAM. 3. Narrow particle size distribution confirmed by light scattering and electron microscopy. T2 - Nanosafety 2020 CY - Online meeting DA - 05.10.2020 KW - Iron oxide nanoparticles KW - Reference material KW - Particle size KW - Electron microscopy KW - Nanoplattform PY - 2020 AN - OPUS4-52774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Trappe, Volker T1 - The effect of fiber orientation mismatch on scarf joint damage mechanisms under fatigue load N2 - Wind turbine rotor blades commonly fail before their projected 20-year lifespan largely due to defects that originate during manufacturing and are propagated by operational fatigue and environmental conditions. The cost-intensive replacement outcomes lead to a high loss of earnings, and are one of the inhibitors of wind turbine production. A potential repair alternative to restoring the mechanical properties of such lightweight fiber reinforced polymer (FRP) structures is to locally patch these areas with scarf joints. This type of repair allows for a smoother load distribution across the joint, and is favored especially on structures where minor aerodynamic contour changes are key. The effects of such repairs on the structural integrity, however, is still largely unknown. Building upon an understanding of the static load failure mechanism of GFRP scarf joints, presented at the ICCS23 Joint Event in 2020, the influence of the fiber orientation mismatch between parent and repair materials of 1:50 scarf joints on the failure mechanism of monolithic glass FRP specimens under cyclic fatigue load were examined in this study. Specimens with various layups were produced with the vacuum-assisted resin infusion (VARI) process using biaxial E-glass non-crimp fabric (NCF). The patch layers were then joined directly to the parent structure with the VARI using biaxial E-glass NCF with half the areal weight of the parent side to allow for better drapability. This mimics the soft-to-hard patch style utilized in wind turbine blade shell field repairs. The specimens were tested under uniaxial fatigue load, during which they were periodically monitored for damage onset. A comparison of the +45/-45° and 0/90° layups allowed for an understanding of the role of a highly mismatching fiber orientation in the transition zone between parent and patch material on the failure mechanism of the scarf joint. In addition to the tensile strength and stiffness property recovery assessment, a grayscale analysis using in-situ camera images determined the damage state leading to failure in each region across the scarf joint, which varied in the parent material versus scarf joint region, providing insight to the critical regions in this composite structure under cyclic loading. T2 - ICCS24 - 24th International Conference on Composite Structures CY - Online meeting DA - 14.06.2021 KW - Glass fiber reinforced polymers KW - Scarf repairs KW - Damage mechanisms PY - 2021 AN - OPUS4-52817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Sobek, P. A1 - Körner, S. A1 - Müller, Ralf T1 - Silver - alkali borate glass pastes N2 - Network modifier ions can decisively influence properties and structure of low melting alkali-zinc-borate glasses and thus cause complex effects on the liquid phase sintering of silver-glass metallization pastes. This effect was studied for X2O-ZnO-B2O3 (X = Li, Na, Rb) glasses for silver-glass metallization pastes. Viscosity and the glass transition temperature, Tg, were measured with rotational viscometry and dilatometry. Dried model pastes with 30 vol% LZB, NZB or RZB glass were prepared for sintering studies by means of heating microscopy measuring the silhouette area shrinkage of uniaxially pressed powder compacts during heating at 5 K/min. For comparison, the silhouette area shrinkage of pure glass and silver powder compacts were determined. Glass-silver wetting was investigated during heating of bulk glass cylinders placed on silver substrates. Glass RZB turned out to have the lowest viscosity among the glasses under study. Its glass transformation temperature, Tg, was found at 444 °C and it caused the lowest sintering onset for its glass and paste powder compacts. Slightly increased values of Tg were found for NZB and LZB (468 °C and 466 °C, respectively) and a slightly retarded sintering was found for both paste powder compacts. These results indicate that liquid phase sintering of silver-glass pastes under air atmosphere is mainly influenced by glass viscosity. T2 - GLASS MEETING 2020 CY - Online meeting DA - 07.12.2020 KW - Silver-glass metallization paste KW - Sintering KW - Alkali ions KW - Viscosity KW - Silver precipitates PY - 2020 AN - OPUS4-52871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Mechanical anisotropy of LPBF 316L: a modeling approach N2 - The underlying cause of mechanical anisotropy in additively manufactured (AM) parts is not yet fully understood and has been attributed to several different factors like microstructural defects, residual stresses, melt pool boundaries, crystallographic and morphological textures. To better understand the main contributing factor to the mechanical anisotropy of AM stainless steel 316L, bulk specimens were fabricated via laser powder bed fusion (LPBF). Tensile specimens were machined from these AM bulk materials for three different inclinations relative to the build plate. Dynamic Young's modulus measurements and tensile tests were used to determine the mechanical anisotropy. Some tensile specimens were also subjected to residual stress measurement via neutron diffraction, porosity determination with X-ray micro-computed tomography, and texture analysis with electron backscatter diffraction (EBSD). A crystal plasticity model was used to analyze the elastic anisotropy and the anisotropic yield behavior of the AM specimens, and it was able to capture and predict the experimental behavior accurately. Overall, it was shown that the mechanical anisotropy of the tested specimens was mainly influenced by the crystallographic texture. T2 - 2. Online-Workshop "In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys " CY - Online meeting DA - 20.04.2021 KW - Anisotropy KW - Crystal plasticity KW - Additive manufacturing PY - 2021 AN - OPUS4-52603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis Alexander T1 - Creep behavior and microstructural evolution of LPBF 316L N2 - This presentation shows some experimental results of the characterization of the creep behavior of LPBF 316L, which has been poorly studied and understood to date. The presentation includes results regarding the mechanical properties, the initial microstructural state and its evolution under loading, and the damage mechanism. This work was done within the BAM focus area materials project AGIL. As a benchmark to assess the material properties of the LPBF 316L, a conventionally manufactured variant was also tested. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured alloys at BAM CY - Online Meeting DA - 19.04.2021 KW - 316L KW - Additive Manufacturing KW - Creep behavior PY - 2021 AN - OPUS4-52682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Trappe, Volker T1 - Restoring lightweight strength - Effect of localized repairs on the mechanical properties of composites sandwich structures N2 - As a type of high-performance composite material, glass-fiber reinforced plastics (GFRP) are favored for the construction of wind turbine rotor blades due to their high specific strength and stiffness properties (Grasse et al, 2010). During the blade manufacturing process, however, imperfections are often introduced, then further propagated due to harsh environmental conditions and a variety of loads (Caminero et al, 2013; Trappe et al, 2018). This leads to failure significantly before their designed lifespan. Since replacement of entire blades can be a costly potential outcome, localized repairs of the damaged region to restore structural integrity and thus lengthen its lifespan can executed in the field by technicians accessing the blades directly by suspended roping. These methods involve replacing the lost load path with a new material that is joined to the parent structure. In recent years, considerable studies have been conducted to investigate the influence of different repair parameters on the stress distribution, ultimate strength, impact behavior, and residual stresses of bonded repaired structures [Caminero et al, 2013; Trappe et al, 2018; Shufeng et al, 2014; Harman and Rider, 2011; Ahn and Springer, 2000; Lekou and Vionis, 2002). However, there currently do not exist any standardized repair procedures for wind turbine rotor blades. Namely, there is a lack of understanding about the effects of the layup of various repair methods, especially on the damage mechanism and fatigue life of the shells of rotor blades (Caminero et al, 2013; Trappe et al, 2018). This work therefore aims to begin to enrich this knowledge gap by testing the influence of different variables among repair patches on the mechanical properties of sandwich composite structures. Manufactured with the vacuum-assisted resin infusion (VARI) process, the test specimens are produced as a GFRP structure to represent the outer shell portion of a wind turbine blade, then repaired with a scarf joint. Scarf repairs are favored as the most efficient of the common structural joints, as the removal of the damaged area with angled walls leads to a nearly uniform shear stress distribution along the bond surface and no eccentricity in the load distribution (Caminero et al, 2013; Lekou and Vionis, 2002; Siener, 1992). The performance of specific layup methods of repair patches, namely a large-to-small versus small-to-large scheme of repair layers, is studied with static and load-controlled fatigue testing, then compared to pristine test specimens as well as to each other in terms of mechanical property restoration. The transition layer between repair and parent material is especially of interest in the performance of the structure. Damage onset, crack development and eventual failure are monitored in-situ with non-destructive testing methods, including thermography with an infrared camera system and a 3D deformation analysis system, to develop a more robust understanding of the effects of these repair concept variables on wind turbine blade shell structures. T2 - Wind Energy Science Conference CY - Online Meeting DA - 25.05.2021 KW - Glass fiber reinforced polymers KW - Wind turbine blade shell structures KW - Scarf joint repair PY - 2021 AN - OPUS4-52687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan A1 - Rabe, Torsten T1 - Comparative study of suitable preparation methods to evaluate irregular shaped, polydisperse nanoparticles by scanning electron microscopy (SEM). N2 - Reliable characterization of materials at the nanoscale regarding their physio-chemical properties is a challenging task, which is important when utilizing and designing nanoscale materials. Nanoscale materials pose a potential toxicological hazard to the environment and the human body. For this reason, the European Commission amended the REACH Regulation in 2018 to govern the classification of nanomaterials, relying on number-based distribution of the particle size. Suitable methods exist for the granulometric characterization of monodisperse and ideally shaped nanoparticles. However, the evaluation of commercially available nanoscale powders is problematic. These powders tend to agglomerate, show a wide particle size distribution and are of irregular particle shape. Zinc oxide, aluminum oxide and cerium oxide with particle sizes less than 100 nm were selected for the studies and different preparation methods were used comparatively. First, the nanoparticles were dispersed in different dispersants and prepared on TEM-supported copper grids. Furthermore, individual powders were deposited on carbon-based self-adhesive pads. In addition, the samples were embedded by hot mounting and then ground and polished. The prepared samples were investigated by scanning electron microscopy (including the transmission mode STEM-in-SEM) and Dynamic Light scattering. The software package ImageJ was used to segment the SEM images and obtain the particle sizes and shapes and finally the number-based particles size distribution with size expressed as various descriptors. T2 - Ceramics 2021 CY - Online meeting DA - 19.04.2021 KW - Nanoparticles KW - Preparation KW - Characterization PY - 2021 AN - OPUS4-53272 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meyer, Lena A1 - Günster, Jens T1 - Powder based Additive Manufacturing in Space N2 - Abstract of the event: 'The area of New Space is a vastly growing and dynamic field with a high innovative potential and many exciting ideas. After decades where activities in space were dominated and funded mainly by governmental agencies, a new industry is forming and new business models are being developed around ideas like satellite-based internet, space travel, space mining, geo-monitoring etc. For space applications, lightweight design is crucial to keep the costs at a minimum. This Innovation Day will introduce the field of New Space and present the variety of exciting opportunities that arise for composites based on their excellent lightweight potential.' Another research area is now arising in the field of 3D printing or additive manufacturing of fiber composite materials in space. At the event, we presented on the opportunities and our experiences of using a powder based additive manufacturing process for in-space manufacturing applications. T2 - CU Innovation Day - New opportunities and applications in space with composites CY - Online meeting DA - 29.03.2022 KW - μ-gravity KW - In-space manufacturing KW - Additive manufacturing KW - Microgravity KW - Powder PY - 2022 AN - OPUS4-54559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chen, Yue A1 - Schilling, Markus A1 - von Hartrott, P. A1 - Huschka, M. A1 - Olbricht, Jürgen A1 - Pirskawetz, Stephan A1 - Skrotzki, Birgit A1 - Hanke, T. A1 - Todor, A. T1 - Ontopanel: a diagrams.net plugin for graphical semantic modelling N2 - Ontologies that represent a map of the concepts and relationships between them, are becoming an effective solution for data standardization and integration of different resources in the field of materials science, as efficient data storage and management is the building block of material digitization. However, building a domain ontology is not a simple task. It requires not only a collaborative effort between ontologists and domain experts, but also the modeling approaches and tools play a key role in the process. Among all approaches, graphical representation of domain ontologies based on standard conceptual modeling languages is widely used because of its intuitiveness and simplicity. Various tools have been developed to realize this approach in an intuitive way, such as Protégé plugins and web visualization tools. The Materials-open-Lab (MatOLab) project, which aims to develop ontologies and workflows in accordance with testing standards for the materials science and engineering domains, adopted a UML (Unified Modeling Language) approach based on the diagrams.net. It is a powerful, popular, open-source graphical editor. In practical case studies, however, many users’ needs could not be met, such as reusing ontology, conversion, and data mapping. Users must switch between different tools to achieve a certain step, and thereby invariably increase learning cost. The lack of validation also leads to incorrect diagrams and results for users who are not familiar with the ontology rules. To address these issues, we designed Ontopanel, a diagrams.net-based plugin that includes a set of pipeline tools for semantic modeling: importing and displaying protégé-like ontologies, converting diagrams to OWL, validating diagrams by OWL rules, and mapping data. It uses diagrams.net as the front-end for method modeling and Django as the back-end for data processing. As a web-based tool, it is very easy to expand its functionality to meet changing practical needs. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Ontology KW - Tools KW - Material digital KW - Mat-o-lab KW - Graphic design KW - Ontology development KW - Data mapping KW - FAIR KW - Materials testing PY - 2022 AN - OPUS4-55884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bayerlein, Bernd A1 - Zia, Ghezal-Ahmed A1 - Schilling, Markus A1 - Skrotzki, Birgit A1 - von Hartrott, P. A1 - Hanke, T. A1 - Waitelonis, J. T1 - Towards Interoperability: Digital Representation of a Material Specific Characterization Method N2 - Certain metallic materials gain better mechanical properties through controlled heat treatments. For example, in age-hardenable aluminum alloys, the strengthening mechanism is based on the controlled formation of nanometer sized precipitates, which represent obstacles to dislocation movement. Precise tuning of the material structure is critical for optimal mechanical behavior in the application. Therefore, analysis of the microstructure and especially the precipitates is essential to determine the ideal parameters for the interplay of material and heat treatment. Transmission electron microscopy (TEM) is utilized to identify precipitate types and orientations in a first step. Dark-field imaging (DF-TEM) is often used to image the precipitates and to quantify their relevant dimensions. The present work aims at the digital representation of this material-specific characterization method. Instead of a time-consuming, manual image analysis, an automatable, digital approach is demonstrated. Based on DF-TEM images of different precipitation states of a wrought aluminum alloy, a modularizable digital workflow for quantitative precipitation analysis is presented. The integration of this workflow into a data pipeline concept will also be discussed. Thus, by using ontologies, the raw image data, their respective contextual information, and the resulting output data from the quantitative precipitation analysis can be linked in a triplestore. Publishing the digital workflow and the ontologies will ensure the reproducibility of the data. In addition, the semantic structure enables data sharing and reuse for other applications and purposes, demonstrating interoperability. The presented work is part of two digitization initiatives, the Platform MaterialDigital (PMD, materialdigital.de) and Materials-open-Laboratory (Mat-o-Lab). T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Interoperability KW - Ontology KW - Precipitation Analysis PY - 2022 AN - OPUS4-55892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Han, Ying A1 - Kruse, Julius A1 - Madia, Mauro A1 - Skrotzki, Birgit T1 - High cycle fatigue behavior of alloy EN AW-2618A N2 - The presentation shows the results of high cycle fatigue (HCF) tests from the aluminium alloy EN AW-2618A. This study investigates the mean stress influence in the T61 condition and the effect of overaging. For this purpose, axial HCF tests were carried out at room temperature and different stress ratios (R=-1, R=0.1) as well as with overaged conditions (T61+10h@230°C, T61+1000h@230°C). After completion of the tests, the fracture surfaces were examined to study crack initiation. T2 - The 18th International Conference on Aluminium Alloys CY - Toyama, Japan DA - 04.09.2022 KW - High Cycle Fatigue KW - Aluminium Alloy KW - EN AW-2618A PY - 2022 AN - OPUS4-55865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit T1 - Aging processes in precipitation hardened aluminum alloys N2 - The mechanical strength of wrought high-strength aluminum alloys is essentially based on precipitation hardening, possibly in combination with prior forming, e. g. by stretching. Important parameters for achieving an optimum combination of hardness, strength, ductility, toughness, and further properties such as corrosion resistance are age-hardening temperature and time. During thermal (mechanical) treatment, nucleation and growth of precipitates takes place, leading to the desired degree of hardening. In aluminum alloys, precipitation sequences are usually passed through, i. e. a sequence of metastable precipitates is formed before the stable phase can precipitate. The optimum combination of properties is therefore based on a certain (optimum) microstructure, which can, however, change during the use of a component, since the microstructure is not stable. This happens in particular when the operating temperatures are close to the aging temperature and/or the operating times are sufficiently long. An external mechanical load may accelerate the processes. The presentation gives some examples for this. T2 - Materials Science and Engineering Congress MSE 2022 CY - Darmstadt, Germany DA - 27.9.2022 KW - Aluminium alloy KW - Precipitation hardening KW - Aging KW - Degradation PY - 2022 AN - OPUS4-55877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Schubert, Hendrik A1 - Günster, Jens T1 - Additive Manufacturing of advanced ceramics by layerwise slurry deposition and binder jetting (LSD-print) N2 - Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. Powder bed fusion and binder jetting especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder layer. This offers high flexibility in the ceramic feedstock used, especially concerning material and particle size. The LSD technology can be combined with binder jetting to develop the so-called “LSDprint” process for the additive manufacturing of ceramics. The LSDprint technology combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing. In this presentation, the LSD process will be introduced and several examples of application ranging from silicate to high-performance ceramics will be shown. Recent developments towards the scale-up and industrialization of this process will be discussed, alongside future perspectives for the multi-material additive manufacturing. T2 - Ceramics in Europe 2022 CY - Krakow, Poland DA - 10.07.2022 KW - Layerwise slurry deposition KW - Laser induced slipcasting KW - Additive Manufacturing KW - Ceramics PY - 2022 AN - OPUS4-55543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abel, Andreas A1 - Zapala, P. A1 - Michels, H. A1 - Skrotzki, Birgit T1 - Ambient and high-temperature mechanical properties of intermetallic Fe3Al alloys with complex borides N2 - Due to the increasing scarcity of critical raw materials current high-temperature materials are sought to be replaced by alloys based on more abundant metals. One possibility within the class of intermetallics are iron aluminides, which combine sustainability and cost-efficiency with the prospect of mass savings. Iron aluminides show competitive specific strength up to 700 °C and excellent creep and wet corrosion resistance by small additions of Mo, Ti and B. Nevertheless, a Mo content of above 2 at.% which is needed for optimum corrosion resistance results in enhanced brittleness, especially at room temperature. This is why alloys with these Mo fractions were only mechanically tested under compressive loading so far. Still, testing of static and creep properties under tensile loading is required for reliable component design. Besides high standards for crack-free processing, data acquisition for tensile loads is especially complicated by environmental embrittling effects for iron aluminides. To cope with these challenges, the AiF research project “WAFEAL – Materials applications for iron aluminides” was initiated. The main goal is to collect standardised data on ambient and high-temperature tensile properties and creep properties. Samples with a nominal composition of Fe-26Al-4Mo-0.5Ti-1B [at.%] were manufactured via centrifugal casting in ceramic shell moulds followed by machining. Heat treatment for homogenisation and final polishing were carried out where appropriate. A summary of the achieved tensile and creep properties such as yield and tensile strength, maximum elongation, secondary creep rate and stress exponents will be given. Results will be also discussed regarding the influence of temperature, stress level and microstructure on the damage mechanisms. Furthermore, the effect of different alloy concentrations on the mechanical response at different temperatures will be outlined within a small experimental series. T2 - MSE Congress 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Fe-Al alloys KW - Intermetallics KW - Iron aluminides KW - Tensile data KW - High temperature mechanical properties KW - Creep data KW - Fractography PY - 2022 AN - OPUS4-55993 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Trappe, Volker T1 - Fully-reversed fatigue behavior of scarf joint repairs for wind turbine blade shell applications N2 - Due to manufacturing imperfections which can propagate to damage under in-service loads, wind turbine rotor blades, made primarily of glass fiber reinforced polymers (GFRP), often fail significantly before their design life. To enable a quick and cost-effective return to service, localized repairs can be executed by technicians in the field, directly accessing the blades by suspended roping. Scarf joint repairs, shown to be highly efficient with a smooth load transition across angled joint walls and a restored aerodynamic profile, are the focus of this study. The damage mechanisms of these structures were examined under fully-reversed mechanical cyclic loading with a load ratio R = -1, which was made possible on the coupon scale by a custom designed anti-buckling support. The number of cycles to failure were compared across load levels. While the scarf joint ratio was held constant at 1:50, known from industry and literature to be a good compromise between restored mechanical properties and repair size, the layup sequence was varied between small-to-large and large-to-small. Hereby the effect of the presence of resin pockets and fiber orientation mismatch between the parent and repair structure on the failure mechanism as well as fatigue strength of ±45° GFRP scarf joint repair structures was studied. Strain development across the joint length was measured to assess stiffness degradation in addition to the fatigue strength recovery of scarf joint structures with respect to pristine reference specimens. Grayscale analysis was used to monitor the damage state leading to fracture across the specimens. Post-mortem fractography analysis with light microscopy described the global failure mechanisms as well as local damage distribution within the structure, all of which provided insight to critical variables in scarf joint GFRP structures under fully-reversed mechanical cyclic loading, allowing for the tailoring of such repairs on wind turbine blade shells for maximum restoration of service life. T2 - 20th European Conference on Composite Materials (ECCM20) CY - Lausanne, Switzerland DA - 26.06.2022 KW - Glass fiber reinforced polymers KW - Scarf repairs KW - Fatigue PY - 2022 AN - OPUS4-55638 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Müller, Ralf A1 - Nofz, Marianne A1 - Deubener, J. T1 - Liquid phase sintering of alkali zinc borate glass-bearing silver pastes for applications in photovoltaics and microelectronics N2 - Liquid phase sintering of glass bearing silver pastes used in photovoltaics and microelectronics is poorly understood. In particular, the role of different network modifiers acting in the glass component and the question of the most suitable atmospheric oxygen level during sintering are still under considerable debate. To tackle these issues, low-melting and lead-free X2O-ZnO-B2O3 glasses with X = Li, Na, K and Rb (LZB, NZB, KZB and RZB) were prepared. Infrared spectroscopy showed that the glass structure was similar to each other, while an increase of tetrahedrally coordinated boron with increasing field strength of the alkali was evident. In turn, the glass transition temperature (from differential thermal analysis) increased in the order: RZB (449 °C) < KZB (460 °C) < NZB (465 °C) < LZB (472 °C). Powders of each glass were mixed with organics to receive silver-glass-pastes containing 30 vol% glass and these were subjected to heating microscopy in air. Although similar onset temperatures of sintering were recorded for Ag-NZB and Ag-LZB glass pastes, and for Ag-RZB paste and KZB-Ag-paste, respectively, differences in the crystallization behavior and final densification were observed between the former and the latter group. These were translated in terms of differences in silver dissolution and reprecipitation among the two groups. Further, running the experiments in nitrogen gas showed that sintering of all pastes was considerably hampered. The slow-down of the sinter kinetics was found to be in line with the assumed lower oxidation and dissolution of silver ions into the glass-forming liquid. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Silver metallization paste KW - Sintering KW - Glass KW - Alkali zinc borate glasses KW - Viscosity KW - Structure PY - 2022 AN - OPUS4-55728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Zocca, Andrea A1 - Günster, Jens T1 - Additive Manufacturing of Dense Ceramics with Laser Induced Slip Casting (LIS) N2 - The possibility to produce dense monolithic ceramic parts with additive manufacturing is at the moment restricted to small parts with low wall thickness. Up to now, the additive manufacturing of voluminous ceramic parts is realized by powder bed based processes which, however, generate parts with residual porosity. Via infiltration these parts can be processed to dense parts like for example SiC but this is not possible for all ceramics like for example Si3N4. There is a lack of methods for the additive manufacturing of dense voluminous parts for most ceramics. We have developed a new additive manufacturing technology, the Laser Induced Slip casting (LIS), based on the layerwise deposition of slurries and their local drying by laser radiation. Laser Induced Slip casting generates ceramic green bodies which can be sintered to dense ceramic components like traditional formed ceramic powder compacts. We will introduce the LIS technology, green bodies and sintered parts will be shown and their microstructure and mechanical properties will be discussed. T2 - 42nd International Conference and Expo on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 21.01.2018 KW - Additive Manufacturing KW - Ceramics PY - 2018 AN - OPUS4-44182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dümichen, Erik A1 - Eisentraut, Paul A1 - Braun, Ulrike T1 - Fast identification of microplastics using thermal extractions methods N2 - A new and full automated system for the analysis of microplastics in environmental samples is presented. T2 - BAM-BfR Seminar 2018 CY - Berlin, Germany DA - 15.02.2018 KW - Mikroplastik KW - TED KW - Thermal degradation PY - 2018 AN - OPUS4-44179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Braun, Ulrike T1 - Fast identification of microplastics using thermal extraction methods N2 - The presentation presents an overview about existing methods of microplastic detection with a special focus on thermo-analytical methods. T2 - Perkin Elmer Workshop Microplastics CY - Vienna, Austria DA - 11.01.2018 KW - Microplastics KW - TED-GC-MS KW - Analysis PY - 2018 AN - OPUS4-43803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Paulick, C. A1 - Kalinka, Gerhard T1 - Helical zirconia (TZP) springs manufacturing and testing under mechanical and thermal load N2 - Helical springs with a rectangular cross-section have been machined from sintered and grinded hollow cylinders with high geometrical precision and good reproducibility. Such springs made from tetragonal zirconia polycrystal (TZP) ceramic show excellent edge quality because of high fracture toughness and bending strength of the starting material. Hence, springs with desired geometric dimension and tailored spring constant can be manufactured for highly demanding applications at high temperatures and in harsh environments. Prior to any practical use, application limits of springs under mechanical and thermal load have to be analyzed. Therefore, different displacement experiments were carried out on the helical TZP springs. - Dynamic displacement tests at various temperatures from -15°C to +60°C using a piezo actor to load/unload springs with frequencies between 1 and 40 Hz: Springs remained undamaged and the spring constants were not altered, even after more than one million cycles of compression loading. - Long-time displacement measurements under static tensile loading at room temperature with a high-precision interferometer test facility: Significant spring elongation under constant strain was surprisingly proved over a period of many hours already at room temperature. - Creeping experiments for 48 h under static compression load at different temperatures up to 1000 °C: After cooling down and load removing no permanent length reduction of springs was observed for test temperatures up to 700 °C. However, reshaping of TZP springs by plastic deformation is possible at higher temperatures and opens up additional possibilities for spring design and manufacturing. T2 - German Ceramic Society, Annual Meeting 2018 CY - München, Germany DA - 09.04.2018 KW - Ceramic springs KW - Manufacturing KW - Mechanical and thermal testing PY - 2018 AN - OPUS4-44728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kraus, David A1 - Trappe, Volker T1 - Cyclic fatigue behavior of glass fiber reinforced epoxy resin at ambient and elevated temperatures N2 - The fatigue behavior of ±45° glass fiber reinforced epoxy resin under cyclic mechanical and constant thermal loading is investigated in this study. Tests at three different temperature levels in the range 296 K to 343 K have been performed in order to create S-N curves for each temperature level. The specimen damage is measured in-situ using optical grayscale analysis. The characteristic damage state (CDS) is evaluated for each specimen. It is shown that the point of CDS is suitable as a failure criterion to compare the resulting S-N curves. With micromechanical formulations, the temperature-dependent matrix effort is calculated for each stress-temperature level. In terms of matrix effort, the longest fatigue life is reached at high temperatures, while, in terms of stress, the lowest fatigue life is reached at the highest temperatures. T2 - ECCM18 - 18th European conference on composite materials CY - Athens, Greece DA - 24.06.2018 KW - Composite KW - Fatigue KW - Thermomechanics KW - Residual stresses KW - Temperature PY - 2018 AN - OPUS4-45346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Trappe, Volker A1 - Nielow, D. A1 - Schumacher, David A1 - Lange, A. A1 - Hentschel, M.P. A1 - Redmer, Bernhard A1 - Ewert, U. A1 - Bruno, Giovanni T1 - X-ray laminographic inspection of sandwich shell segments for wind turbine rotor blades N2 - 3D structural investigations are described by X-ray laminography studies of sandwich shell segments, made of a PVC foam core, covered by non-crimp fabric glass fibre composite lay-ups processed by vacuum assisted resin infusion of epoxy. The specific scope of this study is to image transversal flaws within the foam core (joints) and of single ply overlaps. Test flaws were purposely implemented in order to simulate typical failure under cyclic load. In a dedicated test rig for shell structures, the flaw evolution/propagation is monitored by thermography and optical 3D inspection of deformation. Due to the unfavourable preconditions for classical computed tomography as of large aspect ratio, the samples were investigated by coplanar translational laminography. Its limited range of observation angles of ± 45°, results in anisotropic artefacts about the normal to the sample surface, but the typical flaws are well visualized in the as-prepared state, in a state of early damage, and in the repaired state. T2 - 12th European Conference on Non-Destructive Testing CY - Gothenburg, Sweden DA - 11.06.2018 KW - X-ray laminography KW - Wind turbine KW - Rotor blade PY - 2018 AN - OPUS4-45438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Diener, S. A1 - Katsikis, N. A1 - Günster, Jens T1 - LSD- 3D printing: Powder based Additive Manufacturing, from porcelain to technical ceramics N2 - Powder based Additive Manufacturing (AM) processes are widely used for metallic and polymeric materials, but rarely commercially used for ceramic materials, especially for technical ceramics. This seemingly contradicting observation is explained by the fact that in powder based AM, a dry flowable powder needs to be used. Technical ceramics powders are in fact typically very fine and poorly flowable, which makes them not suitable for AM. The layerwise slurry deposition (LSD) is an innovative process for the deposition of powder layers with a high packing density for powder based AM. In the LSD process, a ceramic slurry is deposited to form thin powder layers, rather than using a dry powder This allows the use of fine powders and achieves high packing density (55-60%) in the layers after drying. When coupled with a printing head or with a laser source, the LSD enables novel AM technologies which are similar to *Denotes Presenter 42nd International Conference & Exposition on Advanced Ceramics & Composites 127 Abstracts the 3D printing or selective laser sintering, but taking advantage of having a highly dense powder bed. The LSD -3D printing, in particular, offers the potential of producing large (> 100 mm) and high quality ceramic parts, with microstructure and properties similar to traditional processing. This presentation will give an overview of the milestones in the development of this technology, with focus on the latest results applied both to silicate and to technical ceramics. T2 - 42nd International Conference & Exposition on Advanced Ceramics and Composites CY - Daytona, FL, USA DA - 21.01.2018 KW - Additive Manufacturing KW - 3D printing KW - Ceramic KW - Alumina KW - Porcelain KW - Silicon Carbide PY - 2018 AN - OPUS4-44017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Hartrott, P. A1 - Rockenhäuser, Christian A1 - Schriever, Sina A1 - Metzger, M. A1 - Skrotzki, Birgit T1 - Correlation of the precipitate size evolution and the creep rate of the aluminum alloy EN AW 2618A at 190 °C N2 - Ther results of research on correlation of precipitate size Evolution and the creep rate of the Aluminium alloy EN AW 2618A at 190 °C was presented. T2 - ICAA16 CY - Montreal, Canada DA - 17.06.2018 KW - Alloy 2618A KW - Creep KW - Aluminium KW - Coarsening PY - 2018 AN - OPUS4-45283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Augenstein, E. A1 - Skrotzki, Birgit T1 - Long term ageing of alloy 2618A N2 - Results of the in vestigation of the "Long term ageing of alloy 2618A" were presented. T2 - ICAA 16 CY - Montreal, Canada DA - 17.06.2018 KW - Alloy 2618A KW - Aluminium KW - Coarsening KW - Transmission electron microscopy KW - S-phase PY - 2018 AN - OPUS4-45288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick A1 - Kuchenbecker, Petra A1 - Lindemann, Franziska A1 - Güther, Wolfgang A1 - Rabe, Torsten T1 - Strategies to improve spray dried multi-component granules N2 - Dry pressing of ceramic materials requires homogeneously soft granules with good flowability to allow rapid die filling and to avoid packing defects. Spray-drying granulation appears to be the best method for obtaining granules with high flowability in industrial scale. But, strength reducing internal microstructural defects caused by spray-dried granules with hollow and hard shells are often observed using nano and/or multi-component starting powders. Using the example of a ZTA composite, the potential of slurry optimization, ultrasound atomization and infrared drying for better granule properties and compaction behavior were investigated. Starting granules produced in a conventional spray dryer (Niro, Denmark) with a two fluid nozzle showed typical defects like large central pores and dimples. The early step of slurry preparation already possesses an essential optimization possibility in the form of stability adjustments. Granule compaction was clearly improved upon a specific reduction in slurry stability. The second optimization opportunity to improve the granule quality was the atomization step. Implementation of an ultrasound atomizing unit into the conventional spray dryer positively affected granule size distribution and therefor flowability and as well granule yield. But, a combination of both process optimizations delivered the best sinter bodies with highest density and strength due to further reduction in maximum size and fraction of pores. As last step of a spray drying process, the drying is the focus of further investigations. A current setup implying a spray dryer prototype utilizes stacked infrared heater in a countercurrent setup delivering a further increase in granule yield and enduring spraying process stability. T2 - 93. Jahrestagung der Deutschen Keramischen Gesellschaft CY - München, Germany DA - 10.04.2018 KW - Spray drying KW - Granules KW - Destabilization KW - Ultrasound PY - 2018 AN - OPUS4-44700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - von Hartrott, P. A1 - Metzger, M. A1 - Schriever, Sina A1 - Augenstein, E. A1 - Karlin, J. A1 - Piesker, Benjamin A1 - Schweizer, C. A1 - Skrotzki, Birgit T1 - Lifetime Assessment of Aluminium radial compressor wheels considering material ageing N2 - The results of the project "Lifetime Assessment of Aluminium radial compressor wheels considering material ageing" were presented. T2 - FVV Frühjahrstagung 2018 CY - Bad Neuenahr, Germany DA - 22.03.2018 KW - Alloy 2618A KW - Degradation KW - S-phase KW - Dark-field transmission electron microscopy KW - Aluminum PY - 2018 AN - OPUS4-44706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Influence of testing conditions on dielectric strength of alumina N2 - Dielectric strength testing of ceramics is simple and yet challenging. The execution of a breakthrough voltage measurement of a given sample is fast and straightforward. ASTM D149 describes the standardized procedure. But, there are versatile effects of test conditions and sample properties that affect the result of such a measurement. As one example, ASTM D149 allows different sizes of test electrodes and does not unambiguously prescribe the condition of the electrodes. Thus, different electrode configurations are used in the field. We conducted several test series on alumina samples to comprehensively quantify the effect of test conditions and sample properties on dielectric strength results. In our study, testing of alumina substrates using different electrode configurations resulted in differences of mean values of up to 20%. Further test series on alumina focused on the effect of voltage ramp rate. The results are complemented by calculations of failure probability at different voltage levels and corresponding withstand voltage tests. We conclude that a communication and comparison of single dielectric strength values is insufficient and may be misleading. A meaningful comparison of dielectric strength studies from different sources requires a thorough consideration of test conditions. T2 - 93rd DKG Annual Meeting CY - Munich, Germany DA - 10.04.2018 KW - Alumina KW - Dielectric strength KW - Withstand voltage tests PY - 2018 AN - OPUS4-44692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Surface-induced Crystallization of Glass N2 - Up to now, the mechanisms of surface nucleation and surface-induced texture formation are far from being understood. Corresponding phenomena are discussed hypothetically or even controversial, and related studies are restricted to very few glasses. In this talk the state of the art on mechanisms of surface nucleation are summarized. On one hand, mechanical damaged surfaces show high nucleation activity, at which the nucleation occurs at convex tips and edges preferentially. On the other hand, solid foreign particles are dominant nucleation sites at low damaged surfaces. They enable nucleation at temperatures even far above Tg. The nucleation activity of the particles is substantially controlled by their thermal and chemical durability. But no systematic studies on initially oriented crystal growth or nucleation from defined active nucleation sites have been pursued, so far. Therefore, the main objective of a just started project is to advance the basic understanding of the mechanisms of surface-induced microstructure formation in glass ceramics. We shall answer the question whether preferred orientation of surface crystals is the result of oriented nucleation or caused by other orientation selection mechanisms acting during early crystal growth. In both cases, crystal orientation may be caused by the orientation of the glass surface itself or the anisotropy and orientation of active surface nucleation defects. As a first attempt we focused on possible reorientation of separately growing surface crystals during early crystal growth. First results show clear evidence that separately growing crystals can reorient themselves as they are going to impinge each other. T2 - Glasforum der Deutschen Glastechnischen Gesellschaft (DGG) CY - Würzburg, Germany DA - 11.06.2018 KW - Crystallization KW - Silicate Glasses KW - Surface Nucleation PY - 2018 AN - OPUS4-45593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Trappe, Volker A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Evolution of CFRP stress cracks observed by in situ X-ray refractive imaging N2 - Modern air-liners and rotor blades of wind turbines are basically made of fiber reinforced plastics (FRP). Their failure heavily impairs the serviceability and the operational safety. Consequently, knowledge of the failure behavior under static and cyclic loads is of great interest to estimate the operational strength and to compare the performance of different materials. Ideally, the damage evolution under operational load is determined with in-situ non-destructive testing techniques. Here, we report on in-situ synchrotron X-ray imaging of tensile stress induced cracks in carbon fiber reinforced plastics (CFRP) due to inter fiber failure. An in-house designed compact-tensile testing machine with a load range up to 15 kN was integrated into the beam path. Since conventional radiographs do not reveal sufficient contrast to distinct cracks due to inter fiber failure and micro cracking from fiber bundles, the Diffraction Enhanced Imaging technique (DEI) is applied in order to separate primary and scattered (refracted) radiation by means of an analyzer crystal. In the laboratory, scanning X-ray refraction topography of CFRP has been applied long before but it comes along with several disadvantages: the long total measuring time hampers real time (in-situ) measurements and the required small beam size hinders end-to-end imaging. The introduced technique overcomes both drawbacks. Imaging and tensile test rig are run unsynchronized at the greatest possible frame rate (0.7 s-1 at 28.8 µm pixel size) and smallest possible strain rate (5.5∙10-4 s-1). For 0°/90° non-crimped fabrics (ncf) the first inter fiber cracks occurred at 380 MPa (strain 0.7 %). Prior to failure at about 760 MPa (strain 2.0 %) we observe the evolution of a nearly equidistant 1 mm grid of cracks running across the entire sample in the fully damaged state before total failure. T2 - 41st Risø International Symposium on Materials Science - Materials and Design for Next Generation Wind Turbine Blades CY - Online meeting DA - 07.09.2020 KW - X-ray refraction KW - Diffraction Enhanced Imaging KW - Carbon Fiber Reinforced Plastics KW - In situ tensile test KW - Crack evolution PY - 2020 AN - OPUS4-51223 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra A1 - Lindemann, Franziska A1 - Hodoroaba, Vasile-Dan T1 - Nano Powder - a Challenge for Granulometry N2 - If the particle size decreases, the ratio of surface area to volume increases considerably. This provides benefits for all surface-driven processes that run faster or at lower temperatures than larger particles. However, handling and characterization of the nanopowders are much more difficult. Particularly polydisperse powders with irregular shape, as grinding products, represent a challenge. Granulometry in the submicron and nanoscale often leads to incorrect results without knowledge of particle morphology. This presentation demonstrates potentials of using the volume-specific surface area (SV or VSSA) in the granulometric characterization of nanopowders, for instance, correlations between the volume-specific surface area and the median particle size are discussed considering the particle morphology and the model of the logarithmic normal distribution. Moreover, the presentation deals with the optimal dispersion of nanopowders during sample preparation. Indirect ultrasound device with defined cooling was developed to prevent both contamination by sonotrode abrasion and sample changes by heat. Successful granulometric characterization of nanopowders demands both improved dispersion technology and very often an effective combination of two or more measurement methods. T2 - Jahrestagung der Deutschen Keramischen Gesellschaft CY - Leoben, Austria DA - 06.05.2019 KW - Nano screening KW - VSSA KW - Nano particle KW - Particle size PY - 2019 AN - OPUS4-47976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Agea-Blanco, Boris A1 - Blaeß, Carsten A1 - Waurischk, Tina T1 - Sintering and foaming of silicate glass powders N2 - Glass powders are promising candidates for manufacturing a broad diversity of sintered materials like sintered glass-ceramics, glass matrix composites, glass bonded ceramics or pastes. Powder processing, however, can substantially affect sinterability, e.g. by promoting surface crystallization. On the other hand, densification can be hindered by gas bubble formation for slow crystallizing glass powders. Against this background, we studied sintering and foaming of silicate glass powders with different crystallization tendency for wet milling and dry milling in air, Ar, N2, and CO2 by means of heating microscopy, DTA, Vacuum Hot Extraction (VHE), SEM, IR spectroscopy, XPS, and ToF-SIMS. In any case, foaming activity increased significantly with progressive milling. For moderately milled glass powders, subsequent storage in air could also promote foaming. Contrarily, foaming could be substantially reduced by milling in water and 10 wt% HCl. Although all powder compacts were uniaxially pressed and sintered in air, foaming was significantly affected by different milling atmosphere and was found most pronounced for milling in CO2 atmosphere. Conformingly, VHE studies revealed that foaming is mainly driven by carbonaceous species, even for powders milled in other gases. Current results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. T2 - IMAPS/ACerS 15th International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies (CICMT 2019) CY - Shanghai, China DA - 16.04.2019 KW - Glass powder KW - Sintering KW - Foaming PY - 2019 AN - OPUS4-48196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Tielemann, Christopher A1 - Busch, R. A1 - Patzig, C. A1 - Müller, Ralf A1 - Höche, T. T1 - Oriented surface crystallization in 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glasses N2 - Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. The vast majority of previous work does not consider possible effects of surface preparation and surrounding atmosphere. Moreover, very few observations of surface crystal orientation were made on separately grown crystals. The aim of our project is to advance the basic understanding of oriented surface crystallization, e.g. whether preferred orientation of surface crystals results from oriented nucleation or reorientation mechanisms during early crystal growth. In both cases, crystal orientation may reflect the orientation of the glass surface or that of anisotropic active surface nucleation sites. Therefore, we focus on orientation of surface crystals separately growing under controlled conditions. First results on diopside (MgCaSi2O6) and walstromite (BaCa2Si3O9) crystals growing from 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glass surfaces, respectively, indicate that different orientation mechanisms may occur. Neighbored walstromite crystals were found to gradually reorient themselves when they are going to impinge each other during stepwise isothermal treatments (log η = 4,5 Pa*s) of polished glass samples. Nevertheless, no preferred crystal orientation was evident for separate crystals. For diopside crystals growing from polished glass surfaces (1 μm diamond lapping foil), strong preferred orientation was observed for 3.5 to 85 min annealing at 850 °C. Electron Backscatter Diffraction (EBSD) studies showed that the c-axis of surface crystals is oriented parallel to the glass surface and that separated diopside crystals as small as 600 nm are already oriented. Studies on glass surfaces, polished with diamond lapping foils starting from 16 μm down to 1 μm grain, revealed that crystal orientation may scatter arround this preferential orientation and that this scatter progressively decreases with decreasing polishing grain size. T2 - 93rd Annual Meeting of the German Society of Glass Technology (DGG) in conjunction with the French Union for Science and Glass Technology (USTV) Annual Meeting CY - Nuremberg, Germany DA - 13.05.2019 KW - Surface crystallization KW - Orientation KW - Glass KW - Diopside PY - 2019 AN - OPUS4-48198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Addressing ESC using FNCT enhanced by optical fracture surface analysis N2 - During their lifetime, polymer components subjected to mechanical loads and environmental influences show a loss of their mechanical properties required for their specific applications. In this respect, the craze-crack damage mechanism slow crack growth (SCG) is relevant for PE-HD components used in high-performance applications such as pipes and containers for the storage and transport of dangerous goods. SCG is considered to be the major failure mechanism in polyolefins and it typically occurs suddenly and unexpectedly. Due to the fields of application, SCG is a safety relevant issue. To test for the resistance of PE-HD pipe and container materials against SCG, the full-notch creep test (FNCT) is widely applied in Europe. In this study, SCG phenomena in PE-HD are investigated in detail based on an improved FNCT, especially including the consideration of the influence of environmental liquids effecting the damage mechanism. Using an enhanced fracture surface and a crack propagation analysis with imaging techniques such as light microscopy (LM), laser scanning microscopy (LSM), X-ray computed tomography (CT-scan) and scanning electron microscopy (SEM), detailed data concerning SCG are obtained. The combined application of FNCT and such imaging techniques is explicitly advantageous and recommended to gain important information on damage occurring to PE-HD induced by mechanical stress and the influence of environmental liquids, which is essential within the Fourth Industry Revolution. T2 - PPS Europe-Africa 2019 Regional Conference (PPS 2019) CY - Pretoria, South Africa DA - 18.11.2019 KW - Polyethylene, PE-HD KW - Full-Notch Creep Test (FNCT) KW - Fracture surface analysis KW - Slow crack growth KW - Environmental stress cracking KW - Laser Scanning Microscopy (LSM) KW - Scanning Electron Microscopy (SEM) PY - 2019 AN - OPUS4-50939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Popiela, Bartosz A1 - Trappe, Volker T1 - Damage Mechanisms of Scarf Joint Repairs for Wind Turbine Rotor Blade Shell Applications N2 - Wind turbine rotor blades, made of fiber reinforced polymers (FRP), often fail before their projected 20-year lifespan, largely due to defects that originate during manufacturing and are propagated by operational fatigue and environmental conditions. The cost-intensive replacement outcomes lead to a high loss of earnings, and are one of the inhibitors of wind turbine production [1]. A potential repair alternative is to locally patch these areas of the blades with adhesively bonded structural repairs. However, the effects of such repair methods of the outer shell region on the structural integrity of the rotor blades are still largely unknown, and are thus investigated in this project. The shell components of rotor blades are made of FRP composite material sandwiching a lightweight core, often a rigid foam or Balsa wood. The repair methods involve replacing the lost load path with a new material that is joined to the parent structure [2]. Repairs in this project focus on the scarf method, which allow for a smoother load distribution across the joint, aiming to study the damage mechanism of glass FRP scarf repairs for wind turbine blade shell applications. Namely, the source and path of the damage initiation and propagation, role of the interface between parent and patch material, and the role of the fiber orientation mismatch at this interface are examined. Biaxial ±45° and 0/90° FRP specimens are produced with the vacuum-assisted resin infusion (VARI) process using E-glass non-crimp fabric. The patch layers are then joined using VARI with a scarf ratio of 1:50, using glass FRP fabric with half the areal weight of the parent side to allow for better drapability. The methods and practices in specimen production are based on common industry practice in rotor blade shell manufacturing and repairs. The specimens are tested under uniaxial tensile load, during which they are periodically monitored for damage onset. A comparison of the ±45° and 0/90° specimens allows for an understanding of the role of a highly mismatching fiber orientation in the transition zone between parent and patch material on the failure mechanism of the scarf joint. Although failure in both orientations begins as delamination at the joint edge, the difference in the mechanisms at play in the two different specimen types leads ultimately to different fracture paths. Namely, in the inter fiber failure mechanism of the ±45° specimens, the higher interlaminar strength compared to the intralaminar strength of the laminate leads to intralaminar failure of the ±45° scarf joint specimens. Alternatively, the competition in the 0/90° specimens lies between the interlaminar strength and fiber failure strength, and here we experience failure primarily across the scarf joint length. The scarf joint in the 0/90° specimens disrupts the continuity of the load-carrying 0° layers, directing the failure path to remain primarily along the scarf joint. Experimental results are compared to finite element analyses of scarf patch repairs on glass FRP sandwich specimens with the same respective layup orientations, where the damage initiation regions are identified and correlated to fiber orientation, serving as a bridge to future work which will experimentally examine the scarf repair patches on sandwich shell specimens. T2 - Joint Event: ICCS23 - 23rd International Conference on Composite Structures & MECHCOMP6 - 6th International Conference on Mechanics of Composites CY - Online meeting DA - 01.09.2020 KW - Wind turbine blade shells KW - Glass fiber reinforced polymers KW - Scarf repairs PY - 2020 AN - OPUS4-51175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Sobek, P. A1 - Körner, S. A1 - Müller, Ralf T1 - Sintering of silver-alkali zinc borate glass composites N2 - High conductive silver-glass-metallization-pastes are key components in photovoltaics and advanced microelectronics. However, the underlying mechanisms of liquid phase sintering as silver dissolution, diffusion and reprecipitation are poorly understood so far. In the current work, the influence of different network modifier in alkali-zinc-borate paste-glasses on liquid phase sintering of silver-glass-composites was studied. Therefore, silver-glass-composites containing 30 vol% glass were prepared, using low melting X2O-ZnO-B2O3 glasses with X = Na, Li, and Rb (NZB, LZB, and RZB). Glass transition temperature, viscosity, glass-silver wetting, crystallization and sintering behavior was studied by means of thermal analysis, dilatometry, heating microscopy and microscopy. Similar glass transition temperatures of 450 °C (RZB), 460 °C (LZB) and 465 °C (NZB) were found by means of thermal analysis for glasses under study. Also, all glasses have a similar crystallization onset at about 550 °C, even though exhibiting with a different degree of crystallization. Despite these similarities, however, the sintering behavior, measured in terms of area shrinkage, significantly differs for the composites. This finding indicates a different degree of silver dissolution. Assuming that dissolved silver reduces the viscosity, this effect could explain why glass crystallization starts at lower temperature in the composites. For example, the crystallization peak of LZB at 629 °C measured for pure glass powder compacts was decreased to 586 °C for the composite. Confirmatively, microstructure analyses indicate different degrees of silver dissolution, as e.g. revealed by different amount of silver precipitates within the residual glass phase, and reprecipitation. Best silver dissolution appeared for the RZB glass. Nevertheless, the final densification of RZB was retarded probably due to swelling and crystallization. T2 - XRM Workshop CY - Halle, Germany DA - 03.03.2020 KW - Silver-glass-metallization-paste KW - Sintering KW - Alkali ions PY - 2020 AN - OPUS4-51243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Nielow, Dustin T1 - Fatigue loading of sandwich shell test specimens with simulated production imperfections and in-situ NDT N2 - A shell test bench was developed at BAM 5.3 which allows for static and fatigue testing of curved fiber-reinforced plastic (FRP) structures, during which in-situ the damage state can be non-destructively inspected by thermography and strain-field measurement techniques. Sandwich shell specimens with typical wind turbine blade manufacturing defects were designed and tested. The tested imperfections show a fairly significant reduction (up to 90%) of the shell test specimens‘ lifetime, depending on the type of imperfection. Using the in-situ NDT methods incorporated in the shell test bench, the location and cycle time of the initial defects and the damage evolution was investigated. T2 - 7. International Conference on Fatigue of Composites CY - Vicenza, Italy DA - 04.07.2018 KW - Fatigue of sandwich shell structures KW - Non-destructive testing KW - Wind turbine blades PY - 2018 AN - OPUS4-50126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Effective composite testing – from specimen size to component scale N2 - Even for the basic measurements of material data for design and engineering of composite structures there is a need to upgrade standards. With a new shear frame test rig more precise values can be obtained. With advanced methods in the research on the fatigue behaviour of FRP it was found a load level of infinite life for GFRP and CFRP. This is in the range of typical strain values of airliners and rotor blades in normal operation. Statistically the mean time between damage events on rotor blades is 6 years (Deutscher Windenergie Report 2006). Due to imperfection in the production the shell structures get cracks after a few years fare before the designed life time. A shell test rig was built at BAM for efficient research on the effects of defects in production. Test blades of ~10m are an efficient way for SHM research and evaluation of NDT-methods and blade geometry. T2 - colloquium genesis-puc CY - Rio de Janeiro, Brazil DA - 01.11.2019 KW - Polymer matrix composites KW - Nondestructive testing KW - New standards PY - 2019 AN - OPUS4-50129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Polymer matrix composites investigated with NDT at BAM N2 - Statistically the mean time between damage events on rotor blades is 6 years (Deutscher Windenergie Report 2006). Due to imperfection in the production the shell structures get cracks after a few years fare before the designed life time. A shell test rig was built at BAM for efficient research on the effects of defects in production. In-situ and ex-situ NDT give a better understanding from degradation processes in composite materials. With advanced methods in the research on the fatigue behaviour of FRP it was found a load level of infinite life for GFRP and CFRP. This is in the range of typical strain values of airliners and rotor blades in normal operation. Due to the fibre-composite nature NDT techniques have to be suitable to a wide length scale to image micro cracking as well as bigger defects. Therefore different techniques have to be applied and developed. T2 - Colloquium Abendi CY - São Paulo, Brazil DA - 05.11.2019 KW - Polymer matrix composites KW - Non-destructive testing PY - 2019 AN - OPUS4-50130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Fatigue life evaluation and certification according to CS22 N2 - The common fatigue life certification of aircrafts according to the certification Standards 23 and 25 follows a building block approach. Static tests at room temperature as well in humid and high temperature conditions are done on the coupon level. Additionally, a full-scale static and fatigue test must be performed on the complete airframe (minimum on the fuselage together with the wing). For each type-certificate the complete building block approach test program must be performed. Traditionally in Germany, the certification of sailplanes (Certification Standard 22) follows rather a family concept. A shared data base was created over the last 50 years based upon a large number of material testing. In addition to static tests at room temperature and hot-humid conditions, fatigue tests are also done on the coupon level. Additional static and fatigue tests were done on complex structures such as spar-beams, fuselages and full-scale wing structures. However, for each type-certificate, only static tests should be performed in full-scale. This concept is determined by the certification memorandum CM-S-006 “Composite Lightweight Aircraft” 2017. The presentation was given as an introduction to the discussion about the future expectations and developments of the EASA concerning the type-certification of lightweight aircrafts according to CS22 at the OSTIVE Sailplane Development Panel Meeting at the EASA in Cologne on the 11th of October 2019. T2 - OSTIV Sailplane Development Panel Meeting 2019, Europäische Agentur für Flugsicherheit (EASA) CY - Cologne, Germany DA - 11.10.2019 KW - Certification Standard 22 KW - EASA KW - Sailplane Development Panel KW - Fatigue Life Evaluation PY - 2019 AN - OPUS4-50147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Lüchtenborg, Jörg A1 - Lima, P. A1 - Diener, S. A1 - Katsikis, N. A1 - Günster, Jens T1 - Additive Manufacturing of Silicon Carbide by LSD-print N2 - The layerwise slurry deposition (LSD) has been established in the recent years as a method for the deposition of ceramic powder layers. The LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade; each layer is sequentially deposited and dried to achieve a highly packed powder layer. The combination of binder jetting and LSD was introduced as a novel technology named LSD-print. The LSD-print takes advantage of the speed of binder jetting to print large areas, parallel to the flexibility of the LSD, which allows the deposition of highly packed powder layers with a variety of ceramic materials. The working principle and history of the LSD technology will be shortly discussed. A theoretical background will be also discussed, highlighting advantages and drawbacks of the LSD compared to the deposition of a dry powder. The last part of the talk will be dedicated to highlight recent results on the LSD-print of SiSiC of geometrically complex components, in collaboration between BAM and HC Starck Ceramics GmbH. Density, microstructure and mechanical properties of LSD-printed and isostatic pressed samples will be discussed and compared. T2 - XVI ECerS CONFERENCE CY - Torino, Italy DA - 16.06.2019 KW - Additive Manufacturing KW - Silicon Carbide KW - 3D printing KW - Layerwise Slurry Deposition PY - 2019 AN - OPUS4-49220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zocca, Andrea A1 - Mühler, T. A1 - Lima, P. A1 - Günster, Jens A1 - Lüchtenborg, Jörg T1 - Advanced ceramics by powder bed 3D printing N2 - Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. However, the flowability of the powder used in these processes is essential to achieve defect-free and densely packed powder layers. For standard powder bed AM technologies, this limits the use of many raw materials which are too fine or too cohesive. This presentation will discuss the possibilities to either optimize the powder raw material to adapt it to the specific AM process, or to develop novel AM technologies which are able to process powders in a wider range of conditions. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of very fine ceramic particles. T2 - Smart Made CY - Osaka, Japan DA - 01.09.2019 KW - Additive Manufacturing KW - Ceramic KW - Powder KW - Layerwise slurry deposition KW - 3D printing PY - 2019 AN - OPUS4-49221 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Balzer, R. A1 - Kiefer, P. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Subcritical crack growth in hydrous silicate glass N2 - Ambient water influences sub-critical crack growth (SCCG) from microscopic surface flaws, leading to stress corrosion at the crack tip. The complex influence of humidity accelerating slow crack propagation (region I) is well studied only for dry commercial NCS glass (< 1000 ppm water). To shed light on this influence, the effect of water is mimicked by studying SCCG water-bearing glasses. For this purpose, water-bearing silicate glasses of 8 wt% total water were synthesized at 0.5 GPa and compared to dry glasses. SCCG was measured in double cantilever beam geometry. For dry glasses, 3 trends in crack velocity vs. stress intensity, KI, curve were found. The slope in region I increases in the order NCS < NBS < BaCS < NZnS < NAS glass. The velocity range of region II, reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among these glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam0.5. For hydrous glasses, it is found that water strongly decreases Tg, form a new sub-Tg internal friction peak caused by molecular water, and makes the glasses more prone to SCCG. The observed trends will be discussed in terms of the effects of Youngs Modulus on the strain energy release rate and energy dissipation related to mechanical glass relaxation phenomena. T2 - 25th International Congress on Glass (ICG2019) CY - Boston, MA, USA DA - 09.06.2019 KW - Internal friction KW - Soda-lime silicate glass KW - Crack growth KW - Water content KW - DCB PY - 2019 AN - OPUS4-49536 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kiefer, P. A1 - Deubener, J. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Behrens, H. A1 - Balzer, R. T1 - Density, microhardness and elastic moduli of hydrous soda-lime silicate glasses N2 - The effect of structural water on density, elastic constants and microhardness of water-bearing soda-lime-silica glasses of up to 21.5 mol% total water is studied. T2 - 25th International Congress on Glass (ICG2019) CY - Boston, MA, USA DA - 09.06.2019 KW - Elastic constants KW - Soda-lime-silica glass KW - Water content KW - Microhardness PY - 2019 AN - OPUS4-49537 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir A1 - Falkenberg, Rainer A1 - Skrotzki, Birgit A1 - Ávila, Luis A1 - Sommer, Konstantin T1 - Virtual-lab-based determination of a macroscopic yield function for additively manufactured parts N2 - This work aims for an yield function description of additively manufactured (AM) parts of S316L steel at the continuum-mechanical macro-scale by means of so-called virtual experiments using a crystal plasticity (CP) model at meso-scale. Additively manufactured parts require the consideration of the specific process-related microstructure, which prevents this material to be macroscopically treated as isotropic, because of crystallographic as well as topological textures. EBSD/CT-Scans from in-house additively manufactured specimen extract the unique microstructural topology which is converted to a representative volume element (RVE) with grain structure and crystal orientations. Crystal plasticity model parameters on this RVE are calibrated and validated by means of mechanical testing under different texture angles. From virtual experiments on this RVE, yield loci under various loading conditions are simulated. The scale bridging from meso- to macro-scale is realised by the identification of the simulated yield loci as a modified anisotropic Barlat-type yield model representation. T2 - The First European Conference on Structural Integrity of Additively Manufactured Materials (ESIAM19) CY - Trondheim, Norway DA - 09.09.2019 KW - Virtual experiments KW - Additive manufacturing KW - Anisotropy KW - Crystal plasticity KW - Scale-bridging PY - 2019 AN - OPUS4-49376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan T1 - Glass N2 - Überblick über die Arbeitsschwerpunkte des Fachbereichs 5.6 Glas und die Vielfalt des Werkstoffs Glas. An Hand der Vakuumheißgasextraktion (VHE) werden einige Beispiele u.a. zur Bestimmung des Wassergehalts oder des Diffusionskoeffizienten von Wasserstoff in Gläsern gezeigt. Zum Schluss erfolgt ein Ausblick auf die im nächsten Jahr zur Verfügung stehende robotergestützte Glasscreening Anlage. N2 - Overview about the key activities of division 5.6 glass and the diversity of the material glass. For the vacuum hot extraction method (VHE-MS) some examples are presented e. g. for the measurement of water content or the determination of diffusion coefficient of hydrogen in glasses. Finally, an outlook is shown on the robot controlled glass screening device which will be available next year. T2 - BAM - IFW Workshop CY - Berlin, Germany DA - 25.11.2019 KW - Glass KW - Glass screening device KW - Vacuum hot extraction PY - 2019 AN - OPUS4-50452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane T1 - Applied Crystallography as a tool for a better understanding of Fundamental Questions of high temperature corrosion phenomena N2 - Corrosion Science Meets X-Rays, Neutrons and Electrons. The presentation gives an overview on current research activities applying in-situ X-ray diffraction and spectroscopy for a better understanding of fundamental mechanisms of high temperature corrosion. Additionally the knowledge gain by applying neutron powder diffraction and EBSD analysis is presented. T2 - Joint meeting of german and polish crystallographic association 2020 CY - Wroclaw, Poland DA - 24.02.2020 KW - Corrosion KW - Oxidation KW - In situ KW - Diffraction PY - 2020 AN - OPUS4-50483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glass Sintering with Concurrent Crystallization and Foaming N2 - Glass powders are promising candidates for manufacturing a broad diversity of sintered materials like sintered ¬glass-ceramics, glass matrix composites or glass bonded ceramics with tailored mechanical, thermal, electrical and optical properties and complex shape. Its wide and precise adjustability makes this class of materials a key component for advanced technologies. Processing of glass or composite powders often allow even more flexibility in materials design. At the same time, however, processing can have substantial effects on the glass powder surface and sinterability. Thus, mechanical damage and surface contamination can strongly enhance surface crystallization, which may retard or even fully prevent densification. Whereas sintering and concurrent crystallization have been widely studied, partially as cooperative effort of the TC7 of the ICG, and although glass powder sintering is predominantly applied for glasses of low crystallization tendency, sintering is also limited by gas bubble formation or foaming. The latter phenomenon is much less understood and can occur even for slow crystallizing glass powders. The lecture illustrates possible consequences of glass powder processing on glass sintering, crystallization and foaming. T2 - 93rd Annual Meeting German Soc Glass Technol in conjunction with annual meeting French Union for Sci and Glass technol CY - Nuremberg, Germany DA - 13.05.2019 KW - Blähen KW - Glass KW - Kristallisation KW - Sintern PY - 2019 AN - OPUS4-50433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Vacuum hot extraction: Detection of volatiles N2 - Der Vortrag gibt einen Überblick über die Möglichkete und Grenzen der Methode der Vakuum-Heiß-Extraktion an der BAM T2 - Seminar Instrumentelle Analytik, Fakultät III Prozesswissenschaften, Lehrstuhl Keramik TU Berlin CY - Berlin, Germany DA - 25.01.2019 KW - Heißgasextraktion KW - Glas PY - 2019 AN - OPUS4-50434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Reinsch, Stefan T1 - Dynamic Mechanical Analysis (DMA): Viscoelasticity N2 - Der Vortrag gibt einen Überblick über die am FB 56 der BAM betriebene Dynamisch-Mechanische Analyse mit dem Schwerpunkt auf Anwendungen für Glas N2 - The talk presents an overview over the method of Dynamic Mechanical Analysis used at the BAM division 5.6 Glass mainly focussed on glasses. T2 - Seminar Instrumentelle Analytik, Fakultät III Prozesswissenschaften, Lehrstuhl Keramik TU Berlin CY - Berlin, Germany DA - 25.01.2019 KW - Dynamisch Mechanische Analyse KW - Dynamic mechanical analysis KW - Glas PY - 2019 AN - OPUS4-50436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Deubener, J. A1 - Müller, Ralf A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Behrens, H. A1 - Balzer, R. A1 - Bauer, U. A1 - Kiefer, P. T1 - Micromechanical properties of hydrous oxide glasses N2 - Presentation of the results on structure and mechanical properties of water-bearing oxide glasses, which were found during the project at the locations Clausthal, Hanover and Berlin within the priority program SPP1594. T2 - 9th Otto Schott Colloquium CY - Jena, Germany DA - 09.09.2019 KW - Crack growth KW - Glass KW - Water content KW - Mechanical properties KW - IR PY - 2019 AN - OPUS4-50444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Li, Wei T1 - Fatigue on carbon fiber reinforced composite under thermal cycling: Progress in the microscopic experiment 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. In this presentation, I summarized of the first 15 months the whole project. In this period, the basic crack propagation theory for neat polymers is established and the special fracture experiment sample is prepared and tested at room temperature. In addition, the model of the specimen is first established. T2 - Doktorandenseminar von Abteilung 5 CY - Berlin, Germany DA - 25.01.2019 KW - Crack Propagation KW - Polymer PY - 2019 AN - OPUS4-48473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane T1 - Unravelling high temperature oxidation phenomena by in situ x-ray techniques N2 - Unravelling high temperature oxidation phenomena by in situ x-ray techniques. A multi techqnique approach to study high temperature gas corrosion is presented. T2 - Gordon Research Conference on High Temperature Corrosion CY - New London, NH, USA DA - 20.07.2019 KW - Corrosion KW - High temperature KW - Diffraction KW - Spectroscopy PY - 2019 AN - OPUS4-48772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Ou, D. A1 - Ghafafian, Carineh A1 - Zscherpel, Uwe A1 - Trappe, Volker T1 - Wind turbine rotor blade testing by dual-energy laminography N2 - Modern wind turbine rotor blades consist of sandwich shell segments made from glass fiber reinforced polymers. During manufacturing, defects can arise which could lead to failure of the whole component under dynamic mechanical and thermal loads. Hence during operation defects can arise which, if detected, can be repaired locally and in-situ by applying repair patches instead of taking the whole rotor blade down and repair it remotely. This method is much more time and cost effective, since the shut-down time of the energy converter is limited to a minimum. These repair patches can, however, also lead to new defects if not applied optimally. Therefore, it is necessary to control the quality of the repair patches to ensure the best possible restoration of structural integrity of the component. As a rotor blade is an object with a large aspect ratio, X-ray laminography is predestined to provide 3D information of the objective volume. To enhance the amount of information gained from laminographic reconstruction, we use in this study a photon counting and energy discriminating X-ray detector and apply a material decomposition algorithm to the data. By inherently separating the incident spectra within the detection process into two distinct energy bins, the basis material decomposition can provide material resolved images. Choosing glass and epoxy resin as basis materials and numerically solving the inverse dual-energy equation system, the reconstructed laminographic datasets contain highly valuable information about the distribution of the basis materials within the structure. Furthermore, cross- artifacts arising from the limited angle of the projection data can be reduced by this method which allows to investigate structures that were hidden underneath the artefacts. T2 - 1st International Symposium on Photon Counting Technologies & Applications CY - München, Germany DA - 05.07.2019 KW - Laminography KW - Wind energy KW - Fiber reinforced polymer KW - Photon counting detector KW - Dual-energy PY - 2019 AN - OPUS4-48440 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Rabe, Torsten T1 - Design and fabrication of ceramic springs N2 - Ceramic springs offer versatile possibilities for load bearing or sensor applications in challenging environments. Although it may appear unexpected, a wide range of spring constants can be implemented by material selection and especially by the design of the spring. Based on a rectangular cross-section of the windings, it is possible to design a spring geometry that generates the desired spring constant simply by choosing appropriate diameter, height, widths, and number of windings. In a recent research project the calculation of helical compression springs made of rectangular steel (German standard DIN 2090) was applied for the design of ceramic springs. A manufacturing technology has been worked out to fabricate such springs from hollow cylinders of several highly dense technical ceramics by milling. Ceramic springs with precise rectangular section, without edge damage, and mean surface roughness smaller than 0.2 µm were produced after parameter optimization. Tolerances of less than 10 µm were achieved regarding spring diameter, height, and width of cross section. It is shown that the calculations outlined in the standard are valid for a variety of ceramic materials as well. Demonstrator springs with a wide range of spring constants have been fabricated, including zirconia springs with 0.02 N/mm, alumina springs with 1 N/mm and Si3N4 springs with 5 N/mm. A reproducibility study of six zirconia springs with a constant of 0.3 N/mm showed a relative difference in spring constants of less than +/- 1 %. This combination of a valid calculation approach for spring geometry and a reliable manufacturing technology allows for purposeful development and fabrication of ceramic springs with precise mechanical properties and superior chemical stability. T2 - EUROMAT 2019 CY - Stockholm, Sweden DA - 01.09.2019 KW - Ceramic spring KW - Hard machining KW - Spring constant PY - 2019 AN - OPUS4-48870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghafafian, Carineh A1 - Popiela, Bartosz A1 - Nielow, Dustin A1 - Trappe, Volker T1 - Restoration of structural integrity – Repairs for wind turbine blade shells N2 - Wind turbine rotor blade shells are manufactured as sandwich structures with fiber-reinforced polymer (FRP) due to the material’s high specific stiffness and strength. With a growing renewable energy industry and thereby a spread of wind energy farms, especially in offshore applications, the need to fully utilize turbines through their designed lifespan is becoming increasingly essential. However, due to imperfections during manufacturing, which are then propagated by harsh environmental conditions and a variety of loads, blades often fail before their projected lifespan. Thus, the need for localized repair patch methods for the outer shell portions of the blades has become of greater interest in recent years, as it is crucial to the optimal compromise between continuation of wind energy production, cost efficiency, and restoration of structural performance. To increase the understanding of the effect on the fatigue life of the rotor blades, this study tests localized repair patch methods and compares them to each other as well as to reference, non-repaired specimens. Manufactured with the vacuum-assisted resin infusion process, the shell test specimens are produced as a curved structure with glass FRP sandwiching a polyvinyl chloride foam core to best represent a portion of a rotor blade shell. Patch repairs are then introduced with varying layup techniques, and material properties are examined with cyclic fatigue tests. The intermediate scale test specimens allow for the observation of material as well as structural variables, namely of interest being the stiffness and strength restoration due to the repair patches. Damage onset, crack development, and eventual failure are monitored with in-situ non-destructive testing methods to develop a robust understanding of the effects of repair concepts. T2 - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures CY - Potsdam, Germany DA - 27.08.2019 KW - Wind turbine blade shells KW - Fiber reinforced polymers KW - Sandwich structures KW - Fatigue PY - 2019 AN - OPUS4-48859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Paulick, C. T1 - Development of ceramic helical springs for sensor applications N2 - At high temperatures and in harsh environments ceramic springs are often superior to metallic ones and allow for innovative solutions. A further application was proposed by using ceramic springs as capacitive force sensor. Lower and upper coil surfaces are coated by electrically conducting layers. Deformation of such spring results in a change of capacity. Sensor application calls for helical springs with rectangular cross-section, a linear stress-strain characteristic over entire deformation range and low manufacturing tolerances relating to inner and outer diameter, coil cross section and spring pitch. Furthermore, complex spring design with integrated connecting elements has to be realized. Alumina, zirconia (Y-TZP) and silicon nitride springs were produced by hard machining starting from sintered hollow cylinders. After external and internal cylindrical grinding the hollow cylinders were filled with hard wax, followed by multi-stage cutting of spring coils with custom-made cutting discs. Finally, hard wax was removed by melting and burnout. Best surface and edge qualities of springs were reached using Y-TZP material and hot isostatic pressed alumina. Y-TZP springs produced with material-specifically selected cutting discs and optimized process parameters show sharp coil edges without spallings and mean roughness values of inner surfaces < 0.2 μm. Manufacturing tolerances of spring diameters, spring pitch, height and width of coil cross section are in the range of ± 10 microns. Good reproducibility of spring geometry by optimized hard machining technology allows for production of Y-TZP springs with spring constants differing less than ± 1 % within a series. According to DIN 2090 spring constant for rectangular coil cross section is proportional to the square of height and width of coil cross section and indirectly proportional to number of active coils and to the cube of the mean spring diameter. Hence, spring constants can be tailored over a range of many orders of magnitude by changing the spring dimensions. Good agreement was reached between calculated target spring constants and measured values on produced springs. Alumina and zirconia springs were characterized relating to deformation behavior under dynamic compression load with various deformation speeds and under static tensile loads over long periods of time. Contrary to alumina springs, a non-linear stress-strain behavior of TZP springs was proved in both test series. It is supposed, that pseudoelasticity caused by stress-induced transformation of tetragonal to monoclinic phase is responsible for this special feature of TZP springs. Therefore, TZP material cannot be used for capacitive spring sensors. T2 - European Ceramic Society Conference (ECerS) CY - Torino, Italy DA - 16.06.2019 KW - Ceramic spring KW - Sensor KW - Spring constant KW - Failure test KW - Microstructure PY - 2019 AN - OPUS4-48610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian T1 - Obtaining, validating, and storing material parameters N2 - Several aspects of obtaining, validating, and storing material parameters are presented and discussed pertaining especially to calibration, inter-laboratory testing and statistical validation. T2 - 2019 Summer School Priotrity Program 1713 "Chemomechanics" CY - Ebernburg, Germamy DA - 06.05.2019 KW - Materials science KW - Calibration KW - Data storage PY - 2019 AN - OPUS4-48012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Kalinka, Gerhard T1 - Deformation behavior of alumina and zirconia springs at room temperature N2 - At high temperatures and in harsh environments ceramic springs are often superior to metallic springs and allow for innovative solutions. A recently proposed application involves ceramic springs with metallized surfaces as capacitive force sensor. A strictly linear stress-strain characteristic of the spring is a precondition for such a sensor. Helical ceramic springs with rectangular cross-section have been produced from sintered hollow cylinders. Alumina, ATZ, Y-TZP, and Ce-TZP springs with identical dimensions were characterized and compared regarding deformation behavior. Spring deformation was investigated under various load scenarios. Dynamic compression was performed with deformation speeds from 0.3 to 30 mm/min. Spring constants of alumina springs are strain rate independent. By contrast, Y-TZP spring constant increases by approximately 3 % within the experimental framework. A high-precision test facility was developed to characterize spring displacement in nm range under static tensile load over long periods of time. Spring elongation with asymptotic course was observed for zirconia containing materials at room temperature. This effect is particularly strong in the case of Y-TZP. Up to 0.3 % time-dependent elongation was measured after 24 h under constant load. Deformation is completely reversible after unloading. Alumina springs do not show any time-dependent deformation under identical test conditions. Contrary to alumina springs, a non-linear stress-strain behavior of TZP springs at room temperature was proved in both test series. It is supposed, that pseudo-elasticity caused by stress-induced phase transformation from tetragonal to monoclinic is responsible for this special behavior of TZP springs. T2 - D-A-CH Keramiktagung CY - Leoben, Austria DA - 06.05.2019 KW - Phase transformation KW - Ceramic spring KW - Force-distance diagram KW - Deformation behavior PY - 2019 AN - OPUS4-48026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Feldmann, Titus A1 - Charmi, Amir A1 - Epishin, A. T1 - Simulation of pore shrinkage with crystal plasticity and dislocation transport N2 - Single crystal superalloys usually contain pores of sizes 5-10 micro-m after casting and heat treatment. These pores can be reduced under compression by combined creep and diffusion in a subsequent treatment called Hot Isostatic Pressing (HIP). The paper presents a methodology to simulate pore shrinkage under HIP conditions in two dimensions (2D). At the scale of the pores, which is also the scale of the sub-grains (<50 micro-m) the dislocation sources cannot be assumed to be homogeneously distributed. Thus, the applicability of classical crystal plasticity is questionable. In this case, the transport of dislocations under an applied stress from the location where they are nucleated must be explicitly modelled. This is done by solving the transport equations for the dislocation densities and the elasticity equations in 2D. The dislocations are assumed to be nucleated at Low Angle Boundaries. They glide or climb through the sub-grains with a stress dependent velocity. The transport equations are solved by the Flux-Corrected Transport method, which belongs to the predictor-corrector class of algorithms. In the first step, an artificial diffusion is introduced, which suppresses spurious oscillations of the solution. In a second step, the solution is corrected in such a way that no additional extremes appear and that the extremes do not grow. The algorithm is validated by simulating the transport of simple distributions with a constant velocity field. With the dislocation velocities and the computed dislocation densities, the inelastic shear rate at the slip system level is computed by integrating the Orowan equation. In the 2D-setting, three slip systems are considered. The contributions of these slip systems are summed up to obtain the total inelastic strain rate. Dislocation glide and climb and the coupling of climb with vacancies diffusion are considered. The resolution of the equilibrium equations from the inelastic strains turned out to be prone to numerical instabilities. As an alternative, the stresses are directly computed from the distribution of geometrically necessary dislocations following the method presented in. The resulting boundary value problem is solved by the Least-Square Finite Element method. Examples of simulations are presented for a representative region under creep tension and for a pore shrinking under external pressure. T2 - International Conference on Material Modelling, ICMM 6 CY - Lund, Sweden DA - 26.06.2019 KW - Superalloy KW - Pores KW - Creep KW - Dislocations PY - 2019 AN - OPUS4-48488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Balzer, R. A1 - Kiefer, P. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Sub-critical crack growth in hydrous silicate glasses N2 - Environmental conditions are known to influence sub-critical crack growth (SCCG) that starts from microscopic flaws at the glass surface, leading to stress corrosion phenomena at the crack tip. The processes at the crack tip are complex and water has been identified as a key component governing SCCG at low crack velocities (region I). In particular, the influence of humidity accelerating crack propagation is well studied for dry industrial soda-lime silicate glasses (< 1000 ppm water). To shed light on this influence, the effect of water is mimicked by studying SCCG in water-bearing glasses. For this purpose, water-bearing silicate glasses of up to 8 wt% total water were synthesized in an internally heated pressure vessel at 0.5 GPa and compared to dry glasses. SCCG was measured using the double cantilever beam technique. For dry glasses, three trends in the crack growth velocity versus stress intensity, KI, curve were found. The slope in region I, limited by environmental corrosion, increases in the order soda-lime silicate < sodium borosilicate < barium calcium silicate < sodium zinc silicate < sodium aluminosilicate glass. The velocity range of region II, reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among these glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam1/2. For hydrous glasses, it is found that water strongly decreases Tg, form a new sub-Tg relaxation peak caused by molecular water, and makes the glasses more prone to SCCG. The observed trends will be discussed in terms of the effects of Youngs Modulus on strain energy release rate and energy dissipation related to glass relaxation phenomena. T2 - Glastechnische Tagung CY - Nürnberg, Germany DA - 13.05.2019 KW - Glass KW - Crack growth KW - DCB KW - Water speciation PY - 2019 AN - OPUS4-48339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker T1 - Composite materials - focus polymer matrix composites (PMC) N2 - Lecture about polymer matrix composites as part of the first trainings event GW4SHM, properties, production, basic theory, testing. T2 - 1. Training GW4SHM-Project CY - BAM, Berlin, Germany DA - 23.11.2020 KW - Polymer matrix composites KW - Composite testing KW - NDT PY - 2020 AN - OPUS4-51868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis Alexander T1 - Mechanical behaviour of AM metals: Creep of LPBF 316L and low-cycle-fatigue of LMD Ti-6Al-4V N2 - Additively manufactured metallic materials have already started to find application in safety-relevant components. However, this has only happened for certain materials and specific applications and loading conditions, since there is still an extensive lack of knowledge as well as of historical data regarding their mechanical behaviour. This contribution aims to address this lack of understanding and historical data concerning the creep behaviour of the austenitic stainless steel 316L manufactured by Laser-Powder-Bed-Fusion (L-PBF) and the low-cycle-fatigue behaviour of the titanium alloy Ti-6Al-4V manufactured by Laser-Metal-Deposition (LMD). Furthermore, it aims to assess their mechanical behaviour against their conventional counterparts. With that in mind, specimens from conventional and additive materials are tested and their mechanical behaviour analysed based on characteristic curves. To understand the damage behaviours the materials are characterized by destructive and non-destructive techniques before and after failure. T2 - 1st Workshop on In-situ Monitoring and Microstructure Development in Additive Manufacturing CY - Online Meeting DA - 10.12.2020 KW - Ti-6Al-4V KW - 316L KW - Additive manufacturing KW - Creep behaviour KW - Low-cycle-fatigue behaviour PY - 2020 AN - OPUS4-51879 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Orlov, N. K. A1 - Milkin, P. V. A1 - Evdokimov, P. A. A1 - Putlayev, V. I. A1 - Günster, Jens T1 - Sintering of sodium and potassium tcp based ceramic for bone grafting application N2 - Biomaterials for bone replacement and grafting should possess sufficient strength, be bioresorbable and demonstrate osteoconductive and osteoinductive properties. However, resorption of modern materials for bone grafting (hydroxyapatite (HA) and tricalcium phosphate (TCP)) is reported, in some cases, to be not enough, this is why the search for more soluble compounds compared to HA and TCP looks very perspective. A possible way to increase ceramics solubility leads to partial substitution of Ca2+ -ions in Ca3(PO4)2 by alkali cations, like Na+ or/and K+. Improvement of solubility stems from decreasing lattice energy of a substituted phase, as well as the increase in hydration energy of the ions releasing from the phase to ambient solution. From this viewpoint, bioceramics based on compositions from Ca3(PO4)2 - CaKPO4 - CaNaPO4 ternary system seems to be prospective for bone replacement and grafting in the sense of resorption properties. At the same time, one should bear in mind that solubility level (resorbability) is governed not only by reduction of lattice energy but also by microstructure features. Grain sizes and porosity contribute much to dissolution rate making the study of sintering of the ceramics mentioned above highly important. To control Ca3(PO4)2 - CaKPO4 - CaNaPO4 based ceramic microstructure it is necessary to know possible phase transformations in the system and the way to manage microstructure by sintering schedule or sintering process. In this work, an isothermal section for phase diagram of Ca3(PO4)2 - CaKPO4 - CaNaPO4 ternary system is studied with several techniques. According to the XRD of quenched samples, this phase triangle has four single-phase areas at 1200˚C (Figure 1). It was shown that single-phase CaK0.6Na0.4PO4 cannot be sintered to full-dense ceramics by conventional sintering regardless time-temperature schedule. Two-step sintering technique, beneficial in the case of HA-ceramics, was unsuccessful in all cases of calcium-alkali phosphate compositions. However, field-assisted sintering techniques like, e.g. Spark Plasma Sintering (SPS), can overcome this problem due to significant impact on grain boundary diffusion. In connection with this fact, grains grow much slower retaining sintering process in a pore control regime. In this work CaK0.6Na0.4PO4 low-porous ceramics was also fabricated by FAST-methods of sintering. Moreover, other alternative sintering techniques, such as reaction sintering, may be useful in accelerating ions diffusion but stopping excessive grain growth.Strength properties of ceramics were evaluated by B3B-testing, micro- and nanoindentation techniques. Fracture toughness also becomes higher with potassium content increase, guiding porosity level. Resorption properties of sintered ceramics were studied in different solutions with pH=5 and 7.4. Acknowledgements. The research of sintering processes in calcium phosphate materials were funded by RFBR according to the research project № 18-33-00974. T2 - XVI ECerS Conference 2019 CY - Turin, Italy DA - 16.06.2019 KW - Phase transformations KW - Bioceramics KW - Mixed Ca-K-Na phosphates KW - Na and K rhenanites KW - Phase diagram PY - 2019 AN - OPUS4-49622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Zocca, Andrea T1 - Dense Powder Beds for the Additive Manufacturing of Ceramics N2 - Many of the most successful and precise additive manufacturing (AM) technologies are based on the deposition layer-by-layer of a flowable powder. Since the first pioneering work at the end of the 1980th many developments have been introduced, greatly extending the use of different materials, improving the physical properties of the components built and enhancing the accuracy of the process. Still very important issues remain nowadays, hampering a completely autonomous production of parts and even restricting the freedom of design by means of these technologies. One of the major issues is the low density and stability of the parts during the building process, which implies the need of support structures: The powder bed surrounding the part has an essential role, since it should support the structure during building, until it’s ready for removal. Moreover, the microstructure of the powder bed is a template for the microstructure of the part produced. In this context, the use of submicron ceramic powders is still a challenge. Three approaches for the stabilization and densification of powder beds will be presented: The Layerwise Slurry Deposition process LSD, the gas flow assisted powder deposition and the Laser Induced Slipcasting (LIS) of ceramic powder compacts. T2 - 43rd International Conference and Exposition on Advanced Ceramics and Composites (ICACC 2019) CY - Daytona Beach, FL, USA DA - 27.01.2019 KW - Ceramics KW - Additive Manufacturing PY - 2019 AN - OPUS4-49627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens T1 - Powder-based Additive Manufacturing at Micro-Gravity N2 - Are we ready for putting a human footprint on Mars? Obviously, it is possible to send technologically challenging missions to our earth neighbors with a high level of complexity, such as enabling autonomous planetary mobility. As humanity contemplates mounting manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments safely working in space for years. Humans require water and air provided by complicated equipment. Its safe operation is a great challenge and implies being prepared for all eventualities. Instead of foreseeing and preparing for all possible scenarios of machine failures and accidents, it appears logic taking advantage of the flexibility of humans and providing essential equipment for the reaction on critical situations. The supply of spare parts for repair and replacement of lost equipment would be one key pillar of such a strategy. Bearing in mind the absolute distance and flight trajectories for manned missions to Mars, supplying spare parts from Earth is impossible. Thus, in space manufacturing remains the only option for a timely supply. With a high flexibility in design and the ability to manufacture ready to use components directly from a computer aided model, additive manufacturing technologies appear extremely attractive. For metal parts manufacturing the Laser Beam Melting process is the most widely used additive manufacturing process in industrial application. However, envisioning the handling of metal powders in the absence of gravitation is one prerequisite for its successful application in space. A gas flow throughout the powder bed has been successfully applied to compensate for missing gravitational forces in micro gravity experiments. The so-called Gas Flow Assisted Powder Deposition is based on a porous building platform acting as a filter for the fixation of metal particles in a gas flow driven by a pressure difference maintained by a vacuum pump. T2 - 1st Sino-German Workshop on 3D Printing in Space CY - Beijing, China DA - 20.02.2019 KW - Zero-g KW - Additive Manufacturing KW - µ-gravity PY - 2019 AN - OPUS4-49628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens T1 - Powder-based Additive Manufacturing at Micro-Gravity N2 - Are we ready for putting a human footprint on Mars? Obviously, it is possible to send technologically challenging missions to our earth neighbors with a high level of complexity, such as enabling autonomous planetary mobility. As humanity contemplates mounting manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments safely working in space for years. Humans require water and air provided by complicated equipment. Its safe operation is a great challenge and implies being prepared for all eventualities. Instead of foreseeing and preparing for all possible scenarios of machine failures and accidents, it appears logic taking advantage of the flexibility of humans and providing essential equipment for the reaction on critical situations. The supply of spare parts for repair and replacement of lost equipment would be one key pillar of such a strategy. Bearing in mind the absolute distance and flight trajectories for manned missions to Mars, supplying spare parts from Earth is impossible. Thus, in space manufacturing remains the only option for a timely supply. With a high flexibility in design and the ability to manufacture ready to use components directly from a computer aided model, additive manufacturing technologies appear extremely attractive. For metal parts manufacturing the Laser Beam Melting process is the most widely used additive manufacturing process in industrial application. However, envisioning the handling of metal powders in the absence of gravitation is one prerequisite for its successful application in space. A gas flow throughout the powder bed has been successfully applied to compensate for missing gravitational forces in micro gravity experiments. The so-called Gas Flow Assisted Powder Deposition is based on a porous building platform acting as a filter for the fixation of metal particles in a gas flow driven by a pressure difference maintained by a vacuum pump. T2 - 2nd Sino-German Workshop on 3D Printing in Space CY - Berlin, Germany DA - 28.10.2019 KW - µ-gravity KW - Additive Manufacturing KW - Zero-g PY - 2019 AN - OPUS4-49629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Mechanical anisotropy of additively manufactured stainless steel 316l: an experimental and numerical study N2 - This work aims for a yield function description of additively manufactured (AM) parts of stainless steel 316L at the continuum-mechanical macro-scale by means of so-called virtual experiments using a crystal plasticity model at meso-scale. T2 - 1st Workshop on In-situ Monitoring and Microstructure Development in Additive Manufacturing CY - BAM, Berlin DA - 10.12.2020 KW - Anisotropy KW - Crystal plasticity KW - Additive manufacturing PY - 2020 AN - OPUS4-51941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus T1 - Tensile Test: From Standard to PMD Application Ontology N2 - Data analysis methods play an important role in both the experimental and simulation-based digital description of materials but have so far been poorly structured. The platform Material Digital (PMD) should contribute to a standardized description of data processing methods in materials research. The goal is the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications. Therefore, application ontologies are created to explicitly describe processes and test methods. In this presentation, the first efforts in creating a tensile test application ontology in accordance with the ISO standard 6892-1:2019-11 are shown. Especially, the path of ontology development to be pursued based on standards was focused. T2 - Onboarding Workshop der Plattform Material Digital (PMD) CY - Online meeting DA - 13.04.2021 KW - Ontology KW - Platform MaterialDigital KW - PMD KW - Tensile Test KW - Normung KW - Standardization PY - 2021 AN - OPUS4-52425 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ganesh, Rahul A1 - Gesell, Stephan A1 - Kuna, M. A1 - Fedelich, Bernard A1 - Kiefer, B. T1 - Numerical calculation of ΔCTOD for thermomechanical fatigue crack growth N2 - The cyclic crack tip opening displacement ΔCTOD is a promising loading Parameter to quantify the crack propagation under thermomechanical fatigue (TMF). In this work, suitable techniques are investigated and compared for an accurate calculation of ΔCTOD under TMF loading using a viscoplastic temperature dependent material model. It turned out that collapsed special crack tip elements give the best results. An efficient FEM-technique is developed to simulate the incremental crack growth by successive remeshing, whereby the deformations and internal state variables are mapped from the old mesh onto the new one. The developed techniques are demonstrated and discussed for two-dimensional examples like TMF-specimens. Recommendations are made regarding important numerical control parameters like optimal size of crack tip elements, length of crack growth increment in relation to plastic zone size and ΔCTOD value. T2 - 53. Tagung des Arbeitskreises "Bruchmechanik und Bauteilsicherheit" CY - Online meeting DA - 18.02.2021 KW - Crack tip opening displacement KW - Thermomechanical fatigue KW - Crack growth PY - 2021 AN - OPUS4-52520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane T1 - Novel insights into high temperature corrosion phenomena by advanced X-ray methods N2 - A variety of materials of technological interest change their properties through contact with reactive media. Solid-gas reactions lead to a variety of reaction products on the surfaces and internal interfaces. The observation of nucleation and growth processes in the environment where they occur (in situ) from a chemical-structural perspective is especially challenging for aggressive atmospheres. The talk presents innovative approaches to study corrosion mechanisms using advanced X-ray methods. Using energy dispersive X-ray diffraction and X-ray absorption spectroscopy in different tailor made environmental reaction chambers, valuable insights into high temperature oxidation and sulfidation processes were gained. Fe-based alloys were exposed to hot and reactive atmospheres containing gases like SO2, H2O and O2 at 650°C. During the gas exposure the tailor made reaction chambers were connected to a high energy diffraction end station at the synchrotron. The crystallization and growth of oxide and sulfide reaction products at the alloy surfaces were monitored by collecting full diffraction pattern every minute. Careful examination of shape and intensity of phase-specific reflections enabled to a detailed view on growth kinetics. These studies showed, oxides are the first phases occurring immediately after experimental start. As soon as reactive gas media enter the chamber, the conditions change and different reaction products, such as sulfides start to grow. A comparison of different gas environments applied, illustrated the differences in the type of reaction products. The in situ observation of high temperature material degradation by corrosion made it possible to study the contribution of phases, which are not stable at room temperature. For instance, wuestite (Fe1-xO), was frequently observed at high temperatures in humid gases on Fe with 2 wt.% and 9 wt.% chromium, but not at room temperature. The strength of the occurrence of this phase additionally explains why, despite a higher Cr content, ferritic alloys with 9 wt.% Cr in a challenging atmosphere prevent the intrinsic formation of protective layers. The in situ observations were supplemented by careful considerations of thermodynamic boundary conditions and detailed post characterization by classical metallographic analysis. Additionally, the structure and chemistry of the dominant oxide layers were evaluated using X-ray absorption near edge structure spectroscopy. The talk will give an overview about chances and challenges for studying high temperature corrosion phenomena by advanced X-ray methods. T2 - MRS Spring Meeting CT08.02.01 CY - Online Meeting DA - 18.04.2021 KW - XRD KW - Spectroscopy KW - Corrosion KW - High temperature KW - In-situ PY - 2021 AN - OPUS4-52486 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick T1 - Modeling of the cooling behavior of thermoelectric multilayers N2 - Multilayered designs are an attractive approach towards cost-effective manufacturing of thermoelectric generators. Therefore, efforts are being made to co-fire two promising thermoelectric oxides, namely calcium cobaltite and calcium manganate. In this study, ceramic tapes, multilayer technology, and pressure-assisted sintering (PAS) were used. A major challenge for the PAS of low-sintered calcium manganate was cracking during cooling. A relationship between the properties of the release tape used during PAS and the cracking behavior was experimentally observed. To understand the origin of failure, reaction layers in the multilayer were analyzed and thermal stresses during cooling were estimated by finite element (FE) simulations. Thermal expansion, elastic properties, and biaxial strength of the thermoelectric oxides and selected reaction layers were determined on separately prepared bulk samples. The analysis showed that the reaction layers were not the cause for cracking of calcium manganate. Using the FE model, thermal stresses in different manganate multilayer designs with varying properties of the release tape were studied. The FEM study indicated, and a validation experiment proved that the thickness of the release tape has the main effect on thermal stresses during cooling in separately sintered calcium manganate. T2 - Keramik 2021 / Ceramics 2021 CY - Online Meeting DA - 19.04.2021 KW - Fem KW - Thermoelectric KW - Pressure assisted sintering PY - 2021 AN - OPUS4-52489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Sample Preparation of Nano-Powders for Particle Size Determination N2 - The use of increasingly finer starting powders up to nanopowders can also be observed in the field of ceramics. Their advantages consist, for example, in their lower activation energy, an increase in strength or unique optical properties. However, handling and characterization of the powders are much more difficult. The main reason for this is the very high adhesive forces between the particles and between particles and other surfaces, too. Therefore, submicron and even more so nanoparticles tend to agglomerate and their separation into primary particles during sample preparation prior to particle sizing is of particular challenge. A representative measurement sample is only obtained when it no longer contains agglomerates. The evaluation of the dispersion process and a decision on whether it was successful thus increases in importance for the reliability of the measurement results of particle sizing. The presentation uses examples to show possible approaches and provides information on possible sources of error. It is shown that successful granulometric characterisation of fine powders requires both an improved dispersion technique and very often an effective combination of two or more measurement methods. T2 - 96. Jahrestagung der Deutschen Keramischen Gesellschaft CY - Online Meeting DA - 19.04.2021 KW - Agglomerates KW - Nano-powder KW - Dispersion process PY - 2021 AN - OPUS4-52503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abel, Andreas A1 - Zapala, P. A1 - Michels, H. A1 - Skrotzki, Birgit T1 - Microstructural evolution of Fe-26Al-4Mo-0.5Ti-1B with varying wall thicknesses N2 - With an increasing demand in more efficient fuel consumption to reduce CO2 emissions, weight reductions in high-temperature materials at affordable costs gain increasing attention. One potential candidate is the intermetallic material class of iron aluminides, combining the advantages in mass savings, high temperature performance and recyclability of resources. The alloy Fe-26Al-4Mo-0.5Ti-1B was selected to study the microstructural features evolving from two casting processes, five wall thicknesses and three final conditions. Conclusions are drawn upon the correlations of processing variables, grain sizes and hardness. T2 - DGM Fachausschuss "Intermetallische Phasen" CY - Online meeting DA - 09.02.2021 KW - Intermetallics KW - Iron aluminides KW - Fe-Al alloys KW - Wall thickness KW - Microstructure PY - 2021 AN - OPUS4-52288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -