TY - CONF A1 - Trappe, Volker A1 - Sachs, Patrick ED - Vassilopoulos, A. P. ED - Michaud, V. 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 OMA and, based on a linear viscoelastic approach, the storage modulus (E';G'), the loss modulus (E'';G'') and the loss angle tan(δ) 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 CY - Lausanne, Switzerland DA - 26.06.2022 KW - Cross linking KW - Dynamic mechanical analysis (DMA) KW - Thermoset polymers KW - Cure process PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569651 UR - https://infoscience.epfl.ch/record/298799 SN - 978-2-9701614-0-0 VL - Vol. 5 - Applications and structures SP - 181 EP - 186 PB - Composite Construction Laboratory (CCLab) CY - Lausanne AN - OPUS4-56965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Azevedo do Nascimento, A. A1 - Trappe, Volker A1 - Diniz Melo, J. D. A1 - Cysne Barbosa, A. P. T1 - Fatigue behavior of self-healing glass fiber/epoxy composites with addition of poly (ethylene-co-methacrylic acid) (EMAA) N2 - The interest in repair technologies for polymer composites has increased significantly over the last decades, due to the growing use of these materials in structural applications. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was used as self-healing agent to glass fiber/epoxy composite. Materials with EMAA contents of 2 wt% and 5 wt% were manufactured using Resin Transfer Molding (RTM) and the effects of the healing agent on the properties were investigated using tensile tests and Dynamic Mechanical Analysis (DMA). Results show slight variation of properties, which was more pronounced as the content of EMAA increased. In addition, the healing efficiency was investigated through fatigue tests and the addition of higher content of EMAA increased the number of cycles to failure after the healing activation cycle. KW - Fatigue KW - Glass fiber-epoxy composites KW - Self-healing KW - Smart materials PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569661 DO - https://doi.org/10.1016/j.polymertesting.2022.107863 SN - 0142-9418 VL - 117 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-56966 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lunkenheimer, P. A1 - Loidl, A. A1 - Riechers, Birte A1 - Zaccone, A. A1 - Samwer, K. T1 - Thermal expansion and the glass transition N2 - Melting is well understood in terms of the Lindemann criterion, which essentially states that crystalline materials melt when the thermal vibrationsof their atoms become so vigorous that they shake themselves free of the binding forces. This picture does not necessarily have to hold for glasses, where the nature of the solid–liquid cross-over is highly debated. The Lindemann criterion implies that the thermal expansion coefficients of crystals are inversely proportional to their melting temperatures. Here we find that, in contrast, the thermal expansion coefficient of glasses decreases more strongly with increasing glass temperature, which marks the liquid–solid cross-over in this material class. However, this proportionality returns when the thermal expansion coefficient is scaled by the fragility, a measure of particle cooperativity. Therefore, for a glass to become liquid, it is not sufficient to simply overcome the interparticle binding energies. Instead, more energy must be invested to break up the typical cooperative particle network that is common to glassy materials. The thermal expansion coefficient of the liquid phase reveals similar anomalous behaviour and is universally enhanced by a constant factor of approximately 3. These universalities allow the estimation of glass temperatures from thermal expansion and vice versa. KW - Glass transition KW - Lindemann criterion KW - Thermal expansion KW - Glass PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570267 DO - https://doi.org/10.1038/s41567-022-01920-5 SN - 1745-2473 SP - 1 EP - 7 PB - Nature Publishing Group CY - London AN - OPUS4-57026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Malakhov, A. A1 - Epishin, A. A1 - Denisov, I. A1 - Saikov, I. A1 - Nolze, Gert T1 - Morphology and Structure of Brass–Invar Weld Interface after Explosive Welding N2 - This paper presents the results of a study of the morphology and structure at the weld interface in a brass–Invar bimetal, which belongs to the class of so-called thermostatic bimetals, or thermobimetals. The structure of the brass–Invar weld interface was analyzed using optical microscopy and scanning electron microscopy (SEM), with the use of energy-dispersive X-ray (EDX) spectrometry and back-scattered electron diffraction (BSE) to identify the phases. The distribution of the crystallographic orientation of the grains at the weld interface was obtained using an e-Flash HR electron back-scatter diffraction (EBSD) detector and a forward-scatter detector (FSD). The results of the study indicated that the weld interface had the wavy structure typical of explosive welding. The wave crests and troughs showed the presence of melted zones consisting of a disordered Cu–Zn–Fe–Ni solid solution and undissolved Invar particles. The pattern quality map showed that the structure of brass and Invar after explosive welding consisted of grains that were strongly elongated towards the area of the highest intensive plastic flow. In addition, numerous deformation twins, dislocation accumulations and shear bands were observed. Thus, based on the results of this study, the mechanism of Cu–Zn–Fe–Ni structure formation can be proposed. KW - Explosive welding KW - Thermobimetal KW - Grain structure KW - Brass KW - Invar PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565964 DO - https://doi.org/10.3390/ma15238587 SN - 1996-1944 VL - 15 IS - 23 SP - 1 EP - 10 PB - MDPI AN - OPUS4-56596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lemiasheuski, Anton A1 - Kranzmann, Axel A1 - Pfennig, Anja T1 - Herausforderungen und Möglichkeiten des manuellen metallografischen Serienschnittverfahrens anhand einer quantitativen Gefügeanalyse der Grafite eines Gusseisens T1 - Challenges and possibilities of the manual metallographic serial sectioning process using the example of a quantitative microstructural analysis of graphite in cast iron N2 - Die in dieser Studie vorgestellte 3D-Gefüge-Analyse konzentriert sich auf die Kugelgrafite eines Gusseisens des Typs EN-GJS. Es werden die Form anhand des Formfaktors und des Seitenverhältnisses sowie die durchschnittliche Teilchengröße und -verteilung untersucht. Die Form der Grafite in Gusseisenwerkstoffen ist mitentscheidend für die mechanischen Eigenschaften dieser Legierungen und ist bei der Charakterisierung des Werkstoffs unumgänglich. Mittels Metallografischen Serienschnittverfahrens wird von dem Schicht für Schicht abgetragenen und lichtmikroskopisch schichtweise dargestellten Werkstoff ein digitaler Zwilling erstellt. Von diesem dreidimensionalen Zwilling lassen sich beliebige Ebenen digital projizieren und analysieren. Eine konventionelle quantitative 3D-Analyse untersucht die Voxelmenge und -zusammensetzung eines Körpers im 3D-Raum. Die hier vorgestellte Analyse wendet stereologische 2D-Analyseverfahren auf drei Raumebenen des Werkstoffs an. Dabei sind zwei der Ebenen digitale Projektionen des Zwillings. Die zwei rekonstruierten Ebenen des Werkstoffs sind so gewählt, dass die Richtungsvektoren aller drei Ebenen einen 90°-Winkel zueinander bilden. Diese Methodik wird eingehend beschrieben sowie Herausforderungen und Möglichkeiten des hier vorgestellten Serienschnittverfahrens diskutiert. N2 - The 3D microstructure analysis presented in this study focuses on the nodular graphite of an EN-GJS grade cast iron. The shape is analyzed based on shape factor and aspect ratio as well as average particle size and distribution. The shape of graphites in cast iron materials is critical to the mechanical properties of these alloys and is essential for the characterization of the material. Metallographic serial sectioning creates a digital twin of the material, which is removed layer by layer and visualized layer by layer under an optical microscope. From this three-dimensional twin, any number of planes can be digitally projected and analyzed. Conventional quantitative 3D analysis examines the voxel count and composition of a body in 3D space. The analysis presented here applies stereological 2D analysis methods to three spatial planes of the material. Two of the planes are digital projections of the twin. The two reconstructed planes of the material are chosen so that the direction vectors of all three planes form an angle of 90° to each other. The methodology is described in detail and the challenges and opportunities of the serial section method presented here are discussed. KW - Dreidimensionale Gefügeanalyse KW - Three-dimensional microstructure analysis KW - 3D-Metallografie KW - Serienschnittverfahren KW - Gefügerekonstruktion KW - Quantitative Gefügeanalyse KW - 3D metallography KW - Serial sectioning KW - Microstructure reconstruction KW - Quantitative microstructure analysis PY - 2024 DO - https://doi.org/10.1515/pm-2024-0066 SN - 0032-678X VL - 61 IS - 9-10 SP - 746 EP - 768 PB - De Gruyter CY - Berlin/Boston AN - OPUS4-60976 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bacurau, V. P. A1 - Moreira, P. A. F. P. A1 - Bertoli, G. A1 - Andreoli, A. F. A1 - Mazzer, E. A1 - de Assis, F. F. A1 - Gargarella, P. A1 - Koga, G. A1 - Stumpf, G. C. A1 - Figueroa, S. J. A. A1 - Widom, M. A1 - Kaufman, M. A1 - Fantin, Andrea A1 - Cao, Y. A1 - Freitas, R. A1 - Miracle, D. A1 - Coury, F. G. T1 - Comprehensive analysis of ordering in CoCrNi and CrNi2 alloys N2 - Chemical Short-Range Order (CSRO) has attracted recent attention from many researchers, creating intense debates about its impact on material properties. The challenges lie in confirming and quantifying CSRO, as its detection proves exceptionally demanding, contributing to conflicting data in the literature regarding its true effects on mechanical properties. Our work uses highprecision calorimetric data to unambiguously prove the existence and, coupled with atomistic simulations, quantify the type of CSRO. This methodology allows us to propose a mechanism for its formation and destruction based on the heat evolution during thermal analysis and facilitates a precise identification of local ordering in CoCrNi alloys. Samples of CoCrNi (Co33Cr33Ni33) and CrNi2 (Cr33Ni66) alloys are fabricated in varying ordered states, extensively characterized via synchrotron X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. Samples with considerably different ordered states are submitted to tensile tests with in-situ synchrotron X-ray diffraction. We demonstrate, despite inducing varied CSRO levels in CoCrNi, no significant alterations in overall mechanical behavior emerge. However, the CrNi2 alloy, which undergoes long-range ordering, experiences significant shifts in yield strength, ultimate tensile stress and ductility. KW - Mechanical properties KW - Short-range ordering KW - Calorimetry PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611075 DO - https://doi.org/10.1038/s41467-024-52018-w VL - 15 IS - 1 SP - 1 EP - 11 PB - Springer Science and Business Media LLC AN - OPUS4-61107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaddam, Anuraag A1 - Galleani, Gustavo A1 - de Lima Reis, Vitor A1 - de Camargo, Andrea S. S. A1 - Eckert, Hellmut T1 - Structural characterization of gallium fluoride phosphate glasses by advanced solid‐state NMR methods and correlation with photophysical properties N2 - AbstractGallium fluoride phosphate glasses feature low refractive index, high energy radiation resistance, wide transmission range, and favorable emission characteristics of rare‐earth dopants. For the development of optimized glass compositions, a fundamental understanding of these properties in terms of glass structure is sought. We report nuclear magnetic resonance (NMR) structural studies of glasses in the system xGa(PO3)3–(40 − x)GaF3–20BaF2–20ZnF2–20SrF2 (x = 5, 10, 15, 20, and 25 mol%). 31P NMR results with 71Ga recoupling show that the network structure is dominated by P–O–Ga linkages, and no P–O–P linkages exist. 71Ga NMR results show that Ga is mainly six‐coordinated featuring a mixed fluoride/phosphate coordination. Quantitative estimates of this ligand distribution around gallium were obtained by 71Ga{31P} spin echo double resonance (REDOR) measurements. Photophysical properties suggest changes in the Eu(III) ligand distribution toward a fluoride‐dominated environment at low P/F ratio while the glass network is largely sustained by bridging oxygen atoms via P–O–Ga linkages. KW - Gallium KW - Glass KW - NMR KW - Oxyfluoride PY - 2024 DO - https://doi.org/10.1111/jace.20051 SN - 0002-7820 SP - 1 EP - 14 PB - Wiley AN - OPUS4-60785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Merízio, Leonnam Gotardo A1 - Machado, Ian Pompermayer A1 - Vastamäki, Roosa A1 - de Camargo, Andréa Simone Stucchi A1 - Lastusaari, Mika T1 - Multifunctional persistent luminescent and photochromic hackmanite-based materials prepared by microwave-assisted solid-state synthesis N2 - Advanced optical materials inspired by natural minerals and non-toxic light elements, such as the Hackmanites (Na8Al6Si6O24(Cl,S)2), find vast possibilities of applications as they can simultaneously perform photochromism and persistent luminescence (PersL). In this work, we have explored a rapid and energy-efficient microwaveassisted (MASS) methodology for the synthesis of PersL and photochromic hackmanites. In addition, we have prepared hackmanite materials using a zeolite-free precursor to control the Na–Al–Si ratio and study its influence on the materials photoluminescent properties. The PersL hackmanites showed a white-bluish emission color, with up to 2 h of emission time. Zeolite-free photochromic materials were able to change the color from white to purple/blue efficiently with a few seconds of 254 nm excitation, but the usage of zeolite precursors enhanced the overall optical performance. Microwave synthesis times of 10–40 min were demonstrated to be optimal, as longer times boosted the formation of nepheline spurious phase, which decreases luminescence efficiency. In this way, the MASS method led to a reduction of reaction time up to 98 %, yielding hackmanite materials with similar photoluminescent or photochromic properties compared to those obtained by a 24 h conventional solid-state synthesis. This work represents a significant improvement toward coupling eco-friendly synthetic processes to eco-friendly solid-state materials for PersL illumination and PersL/photochromism optical marking. KW - Hackmanite KW - Persistent luminescence KW - Photochromism KW - Microwave-assisted synthesis PY - 2024 DO - https://doi.org/10.1016/j.optmat.2024.115826 SN - 0925-3467 VL - 155 SP - 1 EP - 13 PB - Elsevier B.V. AN - OPUS4-60787 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maaß, Robert T1 - Transitions from scale-free to scale-dependent fluctuations in plasticity N2 - Plastic deformation in crystals is mediated by the motion of line defects known as dislocations. For decades, dislocation activity has been treated as a homogeneous, smooth continuous process that relies on well-average quantities. However, it is now recognized that plasticity can be determined by long-range correlated and intermittent collective dislocation activity, known as avalanches. These abrupt plastic fluctuations often exhibit pure power-law scaling or truncated power-law scaling, which indicates at least some degree of scale-free dislocation behavior. Intriguingly, such statistical signatures can persist across scales exceeding those of the material’s microstructure, raising the question of what relationship there may be between structure and long-range correlated dislocation activity that underlie power-law scaling. In this talk, we address this question by highlighting examples in which a transition from scale-free to scale-dependent plastic deformation is observed either due to changing external testing conditions (stress-state or temperature) or by tuning the microstructure. In particular, we will focus on the details of the temperature-driven change, that demonstrates how scale-free intermittent flow in body-centered cubic Nb is progressively quenched out with decreasing temperature. The plastic response of Nb is shown to be bimodal across the studied temperature regime, with conventional thermally-activated smooth plastic flow coexisting with sporadic bursts controlled by athermal screw dislocation activity, thereby violating the classical notion of temperature-dependent screw dislocation motion at low temperatures. An abrupt increase of the athermal avalanche component is identified at the critical temperature of the material. We combine the experimental observations with 3D dislocation dynamics simulations, identify a possible origin to athermal screw activity, and discuss the co-existence scale-free and scale-dependent plasticity. T2 - Cairo Symposium on The Physics of Metal Plasticity CY - Cairo, Egypt DA - 05.09.2023 KW - Plastic deformation KW - Dislocations KW - Avalanches PY - 2023 AN - OPUS4-60648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Glauer, M. A1 - Schilling, Markus A1 - Stappel, M. T1 - A practical ontology development guide N2 - Knowledge representation is becoming increasingly important in view of the large amounts of data that are handled in the modern scientific landscape. Many of the domains that have most readily realised this problem and worked on potential solutions have been the domain of biochemistry. And although the developments sought here were not accompanied by philosophers, this process organically led to the development of formal and structured representations of certain domains. While the resulting structures were not the first formal ontologies, they are ones that are still in wide use to this day. These approaches have led to major advances in the organisation, structuring and communication of scientific results. Since then, a variety of other domains have tried to adapt a similar process and develop their own ontologies. However, the development of ontologies from the domain of biochemistry was the result of a years-long process that also involved a large number of errors and course corrections. One of the greatest challenges is also one of the greatest strengths of ontologies: Interoperability with other ontologies. To ensure this interoperability, ontologies must follow certain principles. In the field of biochemistry, the OBO Foundry has established itself, which offers functionalities for a rich network of ontologies from the domain, but at the same time also defines rules. The purpose of this document is to define a similar set of rules for open ontology development, but which addresses a broader domain and at the same time lowers the barrier of entry for new ontology developers. To this end, we will outline a workflow that can be used to build new ontologies more efficiently. This workflow is based not only on our own years of experience in ontology development, but also on the rules of external experts such as the OBO Foundry. KW - Ontology KW - Data integration KW - Ontologie KW - Data interoperability PY - 2024 UR - https://scientific-ontology-network.github.io/ UR - https://github.com/scientific-ontology-network/ontology-development-guide/releases/download/v0.1.0/ontology-guide.pdf SP - 1 EP - 27 PB - GitHub CY - San Francisco ET - Version 0.1 AN - OPUS4-61140 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Birkholz, Henk A1 - Bayerlein, Bernd T1 - Evolution of the PMD Core Ontology (PMDco) Towards ISO/IEC 21838-2:2021 Basic Formal Ontology (BFO) N2 - Knowledge representation in the materials science and engineering (MSE) domain is a vast and multi-faceted challenge: Overlap, ambiguity, and inconsistency in terminology are common. Invariant and variant knowledge are difficult to align cross-domain. Generic top-level semantic terminology often is too abstract, while MSE domain terminology often is too specific. In this presentation, an approach how to maintain a comprehensive and intuitive MSE-centric terminology composing a mid-level ontology–the PMD Core Ontology (PMDco)–via MSE community-based curation procedures is shown. The PMDco is designed in direct support of the FAIR principles to address immediate needs of the global experts community and their requirements. The illustrated findings show how the PMDco bridges semantic gaps between high-level, MSE-specific, and other science domain semantics, how the PMDco lowers development and integration thresholds, and how to fuel it from real-world data sources ranging from manually conducted experiments and simulations as well as continuously automated industrial applications. T2 - MSE Congress 2024 - Materials Science and Engineering CY - Darmstadt, Germany DA - 24.09.2024 KW - Ontology KW - Semantic Interoperability KW - Knowledge representation KW - FAIR Data Management KW - PMD Core Ontology PY - 2024 AN - OPUS4-61141 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eisenbart, Miriam T1 - Digitalization of a high-throughput alloy development process N2 - Digitalization is nowadays the central key in developing pharmaceutical products, but it also becomes increasingly important in computer aided material development. In this work it is presented how a collaborative ontology development for the alloy development process is approached and a workflow for chemical optimization of copper alloys is introduced. This is done by employing a combination of a high-throughput alloy development method [1] with the calculation of the corresponding phase compositions. The work presented here is part of the publicly funded project KupferDigital. The project is associated with the innovation platform MaterialDigital (PMD) and focusses on the digitalization of processes as well as knowledge representation along the life-cycle of copper and copper alloys. One part of this life cycle is the alloy development of copper alloys, in this case the alloy development employing a high throughput method based on diffusion couples. The alloy development process can be further broken down into several typical material processing steps such as casting, diffusion welding and annealing. As part of the copper life cycle, the constitution and the properties of an alloy play an important role for processes further down the road during product manufacturing and service life and are also crucial for the recycling properties of the alloy. It is therefore important to, on the one hand, communicate data concerning properties, process history and constitution to the following stations of the life cycle, on the other hand, it is also elementary for the material scientist to be aware of the recycling properties of the alloys constituents. This motivates sharing of data along the life cycle and the development of ontology based data spaces, where life-cycle information can be linked across all involved domains. As part of the alloy development process, it is presented how experimental data created at fem are shared using linked data and ontologies with an example based on the digital representation of the chemical composition of copper alloys further processed by CALculation of PHAse Diagrams (CALPHAD) at the Fraunhofer IWM. The calculation results are used to correlate measured hardness data with the equilibrium phases of the alloys. Selected Compositions are cast and heat treated and subjected to mechanical testing at BAM and the resulting mechanical property-data are again linked to the measured and simulated data from the alloy development process. T2 - MSE2024 CY - Darmstadt, Germany DA - 24.09.2024 KW - Digitalization KW - Alloy development PY - 2024 AN - OPUS4-61150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick 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 - Bettge, Dirk A1 - Klinger, Christian T1 - Schadensanalyse an Fahrradkomponenten - Fraktographie, Ursachen, Prävention N2 - Komponenten von Fahrrädern werden im Betrieb vorwiegend schwingend beansprucht. Typische Werkstoffe sind Stahl, Aluminiumlegierungen, Messing, CFK und thermoplastische Kunststoffe. Da es sich, unabhängig von der Preiskategorie, um konstruktiven Leichtbau handelt, werden einige Bauteile betriebsfest mehr oder weniger weit oberhalb der Dauerfestigkeit ausgelegt. Die im normalen Betrieb auftretenden Schäden sind daher weit überwiegend Schwingbrüche. Andere Schadensmechanismen wie z.B. Korrosion spielen quantitativ eine untergeordnete Rolle. Schwingbrüche treten nach einer Periode unbemerkten Risswachstums oft ohne Vorwarnung und ohne makroskopische Verformung auf. Im Falle von sicherheitsrelevanten Komponenten wie Rahmen, Gabeln, Lenkern, Sattelstützen, Kurbelarmen oder Pedalen kann dies zu erheblichen Personenschäden führen, die den Wert des ursächlichen Bauteilschadens weit überschreiten. Über einen langjährigen Zeitraum wurden gebrochene Komponenten aus dem Alltag und aus Gerichtsverfahren analysiert. Das Hauptaugenmerk lag hierbei auf der fraktographischen Analyse, teilweise wurden die zu Grunde liegenden Schadensursachen ermittelt. Einflussfaktoren sind beispielsweise konstruktive Kerben an ungünstigen Stellen, aber auch Werkstoffwahl und Fertigungsqualität spielen eine Rolle. In den meisten Fällen wurde jedoch die konstruktive Lebensdauer überschritten. Diese wird praktisch nie mitgeteilt, und eine wiederkehrende Prüfung sicherheitsrelevanter Bauteile findet nicht statt. Im Sinne der Vermeidung von Schäden und Unfällen könnte darauf hingewirkt werden, für sicherheitsrelevante Komponenten Lebensdauern besser abzuschätzen und von der Laufleistung abhängige Sichtprüfungen zu empfehlen. T2 - DGM Tagung Werkstoffprüfung CY - Dresden, Germany DA - 26.10.2022 KW - Fraktographie KW - Fahrrad KW - Lebensdauer KW - Öffentliche Sicherheit KW - Schadensanalyse KW - Schadensprävention PY - 2022 AN - OPUS4-56122 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A.I. A1 - Nolze, Gert A1 - Alymov, M.I. T1 - Pore Morphology in Single Crystals of a Nickel-Based Superalloy After Hot Isostatic Pressing N2 - The morphology of pores partially shrunk during a half-hour HIP at temperature of 1288 °C and pressure of 103 MPa has been investigated in nickel-based superalloy CMSX-4. The investigation resulted in the following findings: surrounding the shrinking pores by a c¢-shell (Ni3Al), faceting of the pores surface by {023} and {011} planes, and formation the submicroscopic satellite pores connected by channels with the neighboring larger pores. It is assumed that the formation of the c¢-shell around the pores and the faceting of the pore surface is due to diffusion processes occurring during pore shrinkage, and therefore these findings can be considered as arguments supporting the vacancy model of pore annihilation. The submicroscopic satellite pores are expected to be the result of dividing the casting pores of a complex initial shape during their shrinking. The connecting channels are probably required for the gas to escape from the rapidly shrinking small satellite pores into the slowly shrinking large pore. Thus, it is reasonable to assume that the casting pores may contain some amount of gas. KW - HIP KW - Superalloy KW - Porosity KW - Faceting KW - negative crystal growth PY - 2022 DO - https://doi.org/10.1007/s11661-022-06893-x SN - 1073-5623 SP - 1 EP - 9 PB - Springer Nature AN - OPUS4-56409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Junge, P. A1 - Greinacher, M. A1 - Kober, D. A1 - Stargardt, Patrick A1 - Rupprecht, C. T1 - Metastable Phase Formation, Microstructure, and Dielectric Properties in Plasma-Sprayed Alumina Ceramic Coatings N2 - The need for new solutions for electrical insulation is growing due to the increased electrification in numerous industrial sectors, opening the door for innovation. Plasma spraying is a fast and efficient way to deposit various ceramics as electrical insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed ceramics in the coating industry since it exhibits good dielectric properties, high hardness, and high melting point, while still being cost-effective. Various parameters (e.g., feedstock type, spray distance, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, and metastable phase formation. Consequently, these parameters need to be investigated to estimate the impact on the dielectric properties of plasma-sprayed alumina coatings. In this work, alumina coatings with different spray distances have been prepared via atmospheric plasma spray (APS) on copper substrates. The microstructure, porosity, and corresponding phase formation have been analyzed with optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Moreover, we present an in-depth analysis of the fundamental dielectric properties e.g., direct current (DC) resistance, breakdown strength, dielectric loss tangent, and permittivity. Our results show that decreasing spray distance reduces the resistivity from 6.31 × 109 Ωm (130 mm) to 6.33 × 108 Ωm (70 mm), while at the same time enhances the formation of the metastable δ-Al2O3 phase. Furthermore, space charge polarization is determined as the main polarization mechanism at low frequencies. KW - Alumina KW - Plasma spray KW - Dielectric properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564394 DO - https://doi.org/10.3390/coatings12121847 SN - 2079-6412 VL - 12 SP - 1 EP - 15 PB - MDPI CY - Basel AN - OPUS4-56439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - GLAS DIGITAL - Datengetriebener Workflow für die beschleunigte Entwicklung von Glas N2 - Aktuelle Ergebnisse des Projektes GlasDigital werden kurz zusammenfassend und allgemein verständlich vorgestellt. T2 - MatFo 2022 CY - Cologne, Germany DA - 14.11.2022 KW - Oxidglas KW - robotische Glasschmelzanlage KW - Ontologie KW - ML KW - Digitaler Zwilling KW - Bildanalyse PY - 2022 AN - OPUS4-56492 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina T1 - Glas Digital Datengetriebener Workflow für die beschleunigte Entwicklung von Glas N2 - Der aktuelle Stand des Projektes GlasDigital wird in Kurzform präsentiert. T2 - PMD Vollversammlung CY - Online meeting DA - 17.03.2022 KW - Oxidglas KW - robotische Glasschmelzanlage KW - Ontologie KW - ML KW - Digitaler Zwilling KW - Bildanalyse PY - 2022 AN - OPUS4-56493 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nasr Esfahani, M. A1 - Zare Pakzad, S. A1 - Li, T. A1 - Li, X. A1 - Tasdemir, Z. A1 - Wollschläger, Nicole A1 - Leblebici, Y. A1 - Erdem Alaca, B. T1 - Effect of Native Oxide on Stress in Silicon Nanowires: Implications for Nanoelectromechanical Systems N2 - Understanding the origins of intrinsic stress in Si nanowires (NWs) is crucial for their successful utilization as transducer building blocks in next-generation, miniaturized sensors based on anoelectromechanical systems (NEMS). With their small size leading to ultrahigh-resonance frequencies and extreme surface-to-volume ratios, silicon NWs raise new opportunities regarding sensitivity, precision, and speed in both physical and biochemical sensing. With silicon optoelectromechanical properties strongly dependent on the level of NW intrinsic stress, various studies have been devoted to the measurement of such stresses generated, for example, as a result of harsh fabrication processes. However, due to enormous NW surface area, even the native oxide that is conventionally considered as a benign surface condition can cause significant stresses. To address this issue, a combination of nanomechanical characterization and atomistic simulation approaches is developed. Relying only on low-temperature processes, the fabrication approach yields monolithic NWs with optimum boundary conditions, where NWs and support architecture are etched within the same silicon crystal. Resulting NWs are characterized by transmission electron microscopy and micro-Raman spectroscopy. The interpretation of results is carried out through molecular dynamics simulations with ReaxFF potential facilitating the incorporation of humidity and temperature, thereby providing a close replica of the actual oxidation environment - in contrast to previous dry oxidation or self-limiting thermal oxidation studies. As a result, consensus on significant intrinsic tensile stresses on the order of 100 MPa to 1 GPa was achieved as a function of NW critical dimension and aspect ratio. The understanding developed herein regarding the role of native oxide played in the generation of NW intrinsic stresses is important for the design and development of silicon-based NEMS. KW - Nanoelectromechanical systems (NEMS) KW - Silicon nanowires KW - Native oxide KW - Intrinsic stress KW - Raman spectroscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560471 DO - https://doi.org/10.1021/acsanm.2c02983 SN - 2574-0970 VL - 5 SP - 13276 EP - 13285 PB - ACS Publ. CY - Washington, DC AN - OPUS4-56047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, M. A1 - Bettge, Dirk A1 - Hilgenberg, Kai A1 - Binder, M. A1 - Dollmeier, K. A1 - Dreyer, M. A1 - Klöden, B. A1 - Schlingmann, T. A1 - Schmidt, J. T1 - Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy T1 - Reproduzierbarkeit und Streuung bei der additiven Fertigung: Ergebnisse eines Ringversuchs mit einer PBF-LB/M AlSi10Mg-Legierung N2 - The round robin test investigated the reliability users can expect for AlSi10Mg additive manufactured specimens by laser powder bed fusion through examining powder quality, process parameter, microstructure defects, strength and fatigue. Besides for one outlier, expected static material properties could be found. Optical microstructure inspection was beneficial to determine true porosity and porosity types to explain the occurring scatter in properties. Fractographic analyses reveal that the fatigue crack propagation starts at the rough as-built surface for all specimens. Statistical analysis of the scatter in fatigue using statistical derived safety factors concludes that at a stress of 36.87 MPa the fatigue limit of 107 cycles could be reached for all specimen with a survival probability of 99.999 %. N2 - Im Rahmen eines Ringversuchs wurde durch die Untersuchung der Pulverqualität, der Prozessparameter, der Gefügefehler, der Festigkeit und der Ermüdung die Zuverlässigkeit bestimmt, die Nutzer von AlSi10Mg-Proben erwarten können, die mit pulverbettbasiertes Schmelzen mittels Laser (engl. Laser Powder Bed Fusion) gefertigt worden sind. Abgesehen von einem Ausreißer wurden die erwarteten statischen Materialeigenschaften erreicht. Eine optische Gefügeprüfung diente dazu, die tatsächliche Porosität und Arten von Porosität zu ermitteln, um die bei den Eigenschaften auftretende Streuung zu erklären. Fraktographische Unterschungen zeigen eine bei allen Proben von der rauen Oberfläche im As-built-Zustand ausgehende Ermüdungsrissausbreitung. Aus der statistischen Analyse der Streuung bezüglich der Ermüdung unter Anwendung von statistischen abgeleiteten Sicherheitsfaktoren geht hervor, dass alle Proben die Dauerfestigkeit von 107 Zyklen bei einer Spannung von 36,87 MPa mit einer Überlebenswahrscheinlichkeit von 99,999 % erreichten. KW - Additive manufacturing KW - Reproducibility KW - Reliability PY - 2022 DO - https://doi.org/10.1515/pm-2022-1018 SN - 2195-8599 VL - 59 IS - 10 SP - 580 EP - 614 PB - De Gruyter AN - OPUS4-55935 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -