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 - Grun, Benthe Birger A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit A1 - Avila, Luis A1 - Charmi, Amir T1 - Charakterisierung von Hochtemperaturwerkstoffen durch Zug- und Ermüdungsversuche an Kleinproben N2 - Die Verwendung von miniaturisierten Probengeometrien in der mechanischen Prüfung ermöglicht die Entnahme des Probenmaterials direkt aus kritischen Bereichen wie Fügeverbindungen und ermöglicht die Prüfung von kleinen Bauteilen wie additiv gefertigten Strukturen. In der vorliegenden Arbeit werden exemplarisch die Ergebnisse von vergleichenden Zug- und niederzyklischen Schwingversuchen (LCF) an dem austenitischen Stahl AISI 316L und der Nickelbasislegierung IN718 vorgestellt. Die Prüfergebnisse der Kleinproben aus AISI 316L weisen die charakteristischen Eigenschaften des Werkstoffs auf, und die Analyse der Zug- und Ermüdungsdaten führt zu Werten, die den Literaturdaten weitgehend entsprechen. Der direkte Vergleich mit Standardprobendaten zeigt jedoch systematische Abweichungen bei Zugfestigkeit, Dehngrenze und Gleichmaßdehnung, die in diesem Beitrag diskutiert werden. T2 - Werkstoffprüfung 2019 CY - Neu-Ulm, Germany DA - 03.12.2019 KW - Kleinprobenprüfung KW - Probengrößeneffekt KW - Low Cycle Fatigue KW - Zugversuch KW - AISI 316L KW - IN 718 PY - 2019 AN - OPUS4-50221 LA - deu 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 - Faserkunststoffverbunde (FKV) in Forschung und Anwendung N2 - Der Fachbereich Mechanik der Polymerwerkstoffe befasst sich mit der Charakterisierung der mechanischen Eigenschaften und der Degradation von Polymeren und Faserverbundwerkstoffen, die in hochbeanspruchten, sicherheitsrelevanten Konstruktionen wie jenen des Flugzeugbaus, des Automobilbaus und der Windenergie-Industrie eingesetzt werden. Auch die Analyse der chemischen und physikalischen Eigenschaften von Polymeren zählt zu unserem Aufgabenbereich. Das Spektrum reicht von der statischen Festigkeit über die Betriebsfestigkeit, die Messung bruchmechanischer und viskoelastischer Parameter bis hin zur Formulierung molekularer Schädigungsmechanismen. T2 - VDI Arbeitskreis Kunststofftechnik, BAM, Unter den Eichen 87 CY - Berlin, Germany DA - 14.08.2019 KW - Faserkunststoffverbunde KW - Werkstoffprüfung KW - Normung PY - 2019 AN - OPUS4-50128 LA - mul 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 -