TY - GEN A1 - Miah, Kamal Uddin Mohammad A1 - Kloshek, Alexander A1 - González-Castaño, Miriam A1 - Kehm, Christian A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Herstellen hocheffektiver Mikroreaktoren durch selektives Laserstrahlschmelzen T2 - DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vorträge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beiträge auf USB-Karte) N2 - Das pulverbasierte 3D-Metalldrucken ermöglicht die Fertigung von hochkomplexen Integralbauteilen, die als Trägerstruktur für Mikroreaktoren benutzt werden. Nach einer Beschichtung der Struktur mit einem Katalysatormaterial, können diese Mikroreaktoren höchst effizient für die CO2-Methanisierung eingesetzt werden. Durch die additive Fertigung mit dem selektiven Laserstrahlschmelzen (SLM) wurden adaptierte dreidimensionale periodische Gitterstrukturen mit sehr geringen Wandstärken hergestellt. Diese weisen ein sehr günstiges Verhältnis von Oberfläche zu Volumen (TPMS - Triply periodic minimal surface) auf. Des Weiteren zeigen die TPMS-Strukturen vorteilhafte Strömungseigenschaften, die sowohl für die Beschichtung mit dem Katalysator-Material als auch die Durchströmung mit den Reaktionsmedien im Betrieb essentiell sind. So ist es beispielsweise möglich, durch die Variation der Dimension einer TPMS-Struktur die Oberfläche pro Volumeneinheit, den hydraulischen Durchmesser des Reaktors und somit auch den Transportprozess des Fluids deutlich zu verbessern. Diese Faktoren ermöglichen eine effektivere Gas-Katalysator-Reaktion. Im Vergleich zu Mikroreaktorstrukturen aus den traditionellen Herstellungsverfahren liefern die additiv gefertigten Strukturen sowohl eine höhere CO2-Umwandlungsrate als auch eine CH4-Selektivität innerhalb des diffusionskontrollierten Bereichs. Y1 - 2022 SN - 978-3-96144-189-1 SP - 708 EP - 713 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Kotlarski, Georgi A1 - Ormanova, Maria A1 - Nikitin, Alexander A1 - Morozova, Iuliia A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Doynov, Nikolay A1 - Valkov, Stefan T1 - Structure Formation and Mechanical Properties of Wire Arc Additively Manufactured Al4043 (AlSi5) Components T2 - Metals N2 - In the current paper, the correlation between the physical size of additively built wire arc specimens and their structure and properties is studied. For the purpose of this work, two oval shaped specimens of different lengths were manufactured under the same technological conditions. The specimens have a length of 200 mm and 400 mm and will be referred to as L200 and L400. The microstructure of the samples was studied using X-ray diffraction analysis (XRD), optical microscopy, and scanning electron microscopy (SEM). The microhardness, yield strength (YS), and ultimate tensile strength (UTS) were determined and their correlation with the technological conditions of specimen build-up was clarified. The results of the carried out experiments indicated that the crystallographic structure of both specimens is similar. The scanning electron microscopy images show a higher concentration of irregularly shaped micro-pores formed near the edge of the αAl grains in the structure of the L400 specimen compared to the L200 one. An increase in the size of the αAl solid solution grains in the case of the L200 specimen towards its top section was noticed using optical microscopy. A slightly lower magnitude change was noticed concerning the L400 specimen. The increase in the size of the aluminum crystals was determined to be the increasing interpass temperature. Due to the much smaller thermal dissipation capacity of the smaller specimen, the interpass temperature of the same increased faster compared to the larger specimen. All of the above-mentioned factors led to a decrease in the microhardness of the specimens at higher stages of build-up. Since the specimens were deposited using similar layer deposition conditions, the resultant YS and UTS data are also highly comparable. KW - structure KW - morphology KW - hardness KW - tensile strength KW - defects formation KW - WAAM KW - AlSi5 KW - Al4043 KW - GMAW KW - cold arc pulse Y1 - 2024 U6 - https://doi.org/10.3390/met14020183 SN - 2075-4701 VL - 14 IS - 2 ER - TY - GEN A1 - Miah, Kamal Uddin Mohammad A1 - Kloshek, Alexander A1 - Ossenbrink, Ralf A1 - Seidlitz, Holger T1 - Selective Laser Melting of Pure Copper (Cu-ETP) T2 - 4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts N2 - The main objective of this study is to address the difficulties related to the production of highly dense parts utilizing pure Cu-ETP powder. In order to achieve this goal, the SLM machine was modified by replacing the regular infrared laser with a laser operating in the range of 530 to 534 nm. Following this modification, a detailed experiment was conducted to determine the most effective procedural parameters for producing solid components and gyroid structures of Cu-ETP. The study determined thtat in order to produce a part density of 99.6 ± 0.2%, the following parameters are required: a laser power of 130 ± 10 W, a scanning speed of 350 mm/s, and a layer thickness of 25 µm. The microscopic analysis on the SLM-manufactured components showed a consistent grain structure across the build parts. Furthermore, it was discovered that exceeding the predetermined laser power and scanning speed parameters led to lower density of the parts. Conversely, decreasing the laser power and scanning speed below these thresholds was determined to be economically disadvantageous. Y1 - 2024 UR - https://acmit.at/wp-content/uploads/2024/08/Additive-2024_Book-of-abstracts.pdf SN - 978-3-88355-440-2 SP - 19 PB - Deutsche Gesellschaft für Materialkunde (DGM) e.V. CY - Bremen, Berlin ER - TY - GEN A1 - Kehm, Christian A1 - Wasilewski, Eric A1 - Miah, Kamal Uddin Mohammad A1 - Ossenbrink, Ralf A1 - Seidlitz, Holger T1 - Effects of extended shielding gas coverage on component contour accuracy in Wire Arc Additive Manufacturing T2 - 4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts N2 - Producing near-net-shape components with Wire Arc Additive Manufacturing (WAAM) is a challenging task. Compared to laser-based additive manufacturing technologies, WAAM is characterized by a lower contour accuracy with higher surface roughness and more uneven surface profiles. Therefore, the WAAM requires a high degree of post-processing (machining) which reduces economic efficiency and increases material consumption. Therefore, topics such as process optimization with regard to the component contour are increasingly in the focus of research. This study presents the application of an extended shielding gas coverage in the WAAM process of steel to improve part contour accuracy. A specially adapted shielding gas coverage was manufactured with laser powder bed fusion and following used to study the influence on the resulting component contour and properties in comparison to standard shielding gas nozzles. The investigations include the analysis of temperature profiles, shape deviations, hardness and porosity in the component. In addition, process parameters such as gas flow rate and nozzle geometry were varied in order to evaluate their influence on the accuracy of the component contour. The extended shielding gas coverage reduces the average deviation from the target contour significantly by a degree of 49,44%. In addition, the maximum of the occurring deviation height could be decreased by 42,39%. The results show an improvement in the dimensional accuracy of the contour and the surface quality, resulting in higher reproducibility and less post-processing effort. Y1 - 2024 UR - https://acmit.at/wp-content/uploads/2024/08/Additive-2024_Book-of-abstracts.pdf SN - 978-3-88355-440-2 SP - 29 PB - Deutsche Gesellschaft für Materialkunde (DGM) e.V. CY - Bremen, Berlin ER - TY - GEN A1 - Nikitin, Alexander A1 - Turabov, Dashqin A1 - Ermilova, Evgeniia A1 - Evdokimov, Anton A1 - Ossenbrink, Ralf A1 - Seidlitz, Holger T1 - Using dynamic resistance to predict electrode surface degradation in resistance spot welding of 5182 aluminum alloy T2 - Welding in the World N2 - In this study, the correlation between dynamic resistance during the first 10 ms of welding time and the electrode surface condition in resistance spot welding of 5182 aluminum alloy has been investigated. The electrode surface rapidly degrades due to contamination and morphological changes, adversely affecting the weld spot surface. The accumulation of Cu-Al intermetallic phases on the electrode surface alters its roughness, leading to variations in dynamic resistance. By analyzing this correlation, optimal electrode milling intervals were identified to extend electrode life. This work focused on detecting crater formation on the electrode surface through dynamic resistance monitoring. The results indicate that resistance measurements provide a reliable approach for evaluating electrode wear, optimizing maintenance schedules, and reducing material removal during milling. KW - resistance spot welding KW - aluminum alloy KW - electrode wear KW - dynamic resistance KW - electrode surface Y1 - 2024 U6 - https://doi.org/10.1007/s40194-024-01872-9 VL - 69 SP - 449 EP - 458 ER - TY - GEN A1 - Ormanova, Maria A1 - Kotlarski, Georgi A1 - Kaisheva, Darina A1 - Nikitin, Alexander A1 - Ossenbrink, Ralf A1 - Doynov, Nikolay A1 - Valkov, Stefan T1 - Investigation of the thermal gradients formed during the process of cooling of WAAM built Al99.7 specimen T2 - Journal of Physics: Conference Series N2 - This work presents a preliminary experiment used to determine the possibility of developing a thermal model used to predict the thermal gradients formed during the process of wire and arc additive manufacturing (WAAM). For this purpose, an Al99.7 specimen was built using gas metal arc welding (GMAW) in the cold arc pulse mode. The temperature of both the substrate and each consecutive layer was measured using thermocouples and infrared thermometers and the experimental data was used for the calibration of the developed thermal model. The obtained results can be used for the further development of the thermal model. KW - Thermal model KW - Wire arc additve manufacturing KW - Waam KW - Gas metal arc welding KW - Gmaw KW - Aluminum KW - Al99.7 Y1 - 2024 U6 - https://doi.org/10.1088/1742-6596/2710/1/012038 SN - 1742-6596 VL - 2024 IS - 2710 ER - TY - GEN A1 - Kotlarski, Georgi A1 - Ormanova, Maria A1 - Nikitin, Alexander A1 - Ossenbrink, Ralf A1 - Doynov, Nikolay A1 - Valkov, Stefan A1 - Michailov, Vesselin ED - Tsankov, Plamen ED - Maximov, Jordan ED - Aleksandrov, Anatoliy ED - Todorov, Todor ED - Peneva, Petya T1 - Structure, morphology and hardness of a WAAM built Al99.7 specimen T2 - International Scientific Conference Unitech 2023, Gabrovo : selected papers N2 - The present work discusses the possibility of wire arc additive manufacturing (WAAM) of pure aluminum specimens (Al99.7). The manufactured specimen's structure was studied using X-ray diffraction (XRD) experiments. The morphology of the specimen at different stages of build-up was studied by examining prepared mechanical properties of the specimen, and for this reason the microhardness of the specimen was studied as well. The results of the present study were discussed regarding the change of the structure of the samples with the increase of the specimen's height during the manufacturing process and its influence on the resultant microhardness. KW - WAAM KW - Al99.7 KW - Structure KW - Morphology KW - Hardness Y1 - 2023 UR - https://unitech2023.tugab.bg/images/thematic-sessions/CHEMISTRY_PHYSICS_AND_ECOLOGY/s17_p149_v1.pdf U6 - https://doi.org/10.70456/PJKY7011 SN - 1313-230X VL - 2 SP - 349 EP - 353 PB - Union of Automation & Informatics CY - Gabrovo ER - TY - GEN A1 - Berg, Heinz Peter A1 - Dückershoff, Roland A1 - Hertrampf, Stefan A1 - Kloshek, Alexander A1 - Himmelberg, Axel T1 - Development of an injector spark plug for the injection and ignition of gaseous fuels in internal combustion engines for use in conventional systems T2 - AIP Conference Proceedings N2 - An injection-ignition-system from an additive manufacturing process is presented with which gaseous fuels can be injected into the combustion chamber of an internal combustion engine under pressures of up to 80 bar and ignited. With the presented system, an improvement of the thermal efficiency can be achieved by a late fuel injection in the compression phase and with post-injection. With such a system, the engine becomes purely air-intake and a better filling level is achieved. Injection and ignition can take place simultaneously with this application. The system is designed with a high pressure stability for all components (200 bar) and can therefore also be used with higher compressions and combustion pressures. The spatial distribution of the fuel in the combustion chamber is achieved by angled fluid ports and also allows additional injections and ignitions in the power stroke and in the relief phase. This can improve thermal efficiency. A built-in annular channel also enables two different fuels to be injected as a mixing chamber. Finally, initial measurement results are shown for the use of hydrogen fuel in a single-cylinder engine. Indexing data and performance data of the engine indicate that the system can represent a significant increase in the efficiency of combustion engines with hydrogen fuel. Furthermore, the system can be used in conventional vehicle systems, whereby only fuel conditioning and control systems need to be adapted. KW - Combustion engine KW - Injection KW - Ilnition KW - Hydrogen Y1 - 2024 U6 - https://doi.org/10.1063/5.0238165 VL - 3626 (2024) SP - 1 EP - 8 PB - AIP Publishing CY - Chiang Mai ER - TY - GEN A1 - Florian, Tobias A1 - Schricker, Klaus A1 - Zenz, Constantin A1 - Otto, Andreas A1 - Schmidt, Leander A1 - Diegel, Christian A1 - Friedmann, Hannes A1 - Seibold, Marc A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Nagel, Falk A1 - Kallage, Peter A1 - Buttazzoni, Michele A1 - Rack, Alexander A1 - Requardt, Herwig A1 - Chen, Yunhui A1 - Bergmann, Jean Pierre T1 - Combining in situ synchrotron X-ray imaging and multiphysics simulation to reveal pore formation dynamics in laser welding of copper T2 - International Journal of Machine Tools and Manufacture N2 - Laser beam welding has emerged as a powerful tool for manufacturing copper components in electrical vehicles, electronic devices or energy storage, owing to its rapid processing capabilities. Nonetheless, the material’s high thermal conductivity and low absorption of infrared light can introduce process instabilities, resulting in defects such as pores. This study employs a hybrid approach that combines in situ synchrotron X-ray imaging with compressible multiphysics process simulation to elucidate pore-forming mechanisms during laser beam welding of copper. High-speed synchrotron X-ray imaging with an acquisition rate of 20,000 images/second facilitates the identification of relevant process regimes concerning pore formation during laser beam welding of copper with a wavelength of 1070 nm. Furthermore, in situ observations with high temporal and spatial resolution present a unique database for extensive validation of a multi-physics process simulation based on welding processes using different concentric intensity distributions. These validated simulation results enable thorough comprehension of process-related pore formation based on the interaction between keyhole, melt pool and resulting flow field. The findings show that pore formation is driven by four different mechanisms: bulging, spiking, upwelling waves at the keyhole rear wall and melt pool ejections. The synergy of high- speed synchrotron X-ray imaging and multi-physics modeling provides a fundamental understanding of the chronological sequence of events leading to process-related pore formation during laser beam welding of copper. KW - In situ high-speed synchrotron X-ray imaging KW - Multi-physics simulation KW - Laser beam welding KW - Copper KW - Pore formation KW - Concentric intensity distributions Y1 - 2025 U6 - https://doi.org/10.1016/j.ijmachtools.2024.104224 SN - 0890-6955 VL - 204 SP - 1 EP - 22 PB - Elsevier BV ER - TY - GEN A1 - Köhler, Marcel A1 - Nikitin, Alexander A1 - Sonnenfeld, Peter A1 - Ossenbrink, Ralf A1 - Jüttner, Sven T1 - Wire arc additive manufacturing of aluminum foams using TiH2-Laced Welding Wires T2 - Materials N2 - Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly more geometrically complex components without the need for expensive tooling. Direct Energy Deposition processes like Wire Arc Additive Manufacturing (WAAM) enable the additive production of near-net-shape components at high build rates. This paper presents a technology for producing aluminum foam structures using WAAM. This paper’s focus is on the development of welding wires that are mixed with a foaming agent (TiH2) and produce a foamed weld metal as well as their processing using MIG welding technology. KW - MIG welding KW - wire arc additive manufacturing KW - direct energy deposition KW - aluminum foam KW - titanium hydride KW - foaming agent KW - metal-cored wires KW - continuous powder extrusion KW - energy absorption Y1 - 2024 U6 - https://doi.org/10.3390/ma17133176 SN - 1996-1944 VL - 17 IS - 13 PB - MDPI AG ER -