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  • 51.
    Schneider, J.
    et al.
    Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, Dresden, Germany; Technical University Dresden, Helmholtzstr. 7, 01069, Dresden, Germany.
    Norman, A.
    European Space Research and Technology Centre—ESTEC, Noordwijk, Netherlands.
    Gumpinger, J.
    European Space Research and Technology Centre—ESTEC, Noordwijk, Netherlands.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, Dresden, Germany.
    Bavdaz, M.
    European Space Research and Technology Centre—ESTEC, Noordwijk, Netherlands.
    Leyens, C.
    Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, Dresden, Germany; Technical University Dresden, Helmholtzstr. 7, 01069, Dresden, Germany.
    Ghidini, T.
    European Space Research and Technology Centre—ESTEC, Noordwijk, Netherlands.
    Additive manufacturing of a metallic optical bench—process development, material qualification and demonstration2023Ingår i: CEAS Space Journal, ISSN 1868-2502, E-ISSN 1868-2510, Vol. 15, nr 1, s. 55-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the large-class science mission ATHENA, the European Space Agency (ESA) aims at exploring the hot and energetic universe with advanced X-Ray technology. As a central component of the telescope, hundreds of silicon pore optic (SPO) modules will be assembled in an optical bench with a diameter of about 2.5 m. Several approaches are under investigation for the manufacturing of this supporting structure, and for handling the challenging constraints with respect to size, geometry and material. In cooperation with ESA, the Fraunhofer IWS is currently investigating the manufacturing of the optical bench made from Ti-6Al-4 V by means of Additive Manufacturing using Laser Metal Deposition (LMD) followed by subtractive finishing. Several development steps have been covered in a holistic manner starting with the system engineering of the production site. The main focus of the activity was on the process development for the Additive Manufacturing as well as the subtractive finishing. Furthermore, the properties of the produced material were also investigated. Within the scope of this publication, a general overview is given about the project related developments, achievements, and flanking activities for solving various challenges. The suitability of the developed technologies and workflows are now being evaluated through the manufacture of a representative, large-scale breadboard.

  • 52.
    Schneider, J.
    et al.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Department of Materials Technology, Technische Universität Dresden, Dresden, Germany.
    Seidel, A.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Gumpinger, J.
    ESA/ESTEC, European Space Research and Technology Centre, Noordwijk, The Netherlands.
    Riede, M.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Lopéz, E.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Leyens, C.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Department of Materials Technology, Technische Universität Dresden, Dresden, Germany.
    Advanced manufacturing approach via the combination of selective laser melting and laser metal deposition2019Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, nr 2, artikel-id 022317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Additive manufacturing processes are frequently discussed in a competitive manner instead of being considered synergetically. This is particularly unfavorable since advanced machining processes in combination with additive manufacturing can be brought to the point that the results could not be achieved with the individual constituent processes in isolation [K. Gupta, R. F. Laubscher, and N. K. Jain, Hybrid Machining Processes—Perspectives on Machining and Finishing (Springer, New York, 2016), p. 68]. On that basis, boundary conditions from selective laser melting (SLM) and laser metal deposition (LMD) are considered in mutual contemplation [A. Seidel et al., in Proceedings of 36th International Congress on Applications of Laser & Electro-Optics, Atlanta, GA, 22–26 October 2017(Fraunhofer IWS, Dresden, 2017), pp. 6–8]. The present approach interlinks the enormous geometrical freedom of powder-bed processing with the scalability of the LMD process. To demonstrate the potential of this approach, two different strategies are pursued. Firstly, a hollow structure demonstrator is manufactured layer wise via LMD with powder and subsequently joined with geometrically complex elements produced via SLM. Afterward, possibilities for a microstructural tailoring within the joining zone via the modification of process parameters are theoretically and practically discussed. Therefore, hybrid sample materials have been manufactured and interface areas are subjected to microstructural analysis and hardness tests. The feasibility of the introduced approach has been demonstrated by both fields of observation. The process combination illustrates a comprehensive way of transferring the high geometric freedom of powder-bed processing to the LMD process. The adjustment of process parameters between both techniques seems to be one promising way for an alignment on a microstructural and mechanical scale.

  • 53.
    Seidel, A.
    et al.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Davids, A.
    Technische Universität Dresden, Dresden, Germany.
    Polenz, S.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Straubel, A.
    Technische Universität Dresden, Dresden, Germany.
    Maiwald, T.
    Technische Universität Dresden, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Moritz, J.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Schneider, J.
    Technische Universität Dresden, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Marquardt, A.
    Technische Universität Dresden, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Saha, S.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Riede, M.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Lopéz, E.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Leyens, C.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Surface modification of additively manufactured gamma titanium aluminide hardware2019Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, nr 2, artikel-id 022517Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major part of additive manufacturing focuses on the fabrication of metallic parts in different fields of applications. Examples include components for jet engines and turbines and also implants in the medical sector. Titanium alloys represent a material group which is used cross-sectoral in a large number of applications. The present paper addresses the titanium aluminides in particular. These materials have a low density in combination with a comparatively high-temperature resistance [G. Sauthoff, Intermetallics (Wiley-VCH Verlag, Weinheim, Germany, 2008)]. Nevertheless, the laser material processing is rather challenging because of their distinct tendency to lamellar interface cracking. This requires tailored processing strategies and equipment [C. Leyens et al., in Ti-2015: The 13th World Conference on Titanium, Symposium 5. Intermetallics and MMCs, 16–20 August 2015, San Diego, CA (The Minerals, Metals & Materials Society, Pittsburgh, PA, 2016)]. This work focusses on tailored processing of titanium aluminides with focus on the process-dependent surface characteristics. This includes the as-built status for powder bed processing and direct laser metal deposition but also the surface modification via post and/or advanced machining. Finally, comprehensive characterization is performed using destructive as well as nondestructive testing methods. The latter includes 3D scanning, computed tomography, microscopic analysis, and, in particular, surface roughness measurements.

  • 54.
    Seidel, A.
    et al.
    Fraunhofer Institute for Machine Tools and Forming Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Degener, L.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Schneider, J.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology, Dresden, Germany.
    Beyer, E.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Leyens, C.
    Fraunhofer Institute for Material and Beam Technology, Dresden, Germany; Technische Universität Dresden, Dresden, Germany.
    Novel Approach for Suppressing of Hot Cracking Via Magneto-fluid Dynamic Modification of the Laser-Induced Marangoni Convection2020Ingår i: Superalloys 2020: Proceedings of the 14th International Symposium on Superalloys / [ed] Sammy Tin, Mark Hardy, Justin Clews, Jonathan Cormier, Qiang Feng, John Marcin, Chris O'Brien, Akane Suzuki, Springer, 2020, s. 972-981Konferensbidrag (Refereegranskat)
    Abstract [en]

    The occurrence of hot cracking is a significant problem during welding processing of highly heat resistant nickel-base superalloys. Hot cracking is most often associated with liquid films that are present along grain boundaries in the fusion zone and the partially melted zone and can only be suppressed to a very limited extent. The latter is the case despite remarkable studies and analyses of the phenomenon. In this work, a new approach is presented which intends the suppression of hot cracking by using a non-contact method to influence the solidification process. It is based on the idea of a modification of the laser-induced melt pool convection (Marangoni convection) using customized magnetic fields. As a consequence, special system technology is derived on the basis of theoretical considerations while the effectiveness to be expected is estimated on the basis of the information available in the literature. The implemented system technology is described in detail. The focus of this description is on the magnetic flux density distribution or the temporal change, respectively, with respect to the laser-induced melt pool. The presented experimental results provide a comparative view of samples welded with and without the influence of a magnetic field while a significant difference is evident. The outlook of this work describes key data of a test stand specially developed for examining the identified topic in in-depth investigations.

  • 55.
    Seidel, André
    et al.
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Finaske, Thomas
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Straubel, Ariane
    Technische Universität Dresden, Dresden, Germany .
    Wendrock, Horst
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Dresden, Germany .
    Maiwald, Tim
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Riede, Mirko
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Lopez, Elena
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Additive Manufacturing of Powdery Ni-Based Superalloys Mar-M-247 and CM 247 LC in Hybrid Laser Metal Deposition2018Ingår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49, nr 9, s. 3812-3830Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present paper addresses the phenomena of hot cracking of nickel-based superalloys in the perspective of hybrid Laser Metal Deposition (combined application of induction and laser). This includes an extract of relevant theoretical considerations and the deduction of the tailored approach which interlinks material–scientific aspects with state-of-the-art manufacturing engineering. The experimental part reflects the entire process chain covering the manufacturing strategy, important process parameters, the profound analysis of the used materials, the gradual process development, and the corresponding hybrid manufacture of parts. Furthermore, hot isostatic pressing and thermal treatment are addressed as well as tensile testing at elevated temperatures. Further investigations include X-ray CT measurements, electron backscattered diffraction (EBSD), and scanning electron microscopy (SEM) as well as light optical microscope evaluation. The fundamental results prove the reliable processibility of the high-performance alloys Mar-M-247 and Alloy 247 LC and describe in detail the process inherent microstructure. This includes the grain size and orientation as well as the investigation of size, shape, and distribution of the γ′ precipitates and carbides. Based on these findings, the manufacturing of more complex demonstrator parts with representative dimensions is addressed as well. This includes the selection of a typical application, the transfer of the strategy, as well as the proof of concept.

  • 56.
    Seidel, André
    et al.
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Lopez, Elena
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Saha, Shuvra
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Maiwald, Tim
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden; Technische Universität Dresden, Helmholtzstr. 7, DE-01069 Dresden.
    Moritz, Juliane
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Polenz, Stefan
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Marquardt, Axel
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden; Technische Universität Dresden, Helmholtzstr. 7, DE-01069 Dresden.
    Kaspar, Joerg
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Finaske, Thomas
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Riede, Mirko
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden.
    Leyens, Cristoph
    Fraunhofer-Institute for Material and Beam Technology, Winterbergstraße 28, DE-01277 Dresden; Technische Universität Dresden, Helmholtzstr. 7, DE-01069 Dresden.
    Hybrid Additive Manufacturing of Gamma Titanium Aluminide Space Hardware2018Ingår i: Contributed Papers from Materials Science and Technology 2018 (MS&T18), Association for Iron and Steel Technology (AISTECH) , 2018, s. 13-21Konferensbidrag (Refereegranskat)
    Abstract [en]

    A major part of laser additive manufacturing focuses on the fabrication of metallic parts for applications in the space and aerospace sector. Especially the processing of the very brittle titanium aluminides can be particularly challenging [1-2].

    In the present paper a gamma titanium aluminide (γ-TiAl) nozzle, manufactured via Electron Beam Melting (EBM), is extended and adapted via hybrid Laser Metal Deposition (LMD). The presented approach considers critical impacts like processing temperatures, temperature gradients and solidification conditions with particular regard to crucial material properties like the phenomena of lamellar interface cracking [3-6]. Furthermore, the potential of microstructural tailoring is going to be addressed by the process-specific manipulation of the composition and/or microstructure.

    In addition to this, selected destructive and non-destructive testing is performed in order to prove the material properties. Finally, post manufacturing and surface modification are briefly addressed.

  • 57.
    Seidel, André
    et al.
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Saha, Shuvra
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Maiwald, Tim
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany;Technische Universität Dresden, Dresden, Germany.
    Moritz, Juliane
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Polenz, Stefan
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Marquardt, Axel
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany;Technische Universität Dresden, Dresden, Germany.
    Kaspar, Joerg
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Finaske, Thomas
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Lopez, Elena
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer-Institute for Material and Beam Technology, Dresden, Germany;Technische Universität Dresden, Dresden, Germany.
    Intrinsic Heat Treatment Within Additive Manufacturing of Gamma Titanium Aluminide Space Hardware2019Ingår i: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 71, nr 4, s. 1513-1519Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major part of laser additive manufacturing focuses on the fabrication of metallic parts for applications in the space and aerospace sectors. Especially, the processing of the very brittle titanium aluminides can be particularly challenging because of their distinct tendency to lamellar interface cracking. In the present paper, a gamma titanium aluminide (γ-TiAl) nozzle, manufactured via electron beam melting, is extended and adapted via hybrid laser metal deposition. The presented example considers a new field of application for this class of materials and approaches the process-specific manipulation of the composition and/or microstructure via the adjustment of processing temperatures, temperature gradients and solidification conditions. Furthermore, intrinsic heat treatment is investigated for electron beam melting and laser metal deposition with powder, and the resulting influence is releated to conventional processing.

  • 58.
    Selbmann, Alex
    et al.
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Gruber, Samira
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Propst, Martin
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Dorau, Tim
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Drexler, Robert
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Toma, Filofteia-Laura
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Mueller, Michael
    Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Lopez, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Bach, Christian
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Leyens, Christoph
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany; Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine2024Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 36, nr 1, artikel-id 012027Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints.

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  • 59.
    Selbmann, Alex
    et al.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden.
    Gruber, Samira
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden.
    Stepien, Lukas
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden.
    Lopez, Elena
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden.
    Marquardt, Axel
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden; Institute for Materials Science, Technische Universität Dresden, 01062 Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden.
    Leyens, Christoph
    Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden; Institute for Materials Science, Technische Universität Dresden, 01062 Dresden, Germany.
    Mechanical and geometrical characterization of additively manufactured INCONEL® 718 porous structures for transpiration cooling in space applications2022Ingår i: Laser 3D Manufacturing IX / [ed] Bo Gu; Hongqiang Chen; Henry Helvajian, SPIE - International Society for Optical Engineering, 2022, Vol. 11992, artikel-id 1199206Konferensbidrag (Refereegranskat)
    Abstract [en]

    The need for ever increasing process temperatures during combustion in space engines and gas turbines to increase efficiency requires the use of thermally resistant materials and novel cooling solutions. For the improved cooling of thermally highly stressed components, the technology of transpiration cooling, in which a cooling medium flows through a porous structure, has been known for a long time. Additive manufacturing and, in particular, laser powder bed fusion (LPBF) offers great potential for the near-net-shape production of porous structures compared to complex conventional manufacturing. In this contribution, porous structures were manufactured and the process parameters were optimized to increase the quality of the pores. The study discloses an adapted exposure parameter set for the improved fabrication of cylindrical pores in an INCONEL® 718 material and the associated mechanical properties of porous and dense components.

  • 60.
    Sheydaeian, Esmat
    et al.
    University of Toronto, Toronto, Canada.
    Gerdt, Leonid
    Fraunhofer IWS, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer IWS, Dresden, Germany.
    Lopez, Elena
    Fraunhofer IWS, Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer IWS, Dresden, Germany; Dresden University of Technology, Germany.
    PBF-LB of zinc composites modified with nanopowders: Initial insights into powder and part characterizations2024Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 361, artikel-id 136076Artikel i tidskrift (Refereegranskat)
  • 61.
    Siva Prasad, Himani
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Winterbergstrasse 28, Dresden, Germany.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Powder catchment in laser metal deposition2019Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, nr 2, artikel-id 022308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser metal deposition (LMD) of Inconel 718 using a coaxial nozzle is investigated by high-speed imaging. The interaction of individualpowder grains with the laser induced melt pool surface and, finally, their catchment in the LMD track is observed. Powder catchment trendsare explained by interpreting physical phenomena, such as the melt flow and surface tension. Distinct zones for powder catchment are categorizeddepending on the position of initial interaction between powder grains and the melt pool. Particles are introduced outside the meltpool ricochet and do not attach to the clad. Particles arriving outside the laser spot, onto the solidifying skin of the melt pool, are caught,and may incorporate. Some particles may remain on the clad surface as surface roughness on the built part. Particles interacting with thelaser-irradiated region of the melt pool tend to move toward its center and readily incorporate into the melt. Quantitative analyses of highspeedvideos are carried out to measure incorporation time of powder grains in the melt pool, their velocity, and distance traveled.

  • 62.
    Thiel, Markus
    et al.
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Senese, Samuel
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Sedlmaier, Thomas
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Redlich, Daniel
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Mulser, Marco
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Van Der Veen, Egbert Jan
    OHB System AG, Manfred-Fuchs-Str. 1, D-82234, Weßling, Germany.
    Pambaguian, Laurent
    ESTEC European Space Technology Centre, Keplerlaan 1, NL-2200, AG Noordwijk, Netherlands.
    Rodrigues, Goncalo
    ESTEC European Space Technology Centre, Keplerlaan 1, NL-2200, AG Noordwijk, Netherlands.
    Zaltron, Paolo
    ESTEC European Space Technology Centre, Keplerlaan 1, NL-2200, AG Noordwijk, Netherlands.
    Brinkers, Sanneke
    TNO Netherlands Organisation for Applied Scientific Research, Stieltjesweg 1, NL-2628CK, Delft, Netherlands.
    Aumund-Kopp, Claus
    Fraunhofer IFAM, Wiener Strasse 12, 28359, Bremen, Germany.
    Klein, Sebastian
    IABG mbH, Einsteinstrasse 20, 85521, Ottobrunn, Germany.
    Domagala, Tim
    Materialise NV, Technologielaan 15, 3001, Leuven, Belgium.
    Kwast, Sander
    SRON Netherlands Institute for Space Research, Sorbonnelaan 2, NL-3584 CA, Utrecht, Netherlands.
    McLoughlin, Anthony
    Altair Engineering GmbH, Edisonstrasse 3, D-85716, Unterschleissheim, Germany.
    Eick, Matthias
    Altair Engineering GmbH, Edisonstrasse 3, D-85716, Unterschleissheim, Germany.
    Melzer, Christian
    Luleå tekniska universitet. RUAG Space Germany GmbH, Am Glaswerk 6, D-01640, Coswig, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Winterbergstrasse 28, D-01277, Dresden, Germany.
    Ricardo, Joao
    Active Space Technologies S.A., Parque Industrial de Taveiro, Lote 12, 3045-508, Coimbra, Portugal.
    Barroqueiro, Bruno
    Department of Mechanical Engineering, Centre for Mechanical Technology & Automation, GRIDS research group, University of Aveiro, Campus Universitario de Santiago, 3810-193, Aveiro, Portugal.
    OHB Initiatives in Development of Additive Manufacturing Technology for Opto-mechanical and Mechatronic Space Systems2018Ingår i: IAC 2018 Congress Proceedings, 69th International Astronautical Congress (IAC), 1–5 October 2018, Bremen, Germany, International Astronautical Federation, IAF , 2018, artikel-id 44583Konferensbidrag (Refereegranskat)
  • 63.
    Tkachov, Roman
    et al.
    Institute of Materials Science, Technische Universität Dresden, Dresden, Germany; Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Dresden, Germany.
    Stepien, Lukas
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS),Dresden, Germany.
    Greifzu, Moritz
    Institute of Materials Science, Technische Universität Dresden, Dresden, Germany; Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Dresden, Germany.
    Kiriy, Anton
    Leibniz-Institut für Polymerforschung Dresden e.V. (IPF), Dresden, Germany.
    Kiriy, Nataliya
    Leibniz-Institut für Polymerforschung Dresden e.V. (IPF), Dresden, Germany.
    Schüler, Tilman
    Institute of Aerospace Engineering, Technische Universität Dresden, Dresden, Germany.
    Schmiel, Tino
    Institute of Aerospace Engineering, Technische Universität Dresden, Dresden, Germany.
    López, Elena
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS),Dresden, Germany.
    Leyens, Christoph
    Institute of Materials Science, Technische Universität Dresden, Dresden, Germany; Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Dresden, Germany.
    A Printable Paste Based on a Stable n-Type Poly[Ni-tto] Semiconducting Polymer2019Ingår i: Coatings, ISSN 2079-6412, Vol. 9, nr 11, artikel-id 764Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polynickeltetrathiooxalate (poly[Ni-tto]) is an n-type semiconducting polymer having outstanding thermoelectric characteristics and exhibiting high stability under ambient conditions. However, its insolubility limits its use in organic electronics. This work is devoted to the production of a printable paste based on a poly[Ni-tto]/PVDF composite by thoroughly grinding the powder in a ball mill. The resulting paste has high homogeneity and is characterized by rheological properties that are well suited to the printing process. High-precision dispenser printing allows one to apply both narrow lines and films of poly[Ni-tto]-composite with a high degree of smoothness. The resulting films have slightly better thermoelectric properties compared to the original polymer powder. A flexible, fully organic double-leg thermoelectric generator with six thermocouples was printed by dispense printing using the poly[Ni-tto]-composite paste as n-type material and a commercial PEDOT-PSS paste as p-type material. A temperature gradient of 100 K produces a power output of about 20 nW.

  • 64.
    Torims, Toms
    et al.
    Centre of High-Energy Physics and Accelerator Technologies, Riga Technical University, Azenes iela 12/1-406, LV-1048 Riga, Latvia; CERN, The European Organization for Nuclear Research, 1211 Meyrin, Switzerland.
    Pikurs, Guntis
    Centre of High-Energy Physics and Accelerator Technologies, Riga Technical University, Azenes iela 12/1-406, LV-1048 Riga, Latvia; CERN, The European Organization for Nuclear Research, 1211 Meyrin, Switzerland.
    Gruber, Samira
    Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
    Vretenar, Maurizio
    CERN, The European Organization for Nuclear Research, 1211 Meyrin, Switzerland.
    Ratkus, Andris
    Centre of High-Energy Physics and Accelerator Technologies, Riga Technical University, Azenes iela 12/1-406, LV-1048 Riga, Latvia; CERN, The European Organization for Nuclear Research, 1211 Meyrin, Switzerland.
    Vedani, Maurizio
    Department of Mechanical Engineering, Politecnico di Milano, 20156 Milan, Italy.
    López, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
    First proof-of-concept prototype of an additive manufactured radio frequency quadrupole2021Ingår i: Instruments, ISSN 2410-390X, Vol. 5, nr 4, artikel-id 35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Continuous developments in additive manufacturing (AM) technology are opening up opportunities in novel machining, and improving design alternatives for modern particle accelerator components. One of the most critical, complex, and delicate accelerator elements to manufacture and assemble is the radio frequency quadrupole (RFQ) linear accelerator, which is used as an injector for all large modern proton and ion accelerator systems. For this reason, the RFQ has been selected by a wide European collaboration participating in the AM developments of the I.FAST (Innovation Fostering in Accelerator Science and Technology) Horizon 2020 project. The RFQ is as an excellent candidate to show how sophisticated pure copper accelerator components can be manufactured by AM and how their functionalities can be boosted by this evolving technology. To show the feasibility of the AM process, a prototype RFQ section has been designed, corresponding to one-quarter of a 750 MHz 4-vane RFQ, which was optimised for production with state-of-the-art laser powder bed fusion (L-PBF) technology, and then manufactured in pure copper. To the best of the authors’ knowledge, this is the first RFQ section manufactured in the world by AM. Subsequently, geometrical precision and surface roughness of the prototype were measured. The results obtained are encouraging and confirm the feasibility of AM manufactured high-tech accelerator components. It has been also confirmed that the RFQ geometry, particularly the critical electrode modulation and the complex cooling channels, can be successfully realised thanks to the opportunities provided by the AM technology. Further prototypes will aim to improve surface roughness and to test vacuum properties. In parallel, laboratory measurements will start to test and improve the voltage holding properties of AM manufactured electrode samples.

  • 65.
    Volpp, Joerg
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology IWS, Dresden, German.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Track geometry variations in selective laser melting processes2019Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, nr 2, artikel-id 022310Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Selective laser melting processes are widely used for many industrial applications using a laser beam to melt preplaced powder materiallayer by layer to create technical parts. The building process of those structures requires remelting of adjacent tracks and layers in order toavoid cavities and achieve the joining of the new track to the previous track and layer. In order to achieve a sufficient overlap and minimizecavities, usually conservative processing parameters are chosen. A higher energy and powder usage efficiency would be achieved if knowingabout the formation process of the single tracks and their geometrical dimensions depending on the available powder. In this work, it isshown that the cross-sectional track geometry significantly varies within one layer. A simple model is developed describing the influence ofthe available powder for each track within one layer. Depending on the hatch distance, different variation patterns are observed andmodeled showing that the track variations are inherent phenomena of the process. It can be concluded that the variations of powder avail-ability can cause the geometric variations of the tracks.

  • 66.
    Volpp, Jörg
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Prasad, Himani Siva
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Riede, M.
    Fraunhofer-Institute for Material and Beam Technology IWS, Winterbergstr. 28, 01277 Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology IWS, Winterbergstr. 28, 01277 Dresden, Germany.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Powder particle attachment mechanisms onto liquid material2018Ingår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 74, s. 140-143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to achieve high powder and energy efficiencies of Direct Metal Deposition processes knowledge about the basic effects of the interaction of the particle on the liquid surface is mandatory. Characteristic zones on the melt pool surface were identified in high-speed images. In the melt pool area around the center of the laser beam illumination, particles immediately enter into the melt pool while in its vicinity the particles float on the melt pool until they incorporate. Closer to the solidification line, particles rest on the liquid surface and remain as surface roughness on the track after solidification.

  • 67.
    Willner, Robin
    et al.
    Fraunhofer IWS, Dresden, Germany.
    Lender, Stefan
    INVENT GmbH, Braunschweig, Germany.
    Ihl, Andreas
    INVENT GmbH, Braunschweig, Germany.
    Wilsnack, Christoph
    Fraunhofer IWS, Dresden, Germany.
    Gruber, Samira
    Fraunhofer IWS, Dresden, Germany. Institute of Materials Science, Technical University Dresden, Dresden, Germany.
    Brandão, Ana
    European Space Research and Technology Centre—ESTEC, 2201 AZ Noordwijk, The Netherlands.
    Pambaguian, Laurent
    European Space Research and Technology Centre—ESTEC, 2201 AZ Noordwijk, The Netherlands.
    Riede, Mirko
    Fraunhofer IWS, Dresden, Germany.
    López, Elena
    Fraunhofer IWS, Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer IWS, Dresden, Germany.Institute of Materials Science, Technical University Dresden, Helmholtzstr, Dresden, Germany.
    Potential and challenges of additive manufacturing for topology optimized spacecraft structures2020Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 32, nr 3, artikel-id 032012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study focused on the potential of topology optimization (TO) for metallic tertiary structures of spacecrafts produced by the additive manufacturing (AM) technique laser powder bed fusion. First, a screening of existing conventionally manufactured products was carried out to evaluate the benefits of a redesign concerning product performance and the associated economic impact. As a result of the study, the most suitable demonstrator was selected. This reference structure was redesigned by TO taking into consideration the AM process constraints. Another major aim of this work was to evaluate the possibilities and challenges of AM (accuracies, surface quality, process parameters, postmachining, and mechanical properties) in addition to the redesign process. A comprehensive approach was implemented including detailed analysis of the powder, mechanical properties, in-process parameters, and nondestructive inspection (NDI). All measured values were used for a back loop to the design process, thereby providing a final robust redesign. Finally, the fine-tuned demonstrator was built up in an iterative process. The parts were tested under representative conditions for the application to verify the performance. The demonstrator qualification test campaign contained thermal cycling, vibration testing, static load testing, and NDI. Thus, an improvement in technology readiness level up to "near flight qualified" was reached.

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