TY - JOUR A1 - Podshivalov, L. A1 - Wirth, Cynthia A1 - Zocca, Andrea A1 - Günster, Jens A1 - Bar-Yoseph, P. A1 - Fischer, A. T1 - Design, analysis and additive manufacturing of porous structures for biocompatible micro-scale scaffolds JF - Procedia CIRP N2 - Advancements in the fields of biocompatible materials, manufacturing processes, computational methods and medicine have led to the emergence of a new field: micro-scale scaffolds for bone replacement and regeneration. Yet most such scaffolds produced today are characterized by very basic geometry, and their microstructure differs greatly from that of the actual tissue they are intended to replace. In this paper, we propose a novel approach for generating micro-scale scaffolds based on processing actual micro-CT images and then reconstructing a highly accurate geometrical model. This model is manufactured by means of a state-of-the-art 3D additive manufacturing process from biocompatible materials. At the micro-scale level, these scaffolds are very similar to the original tissue, thus interfacing better with the surrounding tissue and facilitating more efficient rehabilitation for the patient. Moreover, the approach facilitates the design and manufacture of patient-specific scaffolds which can copy patients’ exact structural and mechanical characteristics, taking into account their physical condition and medical history. By means of multi-resolution volumetric modeling methods, scaffold porosity can also be adapted according to specific mechanical requirements. The process of designing and manufacturing micro-scale scaffolds involves five major stages: (a) building a volumetric multi-resolution model from micro-CT images; (b) generation of surface geometric model in STL format; (c) additive manufacturing of the scaffold; (d) scaffold shape verification relative to the geometric design; and (e) verification of mechanical properties through finite element analysis. In this research, all the proposed stages of the approach were tested. The input included micro-CT scans of porous ceramic structure, which is quite similar to commercial porous scaffolds. The results show that the proposed method is feasible for design and manufacture of micro-scale scaffolds. KW - Micro-scale bone scaffolds KW - Additive manufacturing KW - Multiscale FEA KW - Ceramics KW - Multiresolution modeling PY - 2013 DO - https://doi.org/10.1016/j.procir.2013.01.049 SN - 2212-8271 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 5 SP - 247 EP - 252 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-28003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Bernardo, E. A1 - Müller, Ralf A1 - Günster, Jens A1 - Colombo, P. T1 - LAS glass-ceramic scaffolds by three-dimensional printing JF - Journal of the European Ceramic Society N2 - Highly porous (>60% open porosity) glass–ceramic scaffolds with remarkable mechanical properties (compression strength of ~15 MPa) were produced by indirect 3D printing. Precursor glass powders were printed into 3D ordered structures and then heat treated to sinter and develop crystalline phases. The final glass–ceramic contained a β-spodumene solid solution together with a secondary phase of lithium disilicate. The precision of the printed geometry and the density of the struts in the scaffold depended on several processing parameters (e.g. powder size and flowability, layer thickness) and were improved by increasing the binder saturation and drying time. Two types of powders with different particle size distribution (PSD) and flowability were used. Powders with a larger PSD, could be processed within a wider range of printing parameters due to their good flowability; however, the printing precision and the struts density were lower compared to the scaffolds printed using the powder in a smaller average PSD. KW - Glass ceramics KW - Porosity KW - Shaping KW - Strength KW - Additive manufacturing PY - 2013 DO - https://doi.org/10.1016/j.jeurceramsoc.2012.12.012 SN - 0955-2219 SN - 1873-619X N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 33 IS - 9 SP - 1525 EP - 1533 PB - Elsevier CY - Oxford AN - OPUS4-28284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Staude, Andreas A1 - Bernardo, E. A1 - Günster, Jens A1 - Colombo, P. T1 - SiOC ceramics with ordered porosity by 3 D-printing of a preceramic polymer JF - Journal of materials research N2 - Ceramic parts possessing an ordered porosity were produced for the first time by powder-based three-dimensional printing of a preceramic polymer followed by pyrolysis in an inert atmosphere. The main parameters involved in the process were investigated, and the precision of the printed and ceramized parts was assessed by means of scanning electron microscopy and micro computed tomography. The influence of two different printing solvents was investigated and the use of a mixture of 1-hexanol and hexylacetate in particular allowed the production of parts with a relative density of 80% both in the polymeric and in the ceramic state. The mixing of a cross-linking catalyst directly with the printing liquid greatly simplified the process, minimizing the necessity of preprocessing the starting powder. Three-dimensional printing of a preceramic polymer not containing any inert or active fillers was proved to be a feasible, convenient and precise process for the production of porous ceramic possessing a complex, ordered structure, such as stretch-dominated lattices. KW - Polymer KW - Ceramic KW - Cellular PY - 2013 DO - https://doi.org/10.1557/jmr.2013.129 SN - 0884-2914 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 28 IS - 17 SP - 2243 EP - 2252 PB - Materials Research Society CY - Warrendale, Pa. AN - OPUS4-29441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Riechers, Birte A1 - Zocca, Andrea A1 - Rosalie, Julian A1 - Maaß, Robert A1 - Sturm, Heinz A1 - Günster, Jens T1 - Entering a new dimension in powder processing for advanced ceramics shaping JF - Advanced materials N2 - Filigree structures can be manufactured via two-photon-polymerization (2PP) operating in the regime of non-linear light absorption. For the first time it is possible to apply this technique to the powder processing of ceramic structures with a feature size in the range of the critical defect size responsible for brittle fracture and, thus, affecting fracture toughness of high-performance ceramics. In this way, tailoring of advanced properties can be achieved already in the shaping process. Traditionally, 2PP relies on transparent polymerizable resins, which is diametrically opposed to the usually completely opaque ceramic resins and slurries. Here we present a transparent and photocurable suspension of nanoparticles (resin) with very high mass fractions of yttria-stabilized zirconia particles (YSZ). Due to the extremely well dispersed nanoparticles, scattering of light can be effectively suppressed at the process-relevant wavelength of 800 nm. Sintered ceramic structures with a resolution of down to 500 nm were obtained. Even at reduced densities of 1 to 4 g/cm³, the resulting compressive strength with 4,5 GPa is equivalent or even exceeding bulk monolithic yttria stabilized zirconia. A ceramic metamaterial is born, where the mechanical properties of yttria stabilized zirconia are altered by changing geometrical parameters and gives access to a new class of ceramic materials. KW - Two-photon-polymerization KW - Ceramics KW - Powder processing KW - Transparency KW - Meta material KW - Yttria stabilized zirconia PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564598 DO - https://doi.org/10.1002/adma.202208653 SN - 1521-4095 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandić Lipińska, M. A1 - Davenport, R. A1 - Imhof, A. B. A1 - Waclavicek, R. A1 - Fateri, M. A1 - Meyer, Lena A1 - Gines-Palomares, J. C. A1 - Zocca, Andrea A1 - Makaya, A. A1 - Günster, Jens T1 - PAVER - Contextualizing laser sintering within a lunar technology roadmap T2 - Proceedings of the IAC 2022 N2 - The Global Exploration Strategy of the International Space Exploration Coordination Group (ISECG) describes a timeframe of 2020 and beyond with the ultimate aim to establish a human presence on Mars towards the 2040ies. The next steps lie on the Moon with a focus on the coming 10 years. Early lunar surface missions will establish a capability in support of lunar science and prepare and test mission operations for subsequent human exploration of Mars and long-duration human activities on the Moon. Given the extreme costs involved in the shipping of material from Earth, a prerequisite for future human exploration is the manufacturing of elements directly on the Moon’s surface. Unlike the equipment, which at the beginning will have to be brought from Earth, raw materials and energy could be available following the concept of In-Situ Resource Utilization. The ESA OSIP PAVING THE ROAD (PAVER) study investigates the use of a laser to sinter regolith into paving elements for use as roadways and launch pads thus mitigating dust issues for transport and exploration vehicles. The ESA-funded study examines the potential of using a laser (12 kW CO2 laser with spot beam up to 100 mm) for layer sintering of lunar and martian regolith powders to manufacture larger 3D elements and provide know-how for the automatic manufacture of paving elements in the lunar environment. The project contributes to the first step toward the establishment of a lunar base and will lead to the construction of equipment capable of paving areas and manufacturing 3D structures. PAVER project sets the starting point for an examination of the larger context of lunar exploration. Mission scenarios will look at different phases of lunar exploration: Robotic Lunar Exploration, Survivability, Sustainability, and Operational Phase. A proposed Technology Roadmap investigates the mission scenario and analyses how, and to which extent, laser melting/sintering will play a role in the various phases of exploration. The paper contextualizes laser sintering within selected mission scenarios and discusses the different kinds of infrastructure that can be produced at each phase of the mission. The outcome of the study includes the detailing of the TRL steps in the project and an outline of a timeline for the different elements. Covered aspects include terrain modelling such as operation pads, roadways, or towers, non-pressurized building structures to protect machinery, and habitat envelopes, to protect and shield humans against dust, micrometeoroids, and radiation. T2 - 73rd International Astronautical Congress (IAC) CY - Paris, France DA - 18.09.2022 KW - Additive manufacturing KW - Solar sintering KW - ISRU KW - Infrastructure KW - Lunar habitat KW - Paving PY - 2022 SP - 1 EP - 9 AN - OPUS4-56519 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chi, J. A1 - Agea Blanco, B. A1 - Bruno, Giovanni A1 - Günster, Jens A1 - Zocca, Andrea T1 - Self-Organization Postprocess for Additive Manufacturingin Producing Advanced Functional Structure and Material JF - Advanced Engineering Materials N2 - Additive manufacturing (AM) is developing rapidly due to itsflexibility in producing complex geometries and tailored material compositions. However, AM processes are characterized by intrinsic limitations concerning their resolution and surface finish, which are related to the layer-by-layer stacking process. Herein, a self-organization process is promoted as an approach to improve surface quality and achieve optimization of 3D minimal surface lightweight structures. The self-organization is activated after the powder bed 3D printing process via local melting, thereby allowing surface tension-driven viscous flow.The surface roughness Ra (arithmetic average of the roughness profile) could bedecreased by a factor of 1000 and transparent lenses and complex gyroid structures could be produced for demonstration. The concept of self-organization is further elaborated by incorporating external magnetic fields to intentionally manipulate magnetic particles, which are mixed with the polymer before printing and self-organization. This concept can be applied to develop programmable materials with specific microtextures responding to the external physical conditions. KW - Additive Manufacturing KW - Self-organization KW - Triply Periodical Minimal Surface PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540588 DO - https://doi.org/10.1002/adem.202101262 VL - 24 IS - 6 SP - 1 EP - 8 PB - Wiley VCH AN - OPUS4-54058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wilbig, Janka A1 - Waske, Anja A1 - Günster, Jens A1 - Widjaja, Martinus A1 - Neumann, C. A1 - Clozel, M. A1 - Meyer, A. A1 - Ding, J. A1 - Zhou, Z. A1 - Tian, X. T1 - Challenges in the Technology Development for Additive Manufacturing in Space JF - Chinese Journal of Mechanical Engineering: Additive Manufacturing Frontiers N2 - Instead of foreseeing and preparing for all possible scenarios of machine failures, accidents, and other challenges arising in space missions, it appears logical to take advantage of the flexibility of additive manufacturing for “in-space manufacturing” (ISM). Manned missions into space rely on complicated equipment, and their safe operation is a great challenge. Bearing in mind the absolute distance for manned missions to the Moon and Mars, the supply of spare parts for the repair and replacement of lost equipment via shipment from Earth would require too much time. With the high flexibility in design and the ability to manufacture ready-to-use components directly from a computer-aided model, additive manufacturing technologies appear to be extremely attractive in this context. Moreover, appropriate technologies are required for the manufacture of building habitats for extended stays of astronauts on the Moon and Mars, as well as material/feedstock. The capacities for sending equipment and material into space are not only very limited and costly, but also raise concerns regarding environmental issues on Earth. Accordingly, not all materials can be sent from Earth, and strategies for the use of in-situ resources, i.e., in-situ resource utilization (ISRU), are being envisioned. For the manufacturing of both complex parts and equipment, as well as for large infrastructure, appropriate technologies for material processing in space need to be developed. KW - Additive manufacturing KW - Space KW - Process PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549204 DO - https://doi.org/10.1016/j.cjmeam.2022.100018 SN - 2772-6657 VL - 1 IS - 1 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-54920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diener, S. A1 - Zocca, Andrea A1 - Günster, Jens T1 - Literature review: Methods for achieving high powder bed densities in ceramic powder bed based additive manufacturing JF - Open Ceramics N2 - In additive manufacturing the powder bed based processes binder jetting and powder bed fusion are increasingly used also for the production of ceramics. Final part properties depend to a high percentage on the powder bed density. Therefore, the aim is to use the best combination of powder deposition method and powder which leads to a high packing of the particles. The influence of flowability, powder properties and deposition process on the powder bed density is discussed and the different deposition processes including slurry-based ones are reviewed. It turns out that powder bed density reached by slurry-based layer deposition exceeds conventional powder deposition, however, layer drying and depowdering are extra steps or more time-consuming for the slurry route. Depending on the material properties needed the most suitable process for the part has to be selected. KW - Additive Manufacturing KW - Powder-based processes KW - Powder bed density PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534992 DO - https://doi.org/10.1016/j.oceram.2021.100191 VL - 8 SP - 100191 PB - Elsevier Ltd. AN - OPUS4-53499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plarre, Rüdiger A1 - Zocca, Andrea A1 - Spitzer, Andrea A1 - Benemann, Sigrid A1 - Gorbushina, Anna A1 - Li, Y. A1 - Waske, Anja A1 - Funk, Alexander A1 - Wilgig, Janka A1 - Günster, Jens T1 - Searching for biological feedstock material: 3D printing of wood particles from house borer and drywood termite frass JF - PLOS One N2 - Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer (EHB) and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the EHB Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of woodbased structures in a layer wise fashion using the Binder Jetting printing process. The Quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a Hausner Ratio HR = 1.1 with ρBulk = 0.67 g/cm3 and ρTap = 0.74 g/cm3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing. KW - 3D printing KW - X-ray tomographic KW - SEM micrography KW - Drywood termite PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521517 DO - https://doi.org/10.1371/journal.pone.0246511 VL - 16 IS - 2 SP - e0246511 AN - OPUS4-52151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hmood, F. J. A1 - Wilbig, Janka A1 - Nicolaides, Dagmar A1 - Zocca, Andrea A1 - Günster, Jens T1 - An approach to monitor the real-time deformation during heat treatment of 3D-printed glass JF - Ceramics International N2 - This study suggests a tool for a better control on the sintering/crystallization of 3D-printed bioactive glassceramics bodies. A small cantilever in form of a bar with square cross section attached to a base and inclined 34◦ with the horizon, was used to monitor the viscous flow and sintering/crystallization headway of a glassceramic systems. 3D printing and sintering of bioactive glass-ceramics is of great interest for medical care applications. Viscous flow ensures sufficient densification of the typically low density printed green bodies, while crystallization prevents the structure from collapsing under the gravitational load. As a model system, a bioactive glass called BP1 (48.4 SiO2, 1 B2O3, 2 P2O5, 36.6 CaO, 6.6 K2O, 5.6 Na2O (mol%)), which has a chemical composition based on that of ICIE16, was employed in this work. In addition, ICIE16 was used as a reference glass. The results show that the suggested design is a very promising tool to track the real-time deformation of 3D printed glass-ceramic specimens and gives a good indication for the onset of crystallization as well. KW - Real-time deformation KW - Sintering KW - 3D-printing KW - Bioactive glass PY - 2021 DO - https://doi.org/10.1016/j.ceramint.2021.03.334 VL - 47 IS - 14 SP - 20045 EP - 20050 PB - Elsevier Ltd. AN - OPUS4-53449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baesso, Ilaria A1 - Karl, D. A1 - Spitzer, Andrea A1 - Gurlo, A. A1 - Günster, Jens A1 - Zocca, Andrea T1 - Characterization of powder flow behavior for additive manufacturing JF - Additive manufacturing N2 - The flow behavior of powders has an essential role in many industrial processes, including powder bed additive manufacturing. The characterization of the flow behavior is challenging, as different methods are available, and their suitability for an application in additive manufacturing is still controversial. In this study, six standardized methods (measurement of bulk density by ISO 60 and by ASTM B329, angle of repose by ISO 4324, discharge time by ISO 6186 and by ASTM B964-16, and Hausner Ratio by ASTM 7481 – 18), the rotating drum method (by GranuDrum) and powder rheometry (Anton Paar powder cell), were applied to five size fractions of a crushed quartz sand powder and compared. A statistical approach is proposed and discussed to correlate the obtained flowability indexes with the packing density of powder beds deposited layer-by-layer, and these correlations are compared between methods. Overall, the measurement of bulk density by ASTM B329 that showed the best correlation with the powder bed density. Advanced methods such as the rotating drum method and powder rheometry did not demonstrate particularly good correlations, however they provided complementary information which can be useful to assess the dynamic behavior of powders. KW - Powder flow KW - Flowability KW - Powder bed additive manufacturing KW - Powder rheology PY - 2021 DO - https://doi.org/10.1016/j.addma.2021.102250 SN - 2214-8604 VL - 47 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam AN - OPUS4-53229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diener, S. A1 - Schubert, Hendrik A1 - Held, A. A1 - Katsikis, N. A1 - Günster, Jens A1 - Zocca, Andrea T1 - Influence of the dispersant on the parts quality in slurry-based binder jetting of SiC ceramics JF - Journal of the American Ceramic Society N2 - Binder jetting is establishing more and more in the ceramic industry to produce large complex shaped parts. A parameter with a great impact on the quality of the parts is the binder–powder interaction. The use of ceramic slurries as feedstock for this process, such as in the layerwise slurry deposition–print technology, allows a great flexibility in the composition. Such slurries are typically composed of ceramic powder, water, and small amounts of various additives. The understanding of the effect of these components on the printing quality is thus essential for the feedstock development. Four models were developed regarding the impact of additives, such as dispersants on printing. These models were confirmed or rebutted by experiments performed for an SiC slurry system with two different concentrations of a dispersant and a commercial phenolic resin used as a binder. It is shown that for this system the influence of the dispersant on the curing behavior and the clogging of the pores by dispersant can be neglected. The redispersion of the dispersant after the curing of the resin has no or only a minor effect. However, the wetting behavior determined by the surface energies of the system seem to be most crucial. In case the surface energy of the slurry additive is significantly lower than the surface energy of the binder, the strength of the green parts and the printing quality will be low. This was shown by inverse gas chromatography, contact angle measurement, rheological characterization, and mechanical tests with casted samples. KW - Additive Manufacturing KW - Binder Jetting KW - Layerwise slurry deposition KW - Silicon carbide KW - Wetting PY - 2022 DO - https://doi.org/10.1111/jace.18693 SN - 1551-2916 VL - 2022 SP - 1 EP - 15 PB - Wiley-Blackwell CY - Oxford AN - OPUS4-55542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Colombo, P. A1 - Günster, Jens A1 - Mühler, T. A1 - Heinrich, J.G. T1 - Selective laser densification of lithium aluminosilicate glass ceramic tapes JF - Applied surface science N2 - Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane. KW - Selective laser sintering (SLS) KW - Laserwise-slurry-deposition (LSD) KW - Glass-ceramic KW - LAS PY - 2013 UR - http://ac.els-cdn.com/S0169433212020168/1-s2.0-S0169433212020168-main.pdf?_tid=4ba0c92c-31d4-11e4-84f1-00000aab0f02&acdnat=1409575040_15d5256291262aca99cc5321374ab879 DO - https://doi.org/10.1016/j.apsusc.2012.11.058 SN - 0169-4332 SN - 1873-5584 VL - 265 SP - 610 EP - 614 PB - North-Holland CY - Amsterdam AN - OPUS4-31283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Mühler, T. A1 - Günster, Jens T1 - Powder-bed stabilization for powder-based additive manufacturing JF - Advances in mechanical engineering N2 - The most successful additive manufacturing (AM) technologies are based on the layer-by-layer deposition of a flowable powder. Although considered as the third industrial revolution, one factor still limiting these processes to become completely autonomous is the often necessary build-up of support structures. Besides the prevention of lateral shifts of the part during the deposition of layers, the support assures quality and stability to the built process. The loose powder itself surrounding the built object, or so-called powder-bed, does not provide this sustenance in most existent technology available. Here we present a simple but effective and economical method for stabilizing the powder-bed, preventing distortions in the geometry with no need for support structures. This effect, achieved by applying an air flow through the powder-bed, is enabling an entirely autonomous generation of parts and is a major contribution to all powder-based additive manufacturing technologies. Moreover, it makes powder-based AM independent of gravitational forces, which will facilitate crafting items in space from a variety of powdery materials. KW - Additive manufacturing KW - Powder bed PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-314244 DO - https://doi.org/10.1155/2014/491581 SN - 1687-8132 SN - 1687-8140 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 2014 SP - 491581-1 - 491581-6 PB - Hindawi Publishing Corporation CY - New York, NY ; Cairo AN - OPUS4-31424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Gomes, Cynthia A1 - Linow, Ulf A1 - Marx, Heidi A1 - Melcher, J A1 - Colombo, P A1 - Günster, Jens T1 - Structural optimization of printed structures by self-organized relaxation JF - Rapid Prototyping Journal N2 - Purpose – This paper aims to present an additive manufacturing-based approach in which a new strategy for a thermally activated local melting and material flow, which results in densification of printed structures, is introduced. Design/methodology/approach – For enabling this self-organized relaxation of printed objects by the viscous flow of material, two interconnected structures are printed simultaneously in one printing process, namely, Structure A actually representing the three dimensional object to be built and Structure B acting as a material reservoir for infiltrating Structure A. In an additional process step, subsequent to the printing job, an increase in the objects’ temperature results in the melting of the material reservoir B and infiltration of structure A. Findings – A thermally activated local melting of the polymethylsilsesquioxane results in densification of the printed structures and the local formation of structures with minimum surface area. Originality/value – The present work introduces an approach for the local relaxation of printed three-dimensional structures by the viscous flow of the printed material, without the loss of structural integrity of the structure itself. This approach is not restricted only to the materials used, but also offers a more general strategy for printing dense structures with a surface finish far beyond the volumetric resolution of the 3D printing process. KW - Printing KW - 3D PY - 2016 DO - https://doi.org/10.1108/RPJ-07-2014-0087 SN - 1355-2546 VL - 22 IS - 2 SP - 344 EP - 349 PB - Emerald AN - OPUS4-37447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elsayed, H. A1 - Zocca, Andrea A1 - Schmidt, J. A1 - Günster, Jens A1 - Colombo, P. A1 - Bernardo, E. T1 - Bioactive glass-ceramic scaffolds by additive manufacturing and sinter-crystallization of fi ne glass powders JF - Journal Materials Research N2 - Wollastonite (CaSiO 3 ) – diopside (CaMgSi 2 O 6 ) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn in fluenced by the powder size and the sensitivity of CaO – MgO – SiO 2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800 – 900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which bene fit theiruse for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed. KW - 3D-Printing KW - Bio Ceramic KW - Additive manufacturing PY - 2018 DO - https://doi.org/10.1557/jmr.2018.120 SN - 2044-5326 SN - 0884-2914 VL - 33 IS - 14 SP - 1960 EP - 1971 PB - Cambridge University Press AN - OPUS4-45718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günster, Jens A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Acchar, W. T1 - 3D printing of porcelain by layerwise slurry deposition JF - Journal of the European Ceramic Society N2 - The Layerwise Slurry Deposition is a technology for the deposition of highly packed powder layers. A powder bed is achieved by depositing and drying layers of a ceramic suspension by means of a doctor blade. This deposition technique was combined with the binder jetting technology to develop a novel Additive Manufacturing technology, named LSD-print. The LSD-print was applied to a porcelain ceramic. It is shown that it was possible to produce parts with high definition, good surface finish and at the same time having physical and mechanical properties close to those of traditionally processed porcelain, e.g. by slip casting. This technology shows high future potential for being integrated alongside traditional production of porce-lain, as it is easily scalable to large areas while maintaining a good definition. Both the Layerwise Slurry Deposition method and the binder jetting technologies are readily scalable to areas as large as > 1 m2. KW - Binder jetting KW - Additive Manufacturing KW - 3D printing KW - Porcelain PY - 2018 DO - https://doi.org/10.1016/j.jeurceramsoc.2018.03.014 SN - 0955-2219 VL - 38 IS - 9 SP - 3395 EP - 3400 PB - Elsevier Ltd. AN - OPUS4-45713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chi, Jinchun A1 - Zocca, Andrea A1 - Agea Blanco, Boris A1 - Melcher, J. A1 - Sparenberg, M. A1 - Günster, Jens T1 - 3D Printing of Self-Organizing Structural Elements for Advanced Functional Structures JF - Advanced Materials Technologies N2 - A shape evolution approach based on the thermally activated self-organization of 3D printed parts into minimal surface area structures is presented. With this strategy, the present communication opposes currently established additive manufacturing strategies aiming to stipulate each individual volumetric element (voxel) of a part. Instead, a 3D structure is roughly defined in a 3D printing process, with all its advantages, and an externally triggered self-organization allows the formation of structural elements with a definition greatly exceeding the volumetric resolution of the printing process. For enabling the self-organization of printed objects by viscous flow of material, functionally graded structures are printed as rigid frame and melting filler. This approach uniquely combines the freedom in design, provided by 3D printing, with the mathematical formulation of minimal surface structures and the knowledge of the physical potentials governing self-organization, to overcome the paradigm which strictly orrelates the geometrical definition of 3D printed parts to the volumetric resolution of the printing process. Moreover, a transient liquid phase allows local programming of functionalities, such as the alignment of functional particles, by means of electric or magnetic fields. KW - Additive Manufacturing KW - Self-Assembly KW - 3D-Printing KW - Polymeric Materials PY - 2018 DO - https://doi.org/10.1002/admt.201800003 SN - 2365-709X VL - 3 IS - 5 SP - 1800003-1 EP - 1800003-7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-45714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Melo Bernardino, Raphael A1 - Valentino, S. A1 - Franchin, G. A1 - Günster, Jens A1 - Zocca, Andrea T1 - Manufacturing of ceramic components with internal channels by a novel additive/subtractive hybridizazion process JF - Open Ceramics N2 - A new approach for fabrication of ceramic components with inner channels is proposed, as a result of the combination of two additive and one subtractive manufacturing processes. In this project, porcelain parts are manufactured by the Layerwise Slurry Deposition (LSD) process, meanwhile end milling and Direct Ink Writing (DIW) are applied to create channels on the surface of the deposited ceramic. Unique to the LSD process is the Formation of a freestanding powder bed with a mechanical strength comparable to conventional slip casted ceramic green bodies. Combining these three processes allows the manufacturing of ceramic objects containing an internal path of ink, which in this case was a graphite-based ink that can be further eliminated by heat treatment to obtain a porcelain object embedded with channels. The results show the capabilities of this method and its potential to fabricate not only parts with inner channels, but also multi-material and multi-functional components (such as integrated electronic circuits). KW - Additive Manufacturing KW - Layerwise Slurry Deposition KW - Hybrid Manufacturing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510012 UR - https://www.sciencedirect.com/science/article/pii/S2666539520300109?via%3Dihub DO - https://doi.org/10.1016/j.oceram.2020.100010 VL - 2 SP - 100010 PB - Elsevier Ltd. AN - OPUS4-51001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Fateri, M. A1 - Al-Sabbagh, Dominik A1 - Günster, Jens T1 - Investigation of the sintering and melting of JSC-2A lunar regolith simulant JF - Ceramics International N2 - Future lunar exploration can benefit greatly from In-Situ Resource Utilization. Accordingly, the in-Situ Resource Utilization approach highlights the need for detailed analysis of lunar regolith. In this study, JSC-2A Simulant was studied regarding its sintering and melting behaviour using Differential Thermal Analysis under ambient and inert conditions. The minerals at the crystalline peaks were determined using X-Ray Diffraction analysis. Moreover, melting droplet shape and wetting behaviour of pressed regolith samples of different particle size distributions were studied by Hot Stage Microscopy technique. Hot Stage Microscopy experiments were performed at different heating rates under ambient conditions. Bloating effects within the solidified samples were then qualitatively examined by X-ray tomography. Lastly, the optimization of processing strategies for the Additive Manufacturing of lunar regolith is discussed. KW - Lunar regolith KW - Sintering KW - Melting KW - Hot stage microscopy PY - 2020 DO - https://doi.org/10.1016/j.ceramint.2020.02.212 VL - 46 IS - 9 SP - 14097 EP - 14104 PB - Elsevier Ltd. AN - OPUS4-50869 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karl, D. A1 - Duminy, T. A1 - Lima, P. A1 - Kamutzki, F. A1 - Gili, A. A1 - Zocca, Andrea A1 - Günster, Jens A1 - Gurlo, A. T1 - Clay in situ resource utilization with Mars global simulant slurries for additive manufacturing and traditional shaping of unfired green bodies JF - Acta Astronautica N2 - The wet processing of regolith simulant for clay in situ resource utilization (ISRU) on Mars is presented. The two raw materials from the Mars global simulant family, one without clay (MGS-1) and one with clay - sodium montmorillonite smectite - (MGS-1C) were milled and mixed to produce a simulant with small particle size and reduced clay content (MGS-1C/8). All three simulants and the pure clay raw material were extensively characterized using XRF, synchrotron XRD, gas adsorption and gas pycnometry methods. In a straightforward processing approach, MGS-1C/8 was mixed with water and different dispersant approaches were investigated, all of which gave stable slurries. Particle size distribution, rheology, ion concentration, pH and electrical conductivity of these slurries were characterized. The slurry systems can easily be adapted to fit all typical ceramic shaping routes and here parts of varying complexity from slip casting, throwing on a potter's wheel and additive manufacturing, including material extrusion (robocasting) and binder jetting (powder bed 3D printing) were produced. The unique properties of the sodium montmorillonite clay, which is readily accessible in conjunction with magnesium sulfate on the Martian surface, acted as a natural nanosized binder and produced high strength green bodies (unfired ceramic body) with compressive strength from 3.3 to 7.5 MPa. The most elaborate additive manufacturing technique layerwise slurry deposition (LSD) produced water-resistant green bodies with a compressive strength of 30.8 ± 2.5 MPa by employing a polymeric binder, which is similar or higher than the strength of standard concrete. The unfired green bodies show sufficient strength to be used for remote Habitat building on Mars using additive manufacturing without humans being present. KW - Mars KW - Smectite KW - Clay ISRU KW - MGS-1 regolith simulant KW - 3D printing KW - Additive manufacturing PY - 2020 DO - https://doi.org/10.1016/j.actaastro.2020.04.064 VL - 174 SP - 241 EP - 253 PB - Elsevier Ltd. AN - OPUS4-50870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Elsayed, H. A1 - Bernardo, E. A1 - Wirth, Cynthia A1 - Lopez-Heredia, M.A. A1 - Knabe, C. A1 - Colombo, P. A1 - Günster, Jens T1 - 3D-printed silicate porous bioceramics using a non-sacrificial preceramic polymer binder JF - Biofabrication N2 - Silicate bioceramics possess an excellent bioactivity; however, shaping them into complex geometries is still challenging. Therefore, this paper aims to present a new strategy for the shaping of a bioglass-ceramic with controlled geometry and properties starting from a glass powder combined with a preceramic polymer, i.e. a silicon resin, and reactive fillers. The powder-based three-dimensional (3D)-printing of wollastonite (CaSiO3)-based silicate bioceramic parts was demonstrated in this work. The resin plays a dual role, as it not only acts as a non-sacrificial binder for the filler powders in the printing process but it also reacts with the fillers to generate the desired bioceramic phases. The mechanical and physical properties, i.e. ball-on-three-balls test, density, porosity and morphology, were evaluated in 3D-printed discs. These samples possessed a total porosity around 64 vol% and a biaxial flexural strength around 6 MPa. The raw materials used in this work also enabled the 3D-printing of scaffolds possessing a designed multi-scale porosity, suitable bioceramic phase assemblage and a compressive strength of 1 MPa (for cylindrical scaffolds with total porosity ~80 vol%). Solubility in TRIS/HCl and in vitro assays, i.e. viability, cytotoxicity and apoptosis assays, were also performed. In vitro tests indicated good cell viability and no cytotoxicity effect on the cells. KW - KNN KW - Glass microspheres PY - 2015 DO - https://doi.org/10.1088/1758-5090/7/2/025008 SN - 1758-5082 VL - 7 IS - 2 SP - 025008 PB - IOP Publ. CY - Philadelphia AN - OPUS4-34957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Colombo, P. A1 - Wirth, Cynthia A1 - Günster, Jens T1 - Additive manufacturing of ceramics: Issues, potentialities, and opportunities JF - Journal of the American ceramic society N2 - Additive manufacturing (AM) is a technology which has the potential not only to change the way of conventional industrial manufacturing processes, adding material instead of subtracting, but also to create entirely new production and business strategies. Since about three decades, AM technologies have been used to fabricate prototypes or models mostly from polymeric or metallic materials. Recently, products have been introduced into the market that cannot be produced in another way than additively. Ceramic materials are, however, not easy to process by AM technologies, as their processing requirements (in terms of feedstock and/or sintering) are very challenging. On the other hand, it can be expected that AM technologies, once successful, will have an extraordinary impact on the industrial production of ceramic components and, moreover, will open for ceramics new uses and new markets. KW - Additive Fertigung KW - Keramik PY - 2015 DO - https://doi.org/10.1111/jace.13700 SN - 0002-7820 SN - 1551-2916 VL - 98 IS - 7 SP - 1983 EP - 2001 PB - Blackwell Publishing CY - Malden AN - OPUS4-34961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elsayed, H. A1 - Zocca, Andrea A1 - Bernardo, E. A1 - Wirth, Cynthia A1 - Günster, Jens A1 - Colombo, P. T1 - Development of bioactive silicate-based glass-ceramics from preceramic polymer and filler JF - Journal of the European Ceramic Society N2 - 2014AbstractWollastonite/apatite glass-ceramics have been successfully prepared by a novel approach, consisting of the heat treatment of a silicone resinembedding micro-sized CaCO3particles, that act as reactive fillers, and bioactive glass powder in the SiO2–CaO–P2O5–K2O–Na2O–MgO–CaF2system. Zn-containing silicates, such as hardystonite (Ca2ZnSi2O7) and willemite (Zn2SiO4), were also developed either by directly mixing ZnOpowders with the glass, or by embedding them in the preceramic polymer, as additional fillers. KW - Additive manufacturing KW - Ceramics PY - 2015 DO - https://doi.org/10.1016/j.jeurceramsoc.2014.09.020 SN - 0955-2219 SN - 1873-619X VL - 35 SP - 731 EP - 739 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-34955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lima, P. A1 - Diener, S. A1 - Katsikis, N. A1 - Günster, Jens T1 - Additive manufacturing of SiSiC by layerwise slurry deposition and binder jetting (LSD-print) JF - Journal of the European Ceramic Society N2 - The current work presents for the first time results on the Additive Manufacturing of SiSiC complex parts based on the Layerwise Slurry Deposition (LSD) process. This technology allows to deposit highly packed powder layers by spreading a ceramic slurry and drying. The capillary forces acting during the process are responsible for the dense powder packing and the good joining between layers. The LSD process can be combined with binder jetting to print 2D cross-sections of an object in each successive layer, thus forming a 3D part. This process is named LSD-print. By LSD-print and silicon infiltration, SiSiC parts with complex geometries and features down to 1mm and an aspect ratio up to 4:1 could be demonstrated. The density and morphology were investigated for a large number of samples. Furthermore, the density and the mechanical properties, measured by ball-on-three-balls method, were in all three building directions close to isostatic pressed references. KW - Silicon Carbide KW - Additive Manufacturing KW - 3D printing KW - Layerwise slurry deposition KW - LSD print PY - 2019 DO - https://doi.org/10.1016/j.jeurceramsoc.2019.05.009 VL - 2019 IS - 39 SP - 3527 EP - 3533 PB - Elsevier Ltd. AN - OPUS4-48546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Günster, Jens T1 - LSD-based 3D printing of alumina ceramics JF - Journal of Ceramic Science and Technology N2 - An improved method of powder 3D printing leading to dense ceramic parts is presented. The application of powder-based binder jetting 3D printing technologies to technical ceramics is generally limited by the low packing density of the powder and by the need to use a flowable powder. With layer-wise slurry deposition, it is, however, possible to deposit powder beds with high particle packing and furthermore using submicron powders. This method was combined with the binder jetting technology to develop a novel process, named LSD-print. By means of LSD-print, a submicron Al2O3 powder could be processed to produce samples with a density comparable with that of standard pressed samples, both in the green state and after sintering. KW - Additive manufacturing KW - Layer-wise slurry deposition KW - Dense alumina KW - 3D printing PY - 2017 DO - https://doi.org/10.4416/JCST2016-00103 SN - 2190-9385 VL - 8 IS - 1, SI SP - 141 EP - 147 PB - Göller Verlag GmbH CY - Baden Baden AN - OPUS4-39672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karl, D. A1 - Kamutzki, F. A1 - Zocca, Andrea A1 - Görke, O. A1 - Günster, Jens A1 - Gurlo, A. T1 - Towards the colonization of Mars by in-situ resource utilization: Slip cast ceramics from Martian soil simulant JF - Plos One N2 - Here we demonstrate that by applying exclusively Martian resources a processing route involving suspensions of mineral particles called slurries or slips can be established for manufacturing ceramics on Mars. We developed water-based slurries without the use of additives that had a 51 wt. % solid load resembling commercial porcelain slurries in respect to the particle size distribution and rheological properties. These slurries were used to slip cast discs, rings and vases that were sintered at temperatures between 1000 and 1130 °C using different sintering schedules, the latter were set-up according the results of hot-stage microscopic characterization. The microstructure, porosity and the mechanical properties were characterized by SEM, X-ray Computer tomography and Weibull analysis. Our wet processing of minerals yields ceramics with complex shapes that show similar mechanical properties to porcelain and could serve as a technology for future Mars colonization. The best quality parts with completely vitrificated matrix supporting a few idiomorphic crystals are obtained at 1130 °C with 10 h dwell time with volume and linear shrinkage as much as ~62% and ~17% and a characteristic compressive strength of 51 MPa. KW - Ceramic KW - Mars PY - 2018 DO - https://doi.org/10.1371/journal.pone.0204025 SN - 1932-6203 VL - 13 IS - 10 SP - e0204025, 1 EP - 7 PB - Public Library of Science CY - San Francisco, Kalifornien, Vereinigte Staaten AN - OPUS4-46612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Colombo, P. A1 - Schmidt, J. A1 - Franchin, G. A1 - Zocca, Andrea A1 - Günster, Jens T1 - Additive manufacturing techniques for fabricating complex ceramic components from preceramic polymers JF - American Ceramic Society Bulletin N2 - Capsule summary THE MATERIALS Manufacturers can use preceramic polymers to produce ceramic components in a range of compositions using a variety of additive manufacturing technologies. Preceramic polymers even can overcome some of the problems that are intrinsic to additive manufacturing in general. THE APPLICATION Modifying the composition, molecular architecture, and molecular weight of preceramic polymers allows adaptation of these materials to specific processing requirements of individual additive manufacturing technologies. THE OPPORTUNITY Further development of new additive manufacturing technologies, in addition to improvement of existing technologies, will enable manufacturing of advanced ceramic components with enhanced mechanical characteristics and new functional properties. KW - Additive manufacturing KW - Preceramic polymers PY - 2017 VL - 96 IS - 3 SP - 16 EP - 23 AN - OPUS4-40747 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diener, S. A1 - Schubert, Hendrik A1 - Günster, Jens A1 - Zocca, Andrea T1 - Ink development for the additive manufacturing of strong green parts by layerwise slurry deposition (LSD-print) JF - Journal of the American Ceramic Society N2 - Obtaining dense fine ceramics by the binder jetting additive manufacturing process is challenging. A slurry-based binder jetting process, such as the layerwise slurry deposition (LSD-print) process, can enable the printing of dense ceramic parts. This work describes a procedure to develop and qualify a suitable ink to manufacture silicon carbide green parts by LSD-print. Not only the printability but also the compatibility of the ink with the powder bed and the effect of the binding agent on the properties of the green parts are considered. Both aspects are important to obtain high green strength, which is necessary for printing large or thin-walled parts. Characterization methods, such as rheological and surface tension measurements, are applied to optimize three selected inks. The interplay between ink and powder bed is tested by contact angle measurements and by comparing the biaxial strength of cast and additively manufactured specimens. Out of the three binding agents tested, a polyethyleneimine and a phenolic resin have a high potential for their use in the LSD-print of silicon carbide green bodies, whereas a polyacrylate binding agent did not show the required properties. KW - Silicon carbide KW - Binders/binding KW - Inkjet KW - Printing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567911 DO - https://doi.org/10.1111/jace.18951 SN - 0002-7820 SP - 1 EP - 12 PB - Wiley online library AN - OPUS4-56791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Müller, Bernd R. A1 - Laquai, René A1 - Kupsch, Andreas A1 - Wieder, Frank A1 - Benemann, Sigrid A1 - Wilbig, Janka A1 - Günster, Jens A1 - Bruno, Giovanni T1 - Microstructural characterization of AP40 apatite-wollastonite glass-ceramic JF - Ceramics international N2 - The microstructure of an apatite-wollastonite (code name AP40) glass-ceramic is analyzed in this study by combining 2D microscopy, phase analysis, X-ray absorption and synchrotron X-ray refraction computed tomography (XCT and SXRCT, respectively). It is shown that this combination provides a useful toolbox to characterize the global microstructure in a wide scale range, from sub-micrometer to millimeter. The material displays a complex microstructure comprising a glassy matrix with embedded fluorapatite and wollastonite small crystals. In this matrix, large (up to 200 μm) spike-shaped structures are distributed. Such microstructural features are oriented around a central sphere, thereby forming a structure resembling a sea urchin. A unique feature of SXRCT, in contrast to XCT, is that internal interfaces are visualized; this allows one to show the 3D distribution of these urchins with exceptionally good contrast. Furthermore, it is revealed that the spike-shaped structures are not single crystals, but rather composed of sub-micrometric crystals, which are identified as fluorapatite and diopside phases by SEM-EDX analysis. KW - Glass-ceramic KW - X-ray refraction KW - Computed tomography KW - Microstructure PY - 2023 DO - https://doi.org/10.1016/j.ceramint.2022.12.130 SN - 0272-8842 VL - 49 IS - 8 SP - 12672 EP - 12679 PB - Elsevier Science CY - Amsterdam AN - OPUS4-57452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ginés-Palomares, J.-C. A1 - Fateri, M. A1 - Schubert, T. A1 - de Peindray d’Ambelle, L. A1 - Simon, Sebastian A1 - Gluth, Gregor A1 - Günster, Jens A1 - Zocca, Andrea T1 - Material aspects of sintering of EAC-1A lunar regolith simulant JF - Scientific Reports N2 - Future lunar exploration will be based on in-situ resource utilization (ISRU) techniques. The most abundant raw material on the Moon is lunar regolith, which, however, is very scarce on Earth, making the study of simulants a necessity. The objective of this study is to characterize and investigate the sintering behavior of EAC-1A lunar regolith simulant. The characterization of the simulant included the determination of the phase assemblage, characteristic temperatures determination and water content analysis. The results are discussed in the context of sintering experiments of EAC-1A simulant, which showed that the material can be sintered to a relative density close to 90%, but only within a very narrow range of temperatures (20–30 °C). Sintering experiments were performed for sieved and unsieved, as well as for dried and non-dried specimens of EAC-1A. In addition, an analysis of the densification and mechanical properties of the sintered specimens was done. The sintering experiments at different temperatures showed that the finest fraction of sieved simulant can reach a higher maximum sintering temperature, and consequently a higher densification and biaxial strength. The non-dried powder exhibited higher densification and biaxial strength after sintering compared to the dried specimen. This difference was explained with a higher green density of the non-dried powder during pressing, rather than due to an actual influence on the sintering mechanism. Nevertheless, drying the powder prior to sintering is important to avoid the overestimation of the strength of specimens to be fabricated on the Moon. KW - Lunar regolith KW - Ceramics KW - Microstructure KW - Sintering KW - Softening temperature PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592668 DO - https://doi.org/10.1038/s41598-023-50391-y SN - 2045-2322 VL - 13 SP - 1 EP - 14 PB - Springer Nature AN - OPUS4-59266 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Wilbig, Janka A1 - Mohr, Gunther A1 - Villatte, T. A1 - Léonard, Fabien A1 - Nolze, Gert A1 - Sparenberg, M. A1 - Melcher, J. A1 - Hilgenberg, Kai A1 - Günster, Jens T1 - Enabling the 3D Printing of Metal Components in μ-Gravity JF - Advanced Materials Technologies N2 - As humanity contemplates manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments to safely work in space for years. The supply of spare parts for repair and replacement of lost equipment will be one key need, but in-space manufacturing remains the only option for a timely supply. With high flexibility in design and the ability to manufacture ready-to-use components directly from a computeraided model, additive manufacturing (AM) technologies appear extremely attractive. For the manufacturing of metal parts, laser-beam melting is the most widely used AM process. However, the handling of metal powders in the absence of gravity is one prerequisite for its successful application in space. A gas flow throughout the powder bed is successfully applied to compensate for missing gravitational forces in microgravity experiments. This so-called gas-flow-assisted powder deposition is based on a porous Building platform acting as a filter for the fixation of metal particles in a gas flow driven by a pressure difference maintained by a vacuum pump. KW - Additive manufacturing KW - µ-gravity KW - Laser beam melting KW - Parabolic flight KW - 3D printing PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492190 DO - https://doi.org/10.1002/admt.201900506 SP - 1900506 PB - WILEY-VCH Verlag GmbH AN - OPUS4-49219 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Zocca, Andrea T1 - Dense Powder Beds for the Additive Manufacturing of Ceramics N2 - Regarding feedstocks for the additive manufacturing (AM) of ceramics, two features are most critical in classical powder based AM processes: a high particle packing density (typically >50% TD) must be achieved with very fine particles (typically submicron) in order to ensure sufficient sintering activity. Three innovative approaches will be introduced to overcome this problem: 1. Layer wise slurry deposition: The use of water based ceramic slurries as feedstock for the additive manufacture of ceramics has many advantages which are not fully exploit yet. In the layerwise slurry deposition (LSD) process a slurry with no or low organic content is repetitively spread as thin layers on each other by means of a doctor blade. During the deposition, the ceramic particles settle on the previously deposited and dried material to form thin layers with a high packing density (55-60%). The LSD therefore shares aspects both of tape casting and slip casting. The LSD differentiates from the classical powder-based AM layer deposition, which typically achieves with a flowable coarse grained powder a low packing density (35-50%) only, consequently hindering the ability of sintering ceramic parts to full density. The LSD is coupled with the principles of selective laser sintering (SLS) or binder jetting, to generate novel processes which take advantage of the possibility of achieving a highly dense powder-bed. 2. Laser induced slip casting: Contrary to the LSD process, which requires drying of each individual layer, the direct interaction of ceramic slurries with intense laser radiation, for the laser induced slip casting (LIS), is a promising approach for the additive manufacture of voluminous parts. 3. Gas flow assisted powder deposition: By the application of a vacuum pump a gas flow is realized throughout the powder bed. This gas flow stabilizes the powder bed and results into an enhanced flowability and packing density of the powder during layer deposition. The presentation will provide a detailed discussion of potentialities and issues connected to the mentioned technologies and will describe the most recent developments in their application to technical ceramics. T2 - SmatMade 2022 CY - Osaka, Japan DA - 25.10.2022 KW - Additive Manufacturing KW - Advanced ceramics PY - 2022 AN - OPUS4-59886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Moritz A1 - Stawarczyk, Bogna A1 - Günster, Jens A1 - Zocca, Andrea T1 - Influence of additives and binder on the physical properties of dental silicate glass-ceramic feedstock for additive manufacturing JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - Objectives The aim of the study was to investigate the impact of organic additives (binder, plasticizer, and the cross-linking ink) in the formulation of water-based feedstocks on the properties of a dental feldspathic glass-ceramic material developed for the slurry-based additive manufacturing technology “LSD-print.” Material and methods Three water-based feldspathic feedstocks were produced to study the effects of polyvinyl alcohol (AC1) and poly (sodium 4-styrenesulfonate) (AC2) as binder systems. A feedstock without organic additives was tested as the control group (CG). Disc-shaped (n = 15) and bar (n = 7) specimens were slip-cast and characterized in the green and fired states. In the green state, density and flexural strength were measured. In the fired state, density, shrinkage, flexural strength (FS), Weibull modulus, fracture toughness (KIC), Martens parameters, and microstructure were analyzed. Disc-shaped and bar specimens were also cut from commercially available CAD/CAM blocks and used as a target reference (TR) for the fired state. Results In the green state, CG showed the highest bulk density but the lowest FS, while the highest FS in the green state was achieved with the addition of a cross-linking ink. After firing, no significant differences in density and a similar microstructure were observed for all slip-cast groups, indicating that almost complete densification could be achieved. The CAD/CAM specimens showed the highest mean FS, Weibull modulus, and KIC, with significant differences between some of the slip-cast groups. Significance These results suggest that the investigated feedstocks are promising candidates for the slurry-based additive manufacturing of restorations meeting the class 1a requirements according to DIN EN ISO 6871:2019–01. KW - Firing KW - 3D-printing KW - Silicate glass-ceramics KW - Debinding PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600516 DO - https://doi.org/10.1016/j.jmbbm.2024.106563 SN - 1751-6161 VL - 155 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-60051 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -