TY - JOUR A1 - Günster, Jens A1 - Heinrich, J. T1 - 2nd International symposium on materials processing science with lasers as energy sources KW - Materials science PY - 2012 SN - 0173-9913 SN - 0196-6219 VL - 89 IS - 6-7 SP - E 36 PB - Göller CY - Baden-Baden AN - OPUS4-31281 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dombrowski, Felix A1 - Garcia Caso, P.W. A1 - Laschke, M.W. A1 - Klein, M. A1 - Günster, Jens A1 - Berger, Georg T1 - 3-D printed bioactive bone replacement scaffolds of alkaline substituted ortho-phosphates containing meta- and di-phosphates KW - Calcium alkaline phosphates KW - 3-D printing KW - Porosity KW - Compressive strength PY - 2013 DO - https://doi.org/10.4028/www.scientific.net/KEM.529-530.138 SN - 1013-9826 VL - 529-530 SP - 138 EP - 142 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-26972 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 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 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 - 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 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 - Hlavacek, Petr A1 - Gluth, Gregor A1 - Lüchtenborg, Jörg A1 - Sturm, Patrick A1 - Mühler, T. A1 - Kühne, Hans-Carsten A1 - Günster, Jens T1 - A Novel Approach to Additive Manufacturing of Alkali-activated Materials: Laser-induced Slip Casting (LIS) of Lithium Aluminate/Silica Slurries N2 - Additive manufacturing of alkali-activated materials currently attracts a lot of attention, because of the possibility to produce customized high-performance elements for a range of applications, potentially being more resource-efficient than conventionally produced parts. Here, we describe a new additive manufacturing process for alkali-activated materials that is based on selective laser-heating of lithium aluminate/microsilica slurries. The new process-material combination allows to manufacture elements with complex geometries at high building rates and high accuracy. The process is versatile and transferrable to structures of sizes differing by orders of magnitude. The mechanical strength of the obtained materials was in the range of values reported for conventional metakaolin-based geopolymers, and superior to what has been hitherto reported for alkali-activated materials produced by additive manufacturing. This mechanical performance was obtained despite the fact that the degree of reaction of the lithium aluminate and the microsilica was low, suggesting that significant reactions took place only at the surface of the microsilica particles. KW - Laser-induced slip casting KW - Alkali-activated materials KW - Additive manufacturing PY - 2019 DO - https://doi.org/10.29272/cmt.2018.0011 SN - 2612-4882 VL - 1 IS - 2 SP - 138 EP - 144 PB - Techna Group AN - OPUS4-49142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Knabe, C. A1 - Stiller, M. A1 - Kampschulte, M. A1 - Wilbig, Janka A1 - Peleska, B. A1 - Günster, Jens A1 - Gildenhaar, R. A1 - Berger, G. A1 - Rack, A. A1 - Linow, U. A1 - Heiland, M. A1 - Rendenbach, C. A1 - Koerdt, S. A1 - Steffen, C. A1 - Houshmand, A. A1 - Xiang-Tischhauser, L. A1 - Adel-Khattab, D. T1 - A tissue engineered 3D printed calcium alkali phosphate bioceramic bone graft enables vascularization and regeneration of critical-size discontinuity bony defects in vivo N2 - Recently, efforts towards the development of patient-specific 3D printed scaffolds for bone tissue engineering from bioactive ceramics have continuously intensified. For reconstruction of segmental defects after subtotal mandibulectomy a suitable tissue engineered bioceramic bone graft needs to be endowed with homogenously distributed osteoblasts in order to mimic the advantageous features of vascularized autologous fibula grafts, which represent the standard of care, contain osteogenic cells and are transplanted with the respective blood vessel. Consequently, inducing vascularization early on is pivotal for bone tissue engineering. The current study explored an advanced bone tissue engineering approach combining an advanced 3D printing technique for bioactive resorbable ceramic scaffolds with a perfusion cell culture technique for pre-colonization with mesenchymal stem cells, and with an intrinsic angiogenesis technique for regenerating critical size, segmental discontinuity defects in vivo applying a rat model. To this end, the effect of differing Si-CAOP (silica containing calcium alkali orthophosphate) scaffold microarchitecture arising from 3D powder bed printing (RP) or the Schwarzwalder Somers (SSM) replica fabrication technique on vascularization and bone regeneration was analyzed in vivo. In 80 rats 6-mm segmental discontinuity defects were created in the left femur. KW - Additive Manufacturing KW - Bio active ceramic KW - In-vivo KW - Alcium alkali phosphate PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584555 DO - https://doi.org/10.3389/fbioe.2023.1221314 SN - 2296-4185 VL - 11 SP - 1 EP - 20 PB - Frontiers SA CY - Lausanne AN - OPUS4-58455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Homberg, U. A1 - Baum, D. A1 - Prohaska, S. A1 - Günster, Jens A1 - Krauss-Schüler, Stefanie T1 - Adapting trabecular structures for 3D printing: an image processing approach based on μCT data N2 - Materials with a trabecular structure notably Combine advantages such as lightweight, reasonable strength, and permeability for fl uids. This combination of advantages is especially interesting for tissue engineering in trauma surgery and orthopedics. Bone-substituting scaffolds for instance are designed with a trabecular structure in order to allow cell migration for bone ingrowth and vascularization. An emerging and recently very popular technology to produce such complex, porous structures is 3D printing. However, several technological aspects regarding the scaffold architecture, the printable resolution, and the feature size have to be considered when fabricating scaffolds for bone tissue replacement and regeneration. Here, we present a strategy to assess and prepare realistic trabecular structures for 3D printing using image analysis with the aim of preserving the structural elements. We discuss critical conditions of the printing system and present a 3-stage approach to adapt a trabecular structure from μ CT data while incorporating knowledge about the printing system. In the first stage, an image-based extraction of solid and void structures is performed, which results in voxel- and graph-based representations of the extracted structures. These representations not only allow us to quantify geometrical properties such as pore size or strut geometry and length. But, since the graph represents the geometry and the topology of the initial structure, it can be used in the second stage to modify and adjust feature size, volume and sample size in an easy and consistent way. In the final reconstruction stage, the graph is then converted into a voxel representation preserving the topology of the initial structure. This stage generates a model with respect to the printing conditions to ensure a stable and controlled voxel placement during the printing process. KW - Additive manufacturing, 3D printing KW - Trabecular structures KW - Image-based analysis PY - 2017 DO - https://doi.org/10.1088/2057-1976/aa7611 SN - 2057-1976 VL - 3 IS - 3 SP - Article 035027, 1 EP - 14 PB - IOP Publishing Ltd AN - OPUS4-40744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hilgenberg, Kai A1 - Daum, Werner A1 - Maierhofer, Christiane A1 - Altenburg, Simon A1 - Bruno, Giovanni A1 - Heckel, Thomas A1 - Skrotzki, Birgit A1 - Zerbst, Uwe A1 - Kranzmann, Axel A1 - Bettge, Dirk A1 - Sommer, Konstantin A1 - Seeger, Stefan A1 - Nitsche, Michael A1 - Günster, Jens A1 - Evans, Alexander T1 - Additive manufacturing at the BAM: We focus on Safety N2 - In Germany, the Federal Institute for Materials Research and Testing (BAM) is addressing challenges in the implementation of additive manufacturing on the industrial landscape for safety-critical applications. KW - Process development KW - Additive Manufacturing KW - In-situ Process Monitoring KW - Non-destructive Materials KW - Characterisation KW - Safety KW - Fatigue KW - Environment KW - Standardisation PY - 2019 UR - https://static.asminternational.org/amp/201910/22/ SN - 0882-7958 VL - 177 IS - 7 SP - 22 EP - 26 PB - ASM International CY - Materials Park, OH, USA AN - OPUS4-49780 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 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 - Neumann, Christian A1 - Thore, Johannes A1 - Clozel, Mélanie A1 - Günster, Jens A1 - Wilbig, Janka A1 - Meyer, Andreas T1 - Additive manufacturing of metallic glass from powder in space N2 - Additive manufacturing of metals – and in particular building with laser-based powder bed fusion – is highly flexible and allows high-resolution features and feedstock savings. Meanwhile, though space stations in low Earth orbit are established, a set of visits to the Moon have been performed, and humankind can send out rovers to explore Venus and Mars, none of these milestone missions is equipped with technology to manufacture functional metallic parts or tools in space. In order to advance space exploration to long-term missions beyond low Earth orbit, it will be crucial to develop and employ technology for in-space manufacturing (ISM) and in-situ resource utilisation (ISRU). To use the advantages of laser-based powder bed fusion in these endeavours, the challenge of powder handling in microgravity must be met. Here we present a device capable of building parts using metallic powders in microgravity. This was proven on several sounding rocket flights, on which occasions Zr-based metallic glass parts produced by additive manufacturing in space were built. The findings of this work demonstrate that building parts using powder feedstock, which is more compact to transport into space than wire, is possible in microgravity environments. This thus significantly advances ISRU and ISM and paves the way for future tests in prolonged microgravity settings. KW - Metallic Glass KW - Additive Manufacturing KW - Space PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600667 DO - https://doi.org/10.1038/s41526-023-00327-7 VL - 9 SP - 1 EP - 9 PB - Springer Nature AN - OPUS4-60066 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) 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 - 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 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 - 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 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 - 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 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 - 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 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 - 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 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 - Oelgardt, C. A1 - Günster, Jens A1 - Heinrich, J.G. T1 - Characterization of the crystallization behavior of laser-fused transparent microspheres with the eutectic composition Al2O3-Y2O3-ZrO2 (AYZ) N2 - Transparent microspheres with the eutectic composition 65 Al2O3-16 Y2O3-19 ZrO2 (mol%) have been produced by laser fusing with a CO2 laser. The influence of the starting material – not pre-calcined and pre-calcined – as well as the laser power on the resulting microspheres – was investigated. After fabrication, the microspheres were analyzed by means of XRD to quantify the amorphous content of the spheres as well as to identify the residual crystalline phases, with a laser granulometer to measure the particle sizes of the starting material and the resulting microspheres, with DSC to characterize the glass transition temperature and crystallization behavior, and with SEM to investigate the microstructure of the microspheres. The laser-treated materials consist of transparent and opaque beads as well as sintered particles. The amorphous amount in the samples was detected to be ~ 85 %. Based on these results transparent beads were collected and annealed over a range of temperatures to analyze the crystallization behavior. KW - Eutectic ceramics KW - Al2O3-Y2O3-ZrO2 KW - Laser processing KW - Crystallization behavior KW - Microstructure PY - 2011 DO - https://doi.org/10.4416/JCST2011-00010 SN - 2190-9385 VL - 02 IS - 02 SP - 103 EP - 110 PB - Göller CY - Baden-Baden AN - OPUS4-23763 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 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 - Xin, L. A1 - Bungartz, M. A1 - Maenz, S. A1 - Horbert, V. A1 - Hennig, M. A1 - Illerhaus, Bernhard A1 - Günster, Jens A1 - Bossert, J. A1 - Bischoff, S. A1 - Borowski, J. A1 - Schubert, H. A1 - Jandt, K. A1 - Kunisch, E. A1 - Kinne, R. A1 - Brinkmann, O. T1 - Decreased extrusion of calcium phosphate cement versus high viscosity PMMA cement into spongious bone marrow—an ex vivo and in vivo study in sheep vertebrae N2 - Vertebroplasty or kyphoplasty of osteoporotic vertebral fractures bears the risk of pulmonary cement embolism (3.5%–23%) caused by leakage of commonly applied acrylic polymethylmethacrylate (PMMA) cement to spongious bone marrow or outside of the vertebrae. Ultraviscous cement and specific augmentation systems have been developed to reduce such adverse effects. Rapidly setting, resorbable, physiological calcium phosphate cement (CPC) may also represent a suitable alternative. PURPOSE: This study aimed to compare the intravertebral extrusion of CPC and PMMA cement in an ex vivo and in vivo study in sheep. STUDY DESIGN/SETTING: A prospective experimental animal study was carried out. METHODS: Defects (diameter 5 mm; 15 mm depth) were created by a ventrolateral percutane-ous approach in lumbar vertebrae of female Merino sheep (2–4 years) either ex vivo (n = 17) or in vivo (n = 6), and injected with: (1) CPC (L3); (2) CPC reinforced with 10% poly(l-lactide-co-glycolide) (PLGA) fibers (L4); or (3) PMMA cement (L5; Kyphon HV-R). Controls were untouched (L1) or empty defects (L2). The effects of the cement injections were assessed in vivo by blood gas analysis and ex vivo by computed tomography (CT), micro-CT (voxel size: 67 µm), histology, and biomechanical testing. KW - Bone marrow extrusion KW - Brushite-forming calcium phosphate cement KW - Cement injection KW - Ex vivo KW - High- viscosity PMMA cement KW - In vivo KW - Large animal model KW - Sheep KW - Vertebroplasty PY - 2016 DO - https://doi.org/10.1016/j.spinee.2016.07.529 SN - 1529-9430 SN - 1878-1632 VL - 16 IS - 12 SP - 1468 EP - 1477 PB - Elsevier Inc. AN - OPUS4-38058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wilbig, Janka A1 - Borges de Oliveira, F. A1 - Obaton, A.-F. A1 - Schwentenwein, M. A1 - Rübner, Katrin A1 - Günster, Jens T1 - Defect detection in additively manufactured lattices N2 - This paper investigates fast and inexpensive measurement methods for defect detection in parts produced by Additive Manufacturing (AM) with special focus on lattice parts made of ceramics. By Lithography-based Ceramic Manufacturing, parts were built both without defects and with typical defects intentionally introduced. These defects were investigated and confirmed by industrial X-ray Computed Tomography. Alternative inexpensive methods were applied afterwards on the parts such as weighing, volume determination by Archimedes method and gas permeability measurement. The results showed, that defects resulting in around 20% of change in volume and mass could be separated from parts free of defects by determination of mass or volume. Minor defects were not detectable as they were in the range of process-related fluctuations. Permeability measurement did not allow to safely identify parts with defects. The measurement methods investigated can be easily integrated in AM process chains to support quality control. KW - Additive manufacturing KW - Quality assurance KW - Defect detection KW - Lattices KW - Ceramics PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513547 DO - https://doi.org/10.1016/j.oceram.2020.100020 VL - 3 SP - 100020 PB - Elsevier Ltd. AN - OPUS4-51354 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 - Adel-Khattab, D. A1 - Giacomini, F. A1 - Gildenhaar, R. A1 - Berger, G. A1 - Gomes, Cynthia A1 - Linow, Ulf A1 - Hardt, M. A1 - Peleska, B. A1 - Günster, Jens A1 - Stiller, M. A1 - Houshmand, A. A1 - Ghaffar, K. A1 - Gamal, A. A1 - El-Mofty, M. A1 - Knabe, C. T1 - Development of a synthetic tissue engineered three- dimensional printed bioceramic-based bone graft with homogenously distributed osteoblasts and mineralizing bone matrix in vitro N2 - Over the last decade there have been increasing efforts to develop three-dimensional (3D) scaffolds for bone tissue Engineering from bioactive ceramics with 3D printing emerging as a promising technology. The overall objective of the present study was to generate a tissue engineered synthetic bone graft with homogenously distributed osteoblasts and mineralizing bone Matrix in vitro, thereby mimicking the advantageous properties of autogenous bone grafts and facilitating usage for reconstructing segmental discontinuity defects in vivo . To this end, 3D scaffolds were developed from a silica-containing calcium alkali orthophosphate, using, fi rst, a replica technique – the Schwartzwalder – Somers method – and, second, 3D printing, (i.e. rapid prototyping). The mechanical and physical scaffold properties and their potential to facilitate homogenous colonization by osteogenic cells and extracellular bone matrix formation throughout the porous scaffold architecture were examined. Osteoblastic cells were dynamically cultured for 7 days on both scaffold types with two different concentrations of 1.5 and 3 × 10⁹ cells/l. The amount of cells and bone matrix formed and osteogenic marker expression were evaluated using hard tissue histology, immunohistochemical and histomorphometric analysis. 3D-printed scaffolds (RPS) exhibited more micropores, greater compressive strength and silica release. RPS seeded with 3 × 10⁹ cells/l displayed greatest cell and extracellular Matrix formation, mineralization and osteocalcin expression. In conclusion, RPS displayed superior mechanical and biological properties and facilitated generating a tissue engineered synthetic bone graft in vitro, which mimics the advantageous properties of autogenous bone grafts, by containing homogenously distributed terminally differentiated osteoblasts and mineralizing bone matrix and therefore is suitable for subsequent in vivo implantation for regenerating segmental discontinuity bone defects. KW - Bone tissue engineering KW - Calcium alkali orthophosphate KW - Rapid prototyping KW - Scaffold KW - Mandible PY - 2017 DO - https://doi.org/10.1002/term.2362 SN - 1932-6254 SN - 1932-7005 VL - 12 IS - 1 SP - 44 EP - 58 PB - Wiley Online Library AN - OPUS4-40745 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 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 - Xu, F. A1 - Ren, H. A1 - Zheng, M. A1 - Shao, X. A1 - Dai, T. A1 - Wu, Y. A1 - Tian, L. A1 - Liu, Y. A1 - Liu, B. A1 - Günster, Jens A1 - Liu, Y. A1 - Liu, Y. T1 - Development of biodegradable bioactive glass ceramics by DLP printed containing EPCs/BMSCs for bone tissue engineering of rabbit mandible defects N2 - Bioactive glass ceramics have excellent biocompatibility and osteoconductivity; and can form direct chemical bonds with human bones; thus, these ceramic are considered as “Smart” materials. In this study, we develop a new type of bioactive glass ceramic (AP40mod) as a scaffold containing Endothelial progenitor cells (EPCs) and Mesenchymal stem cells (BMSCs) to repair critical-sized bone defects in rabbit mandibles. For in vitro experiments: AP40mod was prepared by Dgital light processing (DLP) system and the optimal ratio of EPCs/BMSCs was screened by analyzing cell proliferation and ALP activity, as well as the influence of genes related to osteogenesis and angiogenesis by direct inoculation into scaffolds. The scaffold showed suitable mechanical properties, with a Bending strength 52.7 MPa and a good biological activity. Additionally, when EPCs/BMSCs ratio were combined at a ratio of 2:1 with AP40mod, the ALP activity, osteogenesis and angiogenesis were significantly increased. For in vivo experiments: application of AP40mod/EPCs/BMSCs (after 7 days of in vitro spin culture) to repair and reconstruct critical-sized mandible defect in rabbit showed that all scaffolds were successfully accurately implanted into the defect area. As revealed by macroscopically and CT at the end of 9 months, defects in the AP40mod/EPCs/BMSCs group were nearly completely covered by normal bone and the degradation rate was 29.9% compared to 20.1% in the AP40mod group by the 3D reconstruction. As revealed by HE and Masson staining analyses, newly formed blood vessels, bone marrow and collagen maturity were significantly increased in the AP40mod/EPCs/BMSCs group compared to those in the AP40mod group. We directly inoculated cells on the novel material to screen for the best inoculation ratio. It is concluded that the AP40mod combination of EPCs/BMSCs is a promising approach for repairing and reconstructing large load bearing bone defect. KW - Three-dimensional Bone tissue engineering KW - Endothelial progenitor cell KW - Bone marrow-derived mesenchymal stem cell KW - Bioactive glass scaffold PY - 2020 DO - https://doi.org/10.1016/j.jmbbm.2019.103532 SN - 1751-6161 VL - 103 SP - 103532 EP - 103532 PB - Elsevier Ltd. AN - OPUS4-50491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lopez-Heredia, M.A. A1 - Gildenhaar, Renate A1 - Berger, Georg A1 - Linow, Ulf A1 - Wirth, Cynthia A1 - Günster, Jens A1 - Houshmand, A. A1 - Stiller, M. A1 - Knabe-Ducheyne, C. T1 - Effect of stressed and unstressed cell culture environments on the viability of MC3T3 cells with calcium phosphates T2 - ISACB-6 - International symposium on apatite and correlative biomaterials CY - Nantes, France DA - 2013-06-05 KW - Cell culture media KW - Fetal bovine serum KW - Stressed KW - Unstressed KW - Calcium alkaline orthophosphates PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-299387 DO - https://doi.org/10.4172/2090-5025.S1-002 SN - 2090-5017 SN - 2090-5025 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. SP - 1 EP - 3(?) PB - Ashdin AN - OPUS4-29938 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 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 - JOUR A1 - Maenz, S. A1 - Brinkmann, O. A1 - Kunisch, E. A1 - Horbert, V. A1 - Gunella, F. A1 - Bischoff, S. A1 - Schubert, H. A1 - Sachse, A. A1 - Xin, L. A1 - Günster, Jens A1 - Illerhaus, Bernhard A1 - Jandt, K. D. A1 - Bossert, J. A1 - Kinne, R. W. A1 - Bungartz, M. T1 - Enhanced bone formation in sheep vertebral bodies after minimally invasive treatment with a novel, PLGA fiber-reinforced brushite cement. N2 - Injectable, brushite-forming calcium phosphate cements (CPC) show potential for bone replacement, but they exhibit low mechanical strength. This study tested a CPC reinforced with poly(l-lactide-co-glycolide) acid (PLGA) fibers in a minimally invasive, sheep lumbar vertebroplasty model. The study aimed to test the in vivo biocompatibility and osteogenic potential of a PLGA fiber-reinforced, brushite-forming CPC in a sheep large animal model. KW - µCT KW - Vertebral KW - PLGA cement PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S152994301631066X DO - https://doi.org/10.1016/j.spinee.2016.11.006 SN - 1529-9430 SN - 1878-1632 VL - 17 IS - 5 SP - 709 EP - 719 PB - Elsevier Science direct AN - OPUS4-40462 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 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 - JOUR A1 - Sun, C. A1 - Tian, X. A1 - Wang, L. A1 - Liu, Y. A1 - Wirth, Cynthia A1 - Günster, Jens A1 - Li, D. A1 - Jin, Z. T1 - Effect of particle size gradation on the performance of glass-ceramic 3D printing process N2 - Particle size gradation is regarded as an effective method for overcoming the contradicting requirements in three-dimensional printing (3DP). In present work, particle size gradation was optimized to obtain both acceptable flowability of the powder material and high-strength 3D-printed glass-ceramic products. The effect of gradation on the printing process, sintering process and performance of the 3D-printed glass-ceramic products was investigated comprehensively. The glass-ceramic powders with three size ranges were mixed in certain proportions and applied to print parts. The result showed parts printed with powder mixed by 60 wt% 45–100 µm and 40 wt% 0–25 µm particles had satisfactory density of 1.60 g/cm³ and bending strength of 13.8 MPa. The flowability decreased with an increasing proportion of fine particles. Part density was determined by the powder bulk density in the powder bed as well as the shrinkage during sintering while strength of part was found to be dependent on the sintering degree. KW - Flowability KW - Glass-ceramic KW - Particle size gradation KW - Three-dimensional printing KW - Mechanical properties PY - 2017 DO - https://doi.org/10.1016/j.ceramint.2016.09.197 SN - 0272-8842 VL - 43 IS - 1 SP - 578 EP - 584 PB - Elsevier AN - OPUS4-39783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Sturm, Heinz A1 - Günster, Jens T1 - First time additively manufactured advanced ceramics by using two-photon polymerization for powder processing N2 - Methods and materials are presented here, which enable the manufacturing of fine structures using a 3D-printing method known as two-photon polymerization (2PP). As traditional photolithography methods for structuring ceramic slurries do not function with 2PP, due to light scattering on ceramic particles, a novel water-based photoresist with high ceramic loading of extremely well dispersed ceramic nano particles was developed. This photoresist is basically a ceramic slurry containing a photocurable agent and a photoinitiator to be crosslinkable with the 780 nm wavelength femtosecond laser light source of the 2PP machine. It is demonstrated that it is possible to gain a highly transparent and low viscous slurry suitable for 2PP processing. This work shows the development of the slurry, first printing results and the post-printing processes required to form three dimensional ceramic microstructures consisting of alumina toughened zirconia (ATZ). KW - 3D-printing KW - Two-photon polymerization KW - 2PP KW - Ceramic nano particles KW - Slurry KW - Alumina toughened zirconia KW - ATZ KW - Additive manufacturing KW - SchwarzP cells KW - Nano-ceramic-additive-manufacturing photoresin KW - NanoCAM PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517441 DO - https://doi.org/10.1016/j.oceram.2020.100040 VL - 4 SP - 100040 PB - Elsevier Ltd. AN - OPUS4-51744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bungartz, M. A1 - Maenz, S. A1 - Kunisch, E. A1 - Horbert, V. A1 - Xin, L. A1 - Gunella, F. A1 - Mika, J. A1 - Borowski, J. A1 - Bischoff, S. A1 - Schubert, H. A1 - Sachse, A. A1 - Günster, Jens A1 - Illerhaus, Bernhard A1 - Bossert, J. A1 - Jandt, K. D. A1 - Kinne, R. W. A1 - Brinkmann, O. T1 - First-time systematic postoperative clinical assessment of a minimally invasive approach for lumbar ventrolateral vertebroplasty in the large animal model sheep N2 - Large animal models are highly recommended for meaningful preclinical studies, including the optimization of cement augmentation for vertebral body defects by vertebroplasty/kyphoplasty. The aim of this study was to perform a systematic characterization of a strictly minimally invasive in vivo large animal model for lumbar ventrolateral vertebroplasty. This is a prospective experimental animal study. Lumbar defects (diameter 5 mm; depth approximately 14 mm) were created by a ventrolateral percutaneous approach in aged, osteopenic, female sheep (40 Merino sheep; 6–9 years; 68–110 kg). L1 remained untouched, L2 was left with an empty defect, and L3 carried a defect injected with a brushite-forming calcium phosphate cement (CPC). Trauma/functional impairment, surgical techniques (including drill sleeve and working canula with stop), reproducibility, bone defects, cement filling, and functional cement augmentation were documented by intraoperative incision-to-suture time and X-ray, postoperative trauma/impairment scores, and ex vivo osteodensitometry, microcomputed tomography (CT), histology, static/fluorescence histomorphometry, and biomechanical testing. Minimally invasive vertebroplasty resulted in short operation times (28±2 minutes; mean±standard error of the mean) and X-ray exposure (1.59±0.12 minutes), very limited local trauma (score 0.00±0.00 at 24 hours), short postoperative recovery (2.95±0.29 hours), and rapid decrease of the postoperative impairment score to 0 (3.28±0.36 hours). Reproducible defect creation and cement filling were documented by intraoperative X-ray and ex vivo conventional/micro-CT. Vertebral cement augmentation and osteoconductivity of the CPC was verified by osteodensitometry (CPC>control), micro-CT (CPC>control and empty defect), histology/static histomorphometry (CPC>control and empty defect), fluorescence histomorphometry (CPC>control; all p<.05 for 3 and 9 months), and compressive strength measurements (CPC numerically higher than control; 102% for 3 months and 110% for 9 months). This first-time systematic clinical assessment of a minimally invasive, ventrolateral, lumbar vertebroplasty model in aged, osteopenic sheep resulted in short operation times, rapid postoperative recovery, and high experimental reproducibility. This model represents an optimal basis for standardized evaluation of future studies on vertebral augmentation with resorbable and osteoconductive CPC. KW - Computed tomography KW - Calcium phosphate cement KW - Large animal model KW - Minimal-invasive KW - Vertebroplasty KW - Void defect PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S152994301630273X DO - https://doi.org/10.1016/j.spinee.2016.06.015 VL - 16 IS - 10 SP - 1263 EP - 1275 PB - Elsevier Inc. AN - OPUS4-38429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chinellato, Fabio A1 - Wilbig, Janka A1 - Al-Sabbagh, Dominik A1 - Colombo, P. A1 - Günster, Jens T1 - Gas flow assisted powder deposition for enhanced flowability of fine powders: 3D printing of alpha-tricalcium phosphate N2 - The possibility of creating patient-specific individual implants makes Additive Manufacturing technologies of special interest for the medical sector. For substitution of bone defects, powder based Additive Manufacturing by Binder Jetting is a suitable method to produce complex scaffold-like structures made of bioceramics with easily adapted geometries and controlled porosity. The process inherent residual porosity in the printed part, even though desired as it supports bone ingrowth, also leads to limited mechanical strength. Currently, bioceramic scaffolds made by Binder Jetting feature suitable biocompatible and biodegradable properties, while a sufficient mechanical stability is rather challenging. The purpose of this work is to apply the gas flow assisted powder deposition introduced in 2014 by Zocca et al., to the powder bed during printing of bioceramic tablets and scaffolds using α-TCP powder as feedstock. This enables exploiting the advantages of an increased powder bed density, thereby improving the mechanical properties of the printed parts. KW - Additive Manufacturing KW - Binder Jetting KW - Gas flow assisted powder deposition KW - Alpha-tricalcium phosphate KW - Scaffold PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510138 DO - https://doi.org/10.1016/j.oceram.2020.100003 SN - 2666-5395 VL - 1 SP - 100003 PB - Elsevier Ltd. AN - OPUS4-51013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bungartz, M. A1 - Kunisch, E. A1 - Maenz, S. A1 - Horbert, V. A1 - Xin, L. A1 - Gunella, F. A1 - Mika, J. A1 - Borowski, J. A1 - Bischoff, S. A1 - Schubert, H. A1 - Sachse, A. A1 - Illerhaus, Bernhard A1 - Günster, Jens A1 - Bossert, J. A1 - Jandt, K. D. A1 - Plöger, F. A1 - Kinne, R. W. A1 - Brinkmann, O. T1 - GDF5 significantly augments the bone formation induced by an injectable, PLGA fiber-reinforced, brushite-forming cement in a sheep defect model of lumbar osteopenia N2 - BACKGROUND CONTEXT: Biodegradable calcium phosphate cement (CPC) represents a promising option for the surgical treatment of osteoporotic vertebral fractures. Because of augmented local bone catabolism, however, additional targeted delivery of bone morphogenetic proteins with the CPC may be needed to promote rapid and complete bone regeneration. PURPOSE: In the present study, an injectable, poly(l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming cement (CPC) containing the bone morphogenetic Protein GDF5 was tested in a sheep lumbar osteopenia model. STUDY DESIGN/SETTING: This is a prospective experimental animal study METHODS: Defined bone defects (diameter 5 mm) were placed in aged, osteopenic female sheep. Defects were treated with fiber-reinforced CPC alone (L4; CPC+ fibers) or with CPC containing different dosages of GDF5 (L5; CPC+ fibers + GDF5; 1, 5, 100, and 500g GDF5; n = 5 or 6 each). The results were compared with those of untouched controls (L1). Three and 9 months postoperation, structural and functional effects of the CPC (±GDF5) were assessed ex vivo by measuring (1) bone mineral density (BMD); (2) bone structure, that is, bone volume/total volume (assessed by micro-computed tomography and histomorphometry), trabecular thickness, and trabecular number; (3) bone formation, that is, osteoid volume/bone volume, osteoid surface/bone surface, osteoid thickness, mineralized surface/bone surface, mineral apposition rate, and bone formation rate/bone surface; (4) bone resorption, that is, eroded surface/bone surface; and (5) compressive strength. RESULTS: Compared with untouched controls (L1), both CPC+ fibers (L4) and CPC+ fibers + GDF5 (L5) numerically or significantly improved all parameters of bone formation, bone resorption, and bone structure. These significant effects were observed both at 3 and 9 months, but for some parameters they were less pronounced at 9 months. Compared with CPC without GDF5, additional significant effects of CPC with GDF5 were demonstrated for BMD and parameters of bone formation and structure (bone volume/total volume, trabecular thickness, and trabecular number, as well as mineralized surface/bone surface). The GDF5 effects were dose-dependent (predominantly in the 5–100g range) at 3 and 9 months. CONCLUSIONS: GDF5 significantly enhanced the bone formation induced by a PLGA fiber-reinforced CPC in sheep lumbar osteopenia. The results indicated that a local dose as low as ≤100g GDF5 may be sufficient to augment middle to long-term bone formation. The novel CPC+ GDF5 combination may thus qualify as an alternative to the bioinert, supraphysiologically stiff poly-(methyl methacrylate) cement currently applied for vertebroplasty/kyphoplasty of osteoporotic vertebral fractures. KW - Bone regeneration KW - Computed tomography KW - Large animal model sheep KW - Osteoporotic vertebral fracture PY - 2017 DO - https://doi.org/10.1016/j.spinee.2017.06.007 SN - 1529-9430 SN - 1878-1632 VL - 17 IS - 11 SP - 1685 EP - 1698 PB - Elsevier Inc. AN - OPUS4-43239 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yao, Dongxu A1 - Xia, Y. A1 - Zuo, K.-h. A1 - Zeng, Y.-P. A1 - Jiang, D. A1 - Günster, Jens A1 - Heinrich, J.G. T1 - Gradient porous silicon nitride prepared via vacuum foaming and freeze drying N2 - Gradient porous silicon nitride (Si3N4) was fabricated by a novel vacuum foaming and freeze drying process. Aqueous Si3N4 slurries were foamed at vacuum pressure of 50–90 kPa, the green body was obtained by the freeze drying process, a gradient pore structure with porosities of 72–90% was achieved after pressureless sintering at 1680 °C. The porosity was increased with decreasing vacuum pressure. The pore structure consists of large pores (~100 μm) on top, medium pores (~45 μm) on the wall of the large pores, and small pores (~0.7 μm) in the matrix. Such gradient porous Si3N4 with macro- and micro-pores has potential application as high temperature filters. KW - Silicon nitride KW - Graded PY - 2015 DO - https://doi.org/10.1016/j.matlet.2014.11.067 SN - 0167-577x SN - 1873-4979 VL - 141 SP - 138 EP - 140 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Schwentenwein, Martin A1 - Bermejo, Raúl A1 - Günster, Jens T1 - Hybridizing Lithography-Based Ceramic Additive Manufacturing with Two-Photon-Polymerization N2 - Stereolithography processes such as lithography-based ceramic manufacturing (LCM) are technologies that can produce centimeter-sized structures in a reasonable time frame. However, for some parts specifications, they lack resolution. Two-photon-polymerization (2PP) ensures the highest geometric accuracy in additive manufacturing so far. Nevertheless, building up parts in sizes as large as a few millimeters or even centimeters is a time-consuming process, which makes the production of 2PP printed parts very costly. Regarding feedstock specification, the requirements for 2PP are different to those for LCM, and generally, feedstocks are designed to meet requirements for only one of these manufacturing technologies. In an attempt to fabricate highly precise ceramic components of a rather large size, it is necessary to develop a feedstock that suits both light-based technologies, taking advantage of LCM’s higher productivity and 2PP’s accuracy. Hybridization should bring the desired precision to the region of interest on reasonably large parts without escalating printing time and costs. In this study, specimens gained from a transparent feedstock with yttria stabilized zirconia (YSZ) particles of 5 nm at 70 wt% were presented. The resin was originally designed to suit 2PP, while being also printable with LCM. This work demonstrates how hybrid parts can be sintered into full YSZ ceramics. KW - Additive Manufacturing KW - Transparent ceramic KW - Nano-powder PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584541 DO - https://doi.org/10.3390/app13063974 SN - 2076-3417 VL - 13 IS - 6 SP - 1 EP - 9 PB - MDPI CY - Basel AN - OPUS4-58454 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 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 - 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 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 - 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) 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 - Hmood, F. A1 - Schmidt, Franziska A1 - Görke, O. A1 - Günster, Jens T1 - Investigation of chemically modified ICIE16 bioactive glass, part II N2 - Chemically modified bioactive glasses based on ICIE16 were prepared with the melt-quenching method using water as a quenching medium. The sinterability of these bioactive glasses was investigated and is discussed in this article. The sintering experiments were conducted with different sintering temperatures, sintering times and heating rates. Those parameters are crucial for dense glass with an amorphous structure. The particle size (d50) of the starting glass powder was determined at 88 μm and kept constant. The pre-pressed glass pellets were cold-isostatically pressed at 300 MPa to a green density of around 63 %. Density development, phase identification, shrinkage behavior and the microstructure were investigated to determine the sinterability of the developed glasses. The glass powders were sintered at different temperatures inside the processing window while crystallization was monitored. The results have shown that the sinterability of the developed glasses strongly dependsonthe proposed chemical additions. The highest density reached was 96 %, which belongs to BP1 glass with sintering conditions of 20 K/min heating rate for 60 min at 750 °C. KW - Bioactive glass KW - Viscous sintering KW - Crystallization KW - Processing window KW - Grain boundary PY - 2019 DO - https://doi.org/10.4416/JCST2019-00031 VL - 11 IS - 1 SP - 1 EP - 9 PB - Göller Verlag AN - OPUS4-49913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gottlieb, Cassian A1 - Gojani, Ardian A1 - Völker, Tobias A1 - Günther, Tobias A1 - Gornushkin, Igor B. A1 - Wilsch, Gerd A1 - Günster, Jens T1 - Investigation of grain sizes in cement-based materials and their influence on laser-induced plasmas by shadowgraphy and plasma imaging N2 - The effect of particle grain sizes in different cement-based mixtures on the laser-induced plasma evolution is studied using two experimental methods: (i) temporal and spatial evolution of the laser-induced shock wave is investigated using shadowgraphy and two-dimensional plasma imaging, and (ii) temporal and spatial distribution of elements in the plasma is investigated using two-dimensional spectral imaging. This study is motivated by the interest in applying laser-induced breakdown spectroscopy (LIBS) for chemical analysis of concrete, and subsequently obtain information related to damage assessment of structures like bridges and parking decks. The distribution of grain sizes is of major interest in civil engineering as for making concrete different aggregate grain sizes defined by a sieving curve (64mm to 0.125 mm) are needed. Aggregates up to a size of 180 μm can be excluded from the data set, therefore only the amount of small aggregates with a grain size below 180 μm must be considered with LIBS. All components of the concrete with a grain size smaller than 0.125mm are related to the flour grain content. Tested samples consisted of dry and hardened cement paste (water-cement ratio w/z=0.5), which served as a reference. Aggregate mixtures were made by adding flour grains (size 40 μm) and silica fume (size 0.1 μm) in different ratios to cement: 10%, 30%, 50% and 60%, all combined to the remaining percentage of dry or hydrated cement. The visualization results show that a dependance in the evolution of the plasma as a function of sample grain size can be detected only in the initial stages of the plasma formation, that is, at the initial 3 μs of the plasma life. Spectral information reveals the elemental distribution of the silicon and calcium in plasma, in both neutral and ionized form. Here also, a significant effect is observed in the first 1 μs of the plasma lifetime. KW - LIBS KW - Cement-based materials KW - Particle size KW - Shadowgraphy KW - Plasma imaging PY - 2020 DO - https://doi.org/10.1016/j.sab.2020.105772 VL - 165 SP - 105772 PB - Elsevier B.V. AN - OPUS4-50319 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 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 - 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 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 - Ginés-Palomares, Juan Carlos A1 - Fateri, Miranda A1 - Kalhöfer, Eckhard A1 - Schubert, Tim A1 - Meyer, Lena A1 - Kolsch, Nico A1 - Brandic Lipinska, Monica A1 - Davenport, Robert A1 - Imhof, Barbara A1 - Waclavicek, René A1 - Sperl, Matthias A1 - Makaya, Advenit A1 - Günster, Jens T1 - Laser melting manufacturing of large elements of lunar regolith simulant for paving on the Moon N2 - The next steps for the expansion of the human presence in the solar system will be taken on the Moon. However, due to the low lunar gravity, the suspended dust generated when lunar rovers move across the lunar soil is a significant risk for lunar missions as it can affect the systems of the exploration vehicles. One solution to mitigate this problem is the construction of roads and landing pads on the Moon. In addition, to increase the sustainability of future lunar missions, in-situ resource utilization (ISRU) techniques must be developed. In this paper, the use of concentrated light for paving on the Moon by melting the lunar regolith is investigated. As a substitute of the concentrated sunlight, a high-power CO2 laser is used in the experiments. With this set-up, a maximum laser spot diameter of 100 mm can be achieved, which translates in high thicknesses of the consolidated layers. Furthermore, the lunar regolith simulant EAC-1A is used as a substitute of the actual lunar soil. At the end of the study, large samples (approximately 250 × 250 mm) with interlocking capabilities were fabricated by melting the lunar simulant with the laser directly on the powder bed. Large areas of lunar soil can be covered with these samples and serve as roads and landing pads, decreasing the propagation of lunar dust. These manufactured samples were analysed regarding their ineralogical composition, internal structure and mechanical properties. KW - Regolith KW - ISRU KW - Moon KW - Laser KW - Additive manufacturing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-585985 DO - https://doi.org/10.1038/s41598-023-42008-1 SN - 2045-2322 VL - 13 SP - 1 EP - 10 PB - Springer AN - OPUS4-58598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Léonard, Fabien A1 - Günster, Jens T1 - Laser-induced slip casting (LIS) – a new additive manufacturing process for dense ceramics demonstrated with Si3N4 N2 - Up to now, there exists a lack of methods for the additive manufacturing of voluminous ceramic parts with properties comparable to those of conventionally manufactured ones. A high density after sintering is needed to reach the superior properties of ceramic materials. We have developed a new additive manufacturing method, Laser-Induced Slip casting (LIS), to generate ceramic green bodies with high particle packing density and with virtually no restriction in the particle size of the feedstock, especially in terms of small particles. This is achieved by laser-induced local drying of slurries, with the process resembling many features of the well-established stereolithography, but without the excessive use of polymeric material. Thus, unlike the stereolithography process, the resulting green bodies can be processed like traditionally produced ceramic parts. This method allows large and dense additive-manufactured parts to be obtained from conventional water-based ceramic slurries. As an example, we will demonstrate the application of this novel technique with Si3N4. KW - Additive manufacturing KW - Ceramics PY - 2017 DO - https://doi.org/10.4416/JCST2017-00091 SN - 2190-9385 VL - 8 IS - 4 SP - 531 EP - 540 PB - Göller Verlag CY - Baden-Baden AN - OPUS4-43738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna A1 - König, N.F. A1 - De Marzi, A. A1 - Zocca, Andrea A1 - Franchin, G. A1 - Bermejo, R. A1 - Colombo, P. A1 - Günster, Jens T1 - Linear volumetric additive manufacturing of zirconia from a transparent photopolymerizable ceramic slurry via Xolography N2 - Advanced ceramics printed with photon-based additive manufacturing deals with anisotropic mechanical properties from the layer-by-layer manufacturing. Motivated by the success in using highly filled transparent slurries containing nanoparticles for powder-based two-photon-polymerization (2PP) for advanced ceramic printing, this works approach is the transfer to Xolography, a volumetric additive manufacturing technology based on linear two-photon excitation and without recoating steps. This paper reports the results of a preliminary investigation optimizing the photocurable slurry to the requirements of Xolography in terms of transparency, over a significantly larger mean free path, compared to 2PP. A feedstock filled with 70 % weight fraction of ceramic particles (∼30 vol%) exhibiting an exceptionally high degree of transparency in the relevant wavelength range of 400–800 nm was prepared from 5 nm zirconia nanoparticles. The high transparency of the photocurable slurry is attributed to the near-monomodal particle size distribution of the zirconia nanoparticles used. KW - Additive manufacturing KW - Xolography KW - Ceramic PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608908 DO - https://doi.org/10.1016/j.oceram.2024.100655 VL - 19 SP - 1 EP - 9 PB - Elsevier BV AN - OPUS4-60890 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 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 - Gunella, F. A1 - Kunisch, E. A1 - Bungartz, M. A1 - Maenz, S. A1 - Horbert, V. A1 - Xin, L. A1 - Mika, J. A1 - Borowski, J. A1 - Bischoff, S. A1 - Schubert, H. A1 - Hortschansky, P. A1 - Sachse, A. A1 - Illerhaus, Bernhard A1 - Günster, Jens A1 - Bossert, J. A1 - Jandt, K. D. A1 - Plöger, F. A1 - Kinne, R. W. A1 - Brinkmann, O. T1 - Low-dose BMP-2 is sufficient to enhance the bone formation induced by an injectable, PLGA fiber-reinforced, brushite-forming cement in a sheep defect model of lumbar osteopenia N2 - BACKGROUND CONTEXT: Bioresorbable calcium phosphate cement (CPC) may be suitable for vertebroplasty/kyphoplasty of osteoporotic vertebral fractures. However, additional targeted de- livery of osteoinductive bone morphogenetic Proteins (BMPs) in the CPC may be required to counteract the augmented local bone catabolism and support complete bone regeneration. PURPOSE: This study aimed at testing an injectable, poly (l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming cement (CPC) containing low-dose bone morphogenetic Protein BMP-2 in a sheep lumbar osteopenia model. STUDY DESIGN/ SETTING: This is a prospective experimental animal study. METHODS: Bone defects (diameter 5 mm) were generated in aged, osteopenic female sheep and filled with fiber-reinforced CPC alone (L4; CPC+ fibers) or with CPC containing different dosages of BMP-2 (L5; CPC+ fibers + BMP-2; 1, 5, 100, and 500g BMP-2; n=5 or 6 each). The results were compared with those of untouched controls (L1). Three and 9 months after the operation, structural and functional effects of the CPC (±BMP-2) were analyzed ex vivo by measuring (1) bone Mineral density (BMD); (2) bone structure, that is, bone volume/total volume (assessed by micro-computed tomography [micro-CT] and histomorphometry), trabecular thickness, and trabecular number; (3) bone formation, that is, osteoid volume/bone volume, osteoid surface/bone surface, osteoid thickness, mineralizing surface/bone surface, mineral Apposition rate, and bone formation rate/bone surface; (4) bone resorption, that is, eroded surface/bone surface; and (5) compressive strength. RESULTS: Compared with untouched controls (L1), CPC+ fibers (L4) and/or CPC+ fibers + BMP-2(L5) significantly improved all parameters of bone formation, bone resorption, and bone structure. These effects were observed at 3 and 9 months, but were less pronounced for some parameters at 9 months. Compared with CPC without BMP-2, additional significant effects of BMP-2 were demonstrated for bone structure (bone volume/total volume, trabecular thickness, trabecular number) and formation (osteoid surface/bone surface and mineralizing surface/bone surface), as well as for the compressive strength. The BMP-2 effects on bone Formation at 3 and 9 months were dose-dependent, with 5–100g as the optimal dosage. CONCLUSIONS: BMP-2 significantly enhanced the bone formation induced by a PLGA fiber-reinforced CPC in sheep lumbar osteopenia. A single local dose as low as ≤100g BMP-2 was sufficient to augment middle to long-term bone formation. The novel CPC+ BMP-2 may thus represent an alternative to the bioinert, supraphysiologically stiff polymethylmethacrylate cement presently used to treat osteoporotic vertebral fractures by vertebroplasty/kyphoplasty. KW - Bone regeneration KW - Computed tomography KW - Calcium phosphat cement KW - Large animal model sheep KW - Osteoporotic vertebral fracture PY - 2017 DO - https://doi.org/10.1016/j.spinee.2017.06.005 SN - 1529-9430 SN - 1878-1632 VL - 17 IS - 11 SP - 1699 EP - 1711 PB - Elsevier Inc. AN - OPUS4-43237 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 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 - 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 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 -