TY - JOUR A1 - Mühler, T. A1 - Heinrich, J. A1 - Wirth, Cynthia A1 - Günster, Jens T1 - Slurry-based additive manufacturing of ceramics JF - International Journal of Applied Ceramic Technology N2 - Most additive manufacturing (AM) techniques have in common that material is spread out as thin layers of a dried powder/granulate by a roller or a shaker system. These layers are mostly characterized by a low packing rate. On the other hand, appreciable densities can be reached by the use of ceramic slurries. In this context, the layer-wise slurry deposition (LSD) has been developed. Specific features of the LSD process are reflected on the basis of already existing additive manufacturing technologies. The microstructure of laser-sintered bodies will be discussed, and strategies for an improved microstructure during sintering will be introduced. KW - Additive manufacturing KW - Ceramic KW - Selective laser sintering PY - 2015 DO - https://doi.org/10.1111/ijac.12113 SN - 1546-542X SN - 1744-7402 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 12 IS - 1 SP - 18 EP - 25 PB - American Ceramic Soc. CY - Westerville, Ohio AN - OPUS4-29937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Colombo, P. A1 - Günster, Jens A1 - Mühler, T. A1 - Heinrich, J.G. T1 - Selective laser densification of lithium aluminosilicate glass ceramic tapes JF - Applied surface science N2 - Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane. KW - Selective laser sintering (SLS) KW - Laserwise-slurry-deposition (LSD) KW - Glass-ceramic KW - LAS PY - 2013 UR - http://ac.els-cdn.com/S0169433212020168/1-s2.0-S0169433212020168-main.pdf?_tid=4ba0c92c-31d4-11e4-84f1-00000aab0f02&acdnat=1409575040_15d5256291262aca99cc5321374ab879 DO - https://doi.org/10.1016/j.apsusc.2012.11.058 SN - 0169-4332 SN - 1873-5584 VL - 265 SP - 610 EP - 614 PB - North-Holland CY - Amsterdam AN - OPUS4-31283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wirth, Cynthia A1 - Müller, Ralf A1 - Günster, Jens A1 - Mühler, T. A1 - Görke, R. A1 - Heinrich, J.G. T1 - Submicrometer silica spheres generated by laser fuming JF - Journal of ceramic science and technology N2 - The production of agglomerate-free SiO2 particles exhibiting a monomodal distribution of particle sizes of around 300 nm by means of direct laser fuming of micrometric SiO2 powders has been successfully demonstrated. With a 12 kW cw CO2 laser system, a production rate of up to 1 kilogram powder per hour was achieved. Almost ideal spherical amorphous SiO2 particles in a broad particle size distribution between 10 nm and several 100 nm (d50 ≈ 300 nm) were synthesized. Several observations suggest weak agglomeration forces between the particles. A temperature reduction of 200 °C for sintering powder compacts was observed. KW - Laser KW - SiO2 KW - Nanopowder PY - 2013 DO - https://doi.org/10.4416/JCST2012-00033 SN - 2190-9385 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 4 IS - 1 SP - 11 EP - 18 PB - Göller CY - Baden-Baden AN - OPUS4-31423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mühler, T. A1 - Helsch, G. A1 - Heinrich, J.G. A1 - Yao, Dongxu A1 - Gräf, S. A1 - Müller, F.A. A1 - Günster, Jens T1 - Strategies for the selective volume sintering of ceramics JF - Journal of materials research N2 - The present study is dealing with the basic physics for a novel way to generate a free-formed ceramic body, not like common layer by layer, but directly by Selective Volume Sintering (SVS) in a compact block of ceramic powder. To penetrate with laser light into the volume of a ceramic powder compact it is necessary to investigate the light scattering properties of ceramic powders. Compared with polymers and metals, ceramic materials are unique as they offer a wide optical window of transparency. The optical window typically ranges from below 0.3 up to 5 µm wave length. In the present study thin layers of quartz glass (SiO2) particles have been prepared. As a function of layer thickness and the particle size, transmission and reflection spectra in a wave length range between 0.5 and 2.5 µm have been recorded. Depending on the respective particle size and by choosing a proper relation between particle size and wave length of the incident laser radiation, it is found that light can penetrate a powder compact up to a depth of a few millimeters. With an adjustment of the light absorption properties of the compact the initiation of sintering in the volume of the compact is possible. KW - Additive Manufacturing PY - 2014 DO - https://doi.org/10.1557/jmr.2014.174 SN - 0884-2914 VL - 29 IS - 17 SP - 2095 EP - 2099 PB - Materials Research Society CY - Warrendale, Pa. AN - OPUS4-32544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mühler, T. A1 - Wirth, Cynthia A1 - Ascheri, Mary A1 - Nicolaides, Dagmar A1 - Heinrich, J. A1 - Günster, Jens T1 - Slurry-based powder beds for the selective laser sintering of silicate ceramics JF - Journal of ceramic science and technology N2 - Selective laser sintering of ceramic powders is a promising technique for the additive manufacturing of complex- and delicate-shaped ceramic parts. Most techniques have in common that the powder to be sintered is spread to a thin layer as a dry powder by means of a roller or shaker system. These layers have a relatively low density. On the other hand, appreciable densities can be reached with the use of ceramic slurries as the starting material. Therefore, the layer-wise slurry deposition (LSD) process has been developed. Layer stacks, i.e. powder beds, built up by employing the LSD technology exhibit a density comparable to ceramic powder compacts processed by means of conventional forming technologies. Writing the layer information with a focused laser beam in these dense ceramic powder compacts enables the manufacture of ceramic bodies with a high density and precision in contour. KW - Additive Fertigung KW - Keramik PY - 2015 DO - https://doi.org/10.4416/JCST2015-0007 SN - 2190-9385 VL - 6 IS - 2 SP - 113 EP - 118 PB - Göller CY - Baden-Baden AN - OPUS4-34962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -