caa a22 4500 463229355 CHVBK 20180405153237.0 cr unu---uuuuu 170326e20070701xx s 000 0 eng 10.1007/s10853-006-1247-5 doi (NATIONALLICENCE)springer-10.1007/s10853-006-1247-5 Microstructural evolution during direct laser sintering in the Al2O3-SiO2 system [Elektronische Daten] [Jürgen Heinrich, André Gahler, Jens Günster, Martin Schmücker, Jingxian Zhang, Dongliang Jiang, Meiling Ruan] The microstructural evolution during direct laser sintering of LSD (Layerwise Slurry Deposition)—samples in the Al2O3-SiO2 system has been investigated. Slurries with a water content of 34wt.% and a SiO2/Al2O3—ratio of about 3:1 have been used to manufacture layers which—after consecutive drying—have been sintered and laminated by laser treatment. Densified samples can be obtained with laser irradiances from 190 to 270kW/cm2 and scan velocities between 35 and 65mm/s. Elemental mappings of the layers' cross sections suggest an inhomogeneous phase distribution in the laser sintered LSD samples with a slight alumina concentration gradient. A lower degree of particle melting in the bottom region of the layers is plausible due to attenuation of the laser beam intensity. SEM and HRTEM micrographs show that after a few seconds of laser treatment relictic starting phase, crystalline alumina plus amorphous silica, occur together with needle like mullite, the latter formed within an amorphous aluminosilicate phase. The resulting phase assemblage reflects the non-equilibrium conditions which can be expected for short time laser treatments. Mullite nucleation within the bulk of the liquid phase rather than in the vicinity of the parent alumina phase suggests that dissolution of alumina is the rate controlling step. Subsequent thermal post treatment in air in a conventional sintering furnace causes an increase of density to about 96% and leads to additional phase reactions. Amorphous silica transforms into cristobalite and the amount of alumina is reduced by additional mullite formation. By both coalescence of individual crystals and grain growth the morphology of the newly formed mullite changes during post heat treatment. Springer Science+Business Media, LLC, 2007 Heinrich Jürgen Institute of Non-Metallic Materials, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut Gahler André Institute of Non-Metallic Materials, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut Günster Jens Laser Application Centre, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut Schmücker Martin German Aerospace Center, Cologne, Germany aut Zhang Jingxian Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut Jiang Dongliang Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut Ruan Meiling Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/14(2007-07-01), 5307-5311 0022-2461 42:14<5307 2007 42 10853 https://doi.org/10.1007/s10853-006-1247-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10853-006-1247-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Heinrich Jürgen Institute of Non-Metallic Materials, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut NATIONALLICENCE 700 1- Gahler André Institute of Non-Metallic Materials, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut NATIONALLICENCE 700 1- Günster Jens Laser Application Centre, Clausthal University of Technology, Clausthal-Zellerfeld, Germany aut NATIONALLICENCE 700 1- Schmücker Martin German Aerospace Center, Cologne, Germany aut NATIONALLICENCE 700 1- Zhang Jingxian Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut NATIONALLICENCE 700 1- Jiang Dongliang Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut NATIONALLICENCE 700 1- Ruan Meiling Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China aut NATIONALLICENCE 773 0- Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/14(2007-07-01), 5307-5311 0022-2461 42:14<5307 2007 42 10853 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer