Powder preparation and indirect selective laser sintering of alumina

Indirect selective laser sintering (SLS) is a promising additive manufacturing technique to produce ceramic parts with complex shapes in a two step process. In a first step, green parts are produced in a layer by layer sequence by scanning with a laser beam targeting polymer phase melting and binding of the Al2O3 powder. In the second step, the binder is removed from the green parts by slowly heating and the parts are furnace sintered to increase the density. In this work, polyamide 12 and submicrometer sized alumina were used. The composite powders were prepared by planetary ball milling or dissolutionprecipitation. Differential scanning calorimetry (DSC) was used to determine the thermal properties of the composite powder. Laser diffraction allowed to measure the composite agglomerate size, whereas the morphology was studied by scanning electron microscopy (SEM). The powder processing parameters were optimized to tailor the composite powder with suitable thermal and flow properties for SLS. The effect of the laser beam scanning parameters, such as the laser power, scan speed and scan spacing, on the fabrication of green parts was assessed and the influence of the post processing parameters on the sintered density and microstructure of the parts was investigated.Posterstatus: publishe