Selective laser sintering as an additive manufacturing method for manufacturing ceramic components

Selective Laser Sintering (SLS) offers the advantage of directly manufacturing complex-shaped parts without the uneconomic loss of material so common when conventional manufacturing methods are applied. Originating from the laser sintering of polymers, lots of research has been conducted on advanced materials like metals and ceramics. In recent years the Fraunhofer IKTS has conducted research on the laser sintering of SiC and different hydroxyapatite (HAp) powders. The HAp powders have been characterized based on their laser sintering ability with the variation of process parameters like spreading behavior, different grain shape and size, hatch clearance, etc. More elaborate research has been conducted concerning the laser sintering of SiSiC components. After infiltration and pyrolysis of laser-sintered SiC parts, the resulting SiSiC components showed similar mechanical characteristics to those of conventionally processed SiSiC components. Different complex geometries were realized e.g. a 120-mm honeycombstructured mirror support model (wall thickness of 1 mm, for aerospace applications) and a small turbine rotor (minimal wall thickness of 0.3 mm)as a demonstrator part for automotive components.Alaser mirror with integrated cooling channels for application in movable beam arms for laser material processing was also manufactured. Another successfully generated SiSiC component is an injection molding tool insert (ca. 35 x 30 mm; diameter x height) with a complex-structured surface and inner cooling channels. The next steps will be towards research dealing with more complex de signs and other ceramics as well as metal-ceramic hybrids.