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J. Homa, J. Stampfl:
"Direct and Indirect Fabrication of Ceramic Prototypes Using Rapid Prototyping";
Talk: Euromat 2007, Nürnberg, Deutschland; 09-09-2007 - 09-13-2007.

Rapid prototyping (RP) is a well established technique for the fabrication of polymeric and metallic prototypes. The fabrication of ceramic prototypes is still limited due to the lack of the achieved surface quality and the insufficient mechanical properties of the final ceramic parts.
To increase the solid loading of the green part and in order to avoid pores and cluster formation of powder particles, a slurry based process seems to be inevitable. In this work two different RP-technologies are discussed, which reach a high solid loading (> 50 vol%). This leads to parts with a sintered density up to 100 %, which is difficult to achieve with techniques which directly process dry powder (e.g. laser sintering, 3D-printing).

One process used for this work is based on photosensitive ceramic filled resins, which can directly be cured by a laser scanning system (e.g. stereolithography) or by digital mask projection. Alumina parts with a slice sickness of 25 µm and sintered densities of nearly 100 % have been produced. It has to be ensured that the light is not absorbed by the ceramic, which can only be guaranteed for oxide ceramics. Another disadvantage is the need for supporting structures for overhangs, which have to be removed mechanically. Internal overhangs are therefore difficult to manufacture.
Gelcasting in combination with RP-processes overcomes these disadvantages, but it is not a direct fabrication process. A negative wax mould is built with a wax-printer (Solidscape´s Benchtop T612) and a low viscosity slurry is filled in the mould and thermally cured. With that process every powder - ceramic or metallic - can be used and very high solid loadings (up to 70 vol%) are attainable. Alumina screws for cruciate ligament fixation and recrystallized silicon carbide cross flow filters with internal overhangs have been produced by this method.

Rapid Prototyping, Ceramics, DPF,