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J. Stampfl:
"3D-printing of ceramics: Translation to industrial processes";
Keynote Lecture: AMPT 2015, Madrid; 12-14-2015 - 12-17-2015; in: "Advances in Material & Processing Technologies", J. Torralba (ed.); (2015), 202.

In this work, materials and systems for the fabrication of ceramic parts by lithography-based additive manufacturing are presented. Key component of the utilized systems are DLP-based light engines (Digital Light Processing) which use powerful LEDs and a 1080p DMD-chip (Digital Micromirror Device) that generates images (dynamic mask) at 1920x1080 pixels with a pixel size of 40μm. The overall build size of the system is 76.8x43.2x100mm. This 3D-printer is capable of processing a variety of ceramic materials (β-TCP, alumina oxide, zirconia oxide and bioglass) to produce high-precision ceramic parts.
By dispersing the ceramic particles in a photosensitive resin (slurry), these materials are made processible by lithography based additive manufacturing. During the printing process, a thin layer of the slurry is exposed locally as a result the slurry solidifies (polymerizes). Thus, the so called green body is printed layer by layer. The standard layer thickness ranges from 25 to 50µm. In the subsequent drying, debinding and sintering processes, the green body (containing solvents, a cross-linked polymer network and ceramic powder) is transformed to a fully dense ceramic part (>99% of theoretical density).
The combination of modern LED technology, coating mechanisms suitable for high viscously slurries (10-20 Pa·s) and exposure strategies enables the production of complex geometries of virtually any type. Reproducibility and quality of the parts was considerably improved and visualized through the implementation of several sensors. High building speeds of 10 vertical mm/h show the potential of the system for industrial applications. So far, slurries with a solid loading up to 50vol% ceramics could be processed successfully The alumina specimens fabricated in this work showed a biaxial flexural strength of 516 MPa, and a Weibull modulus up to 13. The sintered β-TCP specimens showed a biaxial bending strength of 30 MPa.
The presentation will also point out the issues which are related with the commercialization of this technology.

Project Head Jürgen Stampfl:
Werkzeuglose Fertigung komplexer Strukturen