Talks and Poster Presentations (without Proceedings-Entry):

J. Homa, S. Zellhofer, J. Stampfl:
"Material Properties Of Gel-cast Rsic For Cross Flow Diesel Particulate Filters";
Talk: Materials Science and Engineering, Nürnberg, Deutschland; 09-01-2008 - 09-04-2008.

English abstract:
Diesel Particulate Filters (DPFs) have to be used to reach the tight limits of the European Union, USA and other countries on the emission of particulate matter for diesel vehicles. They have been invented in the early 1980s and are usually extruded in a honeycomb shape. The main problem of the extruded DPFs is the clogging of the filter by inorganic ashes, which remain in the filter due to the alternate plugging of the filter.
Since the inorganic ashes can not be removed the design has been altered to a cross flow filter with an attached ash-chamber, where the inlet channels are orthogonal to the outlet channels. Classical ceramic forming techniques are not capable of producing a monolithic cross flow filter with internal overhangs and fine structures. A process has been developed where a fugitive wax mould, which is build by different solid free form fabrication processes, is used in combination with gelcasting. Cross flow filters with wall thickness down to 0,3 mm have been produced by this method.
Recrystallized silicon carbide was chosen as filter material due to its good suitability for high temperature filter application. For the evaluation of the material different mechanical and thermal properties of the material with different starting powders were determined. The thermal shock resistance was tested through water quenching and following 3 point bending test. At 500 °C temperature difference the strength deceases from about 70  7 MPa without quenching at room temperature to 54  20 MPa, but no significant further decrease was detected up 1000 °C temperature difference. It could also be shown that the flexural strength the Young´s modulus and the heat conductivity decrease with increasing pore diameter.

Gelcasting, RSiC, DPF

Related Projects:
Project Head Jürgen Stampfl:
Rapid Prototyping zellularer Keramiken

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