Matthias Scheiffele

Fabrication and Testing of Corrugated 3D SiSiC Ceramics for Porous Burner Applications

Non-oxide SiC ceramics can withstand high temperatures ~1400 °C in severe combustion environments. Therefore such ceramics are interesting candidates for advanced combustion technologies, e.g. sophisticated porous burners. For the fabrication of porous SiSiC ceramics the DLR developed a new technology based on carbon sheets and lamellae. These basic materials can be combined to lightweight 3D C/C stacks. Through the variation of the amplitude and number of lamellae per inch, the open porosity and orientation of the pore channels could be tailored in a wide range. By using the pyrolysis followed by the liquid silicon-melt infiltration process the carbon stack could be directly converted into SiC in one shot. The residual open porosity can easily be filled with pure silicon to obtain 3D SiSiC structures with adequate mechanical strength and sufficient damage tolerance. Best results from durability tests were obtained with structures which are composed of oriented pore channels. Suitable structures should have angles (α) of about α = ± 60° or less. The results from burner rig tests at LSTM with improved components have been very promising, since a lifetime up to 500 hours and 2000 start-ups could be obtained with α = ± 50° as well as with α = ± 60° sample. So far, no significant oxidation or degradation could be observed after 1939 h/10800 start-ups with α = ± 45° sample. These proof tests are ongoing and show that these novel cardboard like structures have a high potential for industrial applications.