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Porosity and electrical resistance of SiC materials

Porosität und Elektrischer Widerstand von SiC-Werkstoffen
: Martin, H.-P.; Adler, J.; Ihle, J.

Ceramic forum international : CFI. Berichte der Deutschen Keramischen Gesellschaft 82 (2005), Nr.13, S.221-224
ISSN: 0173-9913
Fraunhofer IKTS ()
Porosität; elektrischer Widerstand; SiC; Siliciumcarbid

SiC material types like R-SiC or N-SiC have been known for decades. These materials can be produced only as porous materials. The disadvantages which is associated with porosity is a low mechanical strength. SiC material types like S-SiC and LPS-SiC can be manufactured as dense materials. Consequently are markable increase of mechanical strength was achieved by this material development in the 1970s. It is little known that porous silicon carbide materials of S-SiC and LPS-SiC type offer surprising electrical properties beside the good permeability and the excellent thermal and chemical durability. The relation between porosity and electrical properties was already considered for a number of ceramic materials in the past. Pores are regarded as an additional material component but interactions between gas containing pores and the solid material were not taken into account by those considerations. However this possible interaction can change the electrical properties dramatically. The investigations of porous volume of pores can significantly decrease the electrical resistance in comparison to dense materials of the same type. A three orders of magnitude lower specific electrical resistance was found for different porous SiC-Materials. The temperature coefficient of the electrical resistance is significantly lower as for dense SiC materials.