Microstructure and mechanical properties of novel ternary electroconductive ceramics

Electroconductive ceramic composites, constituted of an insulating matrix (a composite AlN-SiC) containing 30 vol% of an electroconductive phase (MoSi2, ZrB2, or ZrC), were densified through hot-pressing. Microstructure and mechanical properties were compared to those of the AlN-SiC matrix material. All the ternary composites are good electrical conductors, with resistivities in the range 0.3 × 10-3 to 4 × 10-3 ohm·cm. Room temperature properties are improved by the addition of the electroconductive particles. Strength and toughness measurements at high temperature show that MoSi2-containing composite is stable up to 1300 °C (strength 611 MPa, toughness 3.7 MPa·m1/2), whereas ZrB2-containing composite is stable up to 1000 °C. ZrC-containing composite is not suitable for high-temperature applications due to poor oxidation resistance.