ELECTRICAL CONDUCTIVE CNT-DISPERSED Si_3N_4 CERAMICS WITH DOUBLE PERCOLATION STRUCTURE

摘要

The purpose of this study is to control the electrical conductivih of carbon nanotube- (CNT) dispersed silicon nitride (Si_3N_4) ceramics by double percolation. We prepared two kinds of CNT-dispersed Si_3N_4 ceramics. Samples with double percolation structures were prepared using mixed granules having various quantities of CNTs (0.7-2.6 vol%) and without CNTs in the proportion of 50 to 50. The powder mixtures were sintered using a spark plasma sintering technique to obtain fully dense CNT-dispersed Si_3N_4 ceramics. For comparison, single percolation samples with various quantities of CNTs (0.7-2.6 vol%) were also similarly prepared. The rclative density of all the sintered bodies was over 97%. The single percolation sample with 0.7 vol% CNT did not show electrical conductivity because the quantity of CNT was lower than the percolation threshold. On the other hand, the electrical conductivity of the double percolation sample with 0.7 vol% CNT was about five orders of magnitude greater than that of the 0.7 vol% single percolation sample. Consequently, it was shown that it is possible to control the electrical conductivity of CNT-dispersed Si_3N_4 by double pcrcolation.