Percolation study on electrical resistivity of SiC/Si3N4 composites with segregated distribution

Experimental and theoretical studies are made to account for the formation of segregated networks in SiC/Si3N4 particulate composite. It was observed in the present experimental work that fine SIC particles are uniformly dispersed along boundaries of Si3N4 matrix grains. The proposed theoretical model takes into account the volume fraction of dispersed particles necessary to form a percolating network as a function of the size ratio of SiC particle to Si3N4 grain. Threshold particle loading for percolation is estimated by applying a modified two-dimensional bond percolation model and then electrical resistivity of the composite by using percolation and general effective media equations. Both predicted values of threshold particle loading and electrical resistivity were found to agree closely with the present experimental values. (C) 1998 American Institute of Physics.