PERCOLATION STUDY ON ELECTRICAL-RESISTIVITY OF SIC SI3N4 COMPOSITES WITH SEGREGATED DISTRIBUTION/

Experimental and theoretical studies are made to account for the forma tion 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 prop osed theoretical model takes into account the volume fraction of dispe rsed particles necessary to form a percolating network as a function o f the size ratio of SiC particle to Si3N4 grain. Threshold particle lo ading for percolation is estimated by applying a modified two-dimensio nal bond percolation model and then electrical resistivity of the comp osite by using percolation and general effective media equations. Both predicted values of threshold particle loading and electrical resisti vity were found to agree closely with the present experimental values. (C) 1998 American Institute of Physics.