Contribution to the Percolation Threshold Study of Silicon Carbide Filled Polydimethylsiloxane Composites Used For Field Grading Application

Abstract

Nonlinear V-I characteristics of particulate composite prepared from dispersion of silicon carbide in a siloxane elastomer have been measured as a function of ller concentration up to the maximum allowable of about 32 vol.%. Two critical concentrations (percolation thresholds) are obtained at volume fractions of about 17 and 24 vol.% for low and high electric elds. These values are consistent with the critical concentrations predicted by the theory: 14 and 31 vol.% respectively and may come from edge and face contacts between SiC semi-conducting particles.

Contribution to the percolation threshold study of Silicon carbide filled polydimethylsiloxane composites used for field grading application

“…The SiC employed was a doped industrial β-crystal structure grade with a particle size and distribution assesed by laser diffractometry to 26 ± 1 µm and 20 ± 1 µm respectively. 4 The errors due to the weighing of viscous materials are of the order of ± 0.05 g, i.e . less than 0.25%.…”

“…Above a threshold volume fraction, f v , the current/voltage relation is no longer linear. 4 In this phase, electric current is believed to be carried by the network of percolated SiC particles, which is more conductive than the silicone matrix.…”