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Carbon/ceramic composites designed for electrical application

A. M. BONDAR1, I. IORDACHE1,*

Affiliation

  1. National Institute for Research and Development in Electrical Engineering ICPE – Advanced Research, Bucharest, Romania

Abstract

Carbon-ceramic composites were composed of one or more different solid constituents (conductive and insulators) together with a pore phase. The resulting electrical conductivity of the body depends on the amounts and arrangement of each phase present, including the pores, as well as their individual conductivity. These composites were designed to display a combination of characteristics from components acting as microelectrical networks, microresistors (carbon) and microcapacitors (insulators) randomly dispersed in space. To understand the correlation between material microstructure and electrical properties, a basic ideal model is required. Resistance-capacitance values can be used in the form of equivalent circuits. This a lows the active physical and/or chemical processes to be represented as RC elements. These can be logica ly constructed to represent the whole system. Different microstructure features of a composite material contain different charge conduction and susceptibility processes which produce different impedance contributions on a typical Cole Cole - plot and can be modeled by equivalent electrical circuits. The structural texture was investigated by SEM and the electrical behavior was investigated by impedance analyzer. A key result for ceramic matrix composites is the approximately exponential increase in resistivity above the percolation limit enabling the materials to rapidly and effectively absorb the energy associated with current surges in electrical equipment and thus they are very attractive electrical volume resistor materials. EMI shielding was investigated by exposing composite samples to high frequency electromagnetic fields (1 – 17) GHz. The composites tested show an attenuation between 31 – 42 dB..

Keywords

Carbon/ceramic composite, Electrical conductivity.

Submitted at: Jan. 18, 2006
Accepted at: March 23, 2006

Citation

A. M. BONDAR, I. IORDACHE, Carbon/ceramic composites designed for electrical application, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 2, pp. 631-637 (2006)