Electrical Conductivity of a Carbon Reinforced Alumina Resistive Composite Material Based on Synthetic Graphite and Graphene

Resumo

We have prepared samples of carbon reinforced alumina ceramics with different volume fractions of synthetic graphite (0–20%) and graphene (0–4%) and measured their electrical conductivity. It has been shown that increasing the volume percent of the conductive component increases the electrical conductivity of the samples from 10^–8 to 2 × 10^–3 S/cm. The results have been analyzed in terms of percolation theory and tunneling conduction theory. The synthetic graphite-based samples show linear current–voltage behavior and their electrical conductivity increases by a factor of 1.4 to 2.8 in the temperature range 300–550 K, with a sharp rise above 550 K. The temperature dependences of their electrical conductivity are analyzed in terms of hopping transport and thermally induced tunneling conduction mechanisms. The conclusion is made that the conduction mechanism in the corundum–carbon ceramics differs significantly from that in polymer composite materials.