Mohsin E. Aldokheily
Abstract
Silica - mullite powder sieved through 100 mesh, mixed with graphite atcertain proportions and placed in a steel mould, then subjected to ≈ 40Mpa .After air- drying for 24 hours ...
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Silica - mullite powder sieved through 100 mesh, mixed with graphite atcertain proportions and placed in a steel mould, then subjected to ≈ 40Mpa .After air- drying for 24 hours the specimen buried in carbon and fired at 1150 ◦C overnight. DC resistance was measured by the method of two probes. The percolation threshold was not sharp , instead it starts from 10.5% graphite ratio up to 21% were it resembles the conductivity of graphite alone . Resistance and reactance analysis were carried out at three frequencies (0.55, 1.5, 5.0) kHz. The specimen was subjected to heating/cooling cycle and the change in DC resistance value (TCR) was found to be less than 1%for each 100◦C rise in temperature
