Rate of creation of the contacts between grains in a loose array of particles submitted to an uniaxial pressure

Macroscopic resistivity measurements have been performed on TiC/Al₂O₃ random mixtures submitted to uniaxial compression (0-95 kN). Such a random mixture exhibits an insulator-conductor transition which appears at increasing force while decreasing the conductive composition of the TiC/Al₂O₃ mixture. It is demonstrated that the conductivity behavior may be understood in the framework of a site percolation model. Finally, the rate of creation of the contacts between conductive grains is extracted from the macroscopic resistivity measurements. Received 6 December 2000 and Received in final form 30 March 2001