Cr-Al2O3 layered composites with a high electrical anisotropy prepared by repeated deformation processing

Two-phase layered composites were prepared by the repeated rolling and folding of paraffin-wax-based Cr-Al2O3 and Al2O3 suspensions at room temperature. The electrical resistivity of sintered samples was characterized in three mutually perpendicular directions. The ac resistivity of the material is governed by the position of the percolation threshold of this highly anisotropic system composed of an insulating Al2O3 matrix and Cr-Al2O3 conducting clusters. The resisitivity values differed by up to seven orders of magnitude between different directions, depending on the number of foldings and the mismatch in the plastic behavior of the starting suspensions. Above the percolation threshold the anisotropy in the resistivity strongly depends on the mismatch in the plastic behavior of the starting suspensions: it is small for a small mismatch and significantly larger for a large mismatch.