Electrical performance of fine-grained Y-TZP/TiC composites obtained through a hydrothermal-assisted sol-gel process

Y2O3-stabilized tetragonal ZrO2 polycrystal (Y-TZP) composites with various TiC contents were successfully synthesized via a modified hydrothermal-assisted sol-gel method. Fine precursor powders can be obtained with high crystallinity, nanoscale grain size and uniform morphology. SEM images of the ceramic products show that TiC particles are distributed homogeneously in the final Y-TZP matrix, and their average grain sizes are approximately 390-670 nm and 150-230 nm for the Y-TZP and TiC phases, respectively. A higher TiC volume fraction has a negative effect on the relative density and hardness but a significant positive influence on electrical conductivity. The electrical conductivity values are increased from 115 S/m to 1.23 x 10(5)S/m with TiC contents varying, demonstrating that the percolation threshold is approximately as low as 11.6 vol% for the samples, which is much lower than those of previous Y-TZP/TiC ceramics. The high electrical performance is probably due to the high D (the diameters of the insulating particles)/d (the diameters of conducive particles) ratio and submicron-sized grains.