Micro-Crack Healing in Cubic Zirconia (8Y-CSZ) Using Flash Event

Abstract

The e ff ect of the DC electric fi eld / current on the crack healing behavior was examined in 8mol ％ yttria – stabilized cubic zirconia ( 8Y – CSZ ) polycrystals. Microcracks formed in 8Y – CSZ using the micro Vickers technique was healed under the fl ash conditions at sample temperatures of 1040 ℃ and 1230 ℃ by controlling the DC electric fi eld / current. At high temperatures, releasing the external energies, which were stored by the indentation as the elastic / plastic strains and new crack surfaces, would be driving forces for the crack healing. Thus, the crack healing takes place some extent even for the static annealing without the DC electric fi eld / current and the healing length becomes larger in the cracks formed at the larger loads. As compared to the static annealing, the healing behavior was accelerated by several times under the fl ash event condition even at the same temperatures. This suggests that the accelerated healing behavior cannot be explained only by the thermal activated processes, but ascribed to non – thermal processes accelerated by the fl ash event. Since the grain growth behavior was accelerated under the fl ash condition, the fl ash event enhanced the healing behavior of the microcrack damages by accelerating the di ff usional processes.