The mechanical properties of brittle ceramics are influenced strongly by small cracks formed through machining processes. In order to fully utilize mechanical performance of ceramics, the cracks should be healed before industrial applications. More recently, flash event, which occurs at elevated temperatures under large DC electric field, was reported to accelerate high temperature phenomena; Raj and his colleagues succeeded to reduce the sintering time/temperature of several ceramic powders.
We confirmed that the flash event can also accelerate the crack healing of 8mol% yttria-stabilized cubic zirconia (8Y-CSZ) polycrystals without any healing agents. Microcracks formed in 8Y-CSZ using the micro-Vickers technique was healed some extent even for the static annealing without the DC electric field/current. As compared to the static annealing, the healing behavior was accelerated by several times under the flash event 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 through the flash event. Since the grain growth behavior was accelerated under the flash condition, the flash event enhanced the healing behavior of the microcrack damage by accelerating the diffusional processes.