Microcrack healing in zirconia ceramics under a DC electric field/current. Issue 16 (December 2021) - Morita, Koji
Highlights: In this study, flash event caused by a DC electric field/current was applied to the crack healing in 8mol% Y2 O3 stabilized cubic ZrO2 polycrystals (8Y-CSZ). Up to now, the flash event has been examined in superplastic deformation, joining and material synthesis processes in addition to the sintering. This study shows for the first time that the flash event has a potential to apply to the crack healing process in the ceramics. As compared to the healing treatment under static annealing, the crack healing phenomena under the flash treatment were accelerated about 2 times even at the same temperatures, suggesting that the enhanced healing phenomena cannot be explained only by the temperature effect. Since the rate of grain growth was accelerated under the flash treatment, the flash healing would be accelerated through the current-enhanced diffusional processes. Abstract: Flash event caused by a DC electric field/current was applied to the crack healing in 8 mol % Y2 O3 stabilized cubic ZrO2 polycrystals (8Y-CSZ). The flash event, which occurred by applying the DC power higher than a critical value of 100 mW/mm 3, successfully healed the microcrack within several minutes without any healing agents at a furnace temperature of 800 °C. As compared to the healing treatment under static annealing, the healing phenomena were accelerated about 2 times under the flash treatment even at the same temperatures, suggesting that the enhanced healing phenomena cannot be explained only by the temperature effect. Since the rate of grain growth was accelerated under the flash treatment, the flash healing would be accelerated through the current-enhanced diffusional processes. This study shows for the first time that the flash event has a potential to apply to the crack healing process in the ceramic materials and composites.