Effect of Initial Grain Size on Crack Healing Behavior under DC Electric Field of Zirconia (8Y-CSZ) Ceramic

The effect of initial grain size on the flash event was examined in microcrack healing behavior under DC electric field in fine- and coarse-grained 8 mol% Y2O3-stabilized cubic ZrO2 (8Y-CSZ) polycrystals. The healing behavior depends strongly on the initial grain size and is apparently accelerated in fine-grained 8Y-CSZ than in coarse-grained one. Since the crack healing under the flash event is higher than that of static annealing treatment without the electric field, the enhanced healing phenomena cannot be explained only by the thermal effect caused by Joule heating, but nonthermal effects caused by the flash event. The grain size-dependent healing behavior indicates that the grain boundaries play an important role in the flash event and the flash healing would be accelerated through the field/current-enhanced diffusional processes, especially through the grain boundary diffusivity of the cations.