Enhancing the microstructure of DC flash-sintered high-purity Al2O3 ceramics by stepwise increase in current density

A refined control scheme for the current density was implemented to optimize the microstructure of DC flash-sintered high-purity Al 2 O 3 ceramic discs. Compared with conventional DC flash-sintering, which induced a pronounced microstructural gradient along the electric field direction, the introduction of a stepwise increase in current density resulted in higher relative density, finer grains, more uniform microstructure, and increased hardness. The improved homogeneity in the microstructure led to consistent hardness across both sides of the flash-sintered discs. These findings demonstrate that refined control of the current density holds significant potential for tailoring the microstructure and mechanical properties of DC flash-sintered Al 2 O 3 ceramics.