Flash grain welding in yttria stabilized zirconia

Self-standing samples made of isostatically pressed powders of ZrO2:8 mol% Y2O3 were submitted to AC signals of 60 and 1000 Hz. At temperatures of around 900 °C, a current density exceeding approximately 100 mA/cm2 starts an avalanche process with a fast increasing current under constant voltage. It lasts about 60 s and it is preceded by an induction period of the order of 30 s. After that, the material is sintered as confirmed by impedance diagrams. Relative densities of 94% could be obtained.