Constant shrinkage rate control during a flash event for 8 mol %Y₂O₃-doped ZrO₂ polycrystals

抄録

The shrinkage rate during a flash event is controlled at a constant value by current ramping for 8 mol %Y₂O₃–ZrO₂ green compact with a rectangular shape. The green compact is heated at a constant heating rate of 5 °C/min until the occurrence of a flash event under a constant alternative current (AC) field of 50 V_rms/cm and 1000 Hz at a limit current of 100 mA_rms. After the flash event, current ramping is started to keep the shrinkage rate at a constant value of 120 µm/min. Current ramping is conducted by controlling the limit current using a programmable power supply operating in a current control mode. When the limit current reaches 1200 mA_rms, the sintering condition is kept as it is for 5 min, and the sintering process is completed. 8 mol %Y₂O₃–ZrO₂ sintered polycrystal with a relative density of approximately 99 % and a grain size of about 2.5 µm can be obtained at a furnace temperature of 870 °C for a current ramping and soaking regime of approximately 30 min.