Alternating current field flash sintering 99% relative density ZnO ceramics at room temperature

Abstract

The required onset flash sintering temperature of a ZnO ceramic was decreased to as low as room temperature under an applied Alternating Current (AC) field of 3530 V/cm, and the ZnO ceramic achieved 99% of its theoretical density in 40 s without sintering aids. Due to electrical breakdown, flash sintering occurred once the AC field increased to 5 kV even with no increase in sample temperature and conductivity. Electrical breakdown happened at both edges of the sample, a phenomenon observed in thermal infrared images and confirmed by the simulation results. Electrical breakdown can be very useful in flash sintering even at room temperature.