Effect of electric field strength stimulation on phase evolution in flash sintered hydroxyapatite at high-temperature range

Flash sintering (FS) is becoming a popular densification route for high-temperature oxide ceramics because of its rapid sintering performance. In the current study, bar-shaped hydroxyapatite (HA) specimens were hung between two Pt wire electrodes and consolidated by FS through a direct electric field at a constant furnace temperature (1000°C or 1100°C) in air. The electric field facilitated the sintering of HA at relatively lower furnace temperatures than that obtained using the conventional sintering method. The voltage required for the onset of the flash decreased with increasing furnace temperature. The effects of the DC electric field strength at different sintering furnace temperatures were examined in terms of the phase evolution and stability of HA. HA phase dissociation was not observed regardless of the electric field strength or furnace temperature because of the very short FS time. Higher grain growth with fast densification in the flashed-sintered HA samples occurred with increasing electric field strength at each furnace temperature.