Preliminary investigation of hydroxyapatite microstructures prepared by flash sintering

Flash sintering is a novel and emerging route for sintering ceramics within a few seconds, even under pressure-less conditions. In the current study, hydroxyapatite (HA) was fully densified by flash sintering at a furnace temperature of 1020°C. Flash sintering with constant electric fields of 750 and 1000 V cm−1 reduced the grain growth rate significantly compared to that sintered in the absence of an electric field at 1400°C. The microstructure of HA consolidated by flash sintering was compared with that of the without electric field sintered samples. The flash-sintered samples showed smaller grains (160 ∼ 320 nm) than the without electric field sintered samples (∼15 µm). The samples with a higher applied electric field showed slightly better densification than those with the lower field by flash sintering. Overall, the electric flash reduces the sintering temperature effectively and decreases the holding time to densify highly insulating ceramics, such as HA.