Flash sintering of yttria-stabilized zirconia: Fundamental understanding and applications

Flash sintering has emerged as a promising opportunity for ceramic sintering, synthesis and processing. However, three basic questions about flash sintering remain unanswered: what triggers the flash during Stage I? what causes rapid densification during Stage II? How does the microstructure evolve during Stage III? In general, the mechanism of flash sintering is explained by Joule heating and non-equilibrium defect evolution. Herein, the recent findings and status of scientific understanding regarding the mechanism of flash sintering are critically reviewed by taking the example of yttria-stabilized zirconia. Moreover, the potential applications of flash sintering in ceramic synthesis and processing are presented.