On the kinetics of liquid-assisted densification during flash sintering of ceramic nanoparticles

Abstract

We analyzed the liquid-assisted densification kinetics of ceramic nanoparticles during flash sintering in terms of wetting and melt spreading, from the nanoparticle contacts, affected by the local electric field and capillary forces. Homologous wetting and spreading of the melt from the particle contacts reveal wetting velocities of ~0.3 10−6 m s−1 and ~1 m s−1 induced by the electric field and the capillary forces, respectively. The ultrafast densification kinetics by particle rearrangement is consistent with the enhanced diffusion and calculated wetting velocities. Epitaxial solidification of the melt after particle rearrangement is energetically favorable, and its tendency depends on the melt viscosity.