Novel approach of the evaluation of electric current density during the spark plasma sintering: Effect on the densification mechanisms of B4C-based ceramics

The densification mechanism of boron carbide is revealed by considering the effect of electromigration induced by electric current during spark plasma sintering (SPS). Different electric current values are obtained by choosing different heating rate, resulting in the different dislocation density as well as densification behavior. The apparent pressure-particle neck area relationship is applied to estimate the instantaneous electric current density, then a densification model was proposed which taking it into account. Higher electric current responds to lower dislocation density and lower apparent activation energy of the mechanism controlling densification. The densification mechanism exhibits a transformation from atom-diffusion-controlled creep deformation mechanism for low electric current to dislocation-glide-controlled mechanism for high electric current.

Automated summary

The densification mechanism of boron carbide is revealed by considering the effect of electromigration induced by electric current during spark plasma sintering (SPS). Different electric current values are obtained by choosing different heating rate, resulting in the different dislocation density as well as densification behavior. A densification model was proposed which taking into account the instantaneous electric current density, showing a transformation from atom-diffusion-controlled creep deformation mechanism for low electric current to dislocation-glide-controlled mechanism for high electric current.