Evidence of surface cleaning during electric field assisted sintering

The cleaning of nanoparticles from surface oxides or contaminants is critical during the initial stages of spark plasma sintering (SPS). However, so far only indirect evidence has suggested the occurrence of surface cleaning. In situ transmission electron microscopy was used to replicate the processing conditions during SPS to directly observe surface cleaning. Dielectric breakdown was discovered to lead to surface cleaning. Electrothermal depletion of surface oxides is obtained through defect formation, electron trapping and local field enhancement.