Nanophase semi-conductive ceramics: dielectric surface performance when exposed to charges

A nanophase composite that is a mix of a ceramic part and a metallic part was prepared by compacting agglomerated nanocrystals of each constituent, the ceramic and the metal. Considering the low Cu content, the resulting cermet was only mildly conductive at room temperature. An experiment was conceived to differentiate the dielectric performance of the nanophase semi-conductive ceramic from its counterpart, for which more extensive sintering had produced crystalline growth. It was found that the dielectric properties of the cermet differed based on the processing conditions. The solid-state sintered cermet still exhibited a microstructure with nanometric grains that was determinant in limiting the bulk and surface conductivity. In turn, the liquid-sintered cermet with its microstructure showing large grains was found to be a more conductive material. This difference in properties was illustrated by imaging charge accumulation and static breakdown at an interface cermet/epoxy.