Fabrication and microstructure control of electrically conductive AlN with rare-earth oxycarbide grain boundary phase

Abstract

Usually, in the system of AlN with Y2O3 additive, first of all, yttrium aluminate is produced as a grain boundary phase. And, by further heat treatment in nitrogen-reducing atmosphere, it is found that yttrium aluminate at grain boundary is transformed into yttrium oxycarbide from the surface. As a result, fortunately, we found AlN containing yttrium oxycarbide as a grain boundary phase showed electrical conductivity. The purpose of this study is to fabricate electrically conductive AlN ceramics with high thermal conductivity, and to control the electrical conductivity by addition of a small amount of CeO2, which promotes diffusion of carbon into grain boundary phase. In this presentation, we will report the effect of sintering conditions on grain size of electrically conductive AlN ceramics.