Densification and structural development in the sintering of AlN ceramics with CaCN2 additives

Abstract

The effect of CaCN 2 addition on the densification and structural development for sintered AlN ceramics was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron diffraction (ED). Dense sintered specimens (bulk density >3.16 g cm −3 ) with 0.5–3.0 wt.% CaCN 2 additives were obtained depending on sintering temperature and time. When added with CaCN 2 from 0.50 to 3.0 wt.% and sintered at 1650–1800°C, all of the sintered samples exclusively belonged to the same AlN phase and no other phases were found in the XRD patterns. A large fraction of intergranular fractures was found in the SEM observations of the AlN samples sintered without and with CaCN 2 additive. The characterization of the AlN powders sintered with CaCN 2 additive was performed with a microstructural analysis using TEM and ED. In the TEM and ED pattern, the minor phase, 3CaO·Al 2 O 3 , appeared around the AlN grain boundaries.