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

The effect of CaCN2 addition on the densification and structural developmen t for sintered AIN ceramics was investigated by Xray diffraction (XRD), sca nning 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.% CaCN2, additives were obtained depending on sinte ring temperature and time. When added with CaCN2 from 0.50 to 3.0 wt.% and sintered at 1650-1800 degreesC, all of the sintered samples exclusively bel onged to the same AIN phase and no other phases were found in the XRD patte rns. A large fraction of intergranular fractures was found in the SEM obser vations of the AIN samples sintered without and with CaCN2 additive. The ch aracterization of the AIN powders sintered with CaCN2 additive was performe d with a microstructural analysis using TEM and ED. In the TEM and ED patte rn, the minor phase, 3CaO . Al2O3, appeared around the AIN grain boundaries . (C) 2001 Elsevier Science Ltd. All rights reserved.