MICROSTRUCTURE OF LOW-TEMPERATURE SINTERED ALN

A transient liquid-phase sintering process was applied to fabricate AW ceramics, using Dy2O3, Li2O and CaO as additives. Li2O is important i n forming liquid phase but volatile at high temperature. When Li2O was removed, the liquid volume diminished and then finally crystallized, resulting in powerful joint between AlN grains. According to the micro structural observations, the dominant transport progress during sinter ing was solution-precipitation when liquid phase existed. The 1650 deg rees C sintered specimens took an intragranular fracture mode rather t han an intergranular one which happened in 1550 degrees C sintered sam ples. (C) 1998 Elsevier Science B.V. All rights reserved.