High-pressure Sintering and Microstructure Development of Aluminum Nitride Ceramics with Y2O3 as a Aintering Aid

High-density AlN ceramics were prepared without sintering additives by high-pressure sintering at 5.0 GPa and differente temperatures. The characterization of the sintered bodies was determined by XRD, SEM and micro-Raman spectroscopy (MRS). Compared conventional liquid-phase sintering, the sintering temperature was effectively lowered and the sitering time was shortened under high pressure. Controlling fracture mode was intraguanular when the sintering temperature was as low as 1400 °C under 5.0 GPa. The microstructure of single-phase equiaxed polycrystal in AlN body materials formed at 1800°C and 5.0 GPa for 50 min. There are Residual compression stress in AlN bodies prepared by high-pressure and residual compression stress of the AlN ceramics sintered at 5.0 GPa and 1700 °C for 125 min is -2.0 GPa.