Densification and Thermal Conductivity of Y{sub}2O{sub}3-doped AlN Ceramics by Spark Plasma Sintering

摘要

AlN ceramics doped with yttrium oxide (Y{sub}2O{sub}3) as the sintering additive were prepared via the spark plasma sintering (SPS) technique. The sintering behaviors and densification mechanism were mainly investigated. The results showed that Y{sub}2O{sub}3 addition could promote the AlN densification. Y{sub}2O{sub}3-doped AlN samples could be densified at low temperatures of 1600-1700°C in 20-25 minutes. The AlN samples were characterized with homogeneous microstructure. The Y-Al-O compounds were created on the grain boundaries due to the reactions between Y{sub}2O{sub}3 and Al{sub}2O{sub}3 on AlN particle surface. With increasing the sintering temperature, AlN grains grew up, and the location of grain boundaries as well as the phase compositions changed. The Y/Al ratio in the aluminates increased, from Y{sub}3Al{sub}5O{sub}12 to YAlO{sub}3 and to Y{sub}4Al{sub}2O{sub}9. High-density, the growth of AlN grains and the homogenous dispersion of boundary phase were helpful to improve the thermal conductivity of AlN ceramics. The thermal conductivity of 122Wm{sup}(-1)K{sup}(-1) for the 4.0 mass%Y{sub}2O{sub}3-doped AlN sample was reached.