Densification and Thermal Conductivity of Y_2O_3-doped AlN Ceramics by Spark Plasma Sintering

摘要

AlN ceramics doped with yttrium oxide (Y_2O_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_2O_3 addition could promote the AlN densification. Y_2O_3-doped AlN samples could be densified at low temperatures of 1600-1700℃ in 20-25 minutes. The AlN samples were characterized with homogeneous microstrueture. The Y-Al-O compounds were created on the grain boundaries due to the reactions between Y_2O_3 and Al_2O_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_3Al_5O_(12) to YAlO_3 and to Y_4Al_2O_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~(-1)K~(-1) for the 4.0 mass%Y_2O_3-doped AlN sample was reached.