Effect of AlN content on properties of hot-press sintered Sialon ceramics

This article concerns a hot-press sintered Sialon ceramic using Si3N4 and AlN as raw materials, Y2O3 and La2O3 as additives. The influences of AlN adding amount (5~30 wt.%) on the sintered densification, phase compositions and microstructures are discussed. Results showed that the β-Sialon ceramic could be obtained by hot-press sintering of 95~80 wt.% Si3N4, 5~20 wt.% AlN and extra 5 wt% Y2O3-La2O3 additives, while the excess of 25 wt.% AlN would lead to the transformation from β-Sialon to α-phase. The relationships of AlN contents with bending strength and thermal conductivity of the sintered composites were also involved in the study. For the composition of 80 wt.%Si3N4-20 wt.%AlN, the sintered sample showed the fracture strength of 408 MPa and the highest thermal conductivity of 34 W/(m·K) which is 44.7% higher than that of the sample at an adding AlN content of 5 wt.%.