Understanding AlN sintering through computational thermodynamics combined with experimental investigation

Liquid-phase sintering of AlN with Y2O3 as an additive has been studied and compared with the thermodynamic results. Sintering was performed in the temperature range of 1750-1950 °C for upto 4 h under a N2 atmosphere to optimise the sintering conditions for each composition. The relative density exceeded 95% for all the compositions sintered at 1850 °C and full densification was achieved for all four compositions sintered at 1900 °C. The microstructure and assemblage of the secondary phase have a significant effect on the final thermal conductivity of the sintered AlN. Thermodynamic modelling of AlN-Al2O3-Y2O3 system provided an important basis for understanding the sintering behaviour and interpreting the experimental results.