Thermodynamic reassessment of the Si3N4-AlN-Al2O3-SiO2 system-Modeling of the SiAlON and liquid phases

The technically important quasi-ternary section Si3N4-AlN-Al2O3-SiO2 of the Si-Al-O-N system has been thermodynamically reassessed. Improved descriptions for the Gibbs energies of the β- and O′-sialon phases are applied. Different modelings according to the different behaviors of the reciprocal system within the β-sialon phase are discussed. The liquid phase is modeled with a new formula based on the ionic two-sublattice model. The thermodynamic properties of the sialon phases are discussed and various phase diagrams are presented. The self-consistent thermodynamic dataset is useful for the computer simulation of sialon synthesis. Some examples of such applications are illustrated.