Thermodynamic study and syntheses of β-SiAlON ceramics

Based on the thermodynamic study of beta-SiAlON and one section of Si-Al-O-N phase diagram for Si/Al=9 at 1773 K, the pure beta-SiAlON (Si6-ZAlZOZN8-Z ceramics with different Z values (viz. 1.4, 1.8, 2.2, 2.6, 3.0) were synthesized at different temperatures using the pressure-less technique. The relationship of the experimental-saturated Z value (the maximum Z value at a constant temperature) with temperature was then discussed. The experimental results indicated that there is a good linear relationship between Z value and temperature, which is Z= -10.76+0.0071 T (R=0.9985). The beta-SiAlON stability regions at different temperatures were exhibited in a sketch phase diagram Of Si3N4-SiO2-Al2O3-AIN system. In addition, the relationship between experimental-saturated Z value and the lattice parameters was also characterized, and the linear regression results a=7.604+0.02872Z and c=2.908+0.02496Z were obtained, respectively.