Thermodynamic evaluation of the Al_2O_3-H_2O binary system at pressures up to 30 MPa

摘要

The behaviour of the hydrated phases in the Al_2O_3-H_2O system is of major importance in the chemistry of ceramic materials. In this work, stability and metastability relations in the Al_2O_3-H_2O system have been studied. Gibbs free energy functions of the gibbsite and boehmite phases have been critically revised and new optimized functions have been calculated. The functions obtained have been used to predict the stability and metastability relations by calculating a P-T diagram following the CALPHAD methodology. Comparison with the corresponding available experimental data is discussed.