Abstract
Assembling of thermodynamic databases requires the development of consistent analytical descriptions of the functions of states for all phases of the treated system. To provide high-quality data sets the Gibbs energy functions are assessed by computer supported optimisation of phase diagrams using all experimental data available in the literature as well as own experiments. The unary, binary and ternary system descriptions are combined in order to extrapolate to higher-component systems. The CALPHAD method (CALculation of PHAse Diagrams) and the phase modelling is described with special emphasis on ceramic solution phases. The method is illustrated by the thermodynamic assessment of the B-C-N-Si-O system. The results are compared with experimental data.
