Thermodynamic reassessments of the Ti-Si-C/Ti-Si-N systems and thermodynamic calculations of CVD TiSiCN hard-coating based on the Ti-Si-C-N quaternary system

The Ti-Si-C and Ti-Si-N systems were thermodynamically reassessed by using the CALculation of PHAse Diagram (CALPHAD) approach. A more suitable Gibbs energies expression of Ti3SiC2 was obtained to fit better with heat capacity data in the Ti-Si-C system. The thermodynamic parameters of the Ti-Si-N system were adjusted based on the revised Ti-Si system. A self-consistent thermodynamic database of the quaternary Ti-Si-C-N system was established. The calculated thermodynamic data and phase diagrams agree well with the experimental data. The CVD (Chemical Vapor Deposition) process for TiSiCN coatings was simulated using the newly evaluated thermodynamic parameters of the Ti-Si-C-N system. A good agreement between the predicted coating composition and the experimental ones was achieved, verifying the reliability of the thermodynamic database obtained in the present work.