Thermodynamic analysis on the codeposition of SiC-Si₃N ₄ composite ceramics by chemical vapor deposition using SiCl ₄-NH₃-CH₄-H₂-Ar mixture gases

A thermodynamic calculation on the chemical vapor deposition of the SiCl₄-NH₃-CH₄-H₂-Ar system was performed using the FactSage thermochemical software databases. Predominant condensed phases at equilibrium were SiC, Si₃N₄, graphite, and Si. The equilibrium conditions for the deposition of condensed phases in this system were determined as a function of the deposition temperature, dilution ratio (δ), and reactant ratios of CH₄/SiCl₄ and NH₃/SiCl₄. The CVD phase diagrams were used to understand the reactions occurring during the formation of Si-C-N from the gas species and determine the area of SiC-Si₃N₄. The concentration of condensed-phase products was used to determine the deposition conditions of CVD SiC-Si₃N₄. The present work was helpful for further experimental investigation on CVD Si-C-N.