Thermodynamic Analysis on the Codeposition of SiC-Si_3N_4 Composite Ceramics by Chemical Vapor Deposition using SiCI_4-NH_3-CH_4-H_2-Ar Mixture Gases

摘要

A thermodynamic calculation on the chemical vapor deposition of the SiCI_4-NH_3-CH_4-H_2-Ar system was performed using the FactSage thermochemical software databases. Predominant condensed phases at equilibrium were SiC, Si_3N_4, 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 (8), and reactant ratios of CH_4/SiCl_4 and NH_3/SiCl_4. 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-Si_3N_4. The concentration of condensed-phase products was used to determine the deposition conditions of CVD SiC-Si_3N_4. The present work was helpful for further experimental investigation on CVD Si-C-N.