Theoretical and experimental investigation of chemical vapor deposition of yttrium silicate

Abstract

Based on the minimum Gibbs free energy principle, thermodynamic calculations of the Y2O3–CH3SiCl3–CO2–H2-Ar system are carried out using FactSage software. Moreover, the influences of deposition temperature, total pressure, the H2 dilution ratio, and the molar ratio of reactants on thermodynamic phase diagrams and product yield diagrams of the Y2O3–CH3SiCl3–CO2–H2-Ar system have been systematically investigated. Subsequently, based on the calculation results, the X1-Y2SiO5 and β-Y2Si2O7 phases are successfully deposited at a lower deposition temperature of 1100 °C, system pressure of 2 kPa, CH3SiCl3 flow rate of 39 mL/min, H2 dilution ratio of 9, and n(CO2)/n(H2) ratio of 3:10. In addition, NMR results revealed the molecular structure of the as-deposited yttrium silicate coating, and scanning electron microscopy, which was used for morphological analysis, confirmed the dispersion of yttrium silicate particles in the SiC layer.