A Combined Thermodynamic/Kinetic Modeling Approach to Predict SiC Recession Due to SiO2 Scale Volatility Under Combustion Environments

Abstract

A computational approach, which targets on the prediction of SiC recession caused by SiO2 scale volatility under combustion environments, was developed in this study. In this approach, thermodynamic calculation was integrated with a gaseous-diffusion model to calculate the fluxes of volatile species, such as SiO(g), Si(OH)4(g), SiO(OH)2(g), and SiO(OH)(g), produced by the reaction of SiO2 scale with the combustion air. The resulted weight loss of SiC was then calculated under a variety of combustion environments. The benefit of using environmental barrier coating (EBC) in the protection of SiC from recession was demonstrated by the calculation. It is shown that the weight loss of SiC-based ceramics could be significantly reduced when EBCs, such as mullite (Al6Si2O13 or written as 3Al2O3·2SiO2) or SrAS2 (SrO·Al2O3·2SiO2), are used. The effects of combustion conditions, such as temperature and total pressure, on the volatility of SiO2 scale were also discussed.