High-temperature oxidation behavior and mechanism of the Si-based thermal protective coating for SiCf/SiC composites under static oxidation and H2O/O2/Na2SO4 corrosion oxidation

The hot corrosion and oxidation of SiCf/SiC composites have become pivotal challenges in promoting their application in a heat field environment. This study presents an efficient approach for preparing multilayer oxidation/corrosion resistance coating via the sinter-preoxidation and chemical vapor deposition procedures. The results show that the coated SiCf/SiC composites exhibit stable thermal protective performance with a rather light mass change against static oxidation and H2O/O2/Na2SO4 corrosion oxidation at 1200–1400 °C for 600 h. All tested samples possess a high specific strength of more than 91.2% retention. Moreover, the kinetics and protection/failure mechanisms of the coated SiCf/SiC composites are analyzed that the relevance involves the liquid convection, volatilization of the solid–liquid reaction, H2O/O2/Na2SO4 corrosion, Kirkendall cracks and holes, thermal mismatch stress, and thermally grown oxide (TGO) growth. The heat transfer behavior in different heat fields is also investigated based on the finite element analysis (FEA).