The oxidation behavior of multi-layered SiC coated graphite in water vapor containing environment

In this study, an investigation was conducted on the oxidation behavior of multi-layered SiC coated graphite spheres at 1673 K in H2O/Helium gas mixtures with water vapor at a concentration of 5–100 g/m3 under atmospheric pressure. In the 3D X-ray nondestructive test, carbon agglomeration was identified on the as-prepared multi-layered SiC coating. The multi-layered porous SiC coating lower than 0.16% was found to ensure that the graphite spheres would not fail for at least 10 h when oxidized under water-gas mixing conditions of 1673 K. After oxidation for 10 h, a layer of amorphous SiO2 was formed. In the subsequent oxidation, no amorphous SiO2 was transformed to the cristobalite phase. Excessive moisture was found to inhibit SiO2 from being crystallized. Furthermore, water vapor concentration was found to be critical to the oxidation morphology of the coating. •The oxidation behavior of multi-layered SiC coated graphite spheres at 1673 K in H2O/Helium gas mixtures was studied.•The multi-layered SiC coating was found to ensure that the graphite spheres would not fail for at least 10 h.•After oxidation, a layer of amorphous SiO2 was formed and no amorphous SiO2 was transformed to the cristobalite phase.•Excessive moisture was found to inhibit SiO2 from being crystallized.