Evolution of microstructure and radiative property of metal silicide–glass hybrid coating for fibrous ZrO₂ ceramic during high temperature oxidizing atmosphere

To develop a high emissivity, high-temperature-resistant coating for a reusable thermal protection system, a metal silicide–glass hybrid coating was prepared on fibrous ZrO₂ ceramic by rapid sintering method, which comprises a Ta–Si–O glass layer and a dense MoSi₂–TaSi₂–glass layer and exhibits improved oxidation behavior at 1773 K in air for 50 h. During oxidation, the total emissivity in 0.3–2.5 μm slightly fluctuates around 0.9 without obvious degradation. The emissive mechanism was identified as electron transition in interband of metal silicides and in impurity states of amorphous SiO₂ and lattice vibration of crystalline SiO₂.