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 TaSiO 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.