Temperature dependence of thermal energy reflection in layered oxide ceramic for thermal energy window coating

The thermal radiation energy of reflection and transmission properties of all-oxide layered thermal energy window coatings at temperatures up to 1273 K has been studied and four-layered Al2O3–ZrO2 and two-layered Al2O3–TiO2 coated sapphire substrates fabricated. The thicknesses of individual layers were in the range of 300–600 nm, where the interference effect was determined to appear. Light reflection spectrum at the wavelength region from 2.2 to 10 μm was measured from room temperature to 1273 K. The oscillation behavior of light reflection, which originates from the interference effect of the layered structure, appeared in the reflection spectra. This behavior in both coating systems is maintained up to 1273 K and the reflectance values remain nearly the same as those measured at room temperature. Retention of the oscillation behavior up to 1273 K indicates the possibility of controlling the thermal radiation energy in a high temperature environment using the oxide-layered coating.