Improved oxidation resistance of high emissivity coatings for reusable space systems

Improved oxidation resistance of high emissivity coating s on fibrous ceramic for reusable space systems

Here novel disilicides were explored for use in heat shields. 

WSi2 and MoSi2 were applied as coatings on an insulating zirconia substrate.

The high emissivity of these compounds and their mixtures, makes them very attractive for use in spacecraft.

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Abstract

To develop high emissivity coatings on fibrous ceramic substrates with improved thermal resistance for reusable space systems, WSi2–MoSi2–Si–SiB6-borosilicate glass coatings were prepared on fibrous ZrO2 by slurry dipping and subsequent high temperature rapid sintering. A coating with 20 wt% WSi2 and 50 wt% MoSi2 presents optimal thermal stability with only 10.06 mg/cm2 mass loss and 4.0% emissivity decrease in the wavelength regime 1.27–1.73 μm after 50 h oxidation at 1773 K. The advantages of double phase metal-silicide coatings combining WSi2 and MoSi2 include improved thermal compatibility with the substrate and an enhanced glass-mediated self-healing ability.