Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space system

TL;DR

This study develops and evaluates WSi2-MoSi2 based high emissivity coatings on fibrous ZrO2, demonstrating improved oxidation resistance and thermal stability for reusable space system applications.

Contribution

Introduces a novel WSi2-MoSi2-silicate coating with enhanced thermal stability and self-healing properties for fibrous ceramic substrates in space systems.

Findings

Optimal coating with 50 wt% WSi2 and MoSi2 shows minimal mass loss after oxidation.

Coating maintains low emissivity decrease after 50 hours at 1773 K.

Double phase metal silicide coatings improve thermal compatibility and self-healing ability.

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 50 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 of 1.27 to 1.73 microns 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.