Thermal Optical Properties of Plasma-Sprayed Mullite Coatings for Space Launch Vehicles

Thermal optical properties, for example, solar absorptance a and thermal emittance a of thin plasma sprayed mullite coatings, were determined to assess the material's suitability for space application. The mullite coatings were developed in an attempt to find a new material for thermal protection systems as well as thermal barrier coatings for atmospheric reentry vehicles. All mullite coatings show the properties of a solar reflector and hence suggest a potential application as thermal control coating to protect space-bound structures from the effect of heating by solar radiation in the low Earth orbit. Preliminary space stability tests including atomic-oxygen resistance tests confirmed that the coatings show only negligible variations both in their mechanical and thermal optical properties under the conditions selected.