Opportunities for minimizing radiative heat transfer in future thermal and environmental barrier coatings

Abstract

The possibility of identifying new classes of oxides having lower thermal conductivity at high temperatures is unlikely as the values are approaching the theoretical minimum. At the same time, the drive for higher engine efficiency requires higher gas temperatures, increasing the radiative heat flux. The significance of radiative heat transfer in the selection of coating materials is examined. It is concluded that optically opaque materials will perform better as coatings under high convective flow conditions, such as on blades, by minimizing radiative heating through the coating. This can be achieved by a combination of atomic level doping and scattering.