High-Temperature Space-Stable Selective Solar Absorber Coatings

There are several uses in space for high-temperature coatings which selectively absorb solar energy but do not radiate much infrared energy. The most successful method of preparing highly efficient solar absorbers is to evaporate multilayer optical coatings on highly reflective substrates. These multilayer coatings consist of semitransparent metal films between nominally one quarter-wave thick dielectric spacer layers. Four such coating systems with 540°C space-stable properties ranging from a solar absorptance of 85% and emittance of 6% to a solar absorptance of 91% and emittance of 16% are presented.