Stability of plasma-sprayed coatings tested at White Sands Solar Facility

High solar intensity can have a detrimental effect on the absorptivity-emissivity ratio of coatings. Particle structural changes from sintering and crystal growth can be a significant factor which can result in erosion of the optical properties through changes in the surface morphology. Reactions with air can change the nature of the compounds on the surface. Plasma-sprayed coatings of erbium dodecaboride, yttrium hexaboride, and chromium oxide steel samples were heated in a resistance furnace at 800 degree C for 20 hr. Scanning electron micrographs of the specimens before and after heating were essentially identical. The coatings did not crack or flake off, and good adhesion was observed after the heat treatment.