Fabrication of Porous Tantalum and Tungsten Black Coatings for Artificial Earth Satellites

Abstract

Coatings are fabricated using plasma-ion sputtering and codeposition of ultradispersed Ta and Cd particles and Nb- and Mo-doped W and Cd particles. The fabricated coatings consist of a mixture of crystallized cadmium and the amorphized refractory metals. Subjecting the coatings to thermal annealing in vacuum at 800°C for 1 h results in complete evaporation of cadmium from the coatings and the formation of cellular structures, their light-absorbing capacity depending on doping with Nb and Mo. The Nb-doped tantalum coatings and Nb- and Mo-doped tungsten coatings exhibit the highest light absorption. The electrical resistance of fabricated black coatings is sufficient to drain static charge accumulating due to contact with near-Earth plasma.