Evaluation of plasma-deposited protective coatings for multipurpose space applications

Abstract

Summary This paper reports evaluations of protective thin films applied to important polymers used on spacecraft, Kapton® polyimide and graphite-epoxy, that are attacked by atomic oxygen. These films, derived from volatile compounds through microwave glow discharge deposition, include amorphous silicon (a-Si:H) and inorganic silicon compounds (P-SiN and P-SiO 2 ). These materials are shown to provide excellent protection against atomic oxygen attack, as evidenced by the reduction in mass loss compared to unprotected specimens of the same materials after exposure to an atomic oxygen beam source. Scanning electron microscope photomicrographs are presented to confirm the lack of apparent attack of the surface. Results from high-energy (20 keV) electron beam bombardment show that these coatings reduce charge build-up which might otherwise result in electrostatic discharge phenomena. These materials provide promising candidates for coatings for exterior surfaces of spacecraft to protect the underlying materials from the deleterious effects of the space environment.