Black zeolite coatings for stray light reduction and in-orbit molecular decontamination

Black zeolite coatings were developed for two major contaminations encountered by actors of the space field: in-orbit molecular contamination and stray light contamination. They both affect the performance of on-board equipment of satellites and especially optical devices. A silicone binder and FAU-type zeolite were combined together with different amounts of black pigment (bone char or carbon black) in order to develop various coatings. Binder content was fixed at 20 wt % for all black zeolite coatings after the drying procedure whereas zeolite contents varied from 50 to 75 wt % and from 60 to 79 wt % for coatings developed with bone char and carbon black, respectively. Amounts involved of bone char and carbon black ranged from 5 to 30 wt % and from 1 to 20 wt %, respectively. The aim of increasing black pigment amount was to improve light absorption properties of the coatings. Despite the addition of black pigment, interesting adhesion and cohesion properties were obtained. Total reflection measurements showed a clear improvement of light absorption properties by black coatings. Small amounts of black pigment especially with carbon black (1–5 wt %) were sufficient to increase light absorption compared to white zeolite coating. Nitrogen adsorption-desorption experiments showed a partial clogging of black zeolite coatings porosity from 20 to 25 wt %. Nevertheless, interesting results regarding n-hexane adsorption capacities where values varying from 100 to 130 mg/ganhydrous zeolite were determined. Black zeolite coatings developed in this study show a way to deal with the above-mentioned issues.