Property of Protection against Simultaneous Action\nbetween Atomic Oxygen Erosion and Ultraviolet Irradiation by MIL-53(Al)\nCoating

Rapid development\nof coatings with resistance to the space irradiation\nenvironment of low Earth orbit (LEO), which benefits long-duration\nexploration missions in LEO, improves the challenging urgency of revealing\nthe interaction between atomic oxygen (AO) erosion and ultraviolet\n(UV) irradiation. Here, we investigated the simultaneous action of\nAO erosion and UV irradiation using polyimide (PI) and MIL-53(Al)-coated\nPI, confirming a synergistic enhancement effect of 21.20 and 14.96%\ncompared to that of AO erosion alone. The resistance to simultaneous\naction was verified by a more stable chemical state and lower erosion\nyield (<i>E</i><sub>y</sub> = 4.386 × 10<sup>–25</sup> cm<sup>3</sup>/atom, 12% of pristine PI). Through first-principles\ncalculations, the resistance processes to AO erosion and UV irradiation\ninvolve the formation of inert oxides, maintaining an unchanged framework\nand widening the band gap due to microstructure transformation, respectively.\nBased on these, simultaneous action resistance was explained, in which\nthe boundaries between nanoparticle generation during UV irradiation\nprovided a pathway for AO erosion and probability for collision with\nthe framework to reduce the kinetic energy of AO. This work puts forward\nthe novel investigation of simultaneous action in LEO, confirms the\napplication potential of MIL-53(Al), and offers a new idea to protect\nthe spacecraft.