Hyperthermal erosion of thermal protection nanocomposites under atomic oxygen and N2 bombardment

초록

Against the hyperthermal atomic oxygen (AO) bombardment, mitigation of the surface recession has been the main issue in designing surface shielding materials in low earth orbital (LEO) environment. Meanwhile, the role of nitrogen molecules (N2) in LEO and sub-LEO on disintegration of the shielding materials has rarely been studied despite their abundance and non-negligible colliding energy. This study for the first time compared the surface chemistry and disintegration of Kapton polyimide-based nanocomposites under AO and N2 bombardment conditions using a reactive molecular dynamics (MD) simulation. The heat transfer from the surface to the behind layer and the associated boundary condition for the bombardment simulation were primarily discussed to provide the optimum bombardment simulation setup. Polyhedral oligomeric silsesquioxane (POSS), carbon nanotube (CNT) and graphene were respectively blended with Kapton to evaluate the damage mitigation efficacy. The addition of all types of additives to Kapton induced a notable thermo-protection effect. AO bombardment resulted in a sequential disintegration of oxidation and desorption, whereas the surface recession of nanocomposites by exposure to N2 collision was mainly caused by physical desorption. It was also noteworthy that the surface recession caused by N2 bombardment was comparable to that by AO attack at the same fluence. © 2022

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