Minimization of Ice Adhesion to Space Shuttle Component Surfaces

The goals of this two-phase experimental program were to optimize the effectiveness of an icephobic coating for use on several Space Shuttle surfaces. Coating application with a foam brush provided consistent, controlled and reproducible surface coverage. Ice samples were grown slowly and consistently at -10 degrees C prior to cooling to a constant -112 degrees C temperature for cryogenic double lap shear testing. Phase 1 tests were focused on finding an optimal coating mix of Rain-X and varying weight fractions of PTFE powders MP-55 and UF-8TA. The MP-55 coatings produced large reductions in ice adhesion to aluminum coupons while the UF-8TA coatings were similar to uncoated controls. The M4 mixture with 40% MP-55 and 60% Rain-X gave the best and most consistent coating with outstanding performance and durability through five cycles of ice growth and adhesion failure. Phase 2 tests verified the effectiveness and durability of this coating over Koropon, Kapton tape, Kapton film and fire-retardant-paint surfaces on the shuttle and quantified the changes in effectiveness resulting from the addition of an ultraviolet light absorber (UVA). Solvent loss from Rain-X during prolonged mixing of the coating caused a greater increase in ice adhesion than that by adding the UVA. (C) Koninklijke Brill NV, Leiden, 2012