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Atomic oxygen interactions with protected organic materials on the Long Duration Exposure Facility (LDEF)The Long Duration Exposure Facility (LDEF) has provided an excellent opportunity to understand the nature of directed atomic oxygen interactions with protected polymers and composites. Although there were relatively few samples of materials with protective coatings on their external surfaces on LDEF which were exposed to a high atomic oxygen fluence, analysis of such samples has enabled an examination of the shape of atomic oxygen undercut cavities at defect sites in the protective coatings. Samples of front-surface aluminized (Kapton) polyimide were inspected by scanning electron microscopy to identify and measure crack defects in the aluminum protective coatings. After chemical removal of the aluminum coating, measurements were also made of the width of the oxidized undercut cavities below the crack defects. The LDEF flight undercut cavity geometries were then compared with Monte Carlo computational model undercut cavity predictions. The comparison of the LDEF results and computational modeling indicates agreement in specific undercut cavity geometries for atomic oxygen reaction probabilities dependent upon the 0.68 to 3.0 power of the energy. However, no single energy dependency was adequate to replicate flight results over a variety of aluminum crack widths.
Document ID
19950017489
Document Type
Conference Paper
Authors
Banks, Bruce A. (NASA Lewis Research Center Cleveland, OH, United States)
Degroh, Kim K. (NASA Lewis Research Center Cleveland, OH, United States)
Bucholz, Justine L. (Ohio Aerospace Inst. Brook Park, OH., United States)
Cales, Michael R. (Cleveland State Univ. OH., United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1995
Publication Information
Publication: NASA. Langley Research Center, LDEF: 69 Months in Space. Third Post-Retrieval Symposium, Part 2
Subject Category
CHEMISTRY AND MATERIALS (GENERAL)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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