Surface Contamination on LDEF Exposed Materials
Abstract
X-ray photoelectron spectroscopy (XPS) has been used to study the surface composition and chemistry of Long Duration Exposure Facility (LDEF) exposed materials. In each set of samples, silicones were the major contributors to the molecular film accumulated on the LDEF exposed surfaces. All surfaces analyzed have been contaminated with Si, 0, and C; most have low levels (<l atom%) of N, S, and F. The contaminant overlayer is thought to be patchy, with significant areas covered by less than 100 A of molecular film. For most materials analyzed, Si contamination levels were higher on the leading-edge surfaces than on the trailing-edge surfaces. It is probable that the return flux associated with atmospheric backscatter resulted in enhanced deposition of silicones and other contaminants on the leading-edge flight surfaces relative to the trailing edge. XPS analyses, however, did not conclusively show different relative total thicknesses of flight-deposited contamination for leading- and trailing-edge surfaces. Unlike other materials, exposed polymers, such as Kapton and FEP-type Teflon, had very low contamination on the leading-edge surfaces. SEM evidence showed that undercutting of the contaminant overlayer and damaged polymer layers occurred during atomic oxygen erosion, which would enhance loss of material from the exposed surface. LDEF, Contamination, XPS.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 15, 1992
- Accession Number
- ADA279963
Entities
People
- Carol S. Hemminger
Organizations
- The Aerospace Corporation