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Reaction and Protection of Electrical Wire Insulators in Atomic-oxygen EnvironmentsAtomic-oxygen erosion on spacecraft in low Earth orbit is an issue which is becoming increasingly important because of the growing number of spacecraft that will fly in the orbits which have high concentrations of atomic oxygen. In this investigation, the atomic-oxygen durability of three types of electrical wire insulation (carbon-based, fluoropolymer, and polysiloxane elastomer) were evaluated. These insulation materials were exposed to thermal-energy atomic oxygen, which was obtained by RF excitation of air at a pressure of 11-20 Pa. The effects of atomic-oxygen exposure on insulation materials indicate that all carbon-based materials erode at about the same rate as polyamide Kapton and, therefore, are not atomic-oxygen durable. However, the durability of fluoropolymers needs to be evaluated on a case by case basis because the erosion rates of fluoropolymers vary widely. For example, experimental data suggest the formation of atomic fluorine during atomic-oxygen amorphous-fluorocarbon reactions. Dimethyl polysiloxanes (silicone) do not lose mass during atomic-oxygen exposure, but develop silica surfaces which are under tension and frequently crack as a result of loss of methyl groups. However, if the silicone sample surfaces were properly pretreated to provide a certain roughness, atomic oxygen exposure resulted in a sturdy, non-cracked atomic-oxygen durable SiO2 layer. Since the surface does not crack during such silicone-atomic oxygen reaction, the crack-induced contamination by silicone can be reduced or completely stopped. Therefore, with proper pretreatment, silicone can be either a wire insulation material or a coating on wire insulation materials to provide atomic-oxygen durability.
Document ID
19950010860
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hung, Ching-Cheh (NASA Lewis Research Center Cleveland, OH, United States)
Cantrell, Gidget (Cleveland State Univ. OH., United States)
Date Acquired
September 6, 2013
Publication Date
November 1, 1994
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
NASA-TM-106767
NAS 1.15:106767
E-9210
Report Number: NASA-TM-106767
Report Number: NAS 1.15:106767
Report Number: E-9210
Meeting Information
Meeting: AE-8D Wire and Cable Subcommittee Meeting
Location: Albuquerque, NM
Country: United States
Start Date: April 12, 1994
End Date: April 14, 1994
Accession Number
95N17275
Funding Number(s)
PROJECT: RTOP 506-41-41
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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