Leveling coatings for reducing the atomic oxygen defect density in protected graphite fiber epoxy composites
Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept for enhancing the lifetime of materials in low Earth orbits is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center
- OSTI ID:
- 6925111
- Report Number(s):
- N-93-15344; NASA-TM--105732; E--7136; NAS--1.15:105732; CONF-9211170--; CNN: RTOP 506-41-41
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360601 -- Other Materials-- Preparation & Manufacture
360604* -- Materials-- Corrosion
Erosion
& Degradation
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
COATINGS
COMPOSITE MATERIALS
DEFECTS
DENSITY
DEPOSITION
ELECTRON MICROSCOPY
ELEMENTS
ENVIRONMENT
FIBERS
LIFETIME
MATERIALS
MATRIX MATERIALS
MICROSCOPY
NONMETALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASMA
POLYMERS
POPULATIONS
PROTECTIVE COATINGS
RADIATION EFFECTS
RESINS
SCANNING ELECTRON MICROSCOPY
SILICON COMPOUNDS
SILICON OXIDES
SPACE VEHICLE COMPONENTS
SURFACE COATING
SURFACE PROPERTIES
SURFACE TENSION
VISCOSITY