Ellipsometric study of oxide films formed on LDEF metal samples. Final report
The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the long duration exposure facility (LDEF) have been studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, N Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000. The 410 A thick film Of Al203 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin nonporous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.
- Research Organization:
- Army Materials Research Agency, Watertown, MA (United States). Materials Technology Lab.
- OSTI ID:
- 5028625
- Report Number(s):
- AD-A-249856/6/XAB; MTL-TR-92-2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COPPER
OXIDATION
NICKEL
TANTALUM
ZIRCONIUM
AIR
ALUMINIUM OXIDES
COATINGS
COPPER OXIDES
DEPOSITION
ELLIPSOMETRY
FILMS
LEAST SQUARE FIT
METALS
OXIDES
RODS
SPACE
SUBSTRATES
SURFACES
THICKNESS
TUNGSTEN
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COPPER COMPOUNDS
DIMENSIONS
ELEMENTS
FLUIDS
GASES
MAXIMUM-LIKELIHOOD FIT
MEASURING METHODS
NUMERICAL SOLUTION
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion