Incorporation of electrolyte by-products into barrier anodic Al/sub 2/O/sub 3/ coatings
We have observed that substantial amounts of electrolyte by-products are incorporated into barrier anodic Al/sub 2/O/sub 3/ coatings during deposition. The electrolyte used for the process studied consisted of a solution of ammonium tartrate and water which was diluted 1:40 with ethanol. The tartrate concentration in this electrolyte decreases as a function of the amount of aluminium anodized. Fourier transform infrared analysis indicates the coatings produced by this process contain substantial amounts of carboxylates. Auger electron spectroscopy, transmission electron spectroscopy, and other indirect evidence, e.g., Four Transform Infrared Spectroscopy, strongly suggest that the concentration of carboxylates increases with proximity to the outer surface of the coatings. Our results also indicate that these by-products play a substantial role in inhibiting the crystallization of amorphous material present in the coatings. The results of this study support the hypothesis that incorporated electrolyte by-products beneficially contribute to the dielectric properties of barrier anodic coatings. The depletion of tartrate ions from the electrolyte in conjunction with anodic film formation is accompanied by the appearance of acetate and formate. The concentration of these ions increase rapidly and are then depleted along with tartrate late in the bath life. This depletion of the anion species appears to define a practical limit to the area of aluminum which can be anodized in a given volume of the electrolyte without replenishment. 3 figures.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6447804
- Report Number(s):
- SAND-83-0435C; CONF-830443-1; ON: DE83009003
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101* -- Metals & Alloys-- Preparation & Fabrication
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
ACETATES
ALCOHOLS
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMMONIUM COMPOUNDS
ANODIZATION
AUGER ELECTRON SPECTROSCOPY
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHEMICAL COATING
CHEMISTRY
CORROSION PROTECTION
DATA
DEPOSITION
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELECTROCHEMICAL COATING
ELECTROCHEMISTRY
ELECTRODEPOSITION
ELECTROLYSIS
ELECTROLYTES
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ETHANOL
EXPERIMENTAL DATA
HYDROXY COMPOUNDS
INFORMATION
INFRARED SPECTRA
LYSIS
MICROSCOPY
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTRA
SPECTROSCOPY
SURFACE COATING
TARTRATES
TRANSMISSION ELECTRON MICROSCOPY