In situ surface studies of conversion coatings for steel and aluminum. Final report, 15 April 1989-14 September 1992
The primary goals of the work were to develop mechanisms of corrosion protection for cerium based surface layers on aluminum alloys and on polyacrylic acid (PAA) complexed zinc phosphate conversion coatings on steel. Atomic force microscopy (AFM) using tunnel current control was developed and applied to several problems. The cerium based coatings on AI 6061-T6 are shown to consist of two principle components--a poorly ordered monohydrated aluminum oxide, and an insoluble cerium oxide which forms at areas concentrated with impurities and alloying elements. Electrochemical action during the surface modification process fosters the precipitation of cerium compounds which inhibit further attack. The addition of high molecular weight PAA to the phosphating bath can significantly improve both resistance to corrosion and top-coat adherence of zinc phosphate conversion coatings on steel. Raman spectra showed the compositions of both unmodified and PAA modified films to be zinc phosphate dihydrate. Single crystallite surfaces were imaged using AFM. The morphologies of the unmodified and modified films were in general quite similar, but subtle differences were apparent. Several other projects involving surface layers and adsorbates were carried out and are described.
- Research Organization:
- Missouri Univ., Columbia, MO (United States)
- OSTI ID:
- 6519683
- Report Number(s):
- AD-A-261016/0/XAB; CNN: DAAL03-89-K-0084
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM ALLOYS
CORROSION PROTECTION
CERIUM COMPOUNDS
CORROSION RESISTANCE
PROTECTIVE COATINGS
EVALUATION
STEELS
ADHESION
ALUMINIUM OXIDES
CERIUM OXIDES
ELECTROCHEMISTRY
FILMS
MORPHOLOGY
POLYACRYLATES
RAMAN SPECTROSCOPY
RESEARCH PROGRAMS
ZINC PHOSPHATES
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMISTRY
COATINGS
ESTERS
IRON ALLOYS
IRON BASE ALLOYS
LASER SPECTROSCOPY
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
POLYMERS
POLYVINYLS
RARE EARTH COMPOUNDS
SPECTROSCOPY
ZINC COMPOUNDS
360105* - Metals & Alloys- Corrosion & Erosion