In situ surface studies of conversion coatings for steel and aluminum. Final report, 15 April 1989-14 September 1992

Technical Report · Tue Nov 10 04:00:00 EST 1992

OSTI ID:6519683

White, H W; Mansfeld, F; Bryant, P

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

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ADHESION
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
CHEMISTRY
COATINGS
CORROSION PROTECTION
CORROSION RESISTANCE
ELECTROCHEMISTRY
ESTERS
EVALUATION
FILMS
IRON ALLOYS
IRON BASE ALLOYS
LASER SPECTROSCOPY
MORPHOLOGY
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
POLYACRYLATES
POLYMERS
POLYVINYLS
PROTECTIVE COATINGS
RAMAN SPECTROSCOPY
RARE EARTH COMPOUNDS
RESEARCH PROGRAMS
SPECTROSCOPY
STEELS
ZINC COMPOUNDS
ZINC PHOSPHATES