D. Susac

Some observations for effects of copper on zinc phosphate conversion coatings on aluminum surfaces

Abstract X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical measurements have been used to characterize zinc phosphate (ZPO) conversion coatings, formed on high-purity aluminum surfaces, after dipping in coating baths containing different concentrations of Cu2+ up to 50 ppm. Significant variations in the morphology, adhesion and corrosion protection afforded by the ZPO coatings are especially observed as the Cu2+ in the bath varies from 0 to 10 ppm. Comparisons are made with the effects of surface Cu segregation on ZPO coatings formed in a previous study made on Al-2024-T3 alloy.

XPS study of interfaces in a two-layer light-emitting diode made from PPV and Nafion with ionically exchanged Ru(bpy)32+

Abstract X-ray photoelectron spectroscopy (XPS) was used to investigate the interfacial chemistries occurring in a prototype two-layer polymer light-emitting diode that had been fabricated from PPV and Nafion with ion-exchanged Ru(bpy) 3 2+ . Magnesium and indium tin oxide (ITO) were used as electrodes, and XPS observations were made as the different layers were added sequentially. Specifically, Mg was deposited on a layer of Nafion with incorporated Ru(bpy) 3 2+ , and this was itself deposited on PPV-coated ITO. The morphology of Nafion, which is dictated by the strongly hydrophilic and hydrophobic groups that compose it, is indicated to rearrange with the incorporation of Ru(bpy) 3 2+ ; this rearrangement appears reinforced when a thin film is deposited on PPV. The Mg deposition results in substantial changes in XPS spectra, in part due to a direct interaction with the fluorocarbon backbone of Nafion.

Surface Science Studies of the Effect of Mn2+ on Zinc Phosphating of 2024-T3 Al Alloy

The present work is part of a broader investigation of the effects of additives in zinc phosphate (ZPO) coating solutions that are designed for specific applications to Al and its alloys. ZPO conversion coatings improve the corrosion resistance of the Al substrate and increase the adhesion of paint. Coatings formed on 2024-T3 aluminum alloy, after dipping in ZPO coating baths containing Mn2+, have been studied by X-ray photoelectron spectroscopy (XPS), SEM, and scanning Auger microscopy (SAM). Variations are observed in coating morphology and composition as the amount of Mn2+ in the coating solution increases through the 0 to 2500 ppm range. Adhesion tests give information on the relative strength of the coating-substrate interaction at different microstructural areas.

Surface Science Studies of the Effect of Al Alloy Microstructure on the Formation of Chromate Coatings

Surface science methods including scanning Auger microscopy (SAM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy have been used to study the initial growth of chromate conversion coatings on aluminum 2024-T3 alloy, using a coating bath formed by dissolving CrO3, Na2Cr2O7 and NaF in water. The objective is to learn more about growth mechanism on the different microstructural regions of this alloy surface, including the second-phase particles and the alloy matrix.