Abstract
The effects of oxygen plasma treatments on the surface composition and wettability of cold-rolled aluminum foil have been examined using x-ray photoelectron spectroscopy (XPS or ESCA) and contact angle measurements. Results have shown that oxygen plasma treatments have two main effects on the surface composition of cold-rolled aluminum: (i) Residual carbon contamination is removed efficiently, and (ii) the thickness of the aluminum oxide surface layer is increased. The removal of residual carbon species via plasma treatments results in a significant improvement in the foil wettability. The wettability of plasma treated cold-rolled foil has been shown to be as good as, or better than, that of the best annealed foils. However, it was found that the wettability of plasma treated foils can degrade with time following treatment, which is apparently due to the adsorption of airborne carbon species and other contaminants. Oxygen plasma treatments also cause additional aluminum oxide to grow on the metal surface. The composition of this additional oxide is similar to that of the native passivation oxide. The thickness of the aluminum oxide layer has been shown to increase with both the plasma rf power and/or the plasma exposure time.
Published Version
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