Analysis of plasma degreased aluminium foil with XPS

Residuals of lubricants adhere as very thin layers of hydrocarbons to the surfaces of cold rolled aluminium foil. Subsequent processing of the foil requires a cleaning process. In this study, a new approach to degrease the aluminium is examined that employs an atmospheric pressure plasma treatment of the surface. X-ray photoelectron spectroscopy is used to detect hydrocarbon layers on the surface of aluminium foil. The detected carbon content is a measure of the amount of residual lubricants remaining on the surface. Before any treatment, the proportion of carbon on the foil surface amounts to 19% corresponding to a lubricant layer thickness of 3-3 nm. Plasma degreasing reduces the carbon proportion to ~6% corresponding to a layer thickness of 1-3 nm. With conventional heating, there is a layer thickness of ~1 nm remaining on the foil surface. Still, the plasma degreasing is a less time and energy consuming cleaning process.