SURFACE-ANALYSIS OF THIN-FILMS AND INTERFACES IN COMMERCIAL ALUMINUM PRODUCTS

Interfaces in commercial aluminium-based products like surface coated sheet and extrusions, laminates and metal matrix composites are of dec isive importance to the producer and customer as regards product perfo rmance and long term quality. The application of surface-sensitive tec hniques [x-ray photoelectron spectroscopy (XPS), secondary ion mass sp ectrometry (SIMS), secondary neutral mass spectrometry (SNMS), x-ray f luorescence spectroscopy (XRF), transmission electron microscopy (TEM) ] to study and control the composition and structure of oxide layers a nd conversion coatings, which become the interface in aluminium-polyme r products, is discussed. Quantitative evaluation of surface enrichmen t processes of alkali and earth alkaline metals during aluminium foil annealing allows the producer to establish quality relevant upper limi ts for the concentration of these impurity elements. Two further examp les are related to solid-liquid interfaces and cover the influence of oxide films on the etchability of high purity aluminium for electrolyt ic capacitors and the surface composition of aluminium-gallium (AlGa) alloys during alkaline etching with Ga surface enrichment having a lar ge influence on the electrochemical potential of this battery anode ma terial.