REVIEW OF SURFACE PRETREATMENTS FOR ALUMINUM-ALLOYS

The pretreatment of aluminium to enhance adhesion has been the subject of a very large amount of research. In this review, 41 mechanical, ch emical, electro chemical or other treatments specifically designed to modify the surface of aluminium to enhance bond durability have been i dentified. These may be combined with a range of chemical ''add-ons'', such as primers, coupling agents or hydration inhibitors to stabilise the surface during storage or to further enhance bond durability. Fur thermore, a diverse range of surface analytical techniques have also b een identified, these range from simple wettability or optical inspect ion methods to more complex and costly ultra high vacuum based techniq ues, for example, AES and XPS/ESCA. These techniques provide useful da ta in adhesion studies, for example, in studying surface chemistry and topography before and after treatment, or, in failure analysis. An in dication is given, wherever possible, as to how the treatments perform in comparative durability trials.