Review of surface pretreatments for aluminium alloys

The pretreatment of aluminium to enhance adhesion has been the subject of a very large amount of research. In this review, 41 mechanical, chemical, electro chemical or other treatments specifically designed to modify the surface of aluminium to enhance bond durability have been identified. 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. Furthermore, a diverse range of surface analytical techniques have also been identified, these range from simple wettability or optical inspection methods to more complex and costly ultra high vacuum based techniques, for example, AES and XPS/ESCA. These techniques provide useful data in adhesion studies, for example, in studying surface chemistry and topography before and after treatment, or, in failure analysis. An indication is given, wherever possible, as to how the treatments perform in comparative durability trials.