The effect of humidity on the adhesion behavior of AC anodised aluminium

Abstract

The effect of humidity on the surface forces of hot AC anodised AA6060 alloy was studied. The surface adhesion forces were measured in various humidity environments using an atomic force microscope (AFM). The environmental durability of the joints bonded at different humidity conditions was investigated using wedge test experiments. The results from AFM and durability tests indicate that there is a strong capillary effect at around 70-80% relative humidity. This effect was attributed to the change in the adsorption behavior of water on the anodised oxide surface forming bulk liquid and hence dissociating the bonds across the interface. At the lower humidity levels below 60% RH, no capillary effect was observed and the total adhesion forces followed the dry case values. (C) Koninklijke Brill NV, Leiden, 2008.