Interface strength and degradation of adhesively bonded porous aluminum oxides

Abstract

Surface coating: interface strength and degradation Chromic acid anodizing has been the dominant electrochemical process used to create a thin aluminum oxide layer upon aluminum alloys. Such thin layers are critical to the corrosion protection of alloys that enable many of our daily expectations, including aerospace applications. However, such a chromic acid treatment is being forced to be soon phased out as a result of the associated environmental and health concerns. Now a team led by Arjan Mol from Delft University of Technology in the Netherlands, with co-workers from Denmark and Belgium, are working on alternative treatment processes and reveal the fundamental adhesion and degradation mechanism at the interface between the surface oxide and an accompanying resin. Aided by both imaging and spectroscopic characterization, this study provides fresh insights into the interplay between the anodizing conditions and the formation and durability of bond strength, showing that the morphology and chemistry of the surface oxide are the two factors that should be considered in the selection of chromium-free surface treatments.