Anodising as pretreatment of durable aluminum: the behaviour of several aluminum alloys to filiform corrosion

摘要

Aluminium alloys AA 3005, AA 3103 and AA 6063 were anodised in sulphuric acid under different conditions whereby a set of porous layers with varying thicknesses was produced. The influence of porous layer thickness on the filiform corrosion behaviour was examined by means of the Lockheed test. The filiform corrosion behaviour as a function of time was investigated. It appeared that the alloys showed similar filiform corrosion behaviour since for all alloys filiform corrosion was reduced considerably by increasing the porous layer thickness. The number of filaments N and the average filiform corroded surface R increase in time until a saturation level has been reached. However, the saturation level appeared to be different for each combination of alloy and porous layer thickness. The results indicate that the mechanism for filiform corrosion is the same for all three aluminium alloys.